tupp
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I think that this ffmpeg command will create a new file that runs all the frames at 120fps without transcoding:
ffmpeg -r 120 -i original30fps_file.MOV 120fpsoutput_file.mov
If it doesn't transcode, it should make the 120fps copy quickly. Also, it would be easy to make a script based on this command that would batch convert a bunch of files.
Of course, you could always convert the frames to run at 120fps in an NLE.
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23 hours ago, noone said:
A 40mm 1.2 would give a close enough photo. but you could even use an existing Kipon 40mm f0.85 (a lens for both M43 and APSC formats) and keep the change!
That 40mm Kipon f0.85 is designed for APS-C, so it should be slightly closer in look to larger formats than a lens designed for M4/3. Also, as I have mentioned, cropping into a lenses image circle will change the look and make the image softer.
However, I found examples of that lens wide with a open aperture on an APS-C sensor. Although that lens is not an equivalent focal length to the lens of the 8"x10" image I linked earlier in this thread, it yields comparably shallow DOF, so it should give us a rough idea of how lenses for smaller formats behave in such shallow DOF scenarios. Here is one example.
Of course, the Kipon APS-C lens looks softer and more mushy wide open, with the 8"x10" lens exhibiting more resolving power and a crisp image. Also, the plane of focus with the 8"x10" lens seems more solid and well defined than that of the APS-C lens. The APS-C lens additionally suffers from chromatic aberration (remember, Caldwell confirmed that lenses for smaller formats are more prone to aberrations).
I think that these differences between these two lenses are common to most lenses made for lager and smaller formats, and that the such results will largely be consistent in any proper DOF/format comparisons that might follow.
On 9/20/2020 at 2:04 PM, noone said:Just found that interesting and I would love to see someone do a direct comparison (between an 8x10 camera anyone got a digital back that size with a 600mm f8 lens who also has M43 with a Kipon 40 f0.85? Great! I look forward to the tests).
I too would like to see a proper DOF/look comparison done between larger and smaller formats.
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14 hours ago, SteveV4D said:
This argument overlooks the use of speedboosters,
We haven't directly touched on speedboosters in this thread, but there have been other discussions about how speedboosters/focal reducers are involved in format looks.
14 hours ago, SteveV4D said:the fact that smaller sensors can via adapters use lenses designed for larger sensors and the issue that many fullframe lenses have crops for certain frame rates.. ie Panasonic for 60p.
The adapter/crop issue has been addressed in this thread.
14 hours ago, SteveV4D said:For me the visual qualities I require come with codec and colour science. Not sensor size.
The format looks in question do not involve sensor size, per se.
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17 hours ago, hyalinejim said:
On the contrary, the last few pages of discussion gets right to the heart of the question raised.
Exactly.
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18 hours ago, SteveV4D said:
None of it is even proving that fullframe is necessary. I could argue why shooting film is necessary and produces a look different to digital, but it still doesn't prove it necessary.
What makes a format necessary are what someone considers to be desirable qualities. We are discussing the desirable qualites of larger formats vs. smaller formats -- which involves FF.
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22 hours ago, noone said:
You think the tests get close enough but then when you see a(often very small) difference you attribute that to a difference between formats instead of between the optics.
No. You are mistaken. You need to more carefully read what I have said. I usually attribute differences in equivalency comparisons to failures of the testers.
22 hours ago, noone said:There is no reason you would get a difference in vignetting if you used identical formula lenses to match the crop (IE scaled).
It might be helpful for you to actually read what I wrote.
22 hours ago, noone said:I simply can NOT match my ancient 300 2.8 with M43 (other than the $35000 plus Arri 150 1.3) or my ancient 24 1.4 (because there are no 12mm m43 f0.7 lenses) or my ancient 85 1.2 (again, no 42.5mm f0.65 lenses which is approaching the limit in air). No high quality tilt shift lenses either like my favourite 17 f4.
How is this relevant?
By the way, if you use mirrorless cameras with shallow mounts, a tilt/shift adapter works with many lenses.
22 hours ago, noone said:If I could do what i can with m43 (or Pentax Q) what i can with FF, I would only be using that.
So, are you saying that larger formats have qualities that are lacking in smaller formats?
22 hours ago, noone said:A 600mm 8x10 f9 lens would be equivalent to about a 90mm 1.4 FF (so about a 45mm f0.7 M43).
600mm 8"x10" lens is more like an 80mm FF lens (or like a 40mm M4/3 lens).
22 hours ago, noone said:If you COULD get a lens to match it (it IS possible even if there are none) it would yield a very similar photo even without being the exact same lens design.
There are a few 80mm FF lenses.
There would likely be a difference between the look of two formats with such a narrow focal length and with the apertures set for a shallow DOF.
22 hours ago, noone said:If the lens was 600mm f8, then that would be almost impossible to match with m43 as that would be about a 90mm f 1.2 FF so you would need an aprox 45 f0.65 to even give a similar if not exact photo.
