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Cheap 50 mm microscope tube extender for visual use

 
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zzffnn



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PostPosted: Sat Jul 08, 2017 3:39 pm    Post subject: Cheap 50 mm microscope tube extender for visual use Reply with quote

Thank you for checking this thread.

I am looking for two cheap 50 mm microscope tube extenders for binocular visual use. Basically, I have a nice 210TL M Plan 40x NA 0.55 Olympus LWD objective (looking for a LWD M20x) and want to use them on my 160TL Nikon Optiphot and inspection scope.

I know I can extend monocular tube 50 mm with PVC plumber tubes with inside blackened. However, my Nikon bino head has minimal extra space (vertically and horizontally) for putting on extension eye tubes. And I want to use my bino head for visual examination with 210TL objectives. Not to mention the hassle of making extension tube for each eye tube (I have 4) and putting on/taking off extension tubes each time.

I know of 15mm and 5mm parfocal spacers, each of which will cost about $10. So I would have to pay around $90 to get 8 of them (six 15mm spacers and two 5 mm spacers to get two sets of 50mm extension for M20x and M40x). A little bit too much for dumb mechanical spacers, considering that I only paid $30 for my good Olympus MPlan 40x LWD.

http://www.ebay.com/itm/321850604319

I have asked the seller if he can custom make 50 mm spacer for cheap.

Another objective spacer option is this: http://www.ebay.com/itm/162268593012

Seller said he can make custom length for additional $20 each, though I don't know if he can make it 50 mm long (his original spacer extends about 7mm). I have asked him also.

Yes, my stage can go down far enough, if I use objective spacers.

Is there a cheap/better way to achieve what I want? Main application is visual observation and photographing opaque subjects under reflected light, at up to 40x on sensor magnification.

Thank you in advance for your kind comments.
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Pau
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PostPosted: Sat Jul 08, 2017 4:15 pm    Post subject: Reply with quote

The best (and Nikon original) solution is IMO to put an intermediate 50mm tube between the microscope body and the binocular head. Originally the 210 tube just comes from a 160 microscope design with the added epiiluminator avoiding the need of telan lenses like other manufacturers like Zeiss did. If you could find an epiiluminator (even incomplete or damaged) it would do. It also could be done with spare male and female dovetails and a tube...
I'm thinking in making this solution to use some nice Nikon 210 objective at my Zeiss..
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PostPosted: Sat Jul 08, 2017 5:11 pm    Post subject: Reply with quote

Good ideas, Pau. Thank you very much.

I thought epi illuminators would be expensive, but broken ones are not, apparently. I would have to remove the epi light mirror in that case.

I have some confusion about presence or absence of Nikon dovetails on those epi illuminators though. For example, this photo was copied from Mike's web page (figure #10 there) for illustration purpose: https://lavinia.as.arizona.edu/~mtuell/scopes/epi.html



Can anyone tell if that end has a male Nikon dovetail there? It looks like it does not (how does it fit between head and frame, if it does not)? Mike, if you see this, please kindly advise me. If you have a broken epi housing with 50mm depth and without mirror, I may be interested in buying one from you.

A dumb tube with male and female dovetails on either end will work too. I think Raf Camera can make it. It all comes down to cost, I guess.
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zzffnn



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PostPosted: Sun Jul 09, 2017 7:02 am    Post subject: Reply with quote

Pau,
Raf Camera can make one for reasonable price. I have PM'ed you.
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PostPosted: Sun Jul 09, 2017 11:56 am    Post subject: Reply with quote

Thanks
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PostPosted: Mon Jul 10, 2017 8:22 pm    Post subject: Reply with quote

Pau,

50mm Objective extender (that goes between objective shoulder and nosepiece) provides more space for creative lighting though.

For example, my short Olympus M Plan LWD 40/0.55 has parfocal distance of only 36.65 and WD of less than 4mm. That makes it inconvenient to use regular camera speedlight. The bulky nosepiece and scope arm/head takes quote some space.

But with 50mm objective extender, the bulk is 50mm higher up, so I can easily put 2-3 regular speedlights or big LEDs under nosepiece, angle them somewhat and add diffusion.

Easy and fast turret rotation is not really that essential for non-moving subjects. At least not that important for my applications. Nice to have for sure, though.

Your thoughts?

I guess it is better to have both objective extender and epi illuminator house Twisted Evil
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Ichthyophthirius



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PostPosted: Tue Jul 11, 2017 5:01 am    Post subject: Reply with quote

Hi,

Can you actually lower the stage by 50 mm?

