EOS R5 Mark II In what way does higher a higher resolution sensor impact image quality?

[kudro]

Let’s say I’m not planning on printing on large paper or further cropping. Would using and R5ii, for example, in crop mode image quality be noticeably different than using a similar quality lens that with a 1.6 times larger focal length?

For example, does software use those extra pixels to reduce noise or otherwise improve final image quality?

[SignifDigits]

@ebiggs1 "Native focal length..." was meant to imply effective focal length for the sensor, not lens focal length.  A 125mm lens would have an effective focal length of 200mm using a 1.6 crop factor.  Given the discussion about number of pixels I believed that that was what the OP was asking about.  Thus, if we compared a 70-200mm lens at f/4 at 125mm using sensor cropping on the R5 Mark II versus  200mm lens at f/4 at 200mm using the full sensor the "Native" (versus effective) focal length would, all other things being equal (assuming that neither 125mm nor 200mm were especially distorted, for instance) would provide more data in the image and a better quality final result should be possible.

[jrhoffman75]

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@ebiggs1 wrote:

"Answer would be yes because when you select the crop mode you reduce the image size from ~45 megapixels to ~17 megapixels."

I am not sure that is true, of course it technically decreases the total pixel count. The resolution remains the same on the sensor for the selected area. It also uses the center of the sensor which is also using the center of the lens. I am speaking without personal knowledge, I know doesn't stop a lot of folks form chiming in, but I am just using personal experience with photography in general. A smaller overall size of an image doesn't necessarily mean it is less sharp.

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The crop mode on a full frame R-series body is no different than shooting in full frame on any camera and then cropping in post to enlarge the subject. Using a longer lens would always be preferable to cropping. 

If one is happy with the resulting image quality after discarding ~60 percent of the pixels versus using a 1.6 times longer lens then that is fine for them. 

The purpose of the crop mode is to allow RF-S (and EF-S w/adapter) lenses to be used on full frame R-series bodies; something that is not possible on EF DSLRs. It is entirely different than using a crop sensor R-series camera.

[LeeP]

That was a long reply, but it was very well done and wonderfully nuanced. I really enjoyed the master class feel of the commentary. I liked your comment about 8x10 not being large and I agree. I compete in photography and usually do an 8x12. That isn't large. At that scale, no one could tell whether the image was shot by my R100, R8, my Pentax 17, or any of my 35mm SLRs. 

[SignifDigits]

@ LeeP Thanks for the positive feedback.  I just hope we're helping the OP as it seems we haven't heard back from them.

[ebiggs1]

"Using a longer lens would always be preferable to cropping. "

That is a debat that doesn't seem to have an answer and will likly alway be a hot topic.

[ebiggs1]

"If one is happy with the resulting image quality after discarding ~60 percent of the pixels ..."

Except the pixels were never there so nothing is discarded. Is it any different then using a normal crop camera with with around 25 MP? (too early for math)

[ebiggs1]

"if we compared a 70-200mm lens at f/4 at 125mm using sensor cropping on the R5 Mark II versus  200mm lens at f/4 at 200mm using the full sensor the "Native" (versus effective) focal length would, all other things being equal (assuming that neither 125mm nor 200mm were especially distorted, for instance) would provide more data in the image and a better quality final result should be possible."

I am not exactly sure what you are trying to point out. It is not the lens that changes even though you have the 1.6 crop factor.  It is the sensor that is the difference. Both of these lenses are native FL in either case. The  70-200mm at 125mm@f4 remains exactly what it is, a 125mm lens @f4 as well as the 200mm.

 Or, do you mean comparing what the image will look like if somebody was to use a 125mm lens on a cropper and then used a 200mm lens on a FF? You contend the 200mm on the FF will produce the better image? Of course you know with all the possible variables that is impossible to prove or disprove.

[ebiggs1]

SignifDigits, I love these kind of thought experiments. 😁

[SignifDigits]

@ebiggs1.  I'm glad to hear that.   Again, recall the OP asked about the R5 Mark II in cropped mode, thus using fewer pixels, and a "better quality final result should be possible." via a 200mm lens on the whole full-frame sensor versus effective 200mm via a 125mm focal length in cropped mode.  I think in all cases I would, given the choice, prefer to shoot at 200mm native over the full-frame sensor rather than at 125mm in cropped mode.  I think this was the point of their question.

I was not discussing a full frame sensor using a 200mm lens versus a comparable-number-of-pixels APS-C sensor using a 125mm lens with effective focal length of 200mm.   

The only scientific statement that I know that could be made in that case is that the full-frame sensor pixels should gather more photons/light particles due to their larger physical size.  Arguing whether that will mean anything regarding a large image printed at 300dpi or viewed on an 4k or 6K monitor isn't something that is of interest to me personally.  To me it would be like arguing how many angels can fit on the head of a pin.  In general think sharpness fixation is overrated.  Give me a great artistic or human emotion piece over sharpness any day of the week.   Not that I can produce any of the above personally - just my preference, and, of course.  I would love to have all of my images tack-sharp and often publicly bemoan my ineptitude at being skilled enough to get them sharp AND amazingly artistic.

Steve McCurry’s 1985 portrait of the green-eyed "Afghan Girl" (Sharbat Gula) was sharp, but even if it hadn't been quite as sharp I feel confident it would have still made the cover.  There are lots of iconic shots that were not all that sharp.  Of course there was real film grain in many of them, too.

I got very amused as I recently purchased a 4K HDR Top Gun DVD.  Original 1986 cut, not digitally remastered.  One of the negative comments that I noticed when I bought it was that it was "grainy".  I almost fell out of my chair laughing.  Of COURSE it was grainy - it was shot on real film!!!  ALL films from that era were grainy!  And TVs in the US were all NTSC.  Somehow we all managed to enjoy films, magazines, and get addicted to TV shows and sports.

Sorry to digress.  I hope the OP got the answer they were after in all of this.

[March411]

The mechanics of putting a full-frame sensor into crop tells/commands the camera to use and process data from the center portion of the imaging sensor which parallels the size of the smaller APS-C format but, again, it is using prime real estate, the center of the sensor. The sensors pixel size/density does not change; the amount/size of the sensor you are using changes and therefore the clarity of the image is not impacted.

Most lenses today, the sharpest spot is the center of the lens. Using crop technically would improve the image as it reduces soft edges, in some lenses vignetting and distortion that that can be a challenge in/on some lenses.

By using crop, only the number of sensors used to achieve the size/dimensions of the crop change to capture the image they are not altered, they capture the same light regardless of lens. Resolution is defined by the sensor, not the lens. And not I didn’t state sharpness but resolution.

Resolution measures the amount of detail an imaging system (camera, screen) can capture or display, typically defined by pixel count or lines of resolution. Sharpness describes the perceived clarity and edge contrast in an image. High resolution enables detail, while sharpness highlights the transitions between those details.

All that being said, the old adage garbage in garbage out applies, use a poor-quality lens and chances are probable you get a poor-quality image.  

If you are going to print and using crop, that is a completely different conversation. Your composition becomes more critical and sloppy framing can create the need to crop the image further reducing the ability to print larger images. Larger format prints will be a challenge.