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My thoughts on the Kipon Medium Format "Speedbooster"


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3 hours ago, tupp said:

In addition, the linked simulation that you mention did not factor-in several important variables (as I have suggested earlier in this thread), thus the simulation is worthless.

You either have a bad memory or you didn't read the thread. The simulation wasn't created for you. Matthias denied what Timotheus wrote...

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On 29 October 2016 at 1:52 PM,  Timotheus said: 
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* You didn't respond to what I said, i.e. you can get the same framing, same depth of field, shooting from the same spot...with different sensor-sized camera's. The key is using lenses that compensate for the differences in sensor size.

He is talking about the math behind it.


No you cant. Look at the Tony Northup frame I posted. It clearly proves that you can replicate the image from a large sensor in the way YOU earlier suggested.

I tell you what. Take the three lenses and sensor sizes you listed in your first post. Take three photos from the same distance of the same subject. A person with a background similar to the example I posted.
I will give you $100 it they turns out exactly the same. 
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No you cant. Look at the Tony Northup frame I posted. It clearly proves that you can replicate the image from a large sensor in the way YOU earlier suggested.

I tell you what. Take the three lenses and sensor sizes you listed in your first post. Take three photos from the same distance of the same subject. A person with a background similar to the example I posted.
I will give you $100 it they turns out exactly the same. 
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As you can read Matthias suggest it can't be done the way You Timotheus suggest. In other words the math is being denied. 

That's why the simulation was created as it removes the imperfection of the lenses. Meantime the math is no longer the point of discussion, or so it seems.

Film is not reality. Even more so in this day and age, as there are more and more CG generated movies produced. A reality you will have to live with.

@ Matthias, still waiting for the $100,-. btw I settle for a lens.

...and btw I dig this thread and the adapter results.

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When this thing was announced it totally blew my mind. And I have been wanting one ever since the first time I read about it. If you don’t know what this is all about just think of it as a Spee

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

Even crappy jpegs look decent pretty much straight from camera.

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4 hours ago, bunk said:

@ Matthias, still waiting for the $100,-. btw I settle for a lens.

First of all, you didn't even make the test so I could just tell you "No way" right there and then.
But you are in luck, I'm not small minded.
So here is a chance for you at the $100.

Look at the test I made yesterday with the two pictures of the same flowers and identical settings apart from the "equivalent" lens.
Convince me that my eyes are wrong and that one of the pictures isn't darker than the other.

Do that and you have proven to me that the "equivalent" lens thing is at least slightly for real (there are still going to be plenty of things that separates a lens from another imo).

3 hours ago, tweak said:

More pics and video please @Mattias Burling.

I post new pics every day on my Instagram since getting the adapter and have uploaded a quick video test.
Just sold my A7 five minutes ago so the next video will be after I have bought an A7s.
It might be a while because as some of you may know, I pay very very little for my gear compared to retail and list prices.
Sniffing out a deal sometimes takes a little time and dedication :)

(plenty of more stills to come though)

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1 hour ago, Mattias Burling said:
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First of all, you didn't even make the test so I could just tell you "No way" right there and then.

Not sure how I fail as it was doen exactly as you descripted, but with three virtual camera's and lenses. You didn't believe the math behind it remember. The test performed proofed the math.

 

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Look at the test I made yesterday with the two pictures of the same flowers and identical settings apart from the "equivalent" lens.
Convince me that my eyes are wrong and that one of the pictures isn't darker than the other.

You mean the test with the lens cap still on. No idea what it was about and don't care to find out. Maybe you can find somebody else to help you out.
 

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Just sold my A7 five minutes ago so the next video will be after I have bought an A7s.
It might be a while because as some of you may know, I pay very very little for my gear compared to retail and list prices.
Sniffing out a deal sometimes takes a little time and dedication :)

Looking forward to the results with the A7s.

ps Sorry about the 'extra h' in your name. Noticed it too late and couldn't edit it after that for some reason.

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10 hours ago, tupp said:

I think you will find that the bigger the difference in the size of the lenses' image circles, the bigger the discrepancy in their DOF roll-off and look.

Cha-ching!

But what are your comments on the following theory?

"Say you shot with a 24mm APS-C at f/4 and 36mm full-frame at f/6.3 both focused at 10 feet. The lenses / formats would produce a very similar horizontal and vertical field of view. The depth of field would also be very similar. Would these images be nearly identical? What would account for any differences?"

"The perspective will not be the same. The angles may match but your relationship (the cameras relationship) to the angle will not be the same. That is to say, if you picture a wedge representing your field of view, in the full-frame scenario you will be further inside of the wedge than in the APS-C format. In the APS-C format you will be closer to the 'point' of the wedge. Therefore the sense of peripheral vision will not be the same. Some would argue that this is why full-frame looks more natural or realistic than APS-C."