Well, that would actually qualify as a look inherent in a larger format that is impossible in a smaller format, wouldn't it?
23 hours ago, noone said:You have yet to show that there is ANY difference BECAUSE of the differences in sensor size and so far all difference have been because of the optics and not getting an exact match.
You really need to read what I wrote in regards to optics and sensor size.
The failure to get a match is usually due to tester mistakes. In addition, all of the testers so far were not actually testing DOF.
Incidentally, in regards to your earlier claim about it being impossible to get an exact match with two lenses that have the same focal length and that are designed for the same format, here is that very comparison by Shane Hurlbut. It looks like an exact DOF/focus match to me, but the exposure is slightly different (likely due to a difference in lens transmission). So, exact focus matches are possible.
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9 hours ago, noone said:
But if you use the same optics in different formats you get the same result...it is not the format that makes the difference it is the lenses.
Well, not exactly. If you use a S16 lens on a 4"x5" sensor, you will likely see substantial vignetting that won't appear with the same lens on a S16 sensor. The image inside the vignette probably will appear softer, as the pixels on the 4"x5" sensor are likely coarser.
Likewise, if one applies a S16 crop inside the image circle of a lens made for 4"x5", most of the lines of resolution will be thrown away, and the image will appear much softer (which can affect the appearance of the DOF) than using that same lens on a 4"x5" sensor.
9 hours ago, noone said:To get an exact match to satisfy everyone, You would need to firstly pick your cameras of different formats and get the EXACT crop factor. Next you need a lens for one format. You would need to know the actual focal length (not just the marked focal length),
That's not too difficult. Earlier in this thread, I picked the S16, M4/3 and 8"x10" formats, and I found several manufactured lenses for those formats that gave around a 98% match on the equivalence calculator that was linked earlier in this thread. That's a good start, and most of the other variables can be adjusted slightly without suffering invalid results.
In regards to knowing the exact focal length when it changes after focusing on the subject, as long as the focal lengths remain in a nominal range there really is no problem, as one can make adjust the aperture so that the results match more closely (as I have already explained in this thread).
9 hours ago, noone said:You would need the diameter and could then work out the exact f stop.
This is where you (along with the legions of equivalency testers that precede you) and I depart.
There is absolutely no need to stand on the formality of getting the numbers to exactly match the figures dictated by the DOF/equivalency formula, and trying to do so will only lead to difficulty and mismatched, invalid results.
The aperture markings on lenses are not accurate enough (and T-stops are useless for such a test). Also, aperture markings don't account for the change in focal length when the lens is adjusted to put the subject in critical focus. If you wanted to get a precise number match to the DOF formula, you would have to measure the exact focal length when focused and the exact aperture diameter, which is somewhat challenging considering there is no tangible focal point marking on lenses and considering that the aperture is usually inside the lens.
Trying to get the numbers to precisely match the DOF/equivalency formula is a fools errand.
On the other hand, there is nothing wrong with setting up the test with two camera/lens combinations that match as closely as possible, and then merely adjusting the aperture ring on one of the cameras until the two DOF ranges match by eye. If the adjusted aperture reads a little off from where the DOF/equivalency formula says it should be, simply make a note of that adjustment and include that note in the test report.
10 hours ago, noone said:Using the crop factor to get an exact match, you would then need to do the same for the second format.
That's unnecessary, and you would only need to crop one of the images if you want to exactly match the frames.
10 hours ago, noone said:You will also probably need to have the exact same lens formula though to get the same T stop (and take away any possibility of being a difference for other reasons).
No. If you use T-stops markings, you are making an even bigger error than if you just rely on the accuracy of F-stop markings.
The aperture markings on the lens are inaccurate and mostly irrelevant.
10 hours ago, noone said:Yeah, it probably IS possible (maybe even easy for some).
Well, if you like to do things the hard way as prescribed in your method, you will have a tough time and will unlikely get valid results.
10 hours ago, noone said:I could not do it in a lifetime though and again, beyond being a academic exercise, what is the point?
I agree that your method might not work in a lifetime.
I would think that this point of this exercise was obvilus by now -- to demonstrate similarities and/or differences between optics made for different formats.
10 hours ago, noone said:So, unless you (or someone else) does THAT, I will always accept that the theory matches the practice and to date, all tests have satisfied me they do
Good for you!
10 hours ago, noone said:Are there ANY tests that have been done matching equipment EXACTLY?
There are tests that got a close enough match with the equipment. However, they suffered the maladies that afflict most other tests:
- they didn't show the delineation of the DOF limits;
- they used wide angle lenses and/or deep DOF; they used a zoom lens;
- they had camera sharpening enabled;
- and, of course, they didn't adjust the aperture by eye to match the DOF.
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4 hours ago, hyalinejim said:
Can you link to those posts? I'm still no clearer on what the differences in DOF rendering due to large/small format lenses actually looks like in an image.
