Apeture affecte from fulframe too APSC ?

[Jared]

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Why would i have to shoot at f/2 and why would i have to push in PP? I have a f/1.4 lens so i will shoot at f/1.4 and i won't have tu push this way. Sorry Jared but this does not make any sense for me. For all purposes but DoF, at the same aperture, my 50/1.4 lens on FF behaves the same way as my 35/1.4 lens on APS-C. 

 

I meant that you would shoot at f/2 with the 50mm on full frame since that is the maximum aperture for my theoretically equivalent full frame lens.  

 

An exposure of:

  50mm focal length, f/2 aperture, ISO 3200, 1/60s exposure, full frame camera, 24 megapixel chip

Should look identical to:

  35mm focal length, f/1.4 aperture, ISO 1600, 1/60s exposure, APS-C camera, 24 megapixel chip

 

Same field of view, same depth of field, same signal-to-noise ratio (noise characteristics), same resolution, same image brightness, same everything.  You could use your 35mm at f/1.4 on APS-C or your 50mm at f/2 (assuming that was the maximum aperture for each) on full frame to get effectively the same picture. 

 

Jaapv is absolutely correct that there is nothing new here.  The laws of physics were the same in film days.  As always, the best approach is probably not to worry about any of this equivalence and just learn how your various lenses behave on your various bodies by taking actual photographs.  That's the ultimate point, yes?

Edited January 29, 2018 by Jared

[Jared]

Now, this is all nothing new. We had this whole discussion identically when the M9 came out; the sensor was identical to the M8 except for size, yet some people couldn't believe that, as noise performance appeared to be one EV better. 

At any rate, there is your apples-to-apples comparison, nine years ago.

 

As for the DOF comparison. The perception of DOF varies by more than one EV value between different persons because of eye acuity variations, wearing spectacles or not, etc.

Look at a print a bit closer and you'll halve your DOF. Or just print twice as large. Have a look at a 100% crop on your screen and it will have vanished altogether. So who cares?

 

Just learn to use your tools to take the photograph you want to take. And that is done in actual life, not in theoretical discussions.

 

 

Absolutely correct, and the M8/M9 is a great example.

[lct]

I meant that you would shoot at f/2 with the 50mm on full frame since that is the maximum aperture for my theoretically equivalent full frame lens.  [...]

 

This theoritical equivalence is what i am challenging here. Let's agree to differ on this topic as we see it in an opposite way.

[Jared]

I'm fine if we don't end up on the same page with regard to how to understand these lenses, but I'm curious where your difference of opinion lies.  I believe you agree that:

 

-35mm on APS-C gives the same field of view as 50mm on full frame

-For a given field of view, you get one more "stop" (approximately) of depth of field out of APS-C, so a 35mm @ f/1.4 on APS-C would give the DoF of a 50mm @ f/2 on full frame

 

So I assume the difference in perspective is related to exposure?  If it makes you feel any better, I certainly agree that an f/1.4 lens, regardless of focal length or camera format, will need the same ISO and shutter speed for a given exposure brightness--f/1.4 will yield an image that is just as bright on an APS-C camera as it is on a full frame camera or a 4/3" camera.  The same exposure is required to fill the histogram from shadows to highlights.  

[jmahto]

It is astounding that this subject and argument are still going on after what, 100 years?

.

It means only two things

i) it is inherently difficult thing to grasp

or

ii) internet experts confuse the knowledge seekers with complicated (and sometimes inaccurate) responses.

 

I will go with second one.

[scott kirkpatrick]

Short answers draw criticism for their incompleteness.  Long answers confuse.  This can go on for a long time.

[Kim Dahl]

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I think I've got an answer to my question from the start. Thank you so much to all who have participated in the conversation.

vh Kim

- and happy with TL2 35 mm summilux and Leica ME 24, 35 and 90 summichrom

[lct]

[...] I'm curious where your difference of opinion lies. [...]

 

Well if you ask... but this will be my last word here (they all say that ).