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17 hours ago, tupp said:

However, I do not think that a 80mm, MF lens with a 0.7x focal reducer would look the same as a FF, 56mm lens.

Well, the combination of an 80mm lens and a 0.7x focal reducer does have a focal length of 56mm.  After all, focal reducers really do reduce focal length.  You could prove this to yourself by measuring the separation of photographed stars or I could prove it to you in my lab using the nodal slide on my optical bench.  And if you use that 56mm lens on FF (24x36mm) format, then *it is* a FF 56mm lens.  In this case, the use of a focal reducer together with an 80mm lens is a perfectly valid way of designing and creating a true 56mm lens.  As I mentioned in my earlier post, the only possible reason it will look different from any other 56mm lens will be due to lens/reducer aberrations and other flaws. 

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15 hours ago, bunk said:

You either have a bad memory or you didn't read the thread

Or, perhaps you are making an incorrect assumption about why I referenced that simulation and about who I was addressing.

 

 

15 hours ago, bunk said:

The simulation wasn't created for you. Matthias denied what Timotheus wrote...

Not sure of the relevance of the fact that the simulation was not created for me nor of the relevance of Mattias' denial of Timotheus' writing.

 

I was merely responding to another poster who presented that simulation as evidence/proof of the equivalence principle.  Maybe you didn't read (that part of) the thread.

 

 

15 hours ago, bunk said:

No you cant. Look at the Tony Northup frame I posted. It clearly proves that you can replicate the image from a large sensor in the way YOU earlier suggested

Just guessing, but did Mr. "Northup" make yet another equivalence test with a foreground and distant background... but with no middle ground?

 

 

9 hours ago, Viscount Omega said:

But what are your comments on the following theory?

Are you asking me?

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8 hours ago, Brian Caldwell said:

Well, the combination of an 80mm lens and a 0.7x focal reducer does have a focal length of 56mm.  After all, focal reducers really do reduce focal length.

I do not dispute this assertion.

 

 

8 hours ago, Brian Caldwell said:

And if you use that 56mm lens on FF (24x36mm) format, then *it is* a FF 56mm lens.

Right -- it becomes a 56mm FF lens, with the properties of an 80mm lens on MF.

 

 

8 hours ago, Brian Caldwell said:

In this case, the use of a focal reducer together with an 80mm lens is a perfectly valid way of designing and creating a true 56mm lens.

Well, adding a condensing stage as part of a unified lens design merely to achieve a certain focal length (no boost in brightness nor look needed) might seem like a roundabout and expensive way to achieve that focal length.

 

Why not just design a simpler lens with the desired focal length -- without any focal reduction stage?

 

 

8 hours ago, Brian Caldwell said:

As I mentioned in my earlier post, the only possible reason it will look different from any other 56mm lens will be due to lens/reducer aberrations and other flaws.

LMFTFY:  The only reason that it will look different from any other lens will be due to lens/reducer aberrations and other variables.

 

 

7 hours ago, cantsin said:

Since we have the great privilege of having Brian Caldwell, the designer of the Metabones Speed Booster, here on this forum - can we rest the discussion with his above statement? 

No.  The subject of equivalence will not be resolved until a proper test is conducted.

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42 minutes ago, tupp said:

Are you asking me?

Well, anyone could chime in, I don't care.   I'm looking for a rebuttal or counter-argument against this explanation.  (I didn't write it, btw. It's from a DP in another forum).  Here, I'll copy/paste it again:

"Say you shot with a 24mm APS-C at f/4 and 36mm full-frame at f/6.3 both focused at 10 feet. The lenses / formats would produce a very similar horizontal and vertical field of view. The depth of field would also be very similar. Would these images be nearly identical? What would account for any differences?"

"The perspective will not be the same. The angles may match but your relationship (the cameras relationship) to the angle will not be the same. That is to say, if you picture a wedge representing your field of view, in the full-frame scenario you will be further inside of the wedge than in the APS-C format. In the APS-C format you will be closer to the 'point' of the wedge. Therefore the sense of peripheral vision will not be the same. Some would argue that this is why full-frame looks more natural or realistic than APS-C."

 

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On ‎3‎/‎03‎/‎2017 at 5:01 AM, tupp said:
1 hour ago, tupp said:
1 hour ago, tupp said:

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"Right -- it becomes a 56mm FF lens, with the properties of an 80mm lens on MF."

No, it becomes a 56mm lens.

Adding the speedbooster changes the lens, not the camera.        Some lenses are designed by using a focal reducer internally I understand.     All you are doing here is adding it externally.

 

"Why not just design a simpler lens with the desired focal length -- without any focal reduction stage?"

Perhaps he should.    Maybe something like the Coastal Optics 60mm for instance?   Oh wait, he did??