I'll just repeat what has been mentioned in this thread.
The lenses for the smaller formats have to use larger apertures to match the DOF of larger format lenses. So, if one is shooting large format with shallow DOF (as in the above photo), matching that DOF with a with a smaller format lens will require its aperture to be wide open, which not only affects the overall sharpness (As you surmised), but it can also produce a difference in the relative sharpness between center and edges of the frame. This characteristic with the smaller format lessens as the aperture is reduced.
The above 8"x10" photo was shot with a roughly 600mm lens (not sure on the aperture), and the closet lens match that I could find in a smaller format is the Nokton 42.5mm f0.95 for M4/3. Here is a test of that lens set at f.0.95 that not quite as close/tight as the above photo, but it gives a rough idea of how it might behave close and wide open. It doesn't seem as sharp wide open as it does at smaller apertures, and, unfortunately, the DOF isn't quite shallow enough to match that of the above 8"x10" lens.
In addition, at wider apertures, there generally seems to be a faster transition from sharp to soft at the rear DOF limit on lenses made for larger formats. This quality might relate to why the plane of focus seems more solid, more well-defined and flatter on larger formats.
Also, the softness/bokeh outside of the DOF seems cleaner and less mushy.
Here is a photo shot with an 8x10 camera that shows that shows a solid, flat focus plane (although the lens appears to be swung slightly to the right), with the subject nicely separating from the clean and not too mushy background.
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1 hour ago, hyalinejim said:
Are there any conclusions you would draw on the pros and cons of large formats versus small in terms of the qualities of images afforded by the glass associated with each? For example, are large format lenses well suited to narrow DOF pics that maintain sharpness and small format lenses well suited to deep DOF without suffering as much from diffraction?
I don't have any conclusions in regards to larger formats vs. smaller formats other than the ones I have mentioned in this thread and in other threads.
Larger formats don't usually suffer from diffraction with deep DOF, hence the f/64 club.
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7 hours ago, seanzzxx said:
PLEASE point me to that test then,
Most of the test parameters are given in the second half of this post from earlier in this thread.
7 hours ago, seanzzxx said:because I feel like whatever magic properties that should be inherent to sensor size should manifest in sóme way under a controlled test.
The format related properties are inherent in their optics, but the format and its optics are married to each other in regards to the look/sharpness.
I agree that a controlled test should reveal general differences in optics for made for different formats.
7 hours ago, seanzzxx said:So far you are just shooting down any test provided as not being rigorous enough
No. The problem with the tests are not their degree of rigor -- the problem is that every DOF test presented so far completely misses the point of what it is that is being tested.
If one is testing DOF, it is sort of necessary to show the actual DOF. Instead, almost all such tests so far have merely shown the subject and an arbitrarily soft background at some arbitrary distance. Here is the typical set-up that we see in these comparisons;
camera >> AIR >> sharp subject >> AIR >> soft background
The limits of the DOF invariably are located in the "AIR" where there is no object nor surface visible to show the location nor the transitional character of those important limits.
So, instead of testing the DOF, these comparisons actually just show how closely the tester can match the soft background using math along with the aperture markings on the lens.
Usually, these tests also suffer other significant mistakes, such as in-camera sharpening, using zoom lenses, using wide lenses with deep DOF, etc.
Additionally, the "soft background" in most of these tests is usually a wall or some other obstruction, beyond which no detail nor focus falloff is visible.
7 hours ago, seanzzxx said:(why on Earth would foreground unsharpness matter in any way when according to your last example provided the special properties of large format are abundantly clear in a shot that has just as much elements in front of the focus point, that is a nose, as in the examples provided by Yedlin)
Obviously, the foreground limit of DOF is important in DOF tests, because that limit is a major element that determines the DOF.
In addition, the transitional characteristic of the foreground limit and the character of the softness beyond that frontA limit are both crucial to a lot of cinematography. For instance, consider any focus rack from far to near (or vice versa). When the camera is focused on the distant subject, the look of the soft near subject is determined by the DOF.
In regards to Yedlin's test images showing the same elements characteristics as those in the 8"x10" photo that I linked above, there is one important and conspicuous difference -- the 8"x10" image shows the rear DOF limit and its distinctive transitional character quite clearly, while the rear DOF limit in Yedlin's shots are lost in the air.
And, again, Yedlin used wider lenses with a deeper DOF. Not so with my linked image.
7 hours ago, seanzzxx said:but if the differences were significant so as to be meaningful there should be a way to test for this relatively easily right?
Yes. The parameters are:
- Use dramatically different sized formats (with their corresponding optics);
- Use a continuously visible surface (preferably ruled) or a row of uniform objects that starts far in front of the subject and that recedes far behind the subject;
- Use narrow lenses;
- Use a shallow DOF;
- First set the DOF of the smaller format, then match by eye the DOF of the larger format.
