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KrisAK

A7s, Depth-of-Field, and the Micro-4/3 Advantage

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there is a reason why Directors like Tony Scott sat on the end of long lenses for most of their films.

he liked that look !

Scott's Taking of Pelham 1-2-3 remake was shot with only 2 types of lenses

Panavision [Primo] zoom lenses,  3:1 [135-420mm T2.8] and  11:1 [24-275mm T2.8],

 

http://www.theasc.com/ac_magazine/July2009/TheTakingofPelham123/page1.php

 

there is some crazy drop off bokeh on some of the shots in that film ....have a look...

he also used 2x extenders on those lenses - he lost a stop but gained mega drop off by doing that

 

then on the other hand you have Directors like David Fincher who uses mainly a 27mm lens of most of this films for the past 15 + years..

with Harris Savides, Darius Khondji and Jeff Cronenwerth , different DPs same 27mm lens used.

 

another different look ....another different style .....

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EOSHD Pro Color for Sony cameras EOSHD Pro LOG for Sony CamerasEOSHD C-LOG and Film Profiles for All Canon DSLRs

Inversely, Terrence Mallick has shot some of the best looking stuff ever committed to film and uses mostly short focal lengths and deep focus.

 

Having a specific vision and a good one is really the key not full frame.

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Inversely, Terrence Mallick has shot some of the best looking stuff ever committed to film and uses mostly short focal lengths and deep focus.

 

Having a specific vision and a good one is really the key not full frame.

If your happy with your Iphone, that's wonderful for you and for your pocket.

About malick,it's not the first time this is being mentioned, and it's bullshit.

Just take a look at this first:

http://evanerichards.com/2011/2407

The only deep focus there is is when they run around or some landscape shots.

No deep space at all.

 

then read the tecnical specs:

http://www.imdb.com/title/tt0478304/technical?ref_=tt_dt_spec

 

oh wait, what's this?

Dalsa Evolution 
IMAX Cameras 
Panavision 65 HR Camera, Panavision System 65 Lenses
 

Maybe this is the reason why everything pops so much, beside the zeiss, but hey, why use that if you got an iphone.

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If you have watched Malick's films it's pretty hard/impossible to argue they are not predominantly shot on short focal lengths.... sure there is some shallower focus stuff but the style is overwhelmingly built around short focal lengths. I'm not saying its better, but saying full frame is better would be just as silly.

 

Aren't most motion pictures are mostly shot on super 35mm size sensors which are closer in size to aps-c not full frame? Regardless neither is or has to be "better" than the other so cool ya jets.

 

And for the record I don't shoot on an "iphone", nor am I some kid with a 5D who thinks more out of focus the background is the more "filmic" and "cinematic" my shot is.

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I'm not talking about shallow depth of field but the way dof works. Actually it's pretty clear that if the movie had been shot exclusively with s35 it would have lost a lot of the visual appeal it has because he either would have used teles or he'd just sacrificed the overall look.

An example for wides: If I for example take a 28mm @ 1.4-5.6 on FF and stick it up to the face of someone, I will get something from shallow to pleasing dof, but I will never get the whole head or face to be in focus and it will look like thouse tipical "kid with a 5D shot" . If I'd do the same on 6x7 with a 50 f4 I will get something very different, something usable.

On m43 it's just worse. Of course you can stop down, but then you loose the contrast between details and everything looks flat, or difffracted which is even worse.

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Yes it does, in theory. MFT is 2x crop over fullframe. That means you get 2x the dof, but since the sensor is smaller, you can also say the low light performance is 2 stops worse. So ISO 6400 on fullframe gives the same results as ISO 1600 on a MFT sensor.

 

With raw photo files this theory is pretty much reality. You can compare this at dpreview.com. For example:

 

fullframe_vs_mft.jpg

 

When shooting compressed movie files results might be different because of all the image processing going on vs raw files, but fullframe will always have an advantage when it comes to noise. I think the A7S will hold up at ISO 6400 vs ISO 1600 on the GH4.

 

So in a way neither camera/system has a dof advantage or disadvantage.

 

The 2.0x crop only applies if you're shooting at default aspect ratios (A7S at 3:2 & GH4 at 4:3).  

 

When you crop to 16:9 the difference is far greater since you're applying a 16% crop to 3:2 vs a 25% crop to 4:3.