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4 hours ago, Viscount Omega said:

Well, anyone could chime in, I don't care.   I'm looking for a rebuttal or counter-argument against this explanation.  (I didn't write it, btw. It's from a DP in another forum).  Here, I'll copy/paste it again:

"Say you shot with a 24mm APS-C at f/4 and 36mm full-frame at f/6.3 both focused at 10 feet. The lenses / formats would produce a very similar horizontal and vertical field of view. The depth of field would also be very similar. Would these images be nearly identical? What would account for any differences?"

"The perspective will not be the same. The angles may match but your relationship (the cameras relationship) to the angle will not be the same. That is to say, if you picture a wedge representing your field of view, in the full-frame scenario you will be further inside of the wedge than in the APS-C format. In the APS-C format you will be closer to the 'point' of the wedge. Therefore the sense of peripheral vision will not be the same. Some would argue that this is why full-frame looks more natural or realistic than APS-C."

 

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 suppose you could call it the "point of the wedge" in your language.  FYI, technically, the entrance pupil is the image of the aperture stop as seen from the front of the lens.  So, in your experiment, just put the entrance pupil of both the 24mm and 36mm lenses at 10 feet from the subject, and the perspective will be precisely the same.  There are some easy techniques for finding the entrance pupil location with an accuracy of about +/-1mm that stitched panorama shooters use all the time - if you need help just ask.

The subject-to-image plane distance is not what matters.  Its the subject-to-entrance pupil distance that does.  So, this notion that full frame will be "further inside of the wedge than in the APS-C format" is just another way of saying:  "oops, I goofed, and didn't keep the subject distance constant".

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8 hours ago, Brian Caldwell said:

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 suppose you could call it the "point of the wedge" in your language.  FYI, technically, the entrance pupil is the image of the aperture stop as seen from the front of the lens.  So, in your experiment, just put the entrance pupil of both the 24mm and 36mm lenses at 10 feet from the subject, and the perspective will be precisely the same.  There are some easy techniques for finding the entrance pupil location with an accuracy of about +/-1mm that stitched panorama shooters use all the time - if you need help just ask.

The subject-to-image plane distance is not what matters.  Its the subject-to-entrance pupil distance that does.  So, this notion that full frame will be "further inside of the wedge than in the APS-C format" is just another way of saying:  "oops, I goofed, and didn't keep the subject distance constant".

Thanks.  Your explanation seems to focus strictly on distance to explain perspective and ignores the huge difference in lens image circle sizes between the two formats in the comparison.  Are you saying that difference is irrelevant in regards to perspective?   That it has no impact on perspective in the comparison?  Does it have any impact on anything then?  

I was under the impression that perspective was also the way objects appeared spatially and that's why I initially agreed with the DP's assessment--it seemed to jibe with my real-world experience--especially the bit about the sense of peripheral vision being different.  Maybe that was simply lens aberrations.  I don't know. 

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5 hours ago, Viscount Omega said:

I don't know. 

Next time you're about to "lol" and "LYFAO" at people on the internet (and in real life) that are civilly attempting to clarify your misconceptions, it would be better for all concerned if you took the time to ask yourself, "Well, do I really know what I think I know?". This is good advice for everybody, me included, so don't take it personally.

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5 hours ago, Viscount Omega said:

 Maybe that was simply lens aberrations.  I don't know. 

I'm being a little sarcastic here (maybe not hard enough for some people).  As if a little thing like "lens aberrations" could account for what I (and others) are seeing.  Anyway, still waiting for an answer.

p.s. sorry you were offended by the "vignetting" comments earlier but I did think it was funny and insane.  Still do.

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5 hours ago, Viscount Omega said:

Thanks.  Your explanation seems to focus strictly on distance to explain perspective and ignores the huge difference in lens image circle sizes between the two formats in the comparison.  Are you saying that difference is irrelevant in regards to perspective?   That it has no impact on perspective in the comparison?  Does it have any impact on anything then?  

I was under the impression that perspective was also the way objects appeared spatially and that's why I initially agreed with the DP's assessment--it seemed to jibe with my real-world experience--especially the bit about the sense of peripheral vision being different.  Maybe that was simply lens aberrations.  I don't know. 

I have seen absolutely no difference (besides lens signature, aberration, etc) between a 35mm APS-C lens mounted on my APS-C camera and a full frame 35mm lens on the same camera. The larger lens circle doesn't change a thing. 

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13 minutes ago, Julien416 said:

I have seen absolutely no difference (besides lens signature, aberration, etc) between a 35mm APS-C lens mounted on my APS-C camera and a full frame 35mm lens on the same camera. The larger lens circle doesn't change a thing. 

That's because you're not using a larger lens circle.  When you put a full-frame 35mm lens on an APS-C camera you're not using a full-frame lens the way it was intended.  You're only using the center section of glass in the lens. 

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