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Mitutoyo BD Plan Tominon Lens Iris Conversion DIY project

 
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RobertOToole



Joined: 17 Jan 2013
Posts: 405
Location: United States

PostPosted: Fri Feb 21, 2014 5:21 pm    Post subject: Mitutoyo BD Plan Tominon Lens Iris Conversion DIY project Reply with quote

Mitutoyo BD Plan Tominon iris conversion DIY project



I hope this post will help all Mitutoyo BD Plan owners or prospective owners out there choose and install a high quality, easy to find and reasonably priced round iris.

I have to say thanks to Charles Krebs for the idea when he posted an image of his Tominon iris equipped Mitutoyo BD Plan a couple of years ago.

Difficulty rating:

Very easy. The only tool you need is a single small flat-blade or slot-head screwdriver.



Tominon 135mm barrel assembly ready to use with rear and front lens cells.

Parts list:

The Tominon 135mm f4.5 with a 12 bladed iris is my first choice but there are others available.



The image shows the Tominon iris types that are typically available on Ebay. Starting on the left you can see the Tominon 75mm f4.5 with a 6 bladed hexagon shaped aperture, then at the bottom you can see the Tominon 105mm f4.5 with 10 aperture blades. On the right you can see my first choice, the Tominon 135mm f4.5, with the beautiful 12 blade iris that makes a very nice rounded aperture.

Tools needed:

1.2mm flat-blade or slot-head JIS screwdriver. I always try to use Japanese Industrial Standard screwdrivers on japanese camera gear. As an option a pair of bent micro needle-nose pliers makes removing and replacing the click stop ball bearing easier.

Cost:

$20-25 on ebay if you are patient, $30-40 buy it now for a good clean lens.

Procedure:

1. It is important to choose a well lit clean area to work.

2. Back out but don't remove the 3 tiny slotted set screws on the lens trim-ring. The set screws only need to be loosened to remove the trim-ring so removing them will only slow down the reassembly. Tip: you can see one of the set screws in the first image in this post right above the f4.5 mark on the aperture-ring.

3. Remove the trim-ring by lifting up. Tip: This ring is not threaded but held in place by 2 set screws.

4. Lift out and remove the aperture-ring and click stop ball bearing below the ring. Tip: a pair of bent micro needle-nose pliers makes removing and replacing the bearing a lot easier.

5. Unscrew the front lens cell.

6. Replace the aperture-ring click stop ball bearing. Hint: look for the metal lined aperture-ring guide hole.

7. Replace the aperture-ring. Note: make sure to line up the iris control pin.

8. Replace the trim-ring. Note: make sure to line up the aperture indicator mark.

9. While holding down the trim-ring, tighten the 2 shorter set screws. Tip: The longer screw only needs to be turned so that it is flush, this screw was only used to keep the lens cell in place.

10. Unscrew and remove the rear lens cell. Clean up the red anti-seize compound left on the threads.

11. Done.

Pros and cons compared to the Jinfinance Ebay iris when used on Mitutoyo BD Plan objectives.

Pros
No adapters required
More compact
Less expensive
Aperture ring has click stops
40mm rear caps are included (usually)

Cons
Cannot easily be used on anything else other than Mitutoyo BD Plans due to the M40 mount.

Since I keep the Tominon iris barrel mounted on my objectives permanently I have a small disk of protostar flocking material between the iris and the objective to block the BD channels.

Any questions or comments, please share them below. Let me know if you catch any typos or if something is not clear.

Note: cmagno pointed out that technically the Mitutoyo BD plans and Tominon lens mounts have different thread pitch, .706 vs .75. With my equipment they thread without any binding all the way to bottoming out.

Thanks.

Robert


Last edited by RobertOToole on Sun Feb 23, 2014 7:42 pm; edited 1 time in total
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Olympusman



Joined: 15 Jan 2012
Posts: 3427

PostPosted: Sat Feb 22, 2014 12:46 pm    Post subject: Iris conversion Reply with quote

Are these CCTV lenses (C-mount?)
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Michael Reese Much FRMS EMS Bethlehem, Pennsylvania, USA
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RobertOToole



Joined: 17 Jan 2013
Posts: 405
Location: United States

PostPosted: Sat Feb 22, 2014 3:14 pm    Post subject: Re: Iris conversion Reply with quote

Olympusman wrote:
Are these CCTV lenses (C-mount?)