The 50 mm extensions would need to be high spec in order for the two objectives (20 and 40) to still be parcentric.

You wouldn't be able to use more than 2 or 3 objectives at a time because you can't fully rotate the nosepiece any more.

Simply extending the eyepiece tubes might sometimes lead to vignetting (they are not designed to have the eyepieces so far away from the internal prisms).

Building a 50 mm intermediate tube to go between stand and binocular tube seems the best solution.

Regards, Ichty
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PostPosted: Tue Jul 11, 2017 6:31 am    Post subject: Reply with quote

Ichthyophthirius wrote:
Hi,

Can you actually lower the stage by 50 mm?

The 50 mm extensions would need to be high spec in order for the two objectives (20 and 40) to still be parcentric.

You wouldn't be able to use more than 2 or 3 objectives at a time because you can't fully rotate the nosepiece any more.

Simply extending the eyepiece tubes might sometimes lead to vignetting (they are not designed to have the eyepieces so far away from the internal prisms).

Building a 50 mm intermediate tube to go between stand and binocular tube seems the best solution.

Regards, Ichty


Thank you very much, Ichty.

My Optiphot's stage may not be able to go down 50mm (it probably tops at 30-40mm downward), though my Nikon inspection scope (mounted on a long marble check stand) can. Its head focuses and can move up at least 100mm.

I did realize I won't be able to rotate / change objectives (lost parcentricity and parfocality, ect) with objective extender. Though with dead subjects and LWD objectives, I can sacrifice those for more space for lighting.

Does that make sense?

I am indeed trying to get both intermediate tube and objective extender.
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PostPosted: Tue Jul 11, 2017 6:38 am    Post subject: Reply with quote

Quote:
For example, my short Olympus M Plan LWD 40/0.55 has parfocal distance of only 36.65 and WD of less than 4mm. That makes it inconvenient to use regular camera speedlight. The bulky nosepiece and scope arm/head takes quote some space.

But with 50mm objective extender, the bulk is 50mm higher up, so I can easily put 2-3 regular speedlights or big LEDs under nosepiece, angle them somewhat and add diffusion.

Beware that forcing an objective corrected for 160 to work at 210 will degrade its image due to spherical aberration, just the same that forcing a 210 to work at 160. this effect is highly NA dependent as you likely know
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zzffnn



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PostPosted: Tue Jul 11, 2017 6:44 am    Post subject: Reply with quote

Pau wrote:
Quote:
For example, my short Olympus M Plan LWD 40/0.55 has parfocal distance of only 36.65 and WD of less than 4mm. That makes it inconvenient to use regular camera speedlight. The bulky nosepiece and scope arm/head takes quote some space.

But with 50mm objective extender, the bulk is 50mm higher up, so I can easily put 2-3 regular speedlights or big LEDs under nosepiece, angle them somewhat and add diffusion.

Beware that forcing an objective corrected for 160 to work at 210 will degrade its image due to spherical aberration, just the same that forcing a 210 to work at 160. this effect is highly NA dependent as you likely know


Pau, I think that Olympus objective is a 210TL one. Stage micrometer test with it at 160TL revealed quite some SA. Could it be 190/195TL? I guess I have to confirm with Alan Wood.

Edit: it is a 210TL lens (search "MPlan" in the page and you will find it):

http://www.alanwood.net/photography/olympus/microscope-objectives.html
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PostPosted: Thu Jul 13, 2017 2:17 pm    Post subject: Reply with quote

Thanks to Mike's help, I just picked up a Nikon epi illuminator case (with ND filter and internal prism, I think) for $37 shipped.

I just measured my Nikon Optiphot's stage height. Its stage can go down far enough to allow 90mm parfocal height and still function, though that is its absolute maximum. So theoretically, my short (36.65 mm parfocal) Olympus MPlan can work with 50mm RMS objective extension.

Edit: my Optiphot has been modified by raising its stage 12mm. So a stock unmodified Optiphot should allow at least 102 mm of parfocal height.

I will test both and report back.
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PostPosted: Fri Jul 21, 2017 2:34 pm    Post subject: Reply with quote

Raf Camera has made this for public purchases:

https://www.rafcamera.com/extender-50mm-dovetail-48-5mm

The eBay epi illuminator that I bought looks the same as Mike's and works perfectly. Internal prism is easy to remove and put back.

I also DIY made an objective RMS extender, using friction mounts and an adapter with RMS male thread at one end, which I found in a vintage objective nosepiece of unknown brand. The adapter is then glued to a PVC plumber pipe, which is blackened with matte paint inside and in turn friction mounted onto objective.
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