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Kim Dahl

Apeture affecte from fulframe too APSC ?

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Hi

Can some tell me how apeture changes made from apsc lenses relative to fullframe. The link here clearly shows what happens. Please look.

So the question is: what if I put a Leica m (full frame lens fx. Leica m 35 f 2.0) on the apsc (Leica CL) on. How is apeture affected?

Is it a 50 mm f 2 or a 50 mm f ???

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If you put a 35mm f/2 full frame lens on an APS-C camera, you will get the same performance as a 50mm f/2.8 lens on a full frame camera.  The angles of view would be the same. The depth of field wide open would be the same.  The signal to noise ratios would be the same.  I'm over-simplifying on the signal-to-noise side a bit since there are likely to be differences in megapixel count and full well capacity and base ISO, but to a first approximation what I have written is reasonable.

 

Obviously, nothing changed in the lens itself.  It is still a 35mm focal length lens with a maximum aperture of f/2.  The camera body doesn't change anything about the lens.  It's just that it will behave on an APS-C body the exact same a 50mm f/2.8 lens would behave on a full frame body.  They are equivalent in their use.

Edited by Jared

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FYI, the video is quite accurate.  There are a few things I would probably present differently, and it's pretty long considering what it's trying to communicate, but it is still accurate.  For APS-C, just shift everything by the crop factor.  Focal length goes up by the crop factor.  Effective DOF goes up by one f-stop.  Noise performance goes down by one f-stop (i.e., ISO 400 on an APS-C camera should generally behave like ISO 200 on a full frame camera if the sensors are otherwise equivalent).

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Aperture does not change at all. A 35/2 lens remains a 35/2 lens. Its FoV is just 35 x 1.5 = 52mm on APS-C cameras. As for DoF it changes due to the smaller sensor that's all.

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Correct. Nor does the exposure change. My advice: just forget about all this and start using. Nobody agonises about these things when looking through the viewfinder.

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Thanks ☺️ That sounds right.

 

But next question.

 

Because when it comes to full frame, what about my leica TL 35 f 1.4, is it actually a "leica tl 35 f 2.1?

 

So is an apsc summilux really a summichrom?

 

That's to say I'm very happy with my new TL2 and TL 35 summilux.

 

I also have Leica ME with 24-35-90 mm.

 

 

So, according to the calculation, my Leica M 35 f2 has an aperture of 2.8 and my Leica TL 35 f 1.4 has aperture of 2.1. When used on my leica TL?

Edited by Kim Dahl

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Again aperture does not change at all so a 35/1.4 lens on FF remains a 35/1.4 lens on APS-C. Summilux for ever !

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No it is not a different lens. The sensor size changes nothing  about the lens.  You need a screwdriver and pliers to change things on your lens. The only effect sensor size has is introducing a crop. The aperture of the lens remains exactly the same. The focal length of the lens remains the same. Those are physical properties of the lens, whether it is mounted on a camera -whichever camera- or not.

 

You will see the same when you crop a full-frame image down to APS-C size or take the image with an APS-C camera in the first place (assuming  sensor architecture is the same), except for pixel count. All the effects that are mentioned in the previous posts are caused by the enlargement on the final image. See the Leica Q.

 

For photographic purposes you just think of - for instance - a Summilux 35  like a Summilux 50 equivalent with a bit deeper DOF.

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G

 

Thanks ☺️ That sounds right.

But next question.

Because when it comes to full frame, what about my leica TL 35 f 1.4, is it actually a "leica tl 35 f 2.1?

So is an apsc summilux really a summichrom?

That's to say I'm very happy with my new TL2 and TL 35 summilux.

I also have Leica ME with 24-35-90 mm.


So, according to the calculation, my Leica M 35 f2 has an aperture of 2.8 and my Leica TL 35 f 1.4 has aperture of 2.1. When used on my leica TL?

 

God no!

 

Aperture is aperture. It's the relationship between the focal length of a lens and the diameter of the aperture opening. Format is irrelevant. F2 is f2 regardless of camera, sensor size etc etc etc. A summicron is a summicron is a summicron.

 

So if you take a TL camera and fit an M 35. 1.4 the way it behaves will be the same as the TL 35mm 1.4 on the same camera. Same camera. Same focal length. Same Aperture. Same result. It does NOT matter that the M lens is made for a larger sensor. It only matters what size sensor it is used on.

 

Repeat... M35 Summilux = TL 35mm Summilux when used on a TL.

 

Now.......

 

Because the M and TL have a different sensor size a 35mm 1.4 used on each camera will behave differently in respect to angle of view and apparent DoF. They will act the SAME in respect of exposure. Because the TL sensor is smaller the angle of view is reduced. And because the amount of enlargement required to make an equivalent print size the "apparent" DoF will be increased. The difference is the "crop" factor.

 

So if you are shooting on a TL with a 35mm lens at f1.4 and you want to know what 35mm format lens/aperture will give a similar looking images you use the "crop" factor. Multiply the focal length and the aperture numbers by 1.5 . So if you shoot a M with a 50mm lens set at f2 and a TL with a 35mm set at 1.4 the resulting images will look similar (technically it would be 52.5mm and an aperture of 2.1).