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8 hours ago, hyalinejim said:
Well, I think that DOF as defined by circle of confusion etc can be matched because equivalence theory states that you can, if the lens for the smaller format is bright enough. However, I would expect to see a considerably softer image with lots of vignetting as you'd need a very fast lens to replicate the narrow DOF of this shot, and that's how lenses behave wide open. So although the DOF might be technically the same, the images will look different.
Agreed (except for the smaller format having more vignetting), and I think that you have hit upon a prominent general difference between larger and smaller formats. However, I think that there are other general differences between different sized formats.
8 hours ago, hyalinejim said:But this is caused by the glass, not sensor size.
Of course, but, again, cropping into the image circle of a lens reduces the visible lines of resolution (which are related to focus/DOF). So, a lens and it's format are integrated in that sense.
8 hours ago, hyalinejim said:So your choice of format will have an impact on the look of the image. But I think a lot of people are making the point that those differences are derived from the glass and are not inherent to the sensor size.
Regarding points in this thread about lenses having their own particular look, many of those arguments are attempts to dismiss the idea that lenses made for larger formats generally share characteristics that are lacking in lenses made for smaller formats (and vice versa).
Again, it is obvious that optical characteristics are inherent to the lens, but the camera lens and its format cannot be divorced without affecting the look/sharpness.
8 hours ago, hyalinejim said:So theoretically, sensor size makes no difference to DOF.
Yes, unless one crops too severely into the image circle of a lens.
8 hours ago, hyalinejim said:But in practice DOF is rendered qualitatively differently because the lenses are different / behave differently / must be set differently for different formats.
Agreed.
8 hours ago, hyalinejim said:But it does suggest that any equivalence test is really just a comparison of two different lenses. In the same way that one of my 50mm lenses looks different from the other 50mm lenses I have for the same format. So would you agree that once you match focal length and aperture for the same shot on different formats, you're comparing lenses?
Not exactly.
Of course, different lenses of the same focal length made for the same format can have differing looks/sharpness. However, as you have noted, there are general characteristics inherent in lenses made for larger formats that are lacking in lenses designed for smaller formats (and vice versa).
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12 hours ago, hyalinejim said:
It still sounds intriguing though 🙂 You misunderstood my proposed comparison though. The simulated crop on the 50 would simulate a notional sensor 1/4 the size of full frame. But I suspect that any differences observed would have more to do with the glass involved (and the necessary apertures) than the sensor size. Perhaps this is what accounts for your observation that the differences in rendering of DOF are greater when the disparity of sensor size is increased: to maintain equivalence, one lens is quite wide open and/or the other is quite stopped down.
I'm not sure that I understand what you are doing with your proposed comparison, but in any DOF equivalence test it is imperative to use the actual lenses designed for the formats that are being compared. It is also required that one uses the actual sensor/film format appropriate for each lens -- one can't crop in very much without ruining the results.
Look at this image taken with an 8"x10" camera:
This is a very common look with large format photography.
Note the abrupt transition out of the DOF. Look at the quality of the soft edge on the subject's collar and shoulders. Note the character of the softness of the subject's out of focus hair on his shadow side.
Even if one could get that shallow DOF, do you honestly think that this look can be duplicated on a S16 or M4/3 camera?
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12 hours ago, noone said:
The numbers to get an exact match between an 8,8mm lens on the RX100 and the 24mm on FF I use are aprox and the crop factors used are aprox. This is why it would be almost impossible to get an exact match and I doubt even Lens Rentals and their optical bench could get one.
The trick is to first set the smaller format lens to yield the desired DOF and shoot an image/footage. Then, match by eye the larger format lens to the DOF in the first image/footage. It probably also helps if the entrance pupil of the two lenses are positioned at the same location.
The thing is, with your test set-up (and with almost every previous equivalency test set-up), you would merely be matching the focus/softness of the foreground and background, but you wouldn't be matching the DOF. To match the DOF, the front and back limits of the DOF need to be visible on objects/surfaces in the frame.
12 hours ago, noone said:Read the other thread linked to earlier and what Dr Caldwell said (he designed the Metabones SpeedBooster as well as one of the highest performance lenses ever).
Caldwell mentioned some of the differences in optical qualities inherent in different sized formats:
On 6/20/2016 at 12:46 PM, Brian Caldwell said:One advantage that larger formats have is that you can use a smaller relative aperture to achieve a given DOF. Since aberration correction tends to be very non-linear with respect to f/# you often wind up with better correction on a larger format. For instance, I used to shoot 11x14" film a fair amount, and aside from an advantage in film grain it allowed me to shoot at f/16 instead of the ~f/1.4 I would have had to use on 24x36 format to achieve an equivalent picture. Focal lengths scaled accordingly, naturally. At f/16 the ultra large format lens was nearly diffraction-limited, whereas a small format lens at f/1.4 is nowhere near that limit.
By the way, Caldwell also admitted that refractive optics can affect DOF:
On 2/27/2017 at 2:29 PM, Brian Caldwell said:techically, aberrations can and do influence DOF.