To me the equivalence between 35/1.4 on APS-C and 50/2 on FF is basically flawed because it makes believe that what is true for DoF is true for the rest. Imagine a young photog or an oldie like me whose technical knowledge could be (much) better. He reads your educated posts and thinks: Great i can get the same results with a cheaper 50/2 on FF as with a 35/1.4 on APS-C. Then he buys the 50/2, tries to take some pics of his children indoor and realizes that he cannot do it for lack of light. Then he complains and you reassure him: No problem suffice it to push in PP. Then the newbie or oldie tries to push this way but the pics were taken at 3200 iso so he gets noisy results at the end of the day. Happy he won't be.

Bottom line: The best advice i can give newbies and oldies (and others) is to buy a 50/1.4 if they're after an equivalent lens on FF as a 35/1.4 on APS-C. The only thing they will miss is the exact same DoF. Now if DoF is of paramount importance, then, and only then, pick a 50/2.

Edited January 30, 2018 by lct

[Jared]

Short answers draw criticism for their incompleteness.  Long answers confuse.  This can go on for a long time.

 

 

Yes, that is often the case.  Give a comprehensive response to someone that accounts for all the subtleties and those same subtleties often obscure the basic point.  Give anything less than a comprehensive response and you will get people correcting or refining your response.  

[Jared]

 

Well if you ask... but this will be my last word here (they all say that ).

To me the equivalence between 35/1.4 on APS-C and 50/2 on FF is basically flawed because it makes believe that what is true for DoF is true for the rest. Imagine a young photog or an oldie like me whose technical knowledge could be (much) better. He reads your educated posts and thinks: Great i can get the same results with a cheaper 50/2 on FF as with a 35/1.4 on APS-C. Then he buys the 50/2, tries to take some pics of his children indoor and realizes that he cannot do it for lack of light. Then he complains and you reassure him: No problem suffice it to push in PP. Then the newbie or oldie tries to push this way but the pics were taken at 3200 iso so he gets noisy results at the end of the day. Happy he won't be.

Bottom line: The best advice i can give newbies and oldies (and others) is to buy a 50/1.4 if they're after an equivalent lens on FF as a 35/1.4 on APS-C. The only thing they will miss is the exact same DoF. Now if DoF is of paramount importance, then, and only then, pick a 50/2.

 

 

OK, I won't ask you to defend your choice any further.  Certainly there is no current substitute for a 50mm f/1.4 full frame lens on APS-C or (even worse) in 4/3" format.  So if that's what you want, a smaller format is not an option.

 

I will mention, though, that your other example--the 50/2 on FF pushed an extra stop vs 35mm/1.4 on APS--is probably not a good one.  If you were unhappy with the noise at ISO 3200 on full frame you will be identically unhappy with the noise on APS at 1600.  They will have the exact same noise characteristics if the chips are of the same quality and design.  Really.

 

I'm not saying this to draw you out again or to bait you in any way.  Feel free to bow out of the thread if you are tired of the repetition or the topic in general.  Just wouldn't want to leave others with the impression that this particular use case is a good reason to one solution over the other.  The noise with a 50/2 on full frame at ISO 3200 should be the same as the noise with a 35mm/1.4 on APS at ISO 1600.  

[jaapv]

[...] Sensor technology and specifications being equal

[wizard]

...

If the distance from the sensor to an M lens is same on on M camera as is using converter for M to T, all would be equal except for field of view the sensor can handle. period. DOF would not change.

...

 

There you go. That's what an adapter is meant for, to make up for a missing distance between the lens and the sensor or film plane. And, to be more exact here, any adapter intended to allow using a given lens on a camera having a smaller flange to sensor (or film) distance is dimensioned to meet exactly (within manufacturing tolerances, of course) the flange to sensor (or film) distance that given lens was designed for. That's also why you will not find any adapters matching a lens designed for a given flange to sensor (or film) distance to a camera having a larger flange to sensor (or film) distance than the given flange to sensor (or film) distance. Note that I am not talking about extension tubes here, as for example used for macro work, but instead about adapters allowing to focus a given lens to infinity.

 

So everyone who stated that f2 remains f2, regardless of whether FF or APSC is concerned, is exactly right. And DoF does not change either, as everyone can find out by doing a simple test: Use a given same lens on both a FF and an APSC camera to photograph exactly the same subject, from exactly the same location and angle. Of course, the FF image will show a wider angle of view, due to the larger size of the sensor. Then blow up your FF image to a size where the field of view covered on the image taken with the APSC camera is identical to the size of the APSC image. That is, print (or generate on a screen) two photographs having exactly the same size and content (which means that you will have to cut away all the portions of the FF image which the APSC sensor did not record, due to its smaller size. THEN compare DoF, and you will find absolutely no difference at all, which is as is should be, since the same lens was used to record the same scene from the same position and angle.

