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Forum: Lens Clubs 12-10-2017, 08:56 PM  
Carl Zeiss T* ZK mounts (Distagon, Planar, Makro-Planar)
Posted By kgivens
Replies: 1,379
Views: 196,575
Fenwoodian--- I suspect you are correct, the soft corners I'm seeing are probably a sign that this lens was not designed/optimized for 1:1 shooting on a 4" long extension tube. I could not overcome this problem by upping the aperture from my initial setting of 5.6 to f11. Surprising. My old Minolta MD 100mm macro did pretty well on similar extension tubes.

Tas--- Thanks for those sample images. I did use Live View (plus focus peaking) to focus. Before I got the Zeiss, I picked up the Pentax100mm macro and was using that for slide copying at 1:1. I think the lens could have better resolution overall, but somewhat amazingly, it had clearly better corners than this Zeiss stretched to 100mm. Again I would have expected better enginieering from Zeiss.

So if my Zeiss specimen can't deliver the goods--- what's left besides the too-rich-for-my blood Voiglander 125? Maybe there's some decent short lens that can be reversed on a short bellows? Thanks in advance for any recommendations---
Forum: Lens Clubs 12-06-2017, 11:28 AM  
Carl Zeiss T* ZK mounts (Distagon, Planar, Makro-Planar)
Posted By kgivens
Replies: 1,379
Views: 196,575
Hey guys, first post, hope I'm not in the wrong forum. I'd appreciate if some of you 100mm Makro-Planar users would comment on the following.

I've been digitizing my large collection of 35mm slides. Thus far the best results I've obtained were by photographing the slides using a full frame DSLR plus a macro lens set at 1:1 magnification. Initially I was doing this with Sony cameras and lenses (A99 plus the historic Minolta/Konica 1-3x zoom macro with dedicated slide copy accessory). I used focus stacking to insure that I got every last drop of information out of each slide, and also to overcome the fact that film is slightly curved. Typically I'd take 5-10 shots at different focal planes through each slide, using focus peaking as a guide.

This system worked pretty well--- better than my Epson Perfection V700 scanner, anyway--- but I still felt that I was not getting all the resolution the slides had to offer. I began to wonder if the Pentax K-1 pixel shift feature could improve my image captures. So I bought a used one, and to improve my odds, also picked up a Zeiss 100 f2 Makro Planar; it was originally a Nikon mount, but the owner had it professionally changed to a ZK (Pentax) mount. I also found 100mm Pentax-made extension tubes on eBay so I could push the lens to 1:1, which is necessary for slide duping. I mounted the K1, extension tubes and Zeiss lens on a Novoflex focusing rail with a dedicated slide copy attachment. Pixel shift was used as well as focus stacking, similar to what I described above.

I was disappointed to discover 1)the pixel shift did not improve on central sharpness; and 2) the bigger let down ---- at 1:1, the Zeiss lens produced very soft focus in all four corners. Not vignetting per se--- just poor focus/resolution. I expected more from this storied lens. Perhaps Zeiss never meant for it to be pushed to 1:1 on a mile-long extension tube. Has anyone here had similar experience?
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