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Appropriate format lenses has a lot to do with how the dof falls off. A 35mm stills lens will falloff unnaturally sharp on a 16mm sensor camera, the same focal length on the same 16mm camera using  a proper 16mm lens will falloff in a pleasing manner in my experience, likewise apertures go a lot lower on 16mm glass because it's a appropriate for the format.

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This is like picking pepper out of fly shit. Turning your camera 1 degrees to the right or left is going to have more positive or negative effect on your shot than this.

 

Your assumption is a little flippant and appears to be lacking comprehension of the subjects being discussed here.  If you are to attempt conclusion of the subject rather than contribute to it please back your conclusion up with some something to fortify your conclusive quotes.   

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What are you trying to say? That a speed booster turns a aps-c into fullframe? Shure, that's the whole point.

 

No. Sensor is not getting bigger with SB. SB is just a part of optics to gather bigger part of available image from particular lens.

That's why it is a good example to show a difference between two sensor sizes, because they use 'almost' the same lens and the same part of the lens.

I was afraid that somebody will say exactly what you did, that this asp-c is no more asp-c... I don't agree. Lens construction is unrestricted and If for example hypothetical Nokton f/0.90 lens were using internally partially similar construction to SB, you will say that now you have bigger sensor inside your camera? And comparing m43 camera with this Nokton to aps-c camera with equivalent lens is not fair?

 

I didn't want to talk about SB, but to find good example to talk about difference between sensor sizes with comparable optics attached. If you don't like this example, it will be difficult to find another because every lens is different and it will be easy to find some differences and say that it's because of sensor size.

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No. Sensor is not getting bigger with SB. SB is just a part of optics to gather bigger part of available image from particular lens.

That's why it is a good example to show a difference between two sensor sizes, because they use 'almost' the same lens and the same part of the lens.

 

A speedbooster does make the sensor virtually bigger, otherwise it wouldn't compress the larger image circle. If the speedbooster would be a perfect system, there would be no differences at all between using a larger sensor, or using a small sensor plus a focal reducer, so it's actually the worst example to talk about sensor differences.

Anyway, I don't think you are actually interested in discussing this.

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Your assumption is a little flippant and appears to be lacking comprehension of the subjects being discussed here.  If you are to attempt conclusion of the subject rather than contribute to it please back your conclusion up with some something to fortify your conclusive quotes.   

Rich, I comprehend the subject, but maybe I was a little short.  "pepper out of fly shit"  was in reference to the post directly above it. As Jacek said, the SB is not literally making the sensor bigger so its a good example  and as the reference images show, the difference is negligible (pepper!), for me atleast. 

 

In addition if you check my following post, I I agree different bokeh can be achieved equiv focal lengths. Using glass designed for the format (i.e 16mm glass on 16mm sensor), amongst other things you will give you a softer dof roll off, where as using 35mm stills lenses just won't, even on equiv focal length on the same sensor.

 

My conclusion is based off experience, if sharp drop off is an issue then just use lenses designed for the format.

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A speedbooster does make the sensor virtually bigger, otherwise it wouldn't compress the larger image circle. If the speedbooster would be a perfect system, there would be no differences at all between using a larger sensor, or using a small sensor plus a focal reducer, so it's actually the worst example to talk about sensor differences.

Anyway, I don't think you are actually interested in discussing this.

Isn't a Speedbooster just a negative teleconverter?

Nobody refers to a normal teleconverter making a sensor virtually smaller so I don't get how this affect the sensor.       Surely it is just changing the lens?      I thought many lenses where made by adding a negative teleconverter to a normal lens?

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Guest Ebrahim Saadawi

I don't think anyone, anywhere on earth, nay, in the universe, ever, remotely implied, that the speedbooster takes the sensor inside the camera body out, and replaces it with a larger one, that's manufactured in the speedbooster's optics.

This argument reminds me of people rudely attacking us when we say using a 50mm of an APS-C makes it an 85mm.

When we say the speedbooster makes an APS-C sensor a fullframe one, we mean it gives the same image as if the same lens was used on a fullframe sensor, and by the same image we mean the same image charcteristics:
-field of view and depth of field.

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I don't think anyone, anywhere on earth, nay, in the universe, ever, remotely implied, that the speedbooster takes the sensor inside the camera body out, and replaces it with a larger one, that's manufactured in the speedbooster's optics.

