Bruce C , Feb 11, 2007; 10:15 p.m.
Wonder if you Nikon mavens might be kind enough to humor a query from a Canon
350D user? I'm looking for a relatively inexpensive, manual focusing 90/100/105
macro lens, and the Nikkor 105mm f4.0 seems like the best candidate at the
moment. Since I want this lens for true macro use, speed is not a relevant
factor. And as you will see, I'm a glutton for punishment, er, I'm used to
focusing manually at insanely small apertures.
I'm looking to replace my old Tamron SP 90mm f2.5, which was my favorite film
lens. But after buying a $139 AdaptAll to EOS adapter, I've discovered that at
apertures above f11 the spherical reflection from the pristinely uncoated rear
element gets progressively tighter and brighter. I would guess that at wider
apertures it encompasses the entire digital sensor and produces a degree of
fogging. Oddly enough the Canon FD 50mm f3.5 macro has exactly the same
"feature" and consequent effect, so maybe it was the fashion not to coat the
rear elements of macro lenses 25 years ago. In any case, my old Canon FD 200mm
f4.0, 70-150mm f4.5 and 35mm f2.8 are properly coated.
So obviously the question is whether or not the Nikkor candidate is free of this
effect? I've had great luck and am very pleased with the Nikon 1000mm f11
mirror lens and the 200mm AI f4.0, so I'm hopeful in this case.
Any information/suggestions would be greatly appreciated.
PS: I know I'm fair game for questions about why I didn't just buy a Nikon body
in the first place -- I can't really deflect those kinds of questions, but I
will point out that I am an EOD (equal opportunity defector): In addition to a
number of Canon EF lenses, I also use or have used Contax, Leica, Pentax and
Carl Zeiss Jena primes. Isn't that why Canon made the EOS mount the way they did?
Michael Axel 
, Feb 11, 2007; 10:38 p.m.
Bruce... don't apologize!<g> I owned all Canon and traded most for Nikon in the early '80's. Love my Nikon and Nikkors, but recently bought a 5D for some fast lenses. It's all about getting the image you want.
Anyway, my 2.8 is coated on the rear, and I seem to remember my f/4 was also, but there were a lot of versions. See: http://www.photosynthesis.co.nz/nikon/serialno.html#105
Unfortunately this resource doesn't say whether they're coated or not, but may depend a lot on how old the lens is. If I can ask you a question: have you seen an adapter that allows a Leica R lens on a FD body? (on a Canon EF body, actually)
John Lehman , Feb 12, 2007; 01:02 a.m.
The rear element on my AI Nikkor 105mm f4.0 appears to be coated (based on the purple-green color reflection). I use it frequently as a macro lens with my new D200 and have had no problems.
Bjorn Rorslett , Feb 12, 2007; 03:28 a.m.
You shouldn't have any issues with the suggested combination. The 105/4 Micro-Nikkor is a fine performer on all digital cameras I've tried. If it works perfectly on a D2X, it certainly ought to do the same on a Canon 5D.
Be aware that this lens, like almost all Micro-Nikkors, gives the best image quality when it is not stopped down too far. So refrain from using f/16 or f/22 unless it is more important to have DOF than maximum sharpness of detail.
Roland Vink , Feb 12, 2007; 03:53 p.m.
Regarding the lenses listed at www.photosynthesis.co.nz, all lenses listed as "A" type are single coated on most or all lens surfaces.
Lenses types "C", "K", "AI", "AIS" and "AF" are multicoated on all lens surfaces, including the AI or AIS 105/4 micro.
Wayne Harridge , Feb 12, 2007; 07:46 p.m.
The effect you are seeing with the Tamron 90/2.5 is not purely related to the coating. I have noticed the same effect with a later coated version, so I believe the shape of the rear element and its distance to the sensor are at least as important. I tested most of my Nikon mount and OM mount lenses on an Olympus E-300 and this effect was significant only with the Tamron 90/2.5 and Nikon Series E 50/1.8. I have an old Micro-Nikkor 105/4 and this was ok.
...Wayne
Joseph Wisniewski , Feb 13, 2007; 12:15 a.m.
Wayne nailed it, shape is at least as important as coating. The older Nikon 105mm f4 has a great shape, fairly tight radius convex rear element (English translation: it has a marble like "bulge") like an enlarger lens or process lens.
You don't have to "defend" the question, entry level Canons blow away Nikons for macro use (and I'm a [number deleted] decade Nikon shooter). Even the digital rebel has mirror lockup and the ability to meter with manual macro lenses, bellows, telescopes, old portrait length telephotos, etc).
To get that in a Nikon means you have to skip D40, D50, D70, and D80 and go right to D200 ($1400 with the lastest price drops). No $500 rebel, no $1000 30D.
But "Canon made the EOS mount the way they did" for two reasons. To accept the Canon 50mm f1.0 (now discontinued, thank God. Miserable soft, soft lens for a hard, hard price) and to accept Canon's Nikon mount adapter. The mount adapter allowed Canon to sneak an EOS body and an AF lens or two into a Nikon sport, wildlife, or PJ shooter's bag. Foot in the door, so to speak.
Bruce C , Feb 13, 2007; 01:31 p.m.
Wayne and Joseph:
Thanks for your further input! It seems ingracious to quibble at such splendid, freely offered consultation, but my results don't support the shape/distance hypotheses.
The Tamron's rear element is indeed as flat as can be, but not the FD 50mm's -- its nicely convex. Also, when you rack out the focus for maximum reproduction ratio with either, and even add an extender, the spot remains -- maybe a bit attentuated, but still, unquestionably there.
FWIW, I screwed a multi-coated 30.5 UV filter behind the Tamron's rear element, but that didn't help much -- it may diffuse the spot a bit but scarcely enough to make a difference. So much money for so little benefit!
But maybe results vary for other lenses/configurations.
I'm now looking at the non-AI version of the 105mm -- when you're doing it all manually, you don't need any auto features :-) Looks like the price will be less than the $155 = $139 (adapter) + $16 (filter) I spent on the Tamron. Chalk it up as the price for my ignorance of this wonderful forum!
