Search found 2817 matches

by ray_parkhurst
Sat Dec 05, 2020 9:28 pm
Forum: Equipment Discussions
Topic: Olympus 20x Objective
Replies: 5
Views: 1373

Re: Olympus 20x Objective

I'm still searching for a 20x ULWD S-Plan.
by ray_parkhurst
Sun Nov 29, 2020 9:38 am
Forum: Equipment Discussions
Topic: first test of my Sigma 105mm F2.8 DG DN Macro Art
Replies: 16
Views: 2934

Re: first test of my Sigma 105mm F2.8 DG DN Macro Art

I don't bother about distortion but I like the excellent CA control and the superb sharpness over the whole frame, a good piece better than my old Sony FE90. Distortion is fairly irrelevant for single frames of many subjects. Only reason it was apparent was that you shot a semiconductor wafer. Dist...
by ray_parkhurst
Sat Nov 28, 2020 1:51 pm
Forum: Equipment Discussions
Topic: first test of my Sigma 105mm F2.8 DG DN Macro Art
Replies: 16
Views: 2934

Re: first test of my Sigma 105mm F2.8 DG DN Macro Art

Ray, you must be right about that. But the error could be of the same order of magnitude as the error between adjacent pixels caused by Bayer interpolation. Perhaps same order, but it's an additional degradation, and in my experience it's very noticeable. It is of course additive to the demosaicing...
by ray_parkhurst
Sat Nov 28, 2020 7:55 am
Forum: Equipment Discussions
Topic: first test of my Sigma 105mm F2.8 DG DN Macro Art
Replies: 16
Views: 2934

Re: first test of my Sigma 105mm F2.8 DG DN Macro Art

Don't those distortion corrections noticeably degrade sharpness due to interpolation effects? I would think they are similar to a small change in scaling, though the effect isn't global.
by ray_parkhurst
Wed Nov 18, 2020 10:42 am
Forum: Equipment Exchange
Topic: For Trade: Tomioka 32mm f3.5 and Gretag 120
Replies: 4
Views: 1731

Re: For Trade: Tomioka 32mm f3.5 and Gretag 120

I bought a bunch of the 120G's several years ago thinking they'd be good for coin photography, and they are indeed excellent for coins, but they are a bit too long for the systems I build. Plus none of the ones I got from the eBay seller are perfect. All have minor coating issues (small coating mark...
by ray_parkhurst
Wed Nov 18, 2020 9:15 am
Forum: Equipment Exchange
Topic: For Sale: Lomo 65mm Mikroplanar
Replies: 1
Views: 1396

Price Lowered

was $200 now $150
by ray_parkhurst
Wed Nov 18, 2020 9:13 am
Forum: Equipment Exchange
Topic: For Trade: Tomioka 32mm f3.5 and Gretag 120
Replies: 4
Views: 1731

Re: For Trade: Tomioka 32mm f3.5 and Gretag 120

Sold one 120G but have several more available.

If you don't have anything to trade and are interested in purchasing a 32T or 120G let me know.
by ray_parkhurst
Wed Nov 18, 2020 8:43 am
Forum: General Discussion Forum and Community Announcements
Topic: Interesting stuff
Replies: 18
Views: 3579

Re: Interesting stuff

Could these be used by dentists for root canals? I remember seeing some dental burrs in the mix of things.
by ray_parkhurst
Tue Nov 17, 2020 7:52 pm
Forum: General Discussion Forum and Community Announcements
Topic: Interesting stuff
Replies: 18
Views: 3579

Re: Interesting stuff

They are about 5-1/2" long.

Some info I forgot to mention...they are stored in cigar tubes, and each tube has hundreds of them. They seem more like material for some purpose rather than measurement tools.
by ray_parkhurst
Tue Nov 17, 2020 5:32 pm
Forum: General Discussion Forum and Community Announcements
Topic: Interesting stuff
Replies: 18
Views: 3579

Interesting stuff

I went to an estate sale of a man who had some very interesting stuff. He was a machinist, watchmaker, woodworker, and perhaps other, though very little had to do with optics unfortunately. Anyway, he had a bunch of precision steel rods in varying diameters from 21 mils up to 45 mils in 1 mil increm...
by ray_parkhurst
Sat Nov 14, 2020 7:03 pm
Forum: Equipment Discussions
Topic: Schneider locking screws
Replies: 29
Views: 5239

Re: Schneider locking screws

I'm still hoping for more folks to join the Schneider thumbscrew order, but so far only 10 screws have been committed out of a minimum order of 20 pieces. Please let me know by PM if you would like to join in the order. I will keep this offer open for a while longer since it's still possible we can ...
by ray_parkhurst
Tue Nov 10, 2020 8:57 pm
Forum: General Discussion Forum and Community Announcements
Topic: Electronics Swap canceled for 2020
Replies: 6
Views: 2374

Re: Electronics Swap canceled for 2020

The electronics swap gave me an opportunity to buy surplus optics, mechanics, tools, plus many surprises. The virus shut down the swap for the whole year of 2020. Hopefully the virus will not have a devastating 2nd wave, or worse a mutation or other multiplying factor, and the swap will come back ne...
by ray_parkhurst
Wed Nov 04, 2020 9:35 pm
Forum: Equipment Exchange
Topic: For Trade: Tomioka 32mm f3.5 and Gretag 120
Replies: 4
Views: 1731

For Trade: Tomioka 32mm f3.5 and Gretag 120

Have Tomioka 32mm f3.5 and Gretag 120mm for trade for interesting stuff.
by ray_parkhurst
Wed Nov 04, 2020 9:19 pm
Forum: Equipment Exchange
Topic: For Sale: Kodak 89mm f3.8 Printing Ektar 2:1 NOS
Replies: 0
Views: 2143

For Sale: Kodak 89mm f3.8 Printing Ektar 2:1 NOS

Kodak 89mm f3.8 Printing Ektar 2:1, original caps, original box, custom Raf M42M adapter. NOS. $350
by ray_parkhurst
Wed Nov 04, 2020 9:14 pm
Forum: Equipment Exchange
Topic: For Sale: Lomo 65mm Mikroplanar
Replies: 1
Views: 1396

For Sale: Lomo 65mm Mikroplanar

Lomo 65mm Mikroplanar in original case with M33-M42M adapter. $200