This argument reminds me of people rudely attacking us when we say using a 50mm of an APS-C makes it an 85mm.

When we say the speedbooster makes an APS-C sensor a fullframe one, we mean it gives the same image as if the same lens was used on a fullframe sensor, and by the same image we mean the same image charcteristics:
-field of view and depth of field.

But that is how it comes off as (not always).      I think it gets confusing the way it is often worded/stated.

It is just changing the lens after all.      Seems a wonderful tool to have.

I like having a 50mm on various formats including 75mm angle of view on APSC.

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Perspective is the same on all focal length at the same distance, the crop doesn't matter either. The only thing that changes is distortion and the part of the perspective you get to see.

You could take a picture with a 50mm and crop it to get the same compression as if it were taken with a 200mm. But the rendering is obviously a lot different.

The explanation about why larger formats rock is rather easy, but I want to explain it also with mathematical formulas so the "I have no live and talent at all" trolls don't eat me alive.

 

Btw, have you ever shot with a pentax 67? It's amazing, I got used to the weight in one day and ever since I don't want to touch my little nikons...

Sorry, but this is wrong… revisit your 101.

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Sorry, but this is wrong… revisit your 101.

Why don't you tell us why it's wrong, write your 101.

 

http://en.wikipedia.org/wiki/Perspective_distortion_(photography)

 

Note that linear perspective changes are caused by distance, not by the lens per se – two shots of the same scene from the same distance will exhibit identical perspective geometry, regardless of lens used. However, since wide-angle lenses have a wider field of view, they are generally used from closer, while telephoto lenses have a narrower field of view and are generally used from farther away.

 

But hey, I guess this is all wrong and you know something secret. Why don't you update the wikipedia entrance?

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A speedbooster does make the sensor virtually bigger, otherwise it wouldn't compress the larger image circle. If the speedbooster would be a perfect system, there would be no differences at all between using a larger sensor, or using a small sensor plus a focal reducer, so it's actually the worst example to talk about sensor differences.

Anyway, I don't think you are actually interested in discussing this.

 

I think you are wrong. SB is nothing special, just few more glasses for optical system (called "lens").

 

Compressing larger image circle is what every lens is doing in their own way (except "pinhole lenses"?) and that's one of the reasons why you have lenses with different fov and especially different max f-stop and different target sensor size (final produced image size).

 

Using a larger sensor makes a lot of sense, not sure if everything is correct, but:

- it's easier to design it for lower noise, better DR or higher resolution...

- maybe it's easier to design lenses producing shallower dof (because of bigger final image)?

- maybe it's easier to avoid some of the optical problems like diffraction limit?..

 

That's why I'm interested in this topic, because not sure about optical (or other) problems with smaller sensors. If there is something like SB, everybody can produce a lens with "build-in SB" for smaller sensors (and probably some of the existing lenses are doing something similar internally), but also SB has it's limits, so maybe one of other differences between sensor sizes is for example shallowest dof available (is it possible to build for example f/0.9 FF (like latest Mitakon FF) equivalent m43 lens)?

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A focal reducer / speed booster does 2 things:-

 

1. changes the focal length of the lens into a shorter one (from 50mm to 35mm or similar).

2. changes the lens format into one for a smaller imaging area.  

 

a 50mm full frame lens on speed booster + aps-c is no longer a 50mm lens.  it is a 35mm lens with an image circle for a smaller imaging area.

 

 

the field of view and depth of field ratio may be the same on paper, but the results are being delivered by two completely different factors.

 

I like to compare it to wheels on a car.  smaller wheels will allow quicker initial start, but bigger wheels will allow a greater top speed.  assuming you worked out the point where the bigger wheeled car caught up with the car with the smaller wheels you could say both are equal, however in order to get to the same point on the track the actual duration from the beginning to the point of stopping the race would have been spent at different speeds for each car.  - the smaller wheels reaching top speed quickly- having the initial advantage, while the bigger wheels take a longer time but due to the slightly faster top speed it eventually catches up.

 

The bigger wheels will dictate a more linear and smoother speed increase. 

The smaller wheels will dictate a more logarithmic and curved speed increase hitting top speed earlier.

Some drivers prefer a fast start, and some prefer a greater top speed.  Same with cameras/lenses

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