Kerry,
Do you know if there's a way to determine optical construction without having to disassemble the groups?
BTW, I often visit your lens pages... great stuff there.
Mike
Kerry,
Do you know if there's a way to determine optical construction without having to disassemble the groups?
BTW, I often visit your lens pages... great stuff there.
Mike
PMFJI. Counting reflections is a start. Use a point source or a single lamp. An air-glass interface makes a strong reflection, a glass-cement-glass interface makes a weak one. Weak reflections can be very hard to see.Do you know if there's a way to determine optical construction without having to disassemble the groups?
Think about it and you'll see that Kerry's two lenses -- 6/6 sort of perhaps double Gauss and 6/4 plasmat -- are easy to tell apart.
Thanks, Dan. I checked again and could only see 4 reflections in each set of cells... all strong reflections. This time I used a small very bright LED flashlight from about 3 feet away. I tried very hard but could not see any weak reflections.
I don't know if this helps but, other than the mounts, the front and rear groups look identical and seem to have identical individual focal lengths.
Well I won't be much help with my images. They are probably not the best to tell corner sharpness, pre-sunrise dark corners... I do have one that is very sharp throughout but it was focused closer so not at infinity. I also have one from Great Sand Dunes NP but would need to re-scan it at higher resolution. Sorry for that. I have a couple getting developed but won't see those for a week unfortunately. Those might be of more help.
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"There is little or no ‘reality’ in the blacks, grays and whites of either the informational or expressive black-and-white image" -Ansel Adams
Thank you, Zaitz. I'm in no hurry. Please post your results as they filter in through your normal routine.
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