Centers and Borders and Mid-frames

Obviously center image quality is tremendously important. But how important are mid-frame and border IQ to you guys?

I've been hunting for a longer lens that is affordable, and find most have "ok" mid and border sharpness/IQ, even when the center is close to excellent. I expect to use whatever I end up with at the longer end, so that's where I'm focusing my comparisons (excuse the pun). It seems that almost every xx-300mm lens out there falls short at the 250-300mm range (excluding the 70-300L which is not in the budget), especially in the mid-frame and border areas.

My long lenses for now are the EF-S 55-250mm, and an older Tamron AF 200-400mm. I find the 55-250 images to be lacking a bit in color and contrast, and the 200-400 lacking in the sharpness area. I'm sure the 200-400 was great for the 8MP bodies in it's day, but I feel I could do better.

Trying to stay within a budget of <$500. So far, I'm strongly considering the Tamron 70-300mm f/4-5.6 Di VC. I've also considered the 70-200 f/4L non-IS, but I'm pretty convinced I need image stabilization as I've found I'm just not that steady handed, and I tend to try and shoot tight, so cropping may/may not work for me.

What else should I look at?

Depends on the lens... For a wide angle, I prefer strong performing corners. For fast lenses, I don't care so much as long as the center is very sharp. Really depends on the lens and intended use.

If looking for a telephoto with strong performance, the 70-200's are excellent.

You are much more likely to notice soft edges and corners with a wide angle lens, due to the deep depth of field and overall image sharpness that's more typical with that type of lens.

Telephotos have inherently shallow DOF, so the edges and corners are often OOF anyway, so some inherent softness there usually isn't noticeable or might even enhance an image.

Depends on the camera too. With a 5DII I'm more likely to use the center AF. With the 7D I'm more likely to use something away from the center. So it's nice to have decent mid-frame, even on fast lenses, especially with FF and decent AF like a 5DIII.

Also with fast lenses I don't care too much about the corners, but if they are really poor it can detrimentally affect bokeh which can be off-putting.

for longer telephotos i don't really care about border performance...i'm usually using the center point, and then cropping to compose, as i tend to still want more and more reach...

also for faster lenses it's not as important for me...however i usually use the outer points for that, but even when using the outer points it's still not the extreme corners that are shown in the digital picture's crops

In contrast to others I do care about border quality on long telephoto lenses.
There I make a lot of the pictures with border details.

Canon FD 300mm/2.8L

A lot of people say the 24-105 has poor border performance, but I disagree.

Zone, I love the colors and crispness of those photos. Very natural and unique!
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So I was curious in how the zeiss 50mm 1.4 performs against the 50L in real world tests.


I found someone posted this comparison http://www.flickr.com …r/sets/72157626​696544534/

I couldn't believe how much sharper the zeiss was from 1.4 all the way to f8.. it was sharper everywhere, from center, to bottom left, right, etc.

I'm sorry, the canon 50L was ever so slightly sharper at f5.6-f8 in the center. .. open it up as an original and take a peak at the larger photos.

I never realized how poor the border performance is on the 50L...

Okay, I now looked at all of the photos.. Seems to me that the 50L performs better with closer objects, than landscapes.. some type of focus shift. (edges/border is still poor though)
http://www.flickr.com …in/set-72157626696544534/

ejenner wrote in post #16504879
Depends on the camera too. With a 5DII I'm more likely to use the center AF. With the 7D I'm more likely to use something away from the center. So it's nice to have decent mid-frame, even on fast lenses, especially with FF and decent AF like a 5DIII.

Also with fast lenses I don't care too much about the corners, but if they are really poor it can detrimentally affect bokeh which can be off-putting.

+1

now I have the 5D3 and can actually AF away from the center, rather than having to place subjects center frame and crop for composition later, I'm more interested in mid-frame performance. I'm still not going to have a subject in an extreem corner, or even along an edge, but I'd like to think that anywhere within the 5D3 AF area would be sharp.

So pretty much, it seems that while sharp corners would be nice, it really isn't a make or break for most photos and photographers. Mid-frame is somewhat important, but we're really interested in the center for the most part.

I went with the Tamron 70-300mm. I think I'll be happy for the meantime.

MIght look at the EF-S 55-250 STM Perhaps one of the best values in canons line up.
It is a upgrade over the older 55-250.