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12 hours ago, seanzzxx said:
I feel like you are kind of moving the goalposts. This guy has a use case where he has shot hundreds of shots on cameras with all kinds of film backs (for camera comparisons), and somehow this does not count because his lenses are too wide?
Ten hours before you first posted about your guy's format test, I stated that equivalency comparisons need to be done in focal lengths narrower than a wide angle lens:
23 hours ago, tupp said:The comparison would need to employ a narrower focal length -- normal or tighter -- to show a more perceptible delineation of the limits of the DOF range. Also, the DOF should be shallower to possibly show a more dramatic difference between formats.
13 hours ago, seanzzxx said:There is an interesting post from cinematographer Steve Yedlin talking about this exact issue.
I welcome your explanation as to how I am moving the goal posts.
Furthermore, if you reread my post, you will see that the second and most important objection that I made to his test was that he shows no delineation of the front and rear DOF limits. With those details missing, the test is not useful.
12 hours ago, seanzzxx said:This is based on real-world experience with everything from an IMAX down to a super 35 camera.
So what? I have real-world experience shooting most formats from 8"x10" reversal film down to 8mm reversal film.
12 hours ago, seanzzxx said:He even admits in the article that his matching is not perfect due to practical limitations (t-stops and f-stops not aligning, lenses not matching exactly to their equivalent counterparts, etc.),
His admission of the inherent problem in his methods does not make the test valid.
Going by the f-stop/t-stop markings is a universal mistake that seems to afflict the every single one of the mathematical equivalency testers. Of course, t-stops are different from f-stops, and the markings aren't accurate. So, the DOF has to be matched by eye.
By the way, the two lenses that I chose earlier in this thread (a 16mm Zeiss Superspeed for S16 and a standard 360mm for 8"x10") should be about a 98% match.
12 hours ago, seanzzxx said:but his argument is that the likeness between shots is so convincing and consistent that the sensor size obviously does not play a role in the actual image,
It's convincing if you want to see a match, but his comparison lacks crucial information and there are devastating, uncontrolled variables. So, his test is not really valid.
In regards to the notion that sensor size does not play a role in the image, I strongly disagree. Lenses made for particular formats give a certain number of lines of resolution within that format. If one crops into that format, one throws away lines of resolution and the overall image is softer/mushier. In addition, cropping into a format can destroy the particular image character inherent with a lens.
12 hours ago, seanzzxx said:and that any perceived difference is due to bias or particular (non image circle-related) lens characteristics, not due to the size of the film back.
The thing is, optics made for larger formats posses characteristics that are lacking in lenses made for smaller formats (and vice versa). I have mentioned some of those characteristics in this thread and elsewhere in this forum.
12 hours ago, seanzzxx said:In fact, where you have been previously arguing about recognizing a larger format due to increased lens blur (in your examples where you are circling a number of shots),
You are mistaken. I was not arguing that I recognized the larger format due to increased lens blur.
I was merely pointing out the dramatic differences in the two images, which the conductor of the comparison evidently still can't discern.
13 hours ago, seanzzxx said:the Alexa 65 actually seems to have slightly LESS lens blur in the examples provided by Steve Yedlin, likely due to my aforementioned reasons.
Agreed. Yedlin's comparison has problems, so his test isn't conclusive
13 hours ago, seanzzxx said:This, again, seems to provide an argument that any perceived differences are more likely to be due to individual lens characteristiscs or other uncontrolled variables which are not related to the film back size.
Or, it provides the argument that such comparisons should be conducted by someone who understands the fundamentals of what is necessary for such a test to be valid.
13 hours ago, seanzzxx said:EDIT: I hope this does not come off as argumentative, as I do appreciate -and enjoy- the discussion!
This is an Internet forum. No worries.
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14 minutes ago, seanzzxx said:
There is an interesting post from cinematographer Steve Yedlin talking about this exact issue.
Thanks for the link!
I doubt that he is talking about this exact issue. Like most other folks who do equivalency tests, he likely limits his attention to mathematical DOF, and his tests use wider angle lenses and there is no delineation of the front and rear DOF limits with a lot of other detail thrown away or ignored.
13 minutes ago, seanzzxx said:He has some pretty rigorous testing to go with it.
I don't have time right now to read the linked page, but if the images shown are the extent of his comparison, his tests are invalid. He does not show how the limits of DOF are delineated. He seems to be using wide angles focal lengths, and I can see a difference in one of the images with just a glance.
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30 minutes ago, hyalinejim said:
How about a test where you simulate a small sensor by using a center crop from a full frame stills camera? Like this:
Full frame
200mm, f7.1Simulated 4x crop sensor
50mm, f1.8These would be different lenses. I could do this (when I have time) with a Canon 50 1.8 and Sigma 70-200 f2.8 and use ACR to correct for lens aberrations. Or instead with an OM Zuiko 50 1.8 and OM Zuiko 200mm f4 (possibly similar primes? But can't correct for aberrations)
Keep in mind that, to do a proper comparison, one must use the optics made for the formats being tested.
