Field number is the objective field in your chart normalized to 1x. The rating on them is nomjnally 24mm. So far I still don’t understand how this characteristic can help me choose a 100-110 mm photo lens...(( The point is that no objective is specced for this kind of use. If it works it is exceedi...

Field number is the objective field in your chart normalized to 1x. The rating on them is nomjnally 24mm.

Oh yes, I was not meaning to suggest you were wrong, you're absolutely right. Some objectives like the BE series or many Mitutoyo objectives go way beyond their nominal spec. It's just good for people to know that it is not typical to get good coverage like this and they shouldn't expect it from obj...

Using a 100mm tube lens on aps-c assumes an objective with a field number of something like 54mm. That's way beyond what any objective has ever been specced for so don't expect many to give great results, only the ones with the widest of fields.

That sure sounds like chatgpt to me. By chatbot you mean me? Not at all, I mean "Ushavilash". Their one other post is nonsensical, this one is probably a chatgpt output (note it's almost relevant but also completely off base of the topic). In a few weeks those posts will likely be automatically edi...

That sure sounds like chatgpt to me.

Are these any good? The impression I'd gotten was that nobody seemed to have good experiences with these computar lenses.

I think you're off to a great start--glad the objective is working for you!

Probably the only major change was the originals were apparently 50x/0.50. There is one on eBay with the old engraved barrel.

This is not the BD version. Infinity non-bd CF objectives have an RMS thread. The infinity CF BDs use an m27x0.75 thread. Normal LU plans use the same 25x0.75mm thread as other eclipse objectives, that should be fixed on the list.

Congrats, I think you'll enjoy it a lot.
I own a few 40/50xes myself. The long working distance is essential for some subjects, while higher res shorter wd is good for others.

I was talking to someone who bought one of those hoopuo 20xes without reading the thread super carefully (ie, missing that Chris was explicitly pretty sure his lens had been specially made to a higher spec) and indeed he said the one he got was much worse than his mitutoyo 20x.

I have used the finite BDs on a metallurgical microscope. If you can deal with the working distance the optical quality is quite good. I've also used a chinese copy of the infinity cf plan bd 40x and it works well, the original must be better.

mkbn wrote: ↑

Fri Jan 26, 2024 1:27 pm

I will look for some of the photos on here!

Something that confused me is, isn't 0.55 NA pretty low for 50x?

Yes, it's workable but low. That's the price for a long working distance, but the results are still pretty good. Hard to beat for the price.

A few days ago I spotted this potential deal on a nikon cf elwd 50x/0.55 https://www.ebay.com/itm/285667205792. Worth making an offer on for a very decent objective, not as good as a mitutoyo 50x but you can find some examples of photos taken with it around here, results are good. Resolution is limi...