Search found 4632 matches

by Lou Jost
Fri Oct 16, 2020 6:08 pm
Forum: Equipment Discussions
Topic: Micro-Symmar 3.5x
Replies: 32
Views: 2513

Re: Micro-Symmar 3.5x

You can get larger image circles by using medium format tube lenses. There are some good ones (Mamiya 200mm Apo for example) and maybe some superlative ones like the Hasselblad 250mm Superachromat; when released, this was said to be the best-corrected commercial lens ever. It is so well corrected th...
by Lou Jost
Fri Oct 16, 2020 3:00 pm
Forum: Equipment Discussions
Topic: Micro-Symmar 3.5x
Replies: 32
Views: 2513

Re: Micro-Symmar 3.5x

The king of 3.5x still goes to the Rayfact I suppose, which needs 600mm of tubing.
Or some lens combo, which would need no extension at all....
by Lou Jost
Fri Oct 16, 2020 2:57 pm
Forum: Equipment Discussions
Topic: New Mitutoyo apo 10x
Replies: 48
Views: 3760

Re: New Mitutoyo apo 10x

The thing that was special about that wafer was the test patterns. That's what we most need to make this useful. I hope we can find something like that again. B+W makes some, and I bought one from a forum member; maybe that is an option for some of us. What does B+W make that's relevant to the cont...
by Lou Jost
Fri Oct 16, 2020 9:52 am
Forum: Equipment Discussions
Topic: New Mitutoyo apo 10x
Replies: 48
Views: 3760

Re: New Mitutoyo apo 10x

The thing that was special about that wafer was the test patterns. That's what we most need to make this useful. I hope we can find something like that again. B+W makes some, and I bought one from a forum member; maybe that is an option for some of us.
by Lou Jost
Fri Oct 16, 2020 6:51 am
Forum: Equipment Discussions
Topic: New Mitutoyo apo 10x
Replies: 48
Views: 3760

Re: New Mitutoyo apo 10x

I think the real purpose of shared targets is not to do super-controilled experiments. It is to provide users with benchmarks to judge the quality of their setup. If a beginner knew that experts were regularly resolving x lines per mm on those resolution targets with some optic and lighting, then he...
by Lou Jost
Thu Oct 15, 2020 11:17 pm
Forum: Equipment Discussions
Topic: New Mitutoyo apo 10x
Replies: 48
Views: 3760

Re: New Mitutoyo apo 10x

I agree, Chris, that someone just starting out can easily miss the non-optical factors that cause unsharp images. I don't think that a beginner will be able to conclude much by comparing his first result with known good results that used the same target. Too much depends on technique rather than opt...
by Lou Jost
Thu Oct 15, 2020 11:01 am
Forum: Equipment Discussions
Topic: New Mitutoyo apo 10x
Replies: 48
Views: 3760

Re: New Mitutoyo apo 10x

Without equipment and a known-good standard for comparison, there is no way to evaluate this lens. Many forum members are starting to get standardized wafers as resolution targets, and this will give us the ability to test and comapre our objectives against a common standard. I hope this standardiz...
by Lou Jost
Wed Oct 14, 2020 3:30 pm
Forum: Nature Photography -- Macro and Close-up
Topic: Cluster of Bees
Replies: 3
Views: 504

Re: Cluster of Bees

What a lovely and unusual shot.
by Lou Jost
Wed Oct 14, 2020 11:34 am
Forum: Equipment Discussions
Topic: Can I push the resolution of a 1:1 macro lens?
Replies: 23
Views: 2244

Re: Can I push the resolution of a 1:1 macro lens?

Yes, it is there now. Maybe my computer was drawing from its cache.
by Lou Jost
Wed Oct 14, 2020 6:51 am
Forum: Equipment Discussions
Topic: Can I push the resolution of a 1:1 macro lens?
Replies: 23
Views: 2244

Re: Can I push the resolution of a 1:1 macro lens?

I added a short discussion and a couple of links about the other methods.

Thanks, that will be helpful to many.

I could not find the new additions, am I missing something?
by Lou Jost
Tue Oct 13, 2020 4:30 pm
Forum: Equipment Discussions
Topic: Micro-Symmar 3.5x
Replies: 32
Views: 2513

Re: Micro-Symmar 3.5x

I'm sorry to hear that. I know that feeling very well :cry:
by Lou Jost
Tue Oct 13, 2020 6:33 am
Forum: Equipment Exchange
Topic: sold: Nikon Scanner ED lens
Replies: 9
Views: 1063

Re: Nikon Scanner ED lens

Even $300 would be a very good deal. These are rare lenses that are typically scavenged from non-functional old high-end Nikon Coolscan medium format scanners, which are themselves hard to find. They are nearly apochromatic and have a large image circle, and have about 7 ED glass elements, far more ...
by Lou Jost
Tue Oct 13, 2020 6:29 am
Forum: Equipment Discussions
Topic: Can I push the resolution of a 1:1 macro lens?
Replies: 23
Views: 2244

Re: Can I push the resolution of a 1:1 macro lens?

Enrico, those are excellent tests! It is striking to see that the best lenses still give best results wide open when used on a good teleconverter; this is not normally the case for cheap teleconverters, which introduce their own significant aberrations, which in turn are redued by stopping down the ...
by Lou Jost
Sun Oct 11, 2020 4:35 pm
Forum: Macro and Micro Technique and Technical Discussions
Topic: Effective aperture with teleconverter + macro lens
Replies: 6
Views: 680

Re: Effective aperture with teleconverter + macro lens

Got it. When you said "The increased distance when using the teleconverter..." I read that as an increase when inserting the teleconverter, while you were really comparing the post-teleconverter distance not to the pre-teleconverter 1:1 distance but to the new 2:1 distance achieved by pure extension.
by Lou Jost
Sun Oct 11, 2020 2:11 pm
Forum: Macro and Micro Technique and Technical Discussions
Topic: Effective aperture with teleconverter + macro lens
Replies: 6
Views: 680

Re: Effective aperture with teleconverter + macro lens

When you reach 2:1 by extension only, the distance from subject to lens will be only FL * (1+1/2) = 1.5 * FL. But when you reach 2:1 as 1:1 plus teleconverter, the distance from subject to lens will be FL * (1+1) = 2 * FL. The increased distance when using the teleconverter produces a narrower entr...