 

But honestly it's a daft thing to get hung up on unless you really know your stuff. All that matters is that smaller aperture numbers gives smaller DoF. Worry about what a camera can do and not what it can't.

 

Gordon

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I always think about this the same way I think about learning a foreign language.  When you are first learning another language, you tend to hear words in the foreign language then translate them in your head to your native language.  Same for crop factor.  You put a 35mm f/1.4 lens onto your APS-C lens and you "translate" it into 50mm f/2 (approximately).  Nothing wrong with that.  It's an accurate translation, because the 35mm f/1.4 will behave on your APS-C just like a 50mm f/2 behaves on your full-frame camera.  Same field of view.  Same depth of field.  

 

However, the best scenario is actually just to get comfortable enough with lenses on an APS-C format camera that you can think in those terms without having to translate into full frame equivalents.  A 35mm f/1.4 lens doesn't change physically because you use a smaller sensor.  It's still a 35mm f/1.4, so just learn how a 35mm f/1.4 behaves on an APS-C camera.  Learn what f-stop will give you the depth of field you want.  Learn what subjects work well with the field of view of a 35mm lens on APS-C.  Then you won't need to worry about the translation.

 

The catch, of course, is for those of us who use both systems.  It definitely takes experience to be equally comfortable in both formats.  I know I'm not yet.  I still translate in my head when I'm using APS-C.  I certainly hope, though, that I will become experienced enough with either to be comfortable without the translations.

 

The same was true in years gone by with people who used both medium format and 35mm--lots of event photographers were caught between the two worlds depending on whether they needed fast response or the best possible image quality.  I think lots of people when they made the jump from 35mm to a Hasselblad 500, for example, started out by trying to translate their lenses into 35mm equivalents in their heads.  This was even worse with a Hasselblad since you were also going from a 3:2 aspect ratio to 1:1.  Most people found they were better served by just learning what lenses were appropriate for what subjects and situations in each format, and forget the translations.  In other words, become fluent in each format language.  Then all the talk of 'equivalence' can drop by the wayside and you can just concentrate on your photography rather than math gymnastics in your head.

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[...] 35mm f/1.4 will behave on your APS-C just like a 50mm f/2 behaves on your full-frame camera.  Same field of view.  Same depth of field. [...]

 

But different light... Under the same light, a 35/1.4 on APS-C behaves like a 50/1.4 on FF with a different DoF due to different sensors. 

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I did a little test between my T and M with same lens. As far as I can tell, no difference in DOF. Is what I suspected, but wanted to verify. Also, no difference in light reaching the sensor so a picture taken at F2 on full frame camera will behave same as F2, same lens, on cropped camera except for sensor sensitivity differences. If there is ANY change in DOF which I didn’t measure scientifically, would be due to an M lens placed further away from the sensor due to conversion ring, but is nominal if it does change the DOF at all.

 

What APSC gives you is a cropped version of FF, period. Everything else is mostly the same. Only difference is the field of view comparison, which is not the same as depth of field.

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I think that to turn the statement " the 35mm f/1.4 will behave on your APS-C just like a 50mm f/2 behaves on your full-frame camera" into a mathematical equation you also have to compare prints of the same field of view enlarged to the same size.  And now we can do that with the same number of pixels behind each image.  But I never do, unless I decide to make a research project of it.

 

Long ago, I realized that 35 mm Tri-X developed in Rodinal was not the way to capture a group shot of a dozen people, I got a nice used Rolleicord which, sadly, I gave away.  But they were different systems for different jobs.  I think that's a good way to work, finding the setup for each camera that gives the most pleasing results. 

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Sorry the lens is not placed further from the sensor; everything would be out of focus. The adapter corrects the difference in register distance.

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I did a little test between my T and M with same lens. As far as I can tell, no difference in DOF. Is what I suspected, but wanted to verify. Also, no difference in light reaching the sensor so a picture taken at F2 on full frame camera will behave same as F2, same lens, on cropped camera except for sensor sensitivity differences. If there is ANY change in DOF which I didn’t measure scientifically, would be due to an M lens placed further away from the sensor due to conversion ring, but is nominal if it does change the DOF at all.

What APSC gives you is a cropped version of FF, period. Everything else is mostly the same. Only difference is the field of view comparison, which is not the same as depth of field.

Sorry the lens is not placed further from the sensor; everything would be out of focus. The adapter corrects the difference in register distance.

The change in DOF is well documented

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Sorry the lens is not placed further from the sensor; everything would be out of focus. The adapter corrects the difference in register distance.

The change in DOF is well documented

Huh???

Every adaptor, extender, etc., puts a lens at a little different distance from the sensor, or film, and there is no correction. Obviously you don’t have an M to TL Mount adapter. There is no lens in the adapter. And the camera itself makes no correction in focus. The way focus works is adjustment of distance within the lens. Take an M lens and move around the focus ring and see what happens. It moves? Magic. The camera itself has nothing to do with focusing. It’s the lens. This is basic stuff.

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