Q3 Crop Modes and Equivalent Depths of Field Question

[PitiWong]

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1 minute ago, David Wien said:

I fail to understand your scruples; one is cropping in the camera, the other cropping on the computer. Either achieves the same result. The 35mm issue is simply to expalin that the photo now extends only as far as that of a 35mm lens, not using the full angle of view of the 28mm actual lens.

David

sorry for my broken English.

What I mean is, if the Q3 crop mode is utilizing a smaller portion of the full frame sensor to achieve 35mm. (for example) equivalent DOF.

then it is far better than a normal "cropping" that we are using on photo edition on computer.  

I am not sure I understanding right or wrong?

[Kozonoh]

If you crop your raw in pp the result is much better than the one you get with in camera cropping which is possible only with jpegs. If you use the crop mode with raw it doesn’t crop anything . It just shows you which portion of the image you would have if…

[David Wien]

DOF is controlled by the lens and its aperture, and thus it is not affected in this mode. You actually have to use appropriate software to show the cropped effect on the raw files. I forget which software this is. I use Photolab and, in that program, the raw version is full frame, while the jpeg is cropped to whatever you have set in the camera. Some software has a setting to allow you to crop the raw file automatically.

Do a couple of experiments and you will see! You will notice that the out of camera jpeg is not as good as the crop you can do to the raw file.

David

[nariza7]

I believe the crop mode is mainly a post-crop, hence the DNGs stay at 28mm field of view. If you cropped in post at 35mm or some other FOV, it’d look similar to the built in crop mode. I don’t think it crops by utilizing a smaller portion of the sensor otherwise it’d affect depth (unlike Sony and others who actually do use a smaller part of the sensor)

[jaapv]

3 minutes ago, nariza7 said:

I don’t think it crops by utilizing a smaller portion of the sensor otherwise it’d affect depth

Isn't the very definition of crop using a smaller portion of the sensor/film? It does affect DOF, also on the Q, any other camera as well.

[ksrhee]

2 hours ago, PitiWong said:

sorry for my broken English.

What I mean is, if the Q3 crop mode is utilizing a smaller portion of the full frame sensor to achieve 35mm. (for example) equivalent DOF.

then it is far better than a normal "cropping" that we are using on photo edition on computer.  

I am not sure I understanding right or wrong?

I don’t see any difference from in-camera cropping versus post cropping.  The advantage in in-camera cropping is that the Q3 shows you the frame line so that you can frame your shot in the cropped mode.  The cropping will impact the DOF since it is equivalent to enlarging, and the COC changes as a result and will impact DOF.  

[Kozonoh]

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The difference is whether you shoot in raw in which case the crop is only an indication or in jpeg in which the crop is implemented but which has a very strong compression inducing a real loss of iq.

[Guest]

11 minutes ago, Kozonoh said:

The difference is whether you shoot in raw in which case the crop is only an indication or in jpeg in which the crop is implemented but which has a very strong compression inducing a real loss of iq.

Two points here:

1) There IS a difference to exposure setting when using crop. The camera will only measure exposure from the cropped area ( obviously not an issue if you are using spot metering).

2) If using Lightroom (classic or cloud) then the crop area is automatically applied when the image is imported (the crop info. is in the metadata)

 

[nariza7]

2 hours ago, jaapv said:

Isn't the very definition of crop using a smaller portion of the sensor/film? It does affect DOF, also on the Q, any other camera as well.

Post crop and pre crop are different I believe. Pre crop is like full frame becoming aps-c with crop factor. It uses partial sensor. Post crop maintains the full frame look since it takes the photo with the full sensor and just cuts out part of it.

[Kozonoh]

To Corius: yes, if, but it’s a big if.

[01af]

vor 51 Minuten schrieb nariza7:

Post-crop and pre-crop are different ...

No, they're not.

.

vor 51 Minuten schrieb nariza7:

Pre-crop is like full-frame becoming APS-C with crop factor. It uses partial sensor.

Yes.

