Zuul wrote: ↑
Tue Jul 07, 2020 5:51 pm
Does the trinoc produce a well corrected image on the 410?
Yes, at least, it is not obviously worse than the other heads I have, to my inexperienced eye. I guess the problem is I don't really have a good idea how dramatic the 34 vs 45 mm correction mismatch should be, and there are a lot of other possible variables since this stuff is mostly well-used surplus from eBay that may or may not have been helped by my fiddling with it.
apochronaut wrote: ↑
Tue Jul 07, 2020 6:34 pm
They no doubt ran out of frames for the series 100 head and since they were alteady in 400 series production it would make sense to use the available option. Fitting a certain number of them with the older telan lens wouldn't have been too hard.
It sounds like there is some possibility that the situation is:
- The trinocular head I got with the 150 is actually designed for it, just using the same housing as the series 400 heads.
- I am thinking the mystery trinocular head works ok on my 410 because the differences between the 34 and 45 mm corrections are subtle and I don't know what to look for.
- The worse CA I notice on the 150 is just the expected performance of the older 34 mm plan achro objectives vs. the 45 mm ones on the 410.
I will try to describe better the difference in CA I see between the 150 and 410 and maybe someone with more experience will have an opinion on whether this sounds normal:
The 10X objective on the 410 looks really nice, I think, good contrast, resolution beyond what my eyes can resolve, and not really any noticeable transverse CA even at the far edges of the field. There is uniform, not-too-distracting axial CA (if I am using the term correctly) where out-of-focus objects get either green or magenta fringe depending on whether they are above or below the focal plane. The 1127 10X plan achro on the 150 gives a sharp image and also not really much noticeable transverse CA, but the axial CA is quite a bit stronger, to the point of being somewhat distracting while focusing up and down, and the fringes are more blue/red than green/magenta.
The 40X objective on the 410 is sensitive to the slide preparation but can look very good also in terms of contrast and CA. Resolution gets close to, but not beyond, what my eyes can resolve, maybe limited by slide preparation? The 1128 40X plan achro on the 150 looks much worse in comparison. Resolution seems ok but in addition to red/blue axial CA as on the 10X there is noticeable transverse CA on in-focus objects near the edge of the field where edges are smeared out red-to-blue.
The objectives on the 150 have no obvious signs of abuse are in considerably better cosmetic condition than the ones I am comparing them to on the 410.
apochronaut wrote: ↑
Tue Jul 07, 2020 6:09 pm
... You can check that be trialling the 400 head with the 100x objective.
Lots of good info, thanks. I have not tried out any of the 100x objectives yet, still need to buy some immersion oil and practice, but I will keep that in mind.