Advice needed on photoeyepiece use and cameras - Olympus BHB

Starting out in microscopy? Post images and ask questions relating to the microscope and get answers from our more advanced users on the subject.

Moderators: rjlittlefield, ChrisR, Chris S., Pau

jmc
Posts: 238
Joined: Fri Apr 17, 2020 3:14 am

Advice needed on photoeyepiece use and cameras - Olympus BHB

Post by jmc »

I need some advice please folks, as I'm struggling to get my head around something.

I have an Olympus BHB with a trinocular head, and am taking photos through the top tube. I am using an Olympus NFK 3.3x photoeyepiece.

In order to attach the camera to the microscope, I am using a Nikon F mount to microscope adapter, which clamps on to the tube and the camera is mounted on top of that. This is an older device from the 70s.

This is where I need the advice, as the Nikon F mount to microscope adapter also has a lens in it.

This setup works, and I'm getting images, but do I actually need a camera mount that has a lens in it, if I'm using the photoeyepiece?

The overall magnification is about 20x when I use the photoeyepiece in combination with the camera adapter, so I can't get low magnification images. I've read that the NFK photoeyepiece is really designed for direct projection on to the image sensor, which makes me think I don't need another lens in the camera mount, and that would also help with reducing my overall magnification.

Hope that makes sense, and any advice welcome.
Jonathan Crowther

Ichthyophthirius
Posts: 1152
Joined: Thu Mar 07, 2013 5:24 am

Post by Ichthyophthirius »

That's right. The NFK projective is enough. If the Nikon adapter had a reducing lens that would be nice but that doesn't seem to be the case for you.

What you would need are Olympus adapters PM-ADF and L http://www.alanwood.net/olympus/photomi ... -l-il5.png or a homemade adapter that has the same length as adapter L. http://www.alanwood.net/olympus/photomi ... ter-l.html

It's easier to understand if you differentiate between projectives and eyepieces.

Projectives = real image at finite camera length (for NFK: 125 mm); no further optics required
Eyepieces = image at infinity; for photoraphy use, camera lens is needed to take a picture (afocal adaptation)

---

The great thing about your Olympus BH (vs. the BH2) is that you don't need to use NFK projectives. You can use normal eyepieces and make an afocal adaptation with much better coverage on your camera sensor. What camera do you have?

Regards, Ichty

jmc
Posts: 238
Joined: Fri Apr 17, 2020 3:14 am

Post by jmc »

Ichthyophthirius wrote:That's right. The NFK projective is enough. If the Nikon adapter had a reducing lens that would be nice but that doesn't seem to be the case for you.

What you would need are Olympus adapters PM-ADF and L http://www.alanwood.net/olympus/photomi ... -l-il5.png or a homemade adapter that has the same length as adapter L. http://www.alanwood.net/olympus/photomi ... ter-l.html

It's easier to understand if you differentiate between projectives and eyepieces.

Projectives = real image at finite camera length (for NFK: 125 mm); no further optics required
Eyepieces = image at infinity; for photography use, camera lens is needed to take a picture (afocal adaptation)

---

The great thing about your Olympus BH (vs. the BH2) is that you don't need to use NFK projectives. You can use normal eyepieces and make an afocal adaptation with much better coverage on your camera sensor. What camera do you have?

Regards, Ichty
Ah right, thanks Ichty. Most of that makes sense to me - I've not looked at afocal routes before, so need to read up more on that.

I use Nikon and Canon SLRs, which makes me think that the original OM tube is not the way to go, given the registration distances of the cameras.

Do you know of anyone (ideally outside of the US, as I am in the UK) that makes something suitable?

EDIT - actually I think I have found a microscope to M42 adapter which should be usable. I can either use extension tubes or helicoid to get the distance right. Fingers crossed :)
Jonathan Crowther

Ichthyophthirius
Posts: 1152
Joined: Thu Mar 07, 2013 5:24 am

Post by Ichthyophthirius »

jmc wrote: I use Nikon and Canon SLRs, which makes me think that the original OM tube is not the way to go, given the registration distances of the cameras.