 

It may take a little while to understand, but in the end you will come to the same conclusion.

 

Andy

[jaapv]

Yes, that has been the confusion all throughout this thread: equalising the field of view through cropping vs. moving.

[wizard]

Yes, that has been the confusion all throughout this thread: equalising the field of view through cropping vs. moving.

 

I have learnt that long ago, do not change more than one parameter at a time, or else you may well be fooled by the results  .

[Jared]

[...] Sensor technology and specifications being equal

 

 

Yes, that is the assumption.  That's why I said, "chips of the same quality and design".  

[Jared]

There you go. That's what an adapter is meant for, to make up for a missing distance between the lens and the sensor or film plane. And, to be more exact here, any adapter intended to allow using a given lens on a camera having a smaller flange to sensor (or film) distance is dimensioned to meet exactly (within manufacturing tolerances, of course) the flange to sensor (or film) distance that given lens was designed for. That's also why you will not find any adapters matching a lens designed for a given flange to sensor (or film) distance to a camera having a larger flange to sensor (or film) distance than the given flange to sensor (or film) distance. Note that I am not talking about extension tubes here, as for example used for macro work, but instead about adapters allowing to focus a given lens to infinity.

 

So everyone who stated that f2 remains f2, regardless of whether FF or APSC is concerned, is exactly right. And DoF does not change either, as everyone can find out by doing a simple test: Use a given same lens on both a FF and an APSC camera to photograph exactly the same subject, from exactly the same location and angle. Of course, the FF image will show a wider angle of view, due to the larger size of the sensor. Then blow up your FF image to a size where the field of view covered on the image taken with the APSC camera is identical to the size of the APSC image. That is, print (or generate on a screen) two photographs having exactly the same size and content (which means that you will have to cut away all the portions of the FF image which the APSC sensor did not record, due to its smaller size. THEN compare DoF, and you will find absolutely no difference at all, which is as is should be, since the same lens was used to record the same scene from the same position and angle.

 

It may take a little while to understand, but in the end you will come to the same conclusion.

 

Andy

 

I agree that what you said is true, but I'm less sure of the relevance.

 

Shoot a 50mm f/2 lens on APS-C

Shoot a 50mm f/2 lens on full frame and then crop it down in software to APS-C

 

Depth of field is the same in both images.  The size of the magnified circles of confusion (either on screen or in a print) will be identical.  The image the lens formed and projected onto the detector does not depend on the detector.  No argument there.  

 

The problem is, that's not how people think about using lenses.  At least, it's not how I think about them.  The first thing I consider in an image is what field of view do I want.  I then choose the focal length that will get me that field of view.  Obviously, if I don't have that focal length available I will make some adjustments (like zooming with my feet or building a mosaic or deciding to crop in software later).  

 

If I want the perspective and field of view of a normal lens for whatever format I'm shooting, I'm going to pick something where the focal length of the lens is approximately equal to (or, often, slightly longer than) the diagonal measurement of the sensor.  Nothing magic about it, but that's what is generally meant by a normal lens.  On a full frame camera, that's a 50mm lens.  On 4/3" camera it's a 25mm.  On an APS-C camera it's a usually a 35mm.  On medium format it's usually a 75mm (depending on which medium format, of course).  If I am only changing one variable with my sensor, the one I would want to change is the focal length of the lens and then see what I get. 

 

I do agree, though, that cropping by using a crop sensor camera is no different from cropping in software.  The sensor does not in affect the light produced by the lens.

Edited January 31, 2018 by Jared

[UliWer]

...

 

The problem is, that's not how people think about using lenses.  At least, it's not how I think about them.  The first thing I consider in an image is what field of view do I want.  I then choose the focal length that will get me that field of view.  Obviously, if I don't have that focal length available I will make some adjustments (like zooming with my feet or building a mosaic or deciding to crop in software later).  

