Comparative “sharpness” at infinity and other distances?

[jim_mohundro1]

<p>There are many comparative lab measurements of lens sharpness or resolving power, both at center and at edges, at various specific apertures. I’ve seen some lens reviews indicating that some lenses fall off in sharpness at various distances, i.e., they may be optimum in a certain range (close-up [macro?], mid-range or infinity). If one is looking for a lens for general purpose image-making, are there reviews from respected reviewers that discuss the relative sharpness of lenses across their ranges?</p>

[leicaglow]

<p>Jim, Photozone.de would be what you're looking for.</p>

[ashim]

<p>If I understand Jim's question correctly, I think he is trying to find out a lenses performance at various focus points (like close/macro, mid-range, infinity etc.) and not across the focal length range (e.g. a zoom). IMO, photozone doesn't do this kind of testing.<br>

It is said that some lenses are not good at infinity in terms of contrast/sharpness and some are not good at close focussed.<br>

I too would be interested to know which lenses perfom very well at infinity focus. All inputs are most welcome.</p>

[alvinyap]

<p>In my experience, the 55mm 2.8 AIS Micro Nikkor performs very well from 1:2 to infinity, wide open at F2.8.<br>

Alvin</p>

[Peter_in_PA]

<p>The sharpest lens at all settings? A sturdy tripod. ;-P</p>

[Ed_Ingold]

<p>Lenses designed for general photography perform best at magnifications of 1:15 or further. You won't see any difference beyond that distance (about 10'). Lenses designed for closeups (1:4 or greater) sometimes aren't as sharp or have field curvature at longer distances.</p>

<p>Macro lenses are designed to have a flat field and high resolution at close range. This is essential when copying documents or flat artwork. General purpose lenses may focus close, but often get very soft at the edge of the frame. The 55/2.8 AIS Micro has special moving elements (CRC) which compensate for distant photography, and are sharp at any distance.</p>

<p>None of this matters unless you use a tripod, modest apertures and good technique.</p>

[tommyinca]

<p>2 cents worth, Lets see. Sharpness can be effected by at least spacial (X, Y, Z distant), aperture, color off-set (aka: CA) (X, Y, Z ), lighting, direct and off view X, Y, sensor micro lens interactions plus Anti-Aliais filter. Just with these, a simple camera A verse camera B compare will result in thousands of pictures. Then there are standard zoom lens and ISO, RAW and different in-camera setting. That is why simple review like take some pictures and tell us what you see are just as useful (or not useful) at time.</p>

[ilkka_nissila]

<p>The review sites think it's just too much work to test lenses at several distances. It does matter a great deal - several modern Nikkors are fairly poor at long distances (i.e. 30 meters or more; try 24-70 at 24mm at infinity - blurry is saying it nicely - yes, I know it's largely field curvature but knowing that doesn't help you if your subject is flat) whereas giving excellent results at a typical PJ photography distances (i.e. a few meters). Nikon seems to largely optimize for relatively close range and ignore the "far field" behaviour in many lenses whereas e.g. Zeiss does not.</p>

<p><em>You won't see any difference beyond that distance</em><em> (about 10'). </em></p>

<p>Edward, I have high respect for your knowledge and photography but you are completely wrong. There are many non-macro Nikon lenses that have serious image quality issues at long distances. The 24-70 and 17-55 are examples of that. Another example is the 85/1.4D. The Zeiss 85/1.4 ZF appears to be better than the Nikkor at long distances whereas the Nikkor is superior near its near focus limit at wide apertures. Since no test site takes this properly into account, all you can do is test the lens and see if it works for your purposes i.e. know your lens and use it for what it does best.</p>

<p>What I find the most annoying about photozone.de is that the use the same size test target for all their measurements! This means they photograph the same size subject with general purpose lenses as with macro lenses! I think it's very telling about this how they characterise the 200mm AF Micro (which is widely regarded as one of the very best macro lenses) - they should really fix this and test macro lenses at macro magnifications instead of what they do now. IMO their macro lens tests are totally invalid as they have published them.</p>

[JDMvW]

<p>Ilkka, given that Photozone.de is not perfect (who is?), what do you recommend as an alternative?</p>

<p>I think we're all aware of the limitations of the chart-and-graph school of judging lenses and cameras, but surely they can be helpful so long as one keeps the limitations in mind.</p>

<p>It sure as heck beats out the poetical waxing of so many users defending their favorite lens...</p>

[dan_south]

<blockquote>

<p>several modern Nikkors are fairly poor at long distances (i.e. 30 meters or more; try 24-70 at 24mm at infinity - blurry is saying it nicely - yes, I know it's largely field curvature but knowing that doesn't help you if your subject is flat) whereas giving excellent results at a typical PJ photography distances (i.e. a few meters).</p>

</blockquote>

<p>That's fascinating. I did all of my 24-70 f/2.8 G sharpness testing at short distances. In that range it's the sharpest lens I own. But I've never been blown away by its behavior when focusing on distant scenes or objects. The 70-200 VR performs better at infinity.</p>

<p>Maybe the 24-70 is better suited for PJ, events, and portraits than for travel and landscape photography where most shots are focused at "infinity."</p>

<p> </p>