I'd like to reduce the field width of an extra or ultrawide set of
binoculars. If the eyepiece were a Kellner I'd know what to do
at the field lens, (the image plane seems to be at the field lens)
but extra-wides don't have Kellners. Not sure
where a clean cut of the image can be made for other types.
I have seen a Plossl with a field lens outside the achromatic pair.
The smutz on the 'field lens' didn't seem as sharp as in a Kellner
before the cleaning.
binoculars. If the eyepiece were a Kellner I'd know what to do
at the field lens, (the image plane seems to be at the field lens)
but extra-wides don't have Kellners. Not sure
where a clean cut of the image can be made for other types.
I have seen a Plossl with a field lens outside the achromatic pair.
The smutz on the 'field lens' didn't seem as sharp as in a Kellner
before the cleaning.
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