# Shooting APS-C on a full frame RP



## JustUs7 (Feb 13, 2020)

Aside from making a 26.4 megapixel full frame sensor effectively a 16.5 megapixel crop sensor, what are the negatives of this technique for extra reach? 

Seems like an economical way to give your 24-240 RF Zoom an effective 384mm reach in a pinch. In case one doesn’t want to get any closer to that bear. 

Our first Rebel was 10.1 megapixels and our second was 18 megapixels. Seems image quality would be at least as good.

What else is changed? Effective aperture?


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## Mt Spokane Photography (Feb 13, 2020)

Its just cropping the image. 

Unless you are using a crop lens, why crop it as you capture? You can crop the image later, and if you use raw, you will still have the original FF image to re-edit in the future. 

You do not gain any reach, APS-C cameras typically have more pixels, so you get more pixels in the cropped image than you do by cropping a FF image. That increased number of pixels in the final image (compared to cropping FF) is where the seemingly extra reach comes from.

I'd just crop in post, that way I can place the subject where I want it in the final crop.


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## JustUs7 (Feb 13, 2020)

I guess you know you’re new to something when you think you have a good idea and one response says (very politely), “That’s dumb.”

I know that’s not what you said. Thanks for the obvious better alternative.


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## Mt Spokane Photography (Feb 15, 2020)

FamilyGuy said:


> I guess you know you’re new to something when you think you have a good idea and one response says (very politely), “That’s dumb.”
> 
> I know that’s not what you said. Thanks for the obvious better alternative.


Its never dumb to ask a question. If you are shooting jpeg and want to upload your photos quickly to a web site with no prior editing. then it makes sense to set the crop in the camera, so there are situations where it might be very useful.


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## AlanF (Feb 16, 2020)

FamilyGuy said:


> Aside from making a 26.4 megapixel full frame sensor effectively a 16.5 megapixel crop sensor, what are the negatives of this technique for extra reach?
> 
> Seems like an economical way to give your 24-240 RF Zoom an effective 384mm reach in a pinch. In case one doesn’t want to get any closer to that bear.
> 
> ...


I’ll echo that there is no thing as a dumb question, and Mt Spokane would never treat a question as dumb. There are many dumb answers and statements. His wasn’t one of them and it was a neat way of explaining it. You won’t get extra reach because you won’t have any more pixels on target as it’s just like cropping afterwards. What is useful to me is that for most of my shots I do crop greatly and I can do them equally well on a crop camera. So a crop mode means my file sizes will be much smaller, saving space on my cards and computer and allowing faster data transfer and possibly processing. 

Keep asking questions because the more experienced like to help.


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## BenB (Feb 16, 2020)

While crop mode is just like cropping the image in post processing. It does have the advantage that your subject appears bigger in the viewfinder making it easier to check focus, exposure and not be distracted by by things near the edge of the frame.

If you only want a little bit more then stick with 240 and crop after.
If you need feel you need a significant amount more reach than your 240 gives you then switch over.


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## AlanF (Feb 16, 2020)

BenB said:


> While crop mode is just like cropping the image in post processing. It does have the advantage that your subject appears bigger in the viewfinder making it easier to check focus, exposure and not be distracted by by things near the edge of the frame.
> 
> If you only want a little bit more then stick with 240 and crop after.
> If you need feel you need a significant amount more reach than your 240 gives you then switch over.


Ben
My turn for a question. I haven't used a Canon in crop mode. Does the cropped image only fill the whole frame, as it is implied by your answer, or can you view it as a central rectangle in the full screen? The latter has the advantage of a wider field of view for locating and tracking.


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## Sharlin (Feb 16, 2020)

FamilyGuy said:


> Aside from making a 26.4 megapixel full frame sensor effectively a 16.5 megapixel crop sensor, what are the negatives of this technique for extra reach?



The amount of surface area you lose by cropping 1.6x is 1.6^2=2.56, so an APS-C size crop of a 26 megapixel sensor is just a bit over 10 MP.


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## unfocused (Feb 16, 2020)

AlanF said:


> Ben
> My turn for a question. I haven't used a Canon in crop mode. Does the cropped image only fill the whole frame, as it is implied by your answer, or can you view it as a central rectangle in the full screen? The latter has the advantage of a wider field of view for locating and tracking.


With the R, when you are in crop mode, the image fills the frame. Ben is right, it makes focusing and composing easier. The downside is that if you accidentally change to one of the crop modes, you might not realize it unless you are shooting with a DSLR as a second body and notice that the image is a lot larger in the R. (The voice of experience.  )


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## AlanF (Feb 16, 2020)

unfocused said:


> With the R, when you are in crop mode, the image fills the frame. Ben is right, it makes focusing and composing easier. The downside is that if you accidentally change to one of the crop modes, you might not realize it unless you are shooting with a DSLR as a second body and notice that the image is a lot larger in the R. (The voice of experience.  )


Thanks. I would find a crop mode useful on a 50-80 Mpx sensor. But, it would have to have a true RAW output.


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