Search found 200 matches

by JKT
Sun Jan 17, 2021 4:55 am
Forum: Equipment Discussions
Topic: Canon RF 70-200 f/2.8 L IS USM
Replies: 0
Views: 58

Canon RF 70-200 f/2.8 L IS USM

Has anyone had a chance to try the above lens as tube? It seems to me that the extending design might allow for larger usable range as tube lens than the old internal zooms. On the other hand, there is the distinct possibility of zoom creep in vertical setup. The optical construction is also a lot l...
by JKT
Mon Jan 11, 2021 10:51 pm
Forum: Equipment Discussions
Topic: Schneider-Kreutznach lens parameters
Replies: 5
Views: 176

Re: Schneider-Kreutznach lens parameters

Thanks Robert! I should have guessed they were yours - much of the useful stuff is. :)
by JKT
Mon Jan 11, 2021 2:46 pm
Forum: Equipment Exchange
Topic: Sell: Photar 25mm f2.0
Replies: 6
Views: 186

Re: Sell: Photar 25mm f2.0

Thanks for the information. I'm interested in full frame corners, so I'll have to think about it a bit. If someone else takes it meanwhile ... I won't have to decide. :wink:
by JKT
Mon Jan 11, 2021 11:37 am
Forum: Equipment Discussions
Topic: Schneider-Kreutznach lens parameters
Replies: 5
Views: 176

Schneider-Kreutznach lens parameters

I seem to recall seeing explanations for Schneider-Kreutznach lens parameters somewhere, but I can't find them now. Anybody have such a document they could share? f' eff is focal length, but what are the others? S F & S' F' are likely distances to focal point, but from where? From nodal points or el...
by JKT
Mon Jan 11, 2021 11:21 am
Forum: Equipment Exchange
Topic: Sell: Photar 25mm f2.0
Replies: 6
Views: 186

Re: Sell: Photar 25mm f2.0

Hi,

Did you use it with APS-C, full frame or some other size sensor?
by JKT
Fri Jan 08, 2021 2:49 pm
Forum: Equipment Discussions
Topic: Raynox dcr150 custom tube lens
Replies: 21
Views: 725

Re: Raynox dcr150 custom tube lens

I suspect that painting the inside thread will lead to unpleasant amount of paint powder inside the system after you screw in the front tube. Not that the flocking would be any easier. What do you think if the outer tube had only 10 ... 20 mm of thread at the front end and the rest would have larger...
by JKT
Thu Jan 07, 2021 6:52 am
Forum: Equipment Discussions
Topic: Raynox dcr150 custom tube lens
Replies: 21
Views: 725

Re: Raynox dcr150 custom tube lens

Unfortunately that article doesn't give the distance from Raynox to sensor in the nominal position.

A quick measurement gives 202.8 mm. The Raynox was much shorter (15.5 mm) than I recalled. So It should be sufficient to use 205 mm as maximum length with reversed DCR-150.
by JKT
Thu Jan 07, 2021 2:24 am
Forum: Equipment Discussions
Topic: Raynox dcr150 custom tube lens
Replies: 21
Views: 725

Re: Raynox dcr150 custom tube lens

Yes, Raynox DCR reverse. +/-2cm means between 18cm and 22cm will be good enough. I'm not entirely sure about that. I'm using it in forward position and the distance from sensor to the rear flange of Raynox is 210.6 mm. There is some uncertainty in that, but that shouldn't be more than 1mm. There mi...
by JKT
Wed Jan 06, 2021 9:48 am
Forum: Equipment Discussions
Topic: Raynox dcr150 custom tube lens
Replies: 21
Views: 725

Re: Raynox dcr150 custom tube lens

Instead of using a helicoid for distance A, I had the intension of machining 2 tubes sliding inside each other like a helicoid. If I make it 20cm and have +/- 2cm for fine adjustment, would that be enough ? and would you recommend that I mount the raynox150 reversed or not ? I would think that inst...
by JKT
Sun Dec 20, 2020 3:44 am
Forum: Equipment Discussions
Topic: Scanner Nikkor 38mm f/2.8 LS30 Scanner Lens Tested
Replies: 49
Views: 1564

Re: Scanner Nikkor 38mm f/2.8 LS30 Scanner Lens Tested

M42x0.75 would have been nice, though. :wink: There is very limited number of rings ending at female M42x1, but almost unlimited number ending with female T2 (M42x0.75). Always thought the opposite, M42x1 was more popular, I have been trying to sell a set of T2 x 25mm extension rings, 5 pieces, Sch...
by JKT
Sat Dec 19, 2020 5:03 am
Forum: Equipment Discussions
Topic: Scanner Nikkor 38mm f/2.8 LS30 Scanner Lens Tested
Replies: 49
Views: 1564

Re: Scanner Nikkor 38mm f/2.8 LS30 Scanner Lens Tested

The inner diameter of RMS is smaller than the D21.8 opening, so that would have to grab the lens from the end only.

M42x0.75 would have been nice, though. :wink: There is very limited number of rings ending at female M42x1, but almost unlimited number ending with female T2 (M42x0.75).
by JKT
Fri Dec 11, 2020 3:42 am
Forum: Equipment Discussions
Topic: 8000ED Scanner lens mounting idea
Replies: 7
Views: 805

Re: 8000ED Scanner lens mounting idea

I supect it should be relatively easy to design and print two sleeves with conical surface between them. On would have full circumference cone and on the other the cone would be split to sections. Then use two fixing rings to tighten them around the scanner lens.
by JKT
Sun Dec 06, 2020 12:11 pm
Forum: Equipment Discussions
Topic: Setup for the Mitutoyo M Plan Apo 50x / 0.55
Replies: 13
Views: 1124

Re: Setup for the Mitutoyo M Plan Apo 50x / 0.55

Are you sure your dimensions are right? It seems that you are using Raynox reversed. I'm not, but the distance from sensor to the rear flange of Raynox was something like 210mm. In your picture the rear flange is roughly 230 mm from the back of the rear cap. The sensor is likely a bit further still....
by JKT
Sat Dec 05, 2020 11:32 am
Forum: Equipment Discussions
Topic: Setup for the Mitutoyo M Plan Apo 50x / 0.55
Replies: 13
Views: 1124

Re: Setup for the Mitutoyo M Plan Apo 50x / 0.55

As a matter of fact, you shouldn't expect very much resolution from 50x/0.55. Something like 1500px from APS-C is my guess.
by JKT
Wed Dec 02, 2020 12:47 pm
Forum: Equipment Discussions
Topic: Choice of processor
Replies: 17
Views: 2373

Re: Choice of processor

32 GB of RAM.

Note the difference in transfer speed. Is this about SSD performance? If your Sabrent is Rocket Q4, it shouldn't be.