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Does cropped sensor improve distant capture?

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DMKAlex

DMKAlex

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Let's say I shoot a FF Nikon D5 (21 mpx) with a 400mm, vs a APS-C D500 (21 mpx) with the same lens. The D500 would have an effective range of 600mm (1.5x multiple).

If I crop the D5 (FF) image to size same as the APS-C so the magnification is the same, would the D5 have the same image quality as the APS-C image?
 
Your example is comparing a 21Mpx APS shot to a 12Mpx* APS shot. The higher resolution shot will almost always get you a better result.

* (someone please double check my math)
 
DMKAlex said:
Let's say I shoot a FF Nikon D5 (21 mpx) with a 400mm, vs a APS-C D500 (21 mpx) with the same lens. The D500 would have an effective range of 600mm (1.5x multiple).

If I crop the D5 (FF) image to size same as the APS-C so the magnification is the same, would the D5 have the same image quality as the APS-C image?
Click to expand...
The resolution in terms of numbers of pixels will be higher on the crop sensor-
- But:
The optical performance of the lens will not be higher.
Everything else that makes out the image quality – tonal response, dynamic range, color fidelity, tonality, etc will not be better on the crop sensor.
Check how well this crop from FF holds up:



 
Last edited:
DMKAlex said:
Let's say I shoot a FF Nikon D5 (21 mpx) with a 400mm, vs a APS-C D500 (21 mpx) with the same lens. The D500 would have an effective range of 600mm (1.5x multiple).

If I crop the D5 (FF) image to size same as the APS-C so the magnification is the same, would the D5 have the same image quality as the APS-C image?
Click to expand...
Image quality has so many attributes, both objectively and subjectively. Pixel count and Resolution is just one of them.

The 41 MP image from Nokia has already proof that :-D

What IQ attribute of D5-vs-D500 do you want to compare?
 
PerL said:
DMKAlex said:
Let's say I shoot a FF Nikon D5 (21 mpx) with a 400mm, vs a APS-C D500 (21 mpx) with the same lens. The D500 would have an effective range of 600mm (1.5x multiple).

If I crop the D5 (FF) image to size same as the APS-C so the magnification is the same, would the D5 have the same image quality as the APS-C image?
Click to expand...
The resolution in terms of numbers of pixels will be higher on the crop sensor-
- But:
The optical performance of the lens will not be higher.
Everything else that makes out the image quality – tonal response, dynamic range, color fidelity, tonality, etc will not be better on the crop sensor.
Check how well this crop from FF holds up:



Click to expand...
The D5 would be like using a very good 8.9MP crop sensor camera, however, the D500 would be a very good 21MP crop sensor camera.

--
drj3
 
MediaArchivist said:
Your example is comparing a 21Mpx APS shot to a 12Mpx* APS shot. The higher resolution shot will almost always get you a better result.

* (someone please double check my math)
Click to expand...
Since you asked... :)

Megapixels are area. Crop factors are linear. Since you will be cropping 1.5x away from the diagonal, you have to square that crop to determine the loss of area. 1.5x1.5= 2.25. So it's actually a 2.25x crop by area. Meaning 21/2.25 = 9.33 MP remaining.

If we want to take it further, a 2x crop from a FF sensor leaves only 1/4 the area (4x area crop). Meaning you'd need a 80MP FF sensor to get the same "reach" as 20MP m4/3 with the same lens. And 2.7x crop means a 7.29x reduction in area, so you need a 146MP FF sensor to be able to crop into a 20MP 1" sensor like the RX10 IV.
 
tkbslc said:
MediaArchivist said:
Your example is comparing a 21Mpx APS shot to a 12Mpx* APS shot. The higher resolution shot will almost always get you a better result.

* (someone please double check my math)
Click to expand...
Since you asked... :)

Megapixels are area. Crop factors are linear. Since you will be cropping 1.5x away from the diagonal, you have to square that crop to determine the loss of area. 1.5x1.5= 2.25. So it's actually a 2.25x crop by area. Meaning 21/2.25 = 9.33 MP remaining.
Click to expand...
Actually that's with a lot of rounding and approximations. If you take the actual dimensions of FF and APS-C sensors you will find the crop by area to be 2.59x, meaning 21/2.59 = 8.1 MP remaining.
tkbslc said:
If we want to take it further, a 2x crop from a FF sensor leaves only 1/4 the area (4x area crop). Meaning you'd need a 80MP FF sensor to get the same "reach" as 20MP m4/3 with the same lens. And 2.7x crop means a 7.29x reduction in area, so you need a 146MP FF sensor to be able to crop into a 20MP 1" sensor like the RX10 IV.
Click to expand...
 
mamallama said:
tkbslc said:
MediaArchivist said:
Your example is comparing a 21Mpx APS shot to a 12Mpx* APS shot. The higher resolution shot will almost always get you a better result.

