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Adding Simple Darkfield to a Nikon Labophot Condenser

Posted: Thu Apr 14, 2016 9:33 pm
by carlh6902
I am posting this here, since it is a bit off topic where I originally posted it. And, as it turns out, the link I used did not work anyway.

So let's try this one:

Edit 4/14/2019: Replaced outdated link with a link to the master index, which always contains the most recent versions:

https://drive.google.com/open?id=0B7ckZ ... nFYVDJSRW8


This applies directly to the finite Nikon scopes, but I developed it to provide easy darkfield on my Olympus BH-2 scope.

Carl

Re: Adding Simple Darkfield to a Nikon Labophot Condenser

Posted: Thu Apr 14, 2016 10:00 pm
by Crater Eddie
Very nice write up!
CE

Re: Adding Simple Darkfield to a Nikon Labophot Condenser

Posted: Fri Apr 15, 2016 1:11 am
by carlh6902
Crater Eddie wrote:Very nice write up!
CE
Thanks, Eddie.

The MXA20495 that makes this thing work is available on "that auction site" for $11, if anybody is interested. I picked up three of them.

Carl

Re: Adding Simple Darkfield to a Nikon Labophot Condenser

Posted: Fri Apr 15, 2016 2:03 am
by wmodavis
Well done Carl and clearly presented.

Re: Adding Simple Darkfield to a Nikon Labophot Condenser

Posted: Sat Apr 16, 2016 5:46 am
by carlh6902
wmodavis wrote:Well done Carl and clearly presented.
Thanks for the feedback. Much appreciated.

Carl

Re: Adding Simple Darkfield to a Nikon Labophot Condenser

Posted: Sat Apr 16, 2016 10:29 pm
by gekko
Excellent article, Carl, and very useful to those of us who have Nikon or Olympus condensers, as it provides a very neat solution. Thank you.

Re: Adding Simple Darkfield to a Nikon Labophot Condenser

Posted: Mon Apr 18, 2016 7:20 pm
by gekko
Coincidentally, a couple of months ago Crater Eddie suggested to me by email basically the same idea for his Olympus condenser, but neither he nor I knew about the Nikon adapter. At the time, my only concern was that the thickness of the plastic tube he intended to use might cut down on the usable condenser aperture and my suggestion was that he consider cutting the wall of an aluminum soda can and rolling it into a tube of the right diameter.

Re: Adding Simple Darkfield to a Nikon Labophot Condenser

Posted: Mon Apr 18, 2016 11:21 pm
by apatientspider
All:

Be very careful what you click on at that link above. I clicked on a thumb of the first page of the pdf. and some kind of malware or ransomeware took over my browser. I couldn't even shut down the browser to escape from it, nor could I shut off the computer the regular way. I had to pull the battery out of my laptop to shut everything down.

However, I went back to the site and clicked the download button for the pdf itself and did not experience any problems.

Jim

Re: Adding Simple Darkfield to a Nikon Labophot Condenser

Posted: Tue Apr 19, 2016 1:35 am
by carlh6902
That's a valid concern with the pipe thickness. There does exist a thin wall PVC, same outer diameter, but only about half the wall thickness. I listed schedule 40 since it's widely available, whereas the thin wall can be hard to find.

Carl

Re: Adding Simple Darkfield to a Nikon Labophot Condenser

Posted: Tue May 03, 2016 2:49 pm
by wmodavis
And as a follow up on this article - I have taken steps to try it on my new old scope. Got the PVC Schedule from a scrap laying around, just placed order for the Filter Holder MXA20495 and will be looking at buying or fabricating some darkfield stops.

Re: Adding Simple Darkfield to a Nikon Labophot Condenser

Posted: Tue May 03, 2016 4:06 pm
by carlh6902
FYI -

Edit 4/14/2019: Replaced outdated link with a link to the master index, which always contains the most recent versions:

https://drive.google.com/open?id=0B7ckZ ... nFYVDJSRW8

Carl

Re: Adding Simple Darkfield to a Nikon Labophot Condenser

Posted: Tue May 03, 2016 5:29 pm
by wmodavis
Gekko - I'm going to try it with my Olympus condenser as they appear very close. The piece of schedule 40 that I have measures about 33.5 mm dia whereas the inside dia to the Olympus condenser measures 34.9 mm. So it's a loose fit. Maybe a turn or two of black electrical tape around the PVC can take up the slack. I'll wait for the MXA20495 before I proceed. Another apparent dimensional difference I find is the length of the PVC pipe. The article says 1-1/8" whereas I measure ~22.5mm or almost 3mm shorter for my condenser. But at this point I'm not accounting for the MXA20495 which might require longer PVC. Not any sort of a real problem for sure. Also I got the MXA20495 for $10 which is certainly less then $17 Carl mentioned.

Carl Hunsinger - Thanks for your rev 2 document wherein the only change I saw was adding the recommendation of SDR-21 PVC which has same OD as schedule 40 but about 1/2 the wall thickness. You say the SDR-21 is preferable. Why is that? Does the thinner wall thickness help that much? Just curious. And you already answered my question in footnote 1 page 4 of 9. Thanks you thorough guy.

Stay tuned for next installment.

