www.photomacrography.net :: View topic - Connecting Olympus BH-2 microscope and E-3 DSLR
www.photomacrography.net Forum Index
An online community dedicated to the practices of photomacrography, close-up and macro photography, and photomicrography.
Photomacrography Front Page Amateurmicrography Front Page
Old Forums/Galleries
 
 FAQFAQ   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups   RegisterRegister 
 ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in 
Connecting Olympus BH-2 microscope and E-3 DSLR
Goto page Previous  1, 2, 3, 4  Next
 
Post new topic   Reply to topic    www.photomacrography.net Forum Index -> Equipment Discussions
View previous topic :: View next topic  
Author Message
allelopath



Joined: 07 Sep 2014
Posts: 37

PostPosted: Sun Sep 14, 2014 8:38 am    Post subject: Reply with quote

Is this lens suitable? (ideal?)
http://www.ebay.com/itm/Olympus-OM-system-G-Zuiko-Auto-s-50mm-f-1-4-Fast-Prime-Standard-MF-lens-/161260699586?_trksid=p2054897.l5660
Back to top
View user's profile Send private message
Ichthyophthirius



Joined: 07 Mar 2013
Posts: 884

PostPosted: Sun Sep 14, 2014 8:58 am    Post subject: Reply with quote

allelopath wrote:
Is this lens suitable? (ideal?)
http://www.ebay.com/itm/Olympus-OM-system-G-Zuiko-Auto-s-50mm-f-1-4-Fast-Prime-Standard-MF-lens-/161260699586?_trksid=p2054897.l5660


You'd only know after testing. Some lenses produce hot spots, others don't.

The 50/1.4 would probably work, but it is both a fast lens (expensive) and quite thick. A fast lens has no advantage as the afocal approach has a very small effective aperture. If you haven't got the 50/1.4 already, buy a 50/1.8 instead which is cheaper and thinner. You can always replace it for something "better" later.
Back to top
View user's profile Send private message
Pau
Site Admin


Joined: 20 Jan 2010
Posts: 4832
Location: Valencia, Spain

PostPosted: Sun Sep 14, 2014 9:03 am    Post subject: Reply with quote

Suitable? Yes
Ideal? I don't know, before you need to have the photoeyepiece to calculate the adequate focal lenght for it. I use the OM 1.8 50mm and it's excellent (and less expensive!), better look for the MC version (multicoated, with green reflections)
_________________
Pau
Back to top
View user's profile Send private message
rjlittlefield
Site Admin


Joined: 01 Aug 2006
Posts: 20040
Location: Richland, Washington State, USA

PostPosted: Sun Sep 14, 2014 9:51 am    Post subject: Reply with quote

Ichthyophthirius wrote:
You then use the afocal method: The trinocular photo tube needs an Olympus NFK 3.3x or NFK 5x projective (they are not very expensive). The projectives generate a real image that you can record with a camera objective of suitable focal length.

For the calculations see http://www.krebsmicro.com/photomic1/photomic1.pdf

Munit = (FL/250)* (Eyepiece Magnification)

...

P.S. If anybody disagrees, please let us know!!!

Icthy, I think I have the same confusion that Pau does.

It looks to me like you're starting with a projection eyepiece that is intended to generate a real image all by itself. Then you're changing focus so that the eyepiece does not generate a real image all by itself, but instead generates a virtual image at infinity just like a normal visual eyepiece would do. Finally the lens on the camera finishes the image formation by refocusing the virtual image at infinity to form a real image on sensor.

This approach will work, but there may be trouble getting the camera to be parfocal with what the user sees through the normal eyepieces. There will also be some aberrations introduced by using the eyepiece outside its normal focus arrangement. I don't know how strong those will be. What you're doing is essentially to reverse the common trick of using a normal visual eyepiece for projection by raising it above its usual focus. This typically introduces some curvature of field and softens the edges, but how bad depends on details of the eyepieces.

The formulas that you have given are for a normal visual eyepiece used in combination with a camera lens. The camera lens is focused at infinity, and the combination of the normal eyepiece and the camera lens makes a closeup combo that has magnification Rear_FL/Front_FL. Rear_FL is the focal length of the camera lens (what you're calling just FL), and Front_FL is 250mm/(Eyepiece Magnification). Then:

Rear_FL/Front_FL = Rear_FL/(250mm/(Eyepiece Magnification)) = (FL/250)*(Eyepiece Magnification)

Quote:
If you use an NFK 3.3x, the eyepiece magn. is 6.6x; cas the camera objective, let's use a simple 50mm prime lens:

Munit = 50/250 * 6.6 = 1.32

Where does the the 6.6x come from? As it's intended to be used, the eyepiece gives 3.3x. But that's in projection mode. I'm guessing that somehow you've figured out that the eyepiece has focal length of 38 mm, and then 6.6 = 250/38 will be its effective magnification after being refocused.

