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Clutching at Straws for a Low Power Projection Lens

 
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dolmadis



Joined: 07 Dec 2011
Posts: 354
Location: UK

PostPosted: Fri Apr 21, 2017 12:03 am    Post subject: Clutching at Straws for a Low Power Projection Lens Reply with quote

http://www.ebay.co.uk/itm/262862995168?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

Too good to be true for use in place of the elusive, expensive, NFK 1.67?

For use with Nikon CF Objectives in a Trino?

Opinions welcome please.

BR


John
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Ichthyophthirius



Joined: 07 Mar 2013
Posts: 730

PostPosted: Fri Apr 21, 2017 4:04 am    Post subject: Reply with quote

Hi John,

It's not a projective. As far as it is described, it's a Barlow lens that will double the magnification of your eyepiece (the eyepiece needs to go in on top).

A barlow lens also changes the tube length of a microscope, as far as I understand, so you would be way off the microscope design.

Also, wouldn't it be a waste to use an expensive Olympus projective (compensating) for Nikon CF, which requires a non-compensating projective?

What trino do you want to use? Most microscopes will allow you to do afocal; even the BH2, after modification.

Regards, Ichty
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dolmadis



Joined: 07 Dec 2011
Posts: 354
Location: UK

PostPosted: Fri Apr 21, 2017 4:27 am    Post subject: Reply with quote

Thanks for the sane analysis. "Clutching at Straws" was for real since I found that that NFK 1.67 was around USD 600.

Afocal is a possibility of course and I have tried it several times over the years with different microscope with optical success but the stability was something of a concern without "scaffolding" and space is an issue on my small work space.

The head this time is a BH2-TR30 and I would prefer to use the trino keeping the benefit of the compact vertical foot print , the eyepieces and parfocal of course.

[I have used a astro digi-scoping attachment on the conical chimney of a Nikon Optiphot Trino with a 2.5 PL (it fits over ending with an EOS adapter)].

Back to the TR30.

I have removed the top part of the BH2-TR30 chimney (with the dovetail) but the diameter of the chimney is too wide for the dig-scope attachment. I am not a fabricator so I look for parts that can be re-purposed. The task is to find a short one just bigger than 58mm to end with an adapter to M 4/3 camera. Direct Projection.

Thoughts welcome !!

I have just come across in Google someone using the NDPL-1 (2X) to Canon EOS reversing the top of the TR30 chimney and inserting an extra 15mm.

http://www.microbehunter.com/microscopy-forum/viewtopic.php?t=3061

Again thoughts welcome !!

BR

John
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Ichthyophthirius



Joined: 07 Mar 2013
Posts: 730

PostPosted: Fri Apr 21, 2017 5:34 am    Post subject: Reply with quote

Hi John,

So you have a BH2-TR30 and you want to use Nikon CF objectives and a m4/3 camera? I assume the camera should be parfocal with the eyepieces?

Most eyepieces won't fit into the BH2-TR30 photoport because it is so narrow.

1) You either have to custom-build a new top for the photoport so other projectives or eyepieces can fit. That gives you maximum flexibility: http://www.mikroskopie-forum.de/pictures004/174327_21031658.jpg

2) Direct projection: According to this image, http://www.mikroskopie-forum.de/pictures004/174327_21031658.jpg the intermediate image ("Zwischenbild") is 28.5 mm above the photoport when you take the top off. That could be just enough for a m4/3 camera (19.25 mm flange focal distance). Is the surface flat when you take off the top of the photoport?

Here is a digiscope adapter for 59 mm eyepieces (haven't tested this) http://srb-photographic.co.uk/olympus-four-thirds-digiscoping-kit-9615-p.asp which might JUST fit around the outside for the tube. The problem is then to find a T2 to m4/3 adapter that is very short (around 7 mm) or some sort of m4/3 adapter that you can glue over the T2 connection.

There are not many clamp adapters around that can fit around a 58 mm tube. I had a look around recently and couldn't find much. Some kind of astronomy adapter should work. Let me know if you find one ...