In addition, testing wide angle focal lengths is going to make it more difficult to discern any differences, so stick to lenses that are a normal focal length or tighter.
200mm is in the normal focal length range for the 4"x5" format. So you need to use a 150mm-210mm lens made for 4"x5" and it has to be focused to a 4"x5" sensor/film sheet/DOF adapter.
50mm is the normal focal length for FF, so you need to use a 50mm FF lens on a FF camera.
By the way, here's another yet another overlooked variable -- view camera lenses for large format (2'x3", 4"x5", 8"X10", 11"X14", etc.) are designed produce image circles that are much larger than their format, because they have to allow for tilts, swings and shifts.
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6 hours ago, tupp said:
However, there is more involved in "format specific looks"
5 hours ago, hyalinejim said:This implies that you maintain that there is a look inherent to a format, independent of variations between lenses.
The quotation marks that I employed imply something else. I'm saying that refractive optical elements can affect focus and the focus range, and, additionally, that there are general tendencies, advantages and problems inherent in refractive optics designed for larger formats and likewise with refractive optics designed for smaller formats. Of course, there are exceptions and some lenses for smaller formats possess some of the qualities generally found in larger format lenses, and vice versa.
6 hours ago, hyalinejim said:If so, it should be consistent as format size changes and it should be describable. How does the look of small format compare to the look of a larger format, at equivalent focal lengths and apertures?
There is consistency, but there is also seems to be more than one variable at play, so there is some complexity.
I would describe the look of larger formats as generally having a flatter and more "solid" focus plane with a faster "rolloff" at the DOF limits, but with a smoother and better resolved "macro-contrast" outside of the DOF limits.
6 hours ago, hyalinejim said:I'm just interested here, as I use DOF calculators to help my understanding when moving between FF, micro 4/3 and speedboosted micro 4/3.
There is not a huge difference between FF and M4/3.
Using a speedbooster or focal reducer can allow the qualities of the larger format optics to be captured on a smaller format.
6 hours ago, hyalinejim said:But I also see a huge difference in the images posted, which I would not have expected.
The dramatic discrepancies between the two images shown above are not due to any tendencies inherent in different sized formats. My guess is that the DOF was not equivalently matched, plus the 1-inch camera likely had a built-in zoom lens (which can look/behave different than a prime) and excessive in-camera sharpening could have been enabled.
There are a lot of variables that need to be controlled in such comparisons, otherwise the tests are invalid.
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24 minutes ago, SteveV4D said:
And to be honest, I don't shoot enough photos to need a camera that does both.
The A7s with the 8"x10" rig is not really intended for stills.
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2 hours ago, hyalinejim said:
So is it fair to say that your position is something like this: "Even though DOF calculators show that the theoretical DOF of equivalent shots is the same, in practice there is an observable difference in how DOF is rendered between equivalent shots"?
Yes, but the differences are not contained only within the front and back DOF limits. Additionally, the character of the focus transitions at the DOF limits can differ between optics designed for different sized formats. Likewise, how the focus behaves outside of the DOF limits can generally differ between formats.
2 hours ago, hyalinejim said:If so, and if I understand you correctly, that would mean that a DOF calculator is showing us 2 points on the DOF continuum, the point of near focus and the point of far focus, and these are the same for both formats if the focal length and aperture is equivalent. But it's not telling us anything about the DOF characteristics elsewhere on the continuum, which is noticeably different.
Yes. However, the differences are very slight (and sometimes non-existent) between optics designed for formats of similar size, for instance, M4/3 and APS-C, or APS-C and FF.
2 hours ago, hyalinejim said:But others may notice and be very interested in differences in DOF behaviour that's not described by equivalence theory...if what you say is true!
The basic idea is that what's in focus is not limited the factors addressed in the DOF calculations (aperture, focal length, subject distance) -- the refractive optical elements have a huge influence over what is in focus, and how things resolve in a camera image.
An obvious example of how refractive optics can affect the range of focus is a split diopter. A split diopter can near objects and distant objects into critical focus, regardless of whether the aperture is wide open or closed to its smallest setting. By the same token, a split diopter can be used in "reverse" to make close objects sharp while making distant objects blurry, even if the aperture is stopped down considerably. There are other examples of refractive optics affecting the focus range.
However, there is more involved in "format specific looks" than DOF and range of focus. Optics for larger formats are generally less prone to aberrations and can usually resolve more lines per format frame. Optics for smaller formats can require more aberration correction (more glass) and, although they necessarily resolve more lines per mm, optics for smaller formats have a harder time squeezing the same number of lines of resolution into the smaller format frame that is possible with lager formats. These properties and limitations can affect focus, the flatness/shape of the focal plane, resolving and, hence, the "look."