* (someone please double check my math)
Click to expand...
Since you asked... :)

Megapixels are area. Crop factors are linear. Since you will be cropping 1.5x away from the diagonal, you have to square that crop to determine the loss of area. 1.5x1.5= 2.25. So it's actually a 2.25x crop by area. Meaning 21/2.25 = 9.33 MP remaining.
Click to expand...
Actually that's with a lot of rounding and approximations. If you take the actual dimensions of FF and APS-C sensors you will find the crop by area to be 2.59x, meaning 21/2.59 = 8.1 MP remaining.
mamallama said:
If we want to take it further, a 2x crop from a FF sensor leaves only 1/4 the area (4x area crop). Meaning you'd need a 80MP FF sensor to get the same "reach" as 20MP m4/3 with the same lens. And 2.7x crop means a 7.29x reduction in area, so you need a 146MP FF sensor to be able to crop into a 20MP 1" sensor like the RX10 IV.
Click to expand...
Click to expand...
If you want to be more precise, then you need to use the specific cameras, instead of the generic APS crop. Based on the DPR reviews, the following is the crop of the D5 to the sensor size of the D500.

[(23.5/35.9) X 5588] X [ (15.7/23.9) X 3712] = 8.9MP

--
drj3
 
Last edited:
DMKAlex said:
Let's say I shoot a FF Nikon D5 (21 mpx) with a 400mm, vs a APS-C D500 (21 mpx) with the same lens. The D500 would have an effective range of 600mm (1.5x multiple).

If I crop the D5 (FF) image to size same as the APS-C so the magnification is the same, would the D5 have the same image quality as the APS-C image?
Click to expand...
...assuming (and these assumptions are key) that the scene is shot from the same position with the same lens at the same focal length, aperture, and exposure time, and also assuming that the sensors have the same pixel count and record the same proportion of light falling on them, and the FF photo is cropped to the same framing as the APS-C photo, then, yes, the APS-C photo will have "higher IQ" because all else is equal and it puts more pixels on the subject.

However, the above presumes the desired photo is taken. If, for example, one camera has faster and/or more accurate AF than the other, then even a small difference in focus accuracy may result in either losing the IQ advantage or extending the IQ advantage. If one camera has a higher frame rate than the other and thus captures a better photo than the other, then this better capture may trump any IQ advantage the other camera has. Etc., etc., etc..
 
mamallama said:
tkbslc said:
MediaArchivist said:
Your example is comparing a 21Mpx APS shot to a 12Mpx* APS shot. The higher resolution shot will almost always get you a better result.

* (someone please double check my math)
Click to expand...
Since you asked... :)

Megapixels are area. Crop factors are linear. Since you will be cropping 1.5x away from the diagonal, you have to square that crop to determine the loss of area. 1.5x1.5= 2.25. So it's actually a 2.25x crop by area. Meaning 21/2.25 = 9.33 MP remaining.
Click to expand...
Actually that's with a lot of rounding and approximations. If you take the actual dimensions of FF and APS-C sensors you will find the crop by area to be 2.59x, meaning 21/2.59 = 8.1 MP remaining.
Click to expand...
Which two sensors did you compare?

mamallama said:
mamallama said:
If we want to take it further, a 2x crop from a FF sensor leaves only 1/4 the area (4x area crop). Meaning you'd need a 80MP FF sensor to get the same "reach" as 20MP m4/3 with the same lens. And 2.7x crop means a 7.29x reduction in area, so you need a 146MP FF sensor to be able to crop into a 20MP 1" sensor like the RX10 IV.
Click to expand...
Click to expand...
 
tkbslc said:
mamallama said:
tkbslc said:
MediaArchivist said:
Your example is comparing a 21Mpx APS shot to a 12Mpx* APS shot. The higher resolution shot will almost always get you a better result.

* (someone please double check my math)
Click to expand...
Since you asked... :)

Megapixels are area. Crop factors are linear. Since you will be cropping 1.5x away from the diagonal, you have to square that crop to determine the loss of area. 1.5x1.5= 2.25. So it's actually a 2.25x crop by area. Meaning 21/2.25 = 9.33 MP remaining.
Click to expand...
Actually that's with a lot of rounding and approximations. If you take the actual dimensions of FF and APS-C sensors you will find the crop by area to be 2.59x, meaning 21/2.59 = 8.1 MP remaining.
Click to expand...
Which two sensors did you compare?
Click to expand...
Don't remember, but I think a Sony FF and a Canon APS-C.
tkbslc said:
tkbslc said:
tkbslc said:
If we want to take it further, a 2x crop from a FF sensor leaves only 1/4 the area (4x area crop). Meaning you'd need a 80MP FF sensor to get the same "reach" as 20MP m4/3 with the same lens. And 2.7x crop means a 7.29x reduction in area, so you need a 146MP FF sensor to be able to crop into a 20MP 1" sensor like the RX10 IV.
Click to expand...
Click to expand...
Click to expand...
 