Re: Adding Simple Darkfield to a Nikon Labophot Condenser

Posted: Tue May 03, 2016 5:57 pm
by carlh6902
wmodavis-

FYI - The MXA20495 will not fit into the BH2-CD condenser because the condenser bore is just a little too small. To fit in a 1" PVC (I suggest SDR-21) you can omit the MXA20495 and just wrap electrical tape to make the whole thing fit snugly, but it takes several wraps and then it tends to be hard to remove after it's been in for a while. Also, without the MXA20495 to help with alignment, it's pretty easy to end up with poor stop centering this way. I'm still experimenting trying to find a more practical solution for the BH2-CD.

In the mean time, I picked up a Nikon Labophot condenser for $35 on that auction site. It works fine in my BH-2 scopes, but can be raised too high if you're not careful, which can be dangerous if it crashes the slide into the objective.

Carl

Re: Adding Simple Darkfield to a Nikon Labophot Condenser

Posted: Tue May 03, 2016 6:40 pm
by gekko
Hi Carl,
I tried the link you provide. It wasn't immediately obvious to me how to look at or download your article, and I got scared away by the very nasty website. It started to beep loudly and said I should immediately do something or other (I didn't continue reading, but exited with haste). I immediately ran a full scan of my computer, and fortunately nothing untoward was found.
Have you considered submitting the article to the Microbe Hunter magazine?

Re: Adding Simple Darkfield to a Nikon Labophot Condenser

Posted: Tue May 03, 2016 6:45 pm
by carlh6902
I have not had those issues with the PDF Archive site, but I've heard others say similar things. How would I go about submitting this?

Carl

Re: Adding Simple Darkfield to a Nikon Labophot Condenser

Posted: Tue May 03, 2016 7:07 pm
by gekko
I think the following link gives the information that you need: http://www.microbehunter.com/submissions/
But you can always post a message for Olive in the About the website, the magazine and this forum section, or email him at nospam_editor@microbehunter.com (remove "nospam_") if you have questions.
Thanks.

Re: Adding Simple Darkfield to a Nikon Labophot Condenser

Posted: Tue May 03, 2016 10:05 pm
by wmodavis
carlh6902 wrote:wmodavis-

FYI - The MXA20495 will not fit into the BH2-CD condenser because the condenser bore is just a little too small. To fit in a 1" PVC (I suggest SDR-21) you can omit the MXA20495 and just wrap electrical tape to make the whole thing fit snugly, but it takes several wraps and then it tends to be hard to remove after it's been in for a while. Also, without the MXA20495 to help with alignment, it's pretty easy to end up with poor stop centering this way. I'm still experimenting trying to find a more practical solution for the BH2-CD.

In the mean time, I picked up a Nikon Labophot condenser for $35 on that auction site. It works fine in my BH-2 scopes, but can be raised too high if you're not careful, which can be dangerous if it crashes the slide into the objective.

Carl
Well I'll either do a mid course correction or darn it get a Nikon condenser. Was hoping to sidestep that option.
Carl what is the actual purpose of the MXA20495? Does it perform a particular function in the one you made for the Nikon? It does give it a very nice finished look.

Re: Adding Simple Darkfield to a Nikon Labophot Condenser

Posted: Wed May 04, 2016 2:04 am
by carlh6902
wmodavis wrote:
carlh6902 wrote:wmodavis-

FYI - The MXA20495 will not fit into the BH2-CD condenser because the condenser bore is just a little too small. To fit in a 1" PVC (I suggest SDR-21) you can omit the MXA20495 and just wrap electrical tape to make the whole thing fit snugly, but it takes several wraps and then it tends to be hard to remove after it's been in for a while. Also, without the MXA20495 to help with alignment, it's pretty easy to end up with poor stop centering this way. I'm still experimenting trying to find a more practical solution for the BH2-CD.

In the mean time, I picked up a Nikon Labophot condenser for $35 on that auction site. It works fine in my BH-2 scopes, but can be raised too high if you're not careful, which can be dangerous if it crashes the slide into the objective.

Carl
Well I'll either do a mid course correction or darn it get a Nikon condenser. Was hoping to sidestep that option.
Carl what is the actual purpose of the MXA20495? Does it perform a particular function in the one you made for the Nikon? It does give it a very nice finished look.
Bill - the Nikon filter holder is the interface between the Nikon condenser and the 1" PVC pipe. The pipe snaps into the filter holder nicely, and the filter holder (with pipe) snaps into the condenser nicely. So it all fits together without having to shim the fit with tape or anything. And the filter holder keeps the pipe nicely aligned in the condenser.

Carl

Re: Adding Simple Darkfield to a Nikon Labophot Condenser

Posted: Wed May 04, 2016 3:09 pm
by carlh6902
For those concerned about the safety of the link I provided for this article, I just submitted it and included the PDF as an attachment in the "Articles and images to be published" section of this forum.

Carl

Re: Adding Simple Darkfield to a Nikon Labophot Condenser

Posted: Wed May 04, 2016 3:43 pm
by gekko
Thank you, Carl.

Re: Adding Simple Darkfield to a Nikon Labophot Condenser

Posted: Thu May 05, 2016 2:22 am
by carlh6902
If anybody figures out a good way to add a darkfield stop to the BH2 abbe condenser, please be sure to post details.

Carl