2 hours ago, hyalinejim said:So we would be talking about a kind of DOF rolloff, which is shorter on larger formats and longer on small formats, according to equivalence sceptics.
DOF "rolloff" is the street name for it. Brian Caldwell expressed it in more technical terms.
I wouldn't say that the rolloff is "shorter" or more rapid on larger formats nor "longer" nor slower on smaller formats. Nor would I say that the rate of the falloff is smooth/constant in larger or smaller formats.
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20 hours ago, SteveV4D said:
Thats odd as S35 cinema cameras cost a lot more than many fullframe hybrids.. and I'd rather have the money to buy a C300, a Red Komodo or an URSA 12k over a fullframe A7C, or any other fullframe hybrids for that matter...
Have you priced an Alexa 65 lately?
If I had the money to buy an C300/Komodo/Ursa-12K, I'd buy an A7s II with an Irix 15mm lens and a shift adapter and build a copy of Zev Hoover's 8"x10" rig. I'd deposit rest of the money.
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On 9/15/2020 at 11:13 AM, noone said:
The differences are quite minor to the point of it proves theory and practice match to me
If you think that an image with a building exhibiting sharp edges matches an image of the same building showing soft edges, so be it. Everyone has a right to an opinion.
To me the differences between the images are so blatant that those discrepancies must be due to some uncontrolled variable(s) -- not to the difference in formats. The differing looks/DOF between formats is usually more subtle than what we see in your comparison. My guess is that the apertures were not at their equivalent settings. Plus, the 1-inch camera used a zoom lens, and it might have had sharpening enabled.
On 9/15/2020 at 11:48 AM, Jay60p said:To test this you could use:
standard 16mm, Bolex (Kern Paillard 10mm at f/1.8
4/3rds, 17mm at f/3.2
APS-C (Nikon DX), 22mm at f/4
Full Frame, 34mm at f/6.3
8x10, 256mm at f/45
The 16mm would have to be wide open and the 8x10 would have to be completely stopped down (my 8x10 270mm is f/4.4 - 45)
This is according to this calculator:
Thank you for posting this!
The comparison would need to employ a narrower focal length -- normal or tighter -- to show a more perceptible delineation of the limits of the DOF range. Also, the DOF should be shallower to possibly show a more dramatic difference between formats.
A Zeiss Superspeed 16mm set to f2 would work as the normal lens for the Super 16 format. A standard, normal 360mm lens for 8"x10" is a close equivalent to that 16mm Ziess Superspeed, and the equivalent aperture on the 360mm lens would be somewhere in the range of f40-f51 (this aperture would need to be dialed-in for a visual match).
Maybe somebody with the resources and with the gumption will eventually make such a comparison. If so, hopefully they will conduct their test in a setting conducive to revealing DOF/focus limits, perhaps with a receding fence as shown in the photo above.
Thank you for the informative and helpful post!
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29 minutes ago, noone said:
make sure you have multiple lenses and cameras for each format otherwise I will just point out the differences why the equipment is not going to be an exact match and say it is invalid.
Uhm... okay.
29 minutes ago, noone said:ALL the photos I have seen about this prove to my satisfaction the theory matches reality and even my crappy photos are close enough to prove that.
Right. So, let's just dismiss outright the discrepancies shown within the colored outlines, without any consideration nor response.
29 minutes ago, noone said:Beyond that I disagree.
Well, denial is not a river in Egypt...
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14 hours ago, noone said:
if someone really went to the trouble of trying for an EXACT match they would need to take into account everything including each individual lenses characteristics, and that would be almost as difficult to do with two M43 lenses of the same focal length as it would with a Pentax Q and a Mamiya 7 with a digital back (assuming you can find lenses to match).
So, if there is no way to get a close enough match in focal length for an equivalency test, how can any of the equivalency tests made so far be accepted as valid?
Actually, there are a lot of 16 and Super 16 prime lenses. Start with that format as the smaller camera. There are also plenty of 8"x10" lenses. It shouldn't be too difficult to use the formula behind the equivalency principle to calculate a close enough match with lenses for those two formats. A little cropping of one of the images is okay, but a zoom lens is not okay.
14 hours ago, noone said:I am satisfied the photos I posted show enough similarity to prove my point and just to satisfy myself I DID test with my Sony Zeiss 55 1.8 VS the RX100 iv Sony Zeiss lens and it is as i suspected a closer match still.....now since it is not an EXACT match and was also just a quick and dirty comparison, there is zero point posting because you would just say it is different.
Well, everyone has a right to their view. You evidently don't see the stark differences that I can see with just a glance at the full frame and 1-inch images.
Perhaps another comparison method of the two images would make the differences more apparent. Here is a gif of the two equivalent images alternately flashed at one-second intervals:
Do you not see in the area outlined in red how the distant white building exhibits sharp edges in the 1-inch image, while it is much softer in the full frame image?
Likewise, inside the green outline, do you not see how the distant trees are significantly blurry in the FF image, yet we can see their individual branches in the 1-inch image?
