Olympus LM PLAN FI 20x/0.40 BD infnity corrected
Moderators: rjlittlefield, ChrisR, Chris S., Pau
Olympus LM PLAN FI 20x/0.40 BD infnity corrected
Hello,
anyone can give me some information about this please?
Thanks
Antonio
anyone can give me some information about this please?
Thanks
Antonio
Thanks Chris S.Chris S. wrote:From off-line communication, I understand that Antonio wants to know if this objective is suitable for use on a macro rig. For example, does it require CA compensating optics? What is its working distance?
--Chris S.
I found this topic in another website: https://foromacrosmuymacros.com/viewtop ... f=12&t=858
Antonio
-
- Posts: 1152
- Joined: Thu Mar 07, 2013 5:24 am
Hi,
Have a look at the Industrial Component Guide, p. 17: https://www.olympusamerica.com/seg_indu ... _guide.pdf
Working distance is 12mm, thread is M26 x 36 TPI, FN is 26.5.
https://www.edmundoptics.eu/p/olympus-l ... ive/29238/
Olympus UIS/UIS2 objectives need no additional CA correction in the tube lens. You just have to find a suitable tube lens. Olympus tube lenses (U-TLU; single port tube with lens, p. 3) are regularly sold on Ebay.
Regards, Ichty
Have a look at the Industrial Component Guide, p. 17: https://www.olympusamerica.com/seg_indu ... _guide.pdf
Working distance is 12mm, thread is M26 x 36 TPI, FN is 26.5.
https://www.edmundoptics.eu/p/olympus-l ... ive/29238/
Olympus UIS/UIS2 objectives need no additional CA correction in the tube lens. You just have to find a suitable tube lens. Olympus tube lenses (U-TLU; single port tube with lens, p. 3) are regularly sold on Ebay.
Regards, Ichty
Excellent!Ichthyophthirius wrote:. . . need no additional CA correction in the tube lens. You just have to find a suitable tube lens.
Antonio, you already have a suitable tube lens, as I know you have an assembly based around the Raynox DCR 150, which we now know will work fine with this objective. Just be aware that this nominally 20x objective will deliver a bit over 23x magnification on your sensor when used with the Raynox.
(Why? Because the Olympus objective is designed to deliver 20x magnification with a 180mm focal length tube lens; your tube lens has a 208mm focal length; and magnification on sensor scales with focal length of tube lens. The math is: 208mm/180mm * 20x = magnification on sensor .)
Also be aware that you will need the proper adapter for your Raynox assembly. Since Ichty reports that the Olympus BD objective takes M26x36 TPI threads (the same as used by Mitutoyo objectives), you can look for either an Olympus BD adapter or Mitutoyo adapter that fits the front of your Raynox assembly. (TPI means "Threads Per Inch", or 0.706mm.)
Lastly, since this is a BD objective, there will be an outer ring that must be blocked to prevent light from leaking onto your sensor. This should be easy to do.
--Chris S.
-
- Posts: 1152
- Joined: Thu Mar 07, 2013 5:24 am
Hello Chris S., about this you said :
I must insert dark material to prevent light?
Thanks
Antonio
what does it mean "blocked"?..there will be an outer ring that must be blocked to prevent light from leaking onto your sensor...
I must insert dark material to prevent light?
Thanks
Antonio
Chris S. wrote:Excellent!Ichthyophthirius wrote:. . . need no additional CA correction in the tube lens. You just have to find a suitable tube lens.
Antonio, you already have a suitable tube lens, as I know you have an assembly based around the Raynox DCR 150, which we now know will work fine with this objective. Just be aware that this nominally 20x objective will deliver a bit over 23x magnification on your sensor when used with the Raynox.
(Why? Because the Olympus objective is designed to deliver 20x magnification with a 180mm focal length tube lens; your tube lens has a 208mm focal length; and magnification on sensor scales with focal length of tube lens. The math is: 208mm/180mm * 20x = magnification on sensor .)
Also be aware that you will need the proper adapter for your Raynox assembly. Since Ichty reports that the Olympus BD objective takes M26x36 TPI threads (the same as used by Mitutoyo objectives), you can look for either an Olympus BD adapter or Mitutoyo adapter that fits the front of your Raynox assembly. (TPI means "Threads Per Inch", or 0.706mm.)
Lastly, since this is a BD objective, there will be an outer ring that must be blocked to prevent light from leaking onto your sensor. This should be easy to do.
--Chris S.
Antonio,anto74 wrote:Hello Chris S., about this you said :what does it mean "blocked"?..there will be an outer ring that must be blocked to prevent light from leaking onto your sensor...
I must insert dark material to prevent light?
Congratulations on acquiring what looks like a very nice lens at a favorable price.
In general, BD lenses (the letters stand for "Brightfield/Darkfield") have an outer barrel and an inner barrel. The inner barrel contains the glass elements of the lens. The outer barrel is hollow, and was intended to conduct light onto the subject (when used on a brightfield/darkfield microscope) from a light source on the microscope, shining through this outer barrel, onto the subject.
In your use, no such light source exists. And worse, this hollow outer barrel can permit light that bounces off the subject, or areas around the subject, to travel up this outer barrel and shine on your sensor. So yes, you must block this outer barrel to keep stray light from fogging your sensor.
That would be one way to do it, and I can think of other ways. This said, I've never had a BD objective in hand, so have not personally blocked this source of light leakage. But many other members of our forum have done this, and I would ask how they have done it.I must insert dark material to prevent light?
Can folks who have experience in blocking off the outer barrel of a BD objective give Antonio practical advice?
--Chris S.
Thanks again Chris S.
Now I'm testing the lens (only for testing I used insulating tape...) and I will post the shot.
Two questions:
1) I must block the light in outer ring near the subject or near the mount lens?
2) This objective has 180mm tube lens distance. I have variable kit lens purchased on Mjzkk website. I must calculate the tube length + Raynox DCR 150 length or I must consider only tubes length? 180m are only tubes or tube + DCR150?
Thanks,
Antonio
PS Sorry for my stupid question...but I'm learning...
Now I'm testing the lens (only for testing I used insulating tape...) and I will post the shot.
Two questions:
1) I must block the light in outer ring near the subject or near the mount lens?
2) This objective has 180mm tube lens distance. I have variable kit lens purchased on Mjzkk website. I must calculate the tube length + Raynox DCR 150 length or I must consider only tubes length? 180m are only tubes or tube + DCR150?
Thanks,
Antonio
PS Sorry for my stupid question...but I'm learning...
Ciao Antonio,
Basically you will set your tube lens focus at infinity. Therefor you focus with your tube lens (without any microscope lens! just the Raynox) on a very distant object.
Your raynox is now set at little more than 200mm. This will give you a little more than 20x mag with the olympus.
In a second step you just have to try out, make some testing reducing distance between sensor and TL. Some people have showed that some objectives work better with reduced distance sensor-TL..
Have fun with your lens!
Edit: Nominal focal length for the raynox seems to be 208mm
And: read mtf testing of the raynox here: https://www.photomacrography.net/forum/ ... hp?t=41049
Basically you will set your tube lens focus at infinity. Therefor you focus with your tube lens (without any microscope lens! just the Raynox) on a very distant object.
Your raynox is now set at little more than 200mm. This will give you a little more than 20x mag with the olympus.
In a second step you just have to try out, make some testing reducing distance between sensor and TL. Some people have showed that some objectives work better with reduced distance sensor-TL..
Have fun with your lens!
Edit: Nominal focal length for the raynox seems to be 208mm
And: read mtf testing of the raynox here: https://www.photomacrography.net/forum/ ... hp?t=41049