Do you know of anyone (ideally outside of the US, as I am in the UK) that makes something suitable?

EDIT - actually I think I have found a microscope to M42 adapter which should be usable. I can either use extension tubes or helicoid to get the distance right. Fingers crossed :)
Microscope to M42 adapter and extension tubes should work. You need to bridge about 15 cm.

Olympus OM to Canon EF mount is also very easy with a simple mechanical mount adapter. I used that myself, works well.

Afocal is simple to test. Just put one of your existing Olympus 10x eyepieces in the phototube and mount the DSLR above it (microscope to M42 adapter, M42 to filter step-down ring) with a prime lens attached (for APS-C Sensor: 40, 45 or 50 mm prime lens, set to infinity, aperture fully open). Take great care not to damage the camera front lens. Use electronic first shutter (LiveView on Canon) to prevent vibration issues whenever you hard-rig a camera directly to the microscope. This should give you excellent coverage.

If you like the afocal approach, chose a very clean (no dust) and mechanically stable prime lens (some old analogue prime lenses work well) for a permanent adaptation.

Regards, Ichty

Alan Wood
Posts: 381
Joined: Wed Dec 29, 2010 3:09 pm
Location: Near London, U.K.
Contact:

Post by Alan Wood »

Jonathan

Sadly, the Olympus PM-ADF and the Photomicro Adapter L have become hard to find and expensive.

It is very easy to use an Adapter L with a Canon EOS digital SLR, there are lots of OM-EOS adapters on eBay that have the necessary 2 mm thickness.

For a Nikon digital SLR, you need to remove the OM rear lens mount from the Adapter L and replace it with a Nikon rear lens mount - there are suitable ones on eBay.

The distance from the top of the vertical tube on your BHB trinocular head to the sensor should be 150 mm:

http://www.alanwood.net/olympus/photo-e ... s.html#125

Alan Wood

jmc
Posts: 238
Joined: Fri Apr 17, 2020 3:14 am

Post by jmc »

Ichty, Alan,

Thanks for the information.

I'm using full frame Canon and Nikon (should have mentioned that before). So would a wider angle prime be better for afocal work, something like a 35mm one?

I did find one of the OM microscope adapters on ebay, but it doesn't look to include the PM-ADF, so didn't bother with it.

I've found an adapter which goes to M42 though, and I have plenty of extension tubes and helicoids for M42 as well as a Canon to M42 and Nikon to M42 (slimline without a lens inside) adapters. Hopefully this should work.
Jonathan Crowther

Ichthyophthirius
Posts: 1152
Joined: Thu Mar 07, 2013 5:24 am

Post by Ichthyophthirius »

Hi Jonathan,

If you have full frame sensors, you can use an NFK 2.5x. Coverage is shown on Alan's website.

For afocal, it's the opposite to wideangle, you need a longer lens! What Olympus eyepieces do you have?

Olympus CWHK 10x/18: combine with 55-60 mm prime lens (recommendation: Zenit MC Helios 44K-7 58mm f/2.0 with M42 mount)
Olympus WHK 10x/20: combine with 50-55 mm prime lens

These combinations will cover the full diagonale (FN 18 and FN 20, respectively). At the upper end (55 mm for FN 18; 50 mm for FN 20) there could be small black corners due to vignetting.

The same prime lenses could be used for the Zeiss optics. Affordable eyepieces that work well for your Zeiss objectives are:
Zeiss Kpl W 10x/18 (glasses) and
Kpl W 10x/20 (glasses)

Regards, Ichty

Pau
Site Admin
Posts: 6038
Joined: Wed Jan 20, 2010 8:57 am
Location: Valencia, Spain

Post by Pau »

If you want to follow the afocal approach here you have info that could be useful:
https://www.photomacrography.net/forum/ ... 9265#99265

For FF cameras a good combo would be a 60mm lens over a 10X eyepiece
Pau

jmc
Posts: 238
Joined: Fri Apr 17, 2020 3:14 am

Post by jmc »

Thanks for the information everyone. Just when I get the feeling I'm understanding something, I find out there is still so much to learn :oops:
Jonathan Crowther

Post Reply Previous topicNext topic