Closer to the camera, within the blue outline do you not notice how the vertical supports on the fence are softer in the FF image and sharper in the 1-inch image?
From your description, I wasn't completely sure which image came from which camera, so please correct me if I got the format labels wrong. Regardless, there is a substantial difference in the look and DOF of the two images.
14 hours ago, noone said:Feel free to set things up to match theoretically lenses of two (or more) different formats but include a couple of lenses for each format used....If you do that, I am sure the photos would be the same, if you are not, then maybe you should disprove it...
I actually offered to collaborate on an equivalency comparison with an EOSHD poster who is a staunch proponent of the equivalency principle and who happens to reside in my town. The equivalency poster refused my offer.
I would not do such a test without an equivalency supporter present to oversee and certify the matching of the DOF. If I did the test alone, without such certification and if the results showed a dramatic difference in look/DOF, folks would just claim that I did something wrong or that I intentionally manipulated the images. Several times in this forum I have pointed out prominent discrepancies in DOF/equivalency tests and those differences were dismissed as unimportant or ignored as unavoidable testing "inaccuracies." I am not going to go through all the effort to do a proper comparison just to have the findings rejected outright.
14 hours ago, noone said:Lastly regards Dr Caldwell,
"Do the experiment properly and you'll find that the perspective is the same. Surely you must have heard countless times before that perspective depends only on the subject distance. This is a truth that you shouldn't ignore. More precisely, perspective depends on the distance from the subject to the entrance pupil of the lens. For this reason, the entrance pupil is sometimes called the center of perspective. "
I disagreed with you in that thread and I disagree with you in this one hence why this is pointless now.
I never disagreed with Caldwell regarding perspective. Certainly, perspective is determined by the distance of the camera/observer from the subject, but there are exceptions to that rule, depending on how one defines "perspective."
However, perspective has little to do with the question of whether different sized formats give contrasting looks or exhibit differing DOF.
By the way, Caldwell agreed that there is more to DOF than the the factors/variables found in the DOF formula (which is the basis for the equivalency principle).
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21 hours ago, BTM_Pix said:
Having to have the FF at f4 because the APS-C had to be at f2.8 and the MFT with the SB could be f2 is not doing the FF any favours.
It's probably best to first set the desired DOF on the smaller format, then match that DOF range on the larger format by eye with a large monitor and/or digital zoom.
In addition, it is important to start out with a set-up that gives all of the information on what is happening with the DOF/focus, visible continually from front to back, both inside and outside of the DOF range. An ideal arrangement might be next to a receding fence, like this:
Note how the vertical rungs in the fence give a good idea of how/where the rear limit of the DOF range is delineated. It probably would show a more precise DOF limit delineation if the horizontal rung behind the subject's head was visible. Also, this set-up could be improved by panning the camera right and/or pulling the camera back to reveal how the front limit of the DOF is delineated on the fence. Additionally, if there were closer trees or other landscaping visible through the fence, that could add extra information on how background objects are rendered/resolved.
22 hours ago, BTM_Pix said:Matching the focal lengths also make it a challenge without using a zoom as well of course as at least they maintain the same contrast and colour for each camera.
A small bit of cropping on one of the images probably wouldn't ruin such a test, but using a zoom would.
22 hours ago, BTM_Pix said:I'm trying to think about which set of cameras and primes that could be used for be a totally accurate test if someone wanted to do it properly and its a tricky ask to get exact matches.
Using two cameras of dramatically differing formats might exhibit a more conspicuous difference in look/DOF that might help overcome some of the minor inaccuracies afflicting tests with camera formats that are close in size.
Is full frame really necessary?
In: Cameras
Posted
That's a good point, and such in-camera "lens correction" features have existed for a long time and are not unique to Fuji cameras.
The primary in-camera feature that might affect DOF tests would be the chromatic aberration correction. In-camera reductions of barrel distortion, vignetting, and local color changes (from frame center to edge) are less involved in DOF/focus.
A few things come into play here.
Firstly, Fuji is no slouch in regards to lenses. Their optics are known for exceptional quality, and I would bet that most Fuji lenses today need very little digital, in-camera corrections.
In regards to comparing your APS-C Fuji zooms to FF Canon, Pentax, Minolta primes and Nikkor zooms, keep in mind that when you crop into the image circle of those FF lenses, you are throwing away resolving power and lens character. A good focal reducer will transfer most of the FF resolution and the lens character to the smaller format.
Also, it's not surprising that chromatic aberration appears on some of your non-Fuji lenses that are modern, as camera manufacturers have a tendency these days to rely more on digital correction over optical correction. So, of course, if your X-T3 isn't correcting the chromatic aberration on the non-Fuji lenses, that would further explain the difference.
Keep in mind that these minor in-camera features will not change the DOF nor focus to make APS-C lenses (especially zooms) render images like those from 8"x10" lenses.