Have I missed something here?

--Rik
Back to top
View user's profile Send private message Visit poster's website
allelopath



Joined: 07 Sep 2014
Posts: 37

PostPosted: Sun Sep 14, 2014 9:57 am    Post subject: Reply with quote

Ok, so this then:
http://www.ebay.com/itm/like/151201832280?lpid=82

Then I will need a micro 4/3 adapter. That would be this?
http://www.bhphotovideo.com/c/product/842941-REG/Olympus_V3230500W000_MMF_3_Four_Thirds_Adapter.html
Back to top
View user's profile Send private message
rjlittlefield
Site Admin


Joined: 01 Aug 2006
Posts: 20040
Location: Richland, Washington State, USA

PostPosted: Sun Sep 14, 2014 10:01 am    Post subject: Reply with quote

rjlittlefield wrote:
Have I missed something here?

Yes -- I missed seeing your posting at the bottom of the previous page, posted while I was writing mine.

I think that what you've said there confirms what I wrote above. But I'll leave the post in place just in case I'm wrong about that.

--Rik
Back to top
View user's profile Send private message Visit poster's website
Pau
Site Admin


Joined: 20 Jan 2010
Posts: 4832
Location: Valencia, Spain

PostPosted: Sun Sep 14, 2014 10:18 am    Post subject: Reply with quote

Yes, but you can get it for less. This one seems newer and cheaper, there are lots of them on offer
http://www.ebay.com/itm/Olympus-OM-System-Zuiko-MC-Auto-S-50mm-f-1-8-lens-OM-Mount-/380995045982?pt=Camera_Lenses&hash=item58b5130a5e
-About the 4/3 to m3/4 adapter, I don't know at what extent the 3/4 mount is compatible with OM (I recall that it can be mounted but not locked, I'm not sure) and the flange focal distance seems different, so a OM to m4/3 seems more adequate.
For this kind of application a simpler chinese one could be equally convenient, like
http://www.ebay.com/itm/Olympus-OM-lens-To-Micro-4-3-m4-3-Adapter-for-E-P1-E-P2-E-P2-E-M5-E-PM2-GF6-GF5-/281435929961?pt=US_Lens_Adapters_Mounts_Tubes&hash=item4186e37d69

(disclaimer: i dont know about its quality, in fact I don't use Oly digital cameras)

EDIT: you need OM to 4/3, I was misleaded because you linked an adapter to m4/3. Red words doesn't apply!
_________________
Pau


Last edited by Pau on Sun Sep 14, 2014 10:34 am; edited 1 time in total
Back to top
View user's profile Send private message
Ichthyophthirius



Joined: 07 Mar 2013
Posts: 884

PostPosted: Sun Sep 14, 2014 10:23 am    Post subject: Reply with quote

allelopath wrote:
Ok, so this then:
http://www.ebay.com/itm/like/151201832280?lpid=82

Then I will need a micro 4/3 adapter. That would be this?
http://www.bhphotovideo.com/c/product/842941-REG/Olympus_V3230500W000_MMF_3_Four_Thirds_Adapter.html


MC lens is good, as recommended by Pau.

4/3 adapter is unnecessarily expensive. Theoretically, you only need a mechanical adapter www.ebay.com/itm/120808320654 . However, I don't know of the Olympus E-3 will take images without a lens. My Canon does; you'll have to find out yourself. There are also adapters with AF confirm chips etc. which cost $10 more; but never $160.
Back to top
View user's profile Send private message
Ichthyophthirius



Joined: 07 Mar 2013
Posts: 884

PostPosted: Sun Sep 14, 2014 10:57 am    Post subject: Reply with quote

rjlittlefield wrote:
This approach will work, but there may be trouble getting the camera to be parfocal with what the user sees through the normal eyepieces. There will also be some aberrations introduced by using the eyepiece outside its normal focus arrangement. I don't know how strong those will be. What you're doing is essentially to reverse the common trick of using a normal visual eyepiece for projection by raising it above its usual focus. This typically introduces some curvature of field and softens the edges, but how bad depends on details of the eyepieces.


EDIT:

Hi Rik,

I have now tried it out myself with an NFK 2.5x. You're right, it doesn't work as projective and eyepieces are not parfocal.


On my Zeiss Standard, I'm using two visual 10x eyepieces in the binoculars and a projective in the phototube.

All three are parfocal when using a Zeiss Mipro or a Leitz objective, but the Olympus NFK is not parfocal.

So the difference between the projectives projecting to infinity and those projecting to 125mm appears to be the reason.

Sorry, allelopath, it appears this won't work. Unless you find an Olympus visual eyepiece that fits into your phototube, afocal won't work.

