A7r 24-70 at 70mm vs EM1 12-40 at 40mm (80mm EFL)

Started Mar 6, 2014 | Discussions thread
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GaryW Veteran Member • Posts: 8,408
Re: Resize the A7/r to 16 MP to see how it compares...

LTZ470 wrote:


Both photos should be sharp and have decent IQ at 100% regardless of format...

Not format so much as megapixels/resolution.

the corners and sides of the A7r 24-70 do not so you would have to resize down to the 16Mp size and/or crop off the smeared/mushy portions...

If you did this and the photos were comparable, that would be helpful information. It would be incomplete information, but it would still be a useful comparison.

So if I make a crop of the A7r shot with 1280 X 900 and a crop of the EM1 shot 1280 x 900 this will show the difference?

When you say "shot with", do you mean like setting the camera to "small" size? I'm with Henry on this one -- not sure what the camera is doing, and besides, two different cameras aren't going to have the same exact resolution. Might as well, use a full original size and resize in the computer where you know it's a controlled situation.

I'll take a few shots with 24mm f/2 and 100% Crop and then we'll see the difference 100% crop or not...

BUT at 100% crop they should both look sharp and have decent details in my book...period...

I think part of the confusing is comparing two different systems. If you took the example of Nex-6 vs Nex-7 and put the same lens on both, it'd be more clear what could happen. You could have a lens which had really poor corners on the Nex-7, as they could be much softer than the center, but on a 16mp sensor, the same corners might not look as bad, and the softness wouldn't be as noticeable when compared to the center. I think by thinking of two similar-format cameras (Nex-6 and Nex-7 are both APS-C), it might be easier to visualize how simply changing resolution also changes the magnification when viewing at 100%. With more magnification, you need more resolution in the lens, or else the magnification is going to be more revealing of errors.

Gary thanks for the help and comments...

I hope it helps...

Packing up the 24-70 to go back, got it for the 24mm, and it's just not good enough for the price...nice lens though! Size is not too bad either...

I'm with Henry here too -- it sounds like the corners are weak at the ends of the zoom, like with a lot of other Sony lenses. If this is not tolerable, then the lens isn't for you. Personally, I look at it as a tradeoff-- if it's not too severe, it won't be noticeable in normal prints. So, just saying that the corners are soft isn't enough for me to disqualify a lens, but it's worth considering whether or not it's worth paying the extra rather than just using the kit lens.

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