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Author Topic: Sensor quality vs lens quality  (Read 6858 times)

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« on: January 27, 2016, 21:55 »
0
Hi folks,

Let's say you have 2 20MP SLRs, one with an APS-C sensor and one with a full-frame sensor, both fitted with the same prime lens, both pointed at the same subject from the same location. Assuming the usual APS-C crop factor of around 1.5 - 1.6, if you take a picture on both cameras then you end up - obviously - with 2 20MP images, with one looking like it came from a lens with around 1.5 - 1.6x the focal length of the other. Let's say that you now crop the image from the full-frame camera so that the two images now look identical.

What I've never understood is if - or at what magnification - there would be an appreciable difference in sharpness between the 2 images. I get that the image from the full-frame camera would now be down to around 13-14MP but wouldn't the APS-C image only come out sharper if the lens can deliver enough detail to let it do so?

Sorry this is a bit muddled... I guess I'm just not sure of whether the sensor's ability to resolve detail is typically greater than the lens's ability, and whether it matters. TIA!


wds

« Reply #1 on: January 27, 2016, 22:36 »
+1
If's it's a quality lens, with proper technique, you should see a difference (the higher density APS 20mp would look more detailed than the cropped full frame)

« Reply #2 on: January 27, 2016, 23:14 »
+1
Your image is a function of the lens + the sensor + the camera's firmware/software. Having a crappy lens is almost never something you want, but arguably you might waste money on an amazing lens if you use it on a poor quality camera body. Lots of people with lots more detailed knowledge (and patience) than me have written lots of blog posts/tutorials on this subject:

http://www.cambridgeincolour.com/tutorials/digital-camera-sensor-size.htm
http://neilvn.com/tangents/full-frame-vs-crop-sensor-cameras-comparison-depth-of-field/
http://www.mdavid.com.au/photography/apscversusfullframe.shtml

From the Cambridge in Colour article's conclusion:

"Larger sensors (and correspondingly higher pixel counts) undoubtedly produce more detail if you can afford to sacrifice depth of field. On the other hand, if you wish to maintain the same depth of field, larger sensor sizes do not necessarily have a resolution advantage. Furthermore, the diffraction-limited depth of field is the same for all sensor sizes. In other words, if one were to use the smallest aperture before diffraction became significant, all sensor sizes would produce the same depth of field even though the diffraction limited aperture will be different."

Are you asking because you have an APS-C camera and are considering whether it's worth it to upgrade to a full frame one?

« Reply #3 on: January 27, 2016, 23:36 »
0
> Are you asking because you have an APS-C camera and are considering whether it's worth it to upgrade to a full frame one?

No, Jo Ann - just curious! I went full frame some time ago, although I do sometimes wonder about getting an APS-C body to get a bit more reach for sports & wildlife. Then I think "...but maybe I could just stick with the full frame body and crop the image, and end up with the same shot as I would have had on APS-C".

Looks like I've got some reading to do! Thanks for the links.

« Reply #4 on: January 28, 2016, 03:19 »
0
If you shoot a 20mp frame and crop it down to 12mp, then blow the result back up to 20mp to compare with the output of a 20mp crop sensor camera, then it seems to me the full frame is bound to be poorer quality.
If you crop full frame to 12mp then compare with 12mp crop sensor camera, they'd probably be pretty much alike.
I would think the main advantage of so-called "reach"  is that you  use smaller, lighter gear (but if you use full-frame lenses than a lot of that advantage is lost) and for small subjects that don't fill the frame you are just eliminating wasted space.
Of course, another alternative would be to get a 1.4x teleconverter and add the "reach" to your full frame, which would probably be cheaper than buying a new body.

« Reply #5 on: January 28, 2016, 03:38 »
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I like using full frame lenses on crop sensor cameras.  Most lenses get a bit softer in the corners and that isn't as much of a problem using a crop sensor.  If I need extra resolution, I can stitch a few photos together.  I do that a lot with compact cameras, great for non-moving objects.  Full frame is good for shallow focus and wide angle when the subject is moving.

Prime lenses are usually much better than zooms but some zooms have good resolution in a limited range.  Full frame really shows any faults with a lens.

ACS

« Reply #6 on: January 28, 2016, 04:46 »
0

What I've never understood is if - or at what magnification - there would be an appreciable difference in sharpness between the 2 images. I get that the image from the full-frame camera would now be down to around 13-14MP but wouldn't the APS-C image only come out sharper if the lens can deliver enough detail to let it do so?


If those sensors from two cameras are identical in terms of resolving ability, there will be no difference in terms of sharpness when looked at %100. But there will be a detail difference; 20 MP one will have more data then the 14 MP one. Lets assume that it is a rural landscape photo. In the 20 MP photo (APS-C),  the tree in the middle of your frame will be %42,9 larger than the tree in the 14 MP (FF) one. If it is 100 pixels wide in the FF 14 MP one, it will be 143 pixels in the APS-C one.

« Reply #7 on: January 28, 2016, 08:28 »
+1
Just a collateral comment: a cropped FF image will NOT be identical to a cropped sensor image, even when the "zoom factor" is matched.
There are DoF differences between the two. At the same aperture, FF has a shallower DoF. And this can make the two versions very different, especially when shooting wide open.

Sent from my SM-N910T using Tapatalk
« Last Edit: January 28, 2016, 15:28 by Zero Talent »

« Reply #8 on: February 20, 2016, 05:19 »
0

If's it's a quality lens, with proper technique, you should see a difference (the higher density APS 20mp would look more detailed than the cropped full frame)

It has the Good Lens Having The Best Quality Glass Should A camera Have for Professional..there is the great Difference and i think You also will feel ..Its Get the Heavy Density Picture also which have the great pixels also ...


 

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