Kind regards,

Ichthy


Last edited by Ichthyophthirius on Sun Sep 14, 2014 6:36 pm; edited 2 times in total
Back to top
View user's profile Send private message
Pau
Site Admin


Joined: 20 Jan 2010
Posts: 4832
Location: Valencia, Spain

PostPosted: Sun Sep 14, 2014 11:20 am    Post subject: Reply with quote

Ichthyophthirius wrote:
Does anybody here have an NFK 3.3x and could literally give it a shot?

I have one somewhere in a drawer or box, when I find it and have the time I'll test it with the OM 50 1.8, but with my Zeiss microscope and Leitz objectives, as I don't have more Oly stuff. I recall it not being parfocal when used as visual eyepiece.
_________________
Pau
Back to top
View user's profile Send private message
allelopath



Joined: 07 Sep 2014
Posts: 37

PostPosted: Sun Sep 14, 2014 3:49 pm    Post subject: Reply with quote

>> Olympus E-3 will take images without a lens
??? I don't get this. Can you elaborate? You point to a mechanical adapter (www.ebay.com/itm/120808320654 ). If it is not adapting a lens to a camera what is it adapting to what?
Back to top
View user's profile Send private message
Ichthyophthirius



Joined: 07 Mar 2013
Posts: 884

PostPosted: Sun Sep 14, 2014 5:29 pm    Post subject: Reply with quote

allelopath wrote:
>> Olympus E-3 will take images without a lens
??? I don't get this. Can you elaborate? You point to a mechanical adapter (www.ebay.com/itm/120808320654 ). If it is not adapting a lens to a camera what is it adapting to what?


Hi, An autofocus camera lens needs an electrical connection between objective and camera (there are pins on the inside; have a look).

When you use a simple mechanical adapter to connect an old analog era lens (simply a way to attach the old lens to the camera at the correct distance), it cannot make the electrical contact. The camera software will register that no lens is attached.

Now, this isn't a problem for some cameras. All or most software functions (like exposure, ISO etc.) will still work, except for the autofocus.

Other cameras might simply give an error message and refuse to work at all.

So I suggested that before you start, take off the Olympus lens from your camera and double-check it it still takes a picture (obviously, you won't see an image, just gray).

Ichthy
Back to top
View user's profile Send private message
allelopath



Joined: 07 Sep 2014
Posts: 37

PostPosted: Sun Sep 14, 2014 7:06 pm    Post subject: Reply with quote

Just tried it. Yes it does take a photo with the lens off.

So I can get the Olympus AUTO Zuiko 50mm F1.8 OM Lens for MC MULTI COATED MODEL and the Olympus 35mm OM Lens to 4/3 Camera Body Mount Adapter Adaptor.

Even if this ends up not working for the microscope, I'll have a prime lens for my camera.
Back to top
View user's profile Send private message
enricosavazzi



Joined: 21 Nov 2009
Posts: 1194
Location: Valdemarsvik, Sweden

PostPosted: Mon Sep 15, 2014 1:37 am    Post subject: Reply with quote

Pau wrote:

[...]
EDIT: you need OM to 4/3, I was misleaded because you linked an adapter to m4/3. Red words doesn't apply!

Olympus makes (or made) an OM to 4/3 adapter. There might be no-name adapters on eBay, but not as common as for Micro 4/3.

In the past, on eBay there was a lot of confusion among OM, 4/3 and Micro 4/3 adapters, with many ads for "Olympus OM" adapters actually referring to 4/3 or Micro 4/3 adapters. There is less confusion now, but still it is necessary to make sure exactly what you are buying.

Perhaps I am missing the point, but why not using a Micro 4/3 mirrorless camera instead of an Olympus 4/3 DSLR? A mirrorless has no mirror slap, which removes one of the main DSLR problems, and it is a lot easier to find Micro 4/3 adapters these days. The Sigma 30 mm f/2.8 for Micro 4/3 is relatively cheap and works very well in an afocal setup with an ordinary 10x eyepiece, which is very easy to find. An OM 50 mm f/1.8 will use only the center of the image circle, with a lot of the periphery wasted.
_________________
--ES
Back to top
View user's profile Send private message Visit poster's website
Pau
Site Admin


Joined: 20 Jan 2010
Posts: 4832
Location: Valencia, Spain

PostPosted: Mon Sep 15, 2014 7:14 am    Post subject: Reply with quote

enricosavazzi wrote:
but why not using a Micro 4/3 mirrorless camera instead of an Olympus 4/3 DSLR?...


Just because allelopath asks about E3 DSLR. A full frame Canon like the 6D will be more convenient and easy to adapt but I think he wants to use his E3.
_________________
Pau
Back to top
View user's profile Send private message
Display posts from previous:   
Post new topic   Reply to topic    www.photomacrography.net Forum Index -> Equipment Discussions All times are GMT - 7 Hours
Goto page Previous  1, 2, 3, 4  Next
Page 2 of 4

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum


Powered by phpBB © 2001, 2005 phpBB Group