 

If I want the perspective and field of view of a normal lens for whatever format I'm shooting, I'm going to pick something where the focal length of the lens is approximately equal to (or, often, slightly longer than) the diagonal measurement of the sensor.  Nothing magic about it, but that's what is generally meant by a normal lens.  On a full frame camera, that's a 50mm lens.  On 4/3" camera it's a 25mm.  On an APS-C camera it's a usually a 35mm.  On medium format it's usually a 75mm (depending on which medium format, of course).  If I am only changing one variable with my sensor, the one I would want to change is the focal length of the lens and then see what I get. 

I do agree, though, that cropping by using a crop sensor camera is no different from cropping in software.  The sensor does not in affect the light produced by the lens.

 

...

 

 

The problem you describe is only relevant if you take a certain focal length with a certain field of view on a certain size of the medium for you pictures as a standard from which you start to think about lenses. The expression "full frame" shows it: it is not "full" but a very tiny crop from the sizes taken for standards before Barnack came and constructed a camera for 35mm film. And your definition of a standard field of view shows it as well: 50mm is way off the diagonal of the medium- that would be something like 43mm which makes some difference. But with 43mm Berek could not design a lens with the resolution they needed to compete with larger formats. He could with 50mm - which btw sounded much better than 43, even when it really was 51.9mm or something like that. So the "standard lens" was created by some needs defined by the glass not by the photographers. It became a mere custom. Gustav Mahler said "Tradition ist Schlamperei" (tradition is sloppiness).

 

It was just sloppiness when we thought that the M8 wasn't a real camera, for we all came from the traditon of "full frame".  

 

I think the approach will change quickly. Most people who start with photography now don't start with 24*36mm formats - but with smartphone cameras which have a sensor size much, much samller - not even defined. Does anyone who starts with a phonecamera know the focal length of its lens? He won't bother. When this person who is used to a very variable field of view mostly on the extreme wide side with extreme deep depth of focus changes to "full frame" he will be shocked - like we who were used to 24*36mm would be shocked if we suddenly changed to 4*5": our lenses wouldn't be  be usabale we would have to learn completely new what depth of focus can be achieved by a certain f-stop. 

 

It will be interesting to see, if those newcomers who started with smartphones will accept our standards. 

Edited January 31, 2018 by UliWer

[Jared]

Yes, needing to discuss equivalence and convert from one reference format to another format is only relevant at all because 35mm is still the lingua franca of the photographic world.   

[david strachan]

Yes, needing to discuss equivalence and convert from one reference format to another format is only relevant at all because 35mm is still the lingua franca of the photographic world.

 

That's the whole point really. And for many, misses it entirely.

 

...

Edited February 1, 2018 by david strachan

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[wizard]

 

If I want the perspective and field of view of a normal lens for whatever format I'm shooting, I'm going to pick something where the focal length of the lens is approximately equal to (or, often, slightly longer than) the diagonal measurement of the sensor.  Nothing magic about it, but that's what is generally meant by a normal lens.  On a full frame camera, that's a 50mm lens.  On 4/3" camera it's a 25mm.  On an APS-C camera it's a usually a 35mm.  On medium format it's usually a 75mm (depending on which medium format, of course).  If I am only changing one variable with my sensor, the one I would want to change is the focal length of the lens and then see what I get. 

 

I do agree, though, that cropping by using a crop sensor camera is no different from cropping in software.  The sensor does not in affect the light produced by the lens.

 

I think we're on the same page here. My argument was a scientifc one so to speak, taking into account the laws of optics and physics. Your argument is based on everyday practice, and I fully agree with what you have said. However, when discussing DoF between various sensor or film formats, I believe it is essential for people to understand some basics in optics, otherwise confusion is inevitable (and I am not talking about the circle of confusion here   ). Turning back to the OP's question whether a f2 35mm Summicron-M is still a f2 35mm Summicron-M if used on an APSC camera or rather turns into an f? 50mm lens, the answer clearly is that the lens stays as it is, a f2 35mm Summicron-M, as mounting it to another camera body will not have any effect on the lens. If the question would have been along the lines 'when I use a f2 35mm Summicron-M on my FF camera, do I have to use a different lens on an APSC camera to obtain the same image', well, then the answer would have been 'Yes, you need a different focal length to capture the same image from the same position, and since you have to use a different (read smaller) focal length, there will be an effect on DoF, too'.

Edited February 1, 2018 by wizard