FF v Crop Sensor hypothetical question ...

[LesC2009]

Notwithstanding the reported better low-light performance of a FF sensor, imagine if you took a photograph, say a landscape in good light with a 70D & a 6D (just picked those two as they both have a 20MP sensor) with the same good quality L series lens at equivalent focal lengths at say F11 ...

Would you notice any difference in IQ? If so, under what conditions - viewing at normal size on your monitor/only at 100%/when printed above a certain size ??

[Nathaniel]

Re: FF v Crop Sensor hypothetical question ...

I don't know about the IQ but I think they would be the same. However using say a 24-105mm lens with the 70D would give you 38.4mm at the wider end whereas with the 6D it would give you 24mm. At the Long end, the same lens at 105mm will give you 168mm with the 70D and only 105mm with the 6D. I am sure the other experienced members will correct me if I am wrong. This is one of the reasons that wild life photographers prefer to use a crop camera like the 70D for wild life pictures and landscape/portrait photographers would use a FF like the 6D or
5D mk3.

[Paulstw]

Re: FF v Crop Sensor hypothetical question ...

In it's simplest terms the 6D image would be wider by 1.6x over the crop, using the same lens and settings. Some will have a more technical answer to this, however, I have my own theory on why I think the 6D files would exhibit a more accurate representation of the scene.

I know how it works in my head but explaining it has never been my strong point. I could draw it lol It was something I came to when using an UWA 11mm lens on a 7D, and something about all that data from the lens being crushed into a small 1.6x sensor and such a high pixel density. I just found that it didn't work.

I often find the best IQ comes from lenses when the FOV is relatively close the size of the sensor without bending the light too much. See I done it again lol can't really explain it. :/

[DrJon]

Re: FF v Crop Sensor hypothetical question ...

Not a great deal, assuming you used similar quality lenses with equivalent field of views (which I think you are suggesting). The better dynamic/tonal ranges of the FF sensor can help with landscapes, plus you can get higher resolution in some brands (Nikon, Sony) which can also be good for landscapes.

You'd get a little diffraction softening with a crop sensor at f11, not a lot but some, you should really open it up to the equivalent DoF of FF at f11 (as well as using equivalent focal length).

If it's the same lens you'll also get a bit more detail out of the FF sensor (the crop sensor uses the best bit of the lens, but the smaller pixels need the lens to be better for the same apparent sharpness). The better the lens the less the sharpness difference.

In summary - most of the differences will only be seen if you zoom in on your monitor or print big. How big depends on the subject, the flatter (tonally, rather than wall-like) it is the less the visible differences.

BTW the 6D's sensor is very good for pattern noise (the best of the Canons), so if you had light and dark bits and raised the shadows a lot that would also act in its favour.

Here's Tony's version of equivalence, which is pretty good:

https://www.youtube.com/watch?v=DtDotqLx6nA&list=PLBE338967F8DB7F2A

(He doesn't mention that diffraction softening goes with depth of field, so FF and Crop sensors have the same maximum DoF before diffraction causes you problems.)
However I think there is the additional point that if you are happy with the noise level for the use you are making of the photo (which can vary shot-to-shot) you are not so fussed about what the FF equivalent f-stop of your lens would be.

Some numbers (about half a stop more DR, quite a bit more tonal range):

http://www.dxomark.com/Cameras/Compare/Side-by-side/Canon-EOS-6D-versus-Canon-EOS-7D___836_619

[LesC2009]

Re: FF v Crop Sensor hypothetical question ...

Thanks Folks :)

As I'm likely to use the camera mainly for landscapes or at least with wide angle/standard zoom type lenses & keep a cropped sensor body for telephoto shots, FF seems to beAnd I know what you're getting at Paul ;) the way to go to get the best of both worlds.

And I think I know what you're getting at Paul. I find it hard to put my finger on it, but FF shots, at least some anyway, just seem to have a 'smoother' texture to them despite being sharp also if that makes sense!

[Mightyquin]

Re: FF v Crop Sensor hypothetical question ...

I doubt you would be able to tell the two images apart, if EVERYTHING was identical.

It would be an interesting little challenge if someone here with a crop and FF body was willing to put the work in. You would need to use say F5.6/8 on the crop and F8/11 on the FF body though.

[S_J_P]

Re: FF v Crop Sensor hypothetical question ...

Last autumn I posted these two images, one taken with a 6D and cropped-in to mimic the f.o.v of the photo taken with a 60D. There's a slight difference in exposure (one at 1/500th the other at 1/400th), but there's also a difference in the dynamic-range, shadow detail, and "smoothness".

One by S.J.P, on Flickr
Two by S.J.P, on Flickr

[Nathaniel]

Re: FF v Crop Sensor hypothetical question ...

The definition on the first image is a wee bit better in that the lines on the chair back is more sharp as well as the plant pot. I presume that was taken with the 60D?

[S_J_P]

Re: FF v Crop Sensor hypothetical question ...

Actually the first image is from the 6D. Neither image has been modified (other than cropping and rescaling) so they're lacklustre raw files without the usual benefits of sharpening, contrast and colour enhancement. Full-size, the 6D's image is certainly smoother and less noisy (at ISO800) in the diffuse background, the tonal-range seems to be spread wider (which actually appears to reduce clarity/local-contrast, but gives a good starting point for post-production) with more detail retained at both extremes. I've also found that less sharpening and NR is required to achieve similar overall results, which is always a bonus.

[LesC2009]

Re: FF v Crop Sensor hypothetical question ...

Interesting stuff Steve. The 6D shot even at this size appears a little smoother & the dynamic range appears better.

[DrJon]

Re: FF v Crop Sensor hypothetical question ...

DPReview have also written a nice article on comparing sensor sizes:

http://www.dpreview.com/articles/2666934640/what-is-equivalence-and-why-should-i-care

[Nathaniel]

Re: FF v Crop Sensor hypothetical question ...

oops! Shame faced. I have let down my beloved 6D!!!!!

[LesC2009]

Re: FF v Crop Sensor hypothetical question ...

oops! Shame faced. I have let down my beloved 6D!!!!!

Should have said it was a typo ;)

[BobSapey]

Re: FF v Crop Sensor hypothetical question ...

Here's Tony's version of equivalence, which is pretty good:

https://www.youtube.com/watch?v=DtDotqLx6nA&list=PLBE338967F8DB7F2A

I watched this and was interested in the way he re-analysed ISO in terms of the total light the camera receives. It seems to me that his argument is based on the condition that one is comparing two photos with the same content. As sensors vary in size they would have to receive different amounts of light to produce the same photo and all else being equal, the larger sensors will produce a better quality picture. However, if one compared the photos taken with different sensors using the same ISO, aperture and speed setting, and again if all else is equal, then different sensors will produce similar quality photos, but with different fields of view. So the questions this leaves me with is whether there is a perfect field of view and whether the quality of sensors has improved so much that some of this really doesn't matter any more?

I bought a 70D because I could afford it and I would love to have a 5D III but cannot justify the cost. But I am not convinced that I would take better quality pictures, rather I would use the camera differently.

[kelly200269]

Re: FF v Crop Sensor hypothetical question ...

I think smaller sensors have advanced so far in design and quality, that it makes the whole FF/cropped sensor argument completely irrelevant, UNLESS you're a pro and produce billboards.
Yes, FF sensors are capable of producing a shallower DOP, but from a purely aesthetic point of view images from my MFT kit are no less loved than the images taken with my DSLR. PLUS my arms hurt less in the process! :) lol