Great Bustard said:
DMKAlex said:
Let's say I shoot a FF Nikon D5 (21 mpx) with a 400mm, vs a APS-C D500 (21 mpx) with the same lens. The D500 would have an effective range of 600mm (1.5x multiple).

If I crop the D5 (FF) image to size same as the APS-C so the magnification is the same, would the D5 have the same image quality as the APS-C image?
Click to expand...
...assuming (and these assumptions are key) that the scene is shot from the same position with the same lens at the same focal length, aperture, and exposure time, and also assuming that the sensors have the same pixel count and record the same proportion of light falling on them, and the FF photo is cropped to the same framing as the APS-C photo, then, yes, the APS-C photo will have "higher IQ" because all else is equal and it puts more pixels on the subject.

However, the above presumes the desired photo is taken. If, for example, one camera has faster and/or more accurate AF than the other, then even a small difference in focus accuracy may result in either losing the IQ advantage or extending the IQ advantage. If one camera has a higher frame rate than the other and thus captures a better photo than the other, then this better capture may trump any IQ advantage the other camera has. Etc., etc., etc..
Click to expand...
We know. There are a lot of "ifs".
 
mamallama said:
tkbslc said:
mamallama said:
tkbslc said:
MediaArchivist said:
Your example is comparing a 21Mpx APS shot to a 12Mpx* APS shot. The higher resolution shot will almost always get you a better result.

* (someone please double check my math)
Click to expand...
Since you asked... :)

Megapixels are area. Crop factors are linear. Since you will be cropping 1.5x away from the diagonal, you have to square that crop to determine the loss of area. 1.5x1.5= 2.25. So it's actually a 2.25x crop by area. Meaning 21/2.25 = 9.33 MP remaining.
Click to expand...
Actually that's with a lot of rounding and approximations. If you take the actual dimensions of FF and APS-C sensors you will find the crop by area to be 2.59x, meaning 21/2.59 = 8.1 MP remaining.
Click to expand...
Which two sensors did you compare?
Click to expand...
Don't remember, but I think a Sony FF and a Canon APS-C.
Click to expand...
Canon is 1.6x crop. so my above method got us to 2.56x crop anyway, vs the 2.59 in your math. Everyone else uses 1.5x crop, which is what I used to get 2.25x.

There are minor variations in size, though, as your math shows. I don't think very many FF sensors are exactly 24x36, nor are any APS-C sensors exactly 1.5 or 1.6x crop, but it's close enough.
 
khunpapa said:
DMKAlex said:
Let's say I shoot a FF Nikon D5 (21 mpx) with a 400mm, vs a APS-C D500 (21 mpx) with the same lens. The D500 would have an effective range of 600mm (1.5x multiple).

If I crop the D5 (FF) image to size same as the APS-C so the magnification is the same, would the D5 have the same image quality as the APS-C image?
Click to expand...
Image quality has so many attributes, both objectively and subjectively. Pixel count and Resolution is just one of them.

The 41 MP image from Nokia has already proof that :-D
Click to expand...
True:

http://evan-theelectricalengineer.blogspot.co.il/2013/10/nikon-d800e-vs-nokia-lumia-1020.html
khunpapa said:
What IQ attribute of D5-vs-D500 do you want to compare?

--
Flashes of my Memory.
Click to expand...
 
Not yet mentioned I think:

if shooting deliberately "wider than wanted" with the intention of cropping back to the desired subject later, the issues of subject focus, Auto WB and Auto exposure must be considered besides the IQ issue.

The larger than relevant field of view "considered" by the camera's automation in this case, can throw things off from what would have otherwise happened with a native framing that concentrates on just your desired bit of the field of view.

For example, face-detect AF may fail to lock on, or may lock onto a different person altogether. Movement tracking AF may get more easily distracted. And pattern based exposure metering may make different and potentially inappropriate compensations - in respect of supposed backlighting, or the amount of bright highlights visible, etc...

One can simulate these effects (aside from focus) in any good Raw converter by showing the whole capture first, using the software's own Auto WB and Auto Exposure functions, and then cropping down to a smaller part of the picture and using those same functions again. Different numbers are seen this second time, from the 'auto' algorithms.
 
tkbslc said:
If we want to take it further, a 2x crop from a FF sensor leaves only 1/4 the area (4x area crop).
Click to expand...
I'm not understanding how a 2x crop becomes a 4x crop??
 
mamallama said:
Actually that's with a lot of rounding and approximations. If you take the actual dimensions of FF and APS-C sensors you will find the crop by area to be 2.59x, meaning 21/2.59 = 8.1 MP remaining.
Click to expand...
To complicate matters more Canon APS sensors have a 1.6 crop factor.
 
mamallama said:
Don't remember, but I think a Sony FF and a Canon APS-C.
Click to expand...
Canon APS sensors are smaller than the APS-C sensor used by other manufacturers. 1.5 vs 1.6 crop factor.
 
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