Olympus BH2 - AFocal vs projection eyepiece?

What is your microscopy history? What are your interests? What equipment do you use?
Post Reply
Message
Author
MikeBradley
Posts: 70
Joined: Sat Sep 22, 2018 4:29 pm
Location: Sunshine Coast, BC, Canada

Olympus BH2 - AFocal vs projection eyepiece?

#1 Post by MikeBradley » Mon Mar 11, 2019 6:59 am

I am experimenting with an afocal setup, coupling my Canon APSC camera to an Olympus BH2 using an Olympus corrected eyepiece in the trinoc. photo-port. Using the 40 mm camera lens with an the 10x eyepiece gives me a field at the sensor very similar in size (1.6x mag) to that that would be produced by the NFK 1.67x projection eyepiece, at a considerable saving. What advantages would the NFK provide if I could find one?
Thanks
Michael
Olympus BH2,
AO110
Carl Zeiss Standard WL
Canon 60Da

User avatar
admin
Site Admin
Posts: 49
Joined: Sat Oct 11, 2014 9:22 am

Re: Olympus BH2 - AFocal vs projection eyepiece?

#2 Post by admin » Tue Mar 12, 2019 11:13 pm

Hello,
The NFK projection eyepieces are so-called compensating eyepieces. This means that they correct lens errors (aberrations) that are still present from the objective. The NFK eyepieces are designed to project the image diretly on flat photographic film or sensor. They are not designed for afocal, but this does not mean that it does not work for this as well. The NFKs are also designed for parfocality when projecting. If you do not project the image directly on the sensor but use afocal photography, then I can imagine that maybe conventional olympus eyepieces might be better, becasue they too correct some aberrations and becasue they adjust the eye relief distance, which makes it possible to mount a camera (with objective) in front of the eyepiece at an appropriate distance. Another thing that should be considered is the diameter of the eyepieces in relation to the diameter of the camera objective (afocal). The NFK have a small diameter. I guess the best way is to try it out and if you get good results with the 10x, then I would stick with it. If the eypiece-objective combination provides a good picture and the camera optics are fine, then I see no reason why the combination of these two would result in a lower quality image.

http://www.alanwood.net/photography/oly ... .html#nfkl

Oliver.
Science may set limits to knowledge, but should not set limits to imagination.
(Bertrand Russell)

MikeBradley
Posts: 70
Joined: Sat Sep 22, 2018 4:29 pm
Location: Sunshine Coast, BC, Canada

Re: Olympus BH2 - AFocal vs projection eyepiece?

#3 Post by MikeBradley » Wed Mar 13, 2019 3:53 am

Thanks Oliver. Sorry, but I wasn’t clear, the comparison I am trying to make is an afocal setup (40mm Canon lens+Olympus 10x compensated eyepiece) versus an NFK 1.67 projection lens directly to camera sensor. Using the formulae from Charles Krebs page the images sizes/degrees magnification of the image are similar in these 2 configuarions.
Anyway, based on your thoughts, I think I’ll stick with my current afocal setup and save a few hundred dollars.
Thanks,
Michael
Olympus BH2,
AO110
Carl Zeiss Standard WL
Canon 60Da

User avatar
admin
Site Admin
Posts: 49
Joined: Sat Oct 11, 2014 9:22 am

Re: Olympus BH2 - AFocal vs projection eyepiece?

#4 Post by admin » Wed Mar 13, 2019 9:06 pm

Hi,
in my setup I project it directly into the camera, but there is the problem of stray light (and thus lower contrast) if you do not have Koehler illumination. So this might be seen as another advantage for the afocal setup.
Oliver.
Science may set limits to knowledge, but should not set limits to imagination.
(Bertrand Russell)

Post Reply