Regards, Ichty
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siliconGary



Joined: 18 Oct 2016
Posts: 63
Location: Canada

PostPosted: Fri Apr 21, 2017 6:39 am    Post subject: Reply with quote

John,
I did that same search looking for good solution for the BH2 trino-head. The NFK solution (even 2.5x forget 1.67x which are rarer than hens teeth today) was out of my budget, and you still the need to get the 150mm extension tube, plus adapter as well as the NFK lens. In the end I went with a compromise - an unbranded 2x camera adapter and I have been pleased with the results. I wrote about it in this post http://www.photomacrography.net/forum/viewtopic.php?t=32847&highlight=
Fits directly into the trino-head and is par-focal with my (NeoDplan) objectives. I believe they make them for several different camera mounts.
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dolmadis



Joined: 07 Dec 2011
Posts: 354
Location: UK

PostPosted: Fri Apr 21, 2017 11:50 am    Post subject: Reply with quote

Thanks Ichthy and Gary.

Quote:
Is the surface flat when you take off the top of the photoport?


Yes

59mm for a digi or astro adapter is hard to guarantee in a description in a retail product.

I am now thinking of using a short 60mm extension tube with shim.

But even then a 7mm tube to m4/3 adapter is a hard ask.

But I could build it up from the position of the top removed for Canon EOS from a shimmed 60mm tube. Direct Projection from the TR30. Tube height based on 150mm from sensor to flange on objective? Is that right?

Gary, thank you for the link. The shipping is USD 50 and the combined unit price plus shipping is subject to UK Customs, Tax and Agent's Fees of around 25%. So USD 129 plus 25%.

I think that I will play around with some tubes first but it is a great fall back if I fail.

Thank you both for your help.

BR


John
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Ichthyophthirius



Joined: 07 Mar 2013
Posts: 730

PostPosted: Fri Apr 21, 2017 1:34 pm    Post subject: Reply with quote

dolmadis wrote:
Direct Projection from the TR30. Tube height based on 150mm from sensor to flange on objective? Is that right?


Yes. I took these numbers from the picture I linked to. The intermediate image is at 150 mm.

What kind of 60 mm tubes are you thinking of?

You have 9.25 mm of space to connect the camera (28.5 mm - 19.25 mm). A very short adapter option would be a m4/3 "reverse ring". Just for illustration: http://www.ebay.co.uk/itm/291973200460 Maybe you find one for 60 mm or you can glue on another size to your 60 mm tubes.
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dolmadis



Joined: 07 Dec 2011
Posts: 354
Location: UK

PostPosted: Fri Apr 21, 2017 2:55 pm    Post subject: Reply with quote

Hi Ichthy

Quote:
What kind of 60 mm tubes are you thinking of?


I have a set of non auto Canon extension tubes at 60mm thread dia.

At first "test" they seem to fit snuggly over the remaining chimney of the TR30 with a shim or two of electrical tape. Alternatively nylon "bolts" could be added to secure with appropriate holes on the circumference.

The http://www.ebay.co.uk/itm/291973200460 at 58 mm could be stepped up to 60mm with an adapter.

It is worthy of a further small investment in the above adapter and a step up ring to see if we can get a m4/3 to mate at the right height.

Many thanks to you for you help.

BR


John
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dolmadis



Joined: 07 Dec 2011
Posts: 354
Location: UK

PostPosted: Wed Oct 25, 2017 2:01 am    Post subject: Reply with quote

Ichthyophthirius wrote:

There are not many clamp adapters around that can fit around a 58 mm tube. I had a look around recently and couldn't find much. Some kind of astronomy adapter should work. Let me know if you find one ...


http://www.ebay.co.uk/itm/T2-digiscoping-adapter-f-photography-telescope-spotting-scope-51-59mm-T2-D59/391435057828?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

The suppliers assure me that this will fit over a 59mm O/D.

Quote:
if your eyepiece [telescope tube] has 59 mm max. outside then it will fit as described.


I have ordered one to kick start what we talked about regarding the BH2-TR30

BR

John
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