.

vor 51 Minuten schrieb nariza7:

Post-crop maintains the full-frame look ...

No, it doesn't.

.

vor 51 Minuten schrieb nariza7:

... it takes the photo with the full sensor and just cuts out part of it.

And why do you think this would effectively be any different from pre-crop? Cropping parts out of a larger sensor means using partial sensor, just like pre-cropping does.

[jaapv]

1 hour ago, nariza7 said:

Post crop and pre crop are different I believe. Pre crop is like full frame becoming aps-c with crop factor. It uses partial sensor. Post crop maintains the full frame look since it takes the photo with the full sensor and just cuts out part of it.

With all due respect, this does not make sense. Cropping is by definition making use of part of the image, no matter at what stage. Be it at camera level or at the end by taking scissors to a larger print.

[David Wien]

12 minutes ago, jaapv said:

With all due respect, this does not make sense. Cropping is by definition making use of part of the image, no matter at what stage. Be it at camera level or at the end by taking scissors to a larger print.

Absolutely — and I see no reason to claim that the DOF is any different in the centre than in the unused part of the full frame.

David

Edited May 12, 2024 by David Wien

[Guest]

Just to circle back to the start of the argument discussion, it's perhaps worth mentioning that the cropped equivalent Aperture is given by:

Aperture Equivalences

A(eq) = Crop/28 * A

E.g. at 50mm crop and f3.2

A(eq) = 50/28 * f3.2 = f5.7

(assuming that you accept the Q3 focal length is 28mm, but that's another topic  )

[Qwertynm]

Just keep in mind that you’re always shooting 28 1.7 in terms of exposure. The resulting image will look like f/1.7 * crop factor but it will expose like a 28 1.7 would in terms of ISO snd shutterspeed

[jaapv]

2 hours ago, Corius said:

Just to circle back to the start of the argument discussion, it's perhaps worth mentioning that the cropped equivalent Aperture is given by:

Aperture Equivalences

A(eq) = Crop/28 * A

E.g. at 50mm crop and f3.2

A(eq) = 50/28 * f3.2 = f5.7

(assuming that you accept the Q3 focal length is 28mm, but that's another topic  )

That is not the aperture but the DOF. The aperture will always be the same, only the magnification differs. 

[nariza7]

Ah, I think you guys are right! While looking into it more, the cropped photo will look the same as long as the distance to the subject doesn't change, and the same lens is used. Many sources mentioned that, but I think this example explains it the clearest for me.

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[PitiWong]

I think the best way is has Leica to answer this question. We don't really know how them designs this Crop Mode.

Or, my humble opinion:

taka a photo, using Q3 vs a 18mm lens on APSC to see distance from the subject is the same or not.

and using crop mode 50mm. VS a 35mm. lens on APSC.

 

[David Wien]

4 hours ago, PitiWong said:

I think the best way is has Leica to answer this question. We don't really know how them designs this Crop Mode.

Or, my humble opinion:

taka a photo, using Q3 vs a 18mm lens on APSC to see distance from the subject is the same or not.

and using crop mode 50mm. VS a 35mm. lens on APSC.

 

There's an easier way: set 90mm crop in the Q3. Take a picture with large jpeg and raw files, remembering what is inside the small square shown in the viewfinder. Compare the jeg with the raw file. If your software doesnt do the crop for you automatically, as PhotoLab doesnt, do it on the jpeg with the mouse.

Compare and contrast.

.My results were identical, with the exception that the compression artifacts were worse on the jpeg that had been made in the camera.

David

 

Edited May 13, 2024 by David Wien

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[Guest]

10 hours ago, jaapv said:

That is not the aperture but the DOF. The aperture will always be the same, only the magnification differs. 

I wrote "Equivalent Aperture". ie the Aperture that would required when capturing with a full frame sensor that yields the same DOF as that produced by a cropped image

So, a Q3 50mm crop at f3.2 has the same DOF as a full frame image captured with a 50mm lens at f5.7.