You are quite correct, apo lenses are fully corrected only at the design distances. But being fully corrected (three-color correct) at any distance means they have a better chance at being better corrected at macro distances than lenses that are corrected for two colors at design distances. I'm sure there are paritally- or uncorrected lenses that perform wonderfully at macro distances, but in general, apo lenses do a little better. This observation may be due to the fact that there are a lot more apo-corrected long lenses than short ones, and long lenses always do better at macro distances. I have never experimented with wide-angle macro work enough to test the apo vs. non-apo lens differences.
</span><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (b.e.wilson @ Sep 17 2002, 04:49 AM)</td></tr><tr><td id='QUOTE'>... being fully corrected (three-color correct) at any distance means they have a better chance at being better corrected at macro distances than lenses that are corrected for two colors at design distances.</td></tr></table><span id='postcolor'>
Well, I'm not sure that follows - an improvement at one point on the scale does not mean that the lens's performance is improved elsewhere (although it may be so in particular cases).
In general, there are many more aberrations for the lens designer to deal with than just chromatic. For example, I would expect something like a G-Claron to be better at 1:1 than, say, an Apo-Symmar, simply because it is optimized for close range use, and things like coma, spherical aberrations, astigmatism, and field curvature (maybe irrelevant except for copy work) will all be better.
Certainly I prefer my 210mm G-Claron over my 240mm Sironar-N (which is the same as the Apo-Sironar N) for close work. Though perhaps if I had the Sironar S instead I might think differently.
Well, whatever. On the basis that a difference is only a difference if it makes a difference, perhaps this is just splitting hairs.
While I do not own a 150Nikkor, I do own a 210 Nikkor W, and I have found that does not perform well for close-up work. I was told once that the Nikkor W's are not symmetrical and therefore do not perform well at close distances....(I have no direct knowledge of this as I am not really interested in optical design; I realize that it surely may be possible that he didn't know what he was talking about) but, as mentioned earlier, I would have to agree with his assessment, at least in regard to the 210W. I do have a Rodenstock 150 N, which I use for virtually all my close-up work, and find it to be marvelous.
To test lens symmetry, close down the aperture a bit and look at the size of the opening from the front and back of the lens. If they are the same size, it's symmetric.
Back to square one. But better to be in square one than to have a lens that I'm not happy with. I'm leaning against the Nikkor because I haven't heard many favorable reviews, and because the other three get raves. Thanks for the input.
Do think about a G-Claron, won't you. Unlike the others mentioned it is actually designed for close work, and is significantly cheaper than any of them.
Thanks for the suggestion. I checked out the G-Claron on bhphoto.com. Their desription:
"The G-Claron is a lens of symmetrical design with six elements in four groups, optimized for 1:1 reproduction. The normally used range of linear magnifications is 5:1 to 1:5. The G-Claron may also be used for distances up to infinity by stopping down to f/22 or less. For photographic work the G-Claron can be used up to an angle of 64 degrees and is free from mechanical vignetting at f/16 and smaller apertures."
I usually photograph macro subjects at very wide apertures, so I'm wondering whether or not I could use a G-Claron, based on the above quote. I'd probably want to use it at f/9 to f/16, but not much beyond that. How much "mechanical vignetting" are they talking about?
there is certainly some mechanical vignetting below f/16, but not more than you would get with any of the other lenses you have mentioned - they will all have mechanical vignetting at apertures larger than f/22. Most LF lenses require to be stopped down to about f/22 to be completely free from vignetting within the stated circle of coverage. At any rate, I would think you might just detect a slight falling off in illumination towards the edges with the lens focussed at infinity on a 4x5, but close up? I doubt it - you really wouldn't be using enough of the coverage to see much variation.
That's very helpful to know. Thank you. Do you know what the image circle is when the lens is wide open at f/9?
Well, it's very difficult to give a straight answer to that, because the circle of coverage is generally defined for a stopped down working aperture - usually f/22. Wide open you will certainly get illumination across the same angle, but it will not be even because of vignetting. Again this will apply more or less equally to all the lenses mentioned.
Usually the published limit seems to be defined to be the angle from the lens axis at which the 20lpmm MTF curve (either radial or tangential) falls to zero. I say 'seems', because I have never come across any statement by any of the lens manufacturers as to exactly how they determine it. I came to my own conclusion on the question from examining many of the published MTF curves.
You can find the MTF curves for the 150mm G-Claron here , as well as curves for the Apo-Symmar close by. Rodenstock MTF curves can be found on Paul Butzi's site here. I can't remember whether the Rodenstock curves include wide aperture performance, but the Schneider ones certainly do. I'm afraid I can't recall ever seeing published curves for the Nikkors.