Right now I'm using a Borg 101ED with a Zeiss binoviewer and 2 Pentax XW 20mm EPs. That gives a magnification of 32X and an exit pupil of 3,15mm. I use it for birding, and it works OK, I just miss some more light and contrast unless it's really bright sunshine. So I'm considering to get a 107FL objective, that will fit my 80mm tube, and being 600mm vs 640 it will give me an enlargement of just 30X and an exit pupil of 3.56mm. The smaller enlargement is no problem, rather an advantage, but it's a very expensive objective and hard to find second hand, so I wonder if it's worth doing that upgrade?
I'm not sure how visible the increase in exit pupil from 3.15 to 3.56mm will be, and how much better the contrast will be in the 107FL? In terms of sharpness there'll probably be very little difference at so low power.
Unfortunately I have no possibility to try it out for myself, I live in Denmark, where there is no Borg dealer, and I don't know anyone having this objective. So I'm interested to hear, if anyone from this forum has compared the 101ED directly to the 107FL and can give me an idea, if there is a clearly visible difference between these 2 objectives.
Thanks for your time,