Hi Olympusman,

These Mitutoyo BD Plan APO Microscope Objectives and Tominon (50-75-105-135mm) are 40mm x 36TPI mount. (36 tpi = 0.706mm)

Here is a good reference PMG.net link for thread sizes:

http://www.photomacrography.net/forum/viewtopic.php?p=76251
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cmagno



Joined: 08 Oct 2012
Posts: 21
Location: Porto, Portugal

PostPosted: Sun Feb 23, 2014 5:01 pm    Post subject: Reply with quote

Hi,

I think that we are talking about different M40 threads.

These Tominon lenses are made by Tomioka for Polaroid to be distributed with their copy / photomacrographic MP-3 and MP-4 cameras series.
The lens are mounted in a Polaroid MP-4 shutter, that has the Copal 1 specifications.

The Copal 1 shutter front lens cell thread is 40x0.75mm.
So, this Tominon lens has a thread pitch of 0.75mm and not 36tpi = 0.706mm.

I use the Tominon 135mm with a M40x0.75mm to M42 ring adapter (200619746279: see the vendor disclaimer).

This is not the first example of a successfully use of a 36tpi thread lens in 0.75mm pitch adapter or vice-versa.

Regards
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RobertOToole



Joined: 17 Jan 2013
Posts: 405
Location: United States

PostPosted: Sun Feb 23, 2014 7:34 pm    Post subject: Reply with quote

cmagno wrote:
Hi,

I think that we are talking about different M40 threads.

These Tominon lenses are made by Tomioka for Polaroid to be distributed with their copy / photomacrographic MP-3 and MP-4 cameras series.
The lens are mounted in a Polaroid MP-4 shutter, that has the Copal 1 specifications.

The Copal 1 shutter front lens cell thread is 40x0.75mm.
So, this Tominon lens has a thread pitch of 0.75mm and not 36tpi = 0.706mm.

I use the Tominon 135mm with a M40x0.75mm to M42 ring adapter (200619746279: see the vendor disclaimer).

This is not the first example of a successfully use of a 36tpi thread lens in 0.75mm pitch adapter or vice-versa.

Regards


Thanks for catching that, you are right.

Thankfully in this case my Mitutoyo BD plans with M40 x 0.706 threads, Tominons with M40 x 0.75 threads, and Jinfinance adapters with M40 x 0.70mm threads are all interchangeable and fit smoothly without any binding.

Now I only wish all my M42 items fit as well as the different spec M40 parts. Even when dealing with all the same M42 X 1 specs parts bind, or when working with all M42 X .75 (T-mount) spec items some still bind.

Robert
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damiafix



Joined: 27 Oct 2017
Posts: 9

PostPosted: Wed Nov 01, 2017 11:47 am    Post subject: Re: Mitutoyo BD Plan Tominon Lens Iris Conversion DIY projec Reply with quote

Hi Robert,

I am trying to disassemble a Tominon 75mm in order to clean the rear side of the frontal element. I suppose it is quite similar to your 135mm. Any advice would be extremely appreciated since, even though I followed your guide, I have not been able to remove the trim-ring but just the first rear element.

Thank you so much. ;-)


Last edited by damiafix on Fri Nov 03, 2017 10:21 am; edited 1 time in total
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concon



Joined: 01 Jun 2017
Posts: 60

PostPosted: Fri Nov 03, 2017 7:51 am    Post subject: Reply with quote

I'm confused I guess (ignorant) with what you're going for. Stop control?

I've been using some Mitutoyo BD Plans for a few months now. I purchased an adapter ring off of Rafcamera and a vintage 200mm tele lens from Goodwill. Less than 50 bucks for all and everything just clicks/screws into place without the need for tooling.
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RobertOToole



Joined: 17 Jan 2013
Posts: 405
Location: United States

PostPosted: Fri Nov 03, 2017 10:12 am    Post subject: Reply with quote

Concon,

Stop control.

RAFs products are fit nicely and the owner is a very helpful guy!


I use a Chinese 42mm adapter from Ebay. I dont think RAF had the adapter for sale back at that time.

Robert
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concon



Joined: 01 Jun 2017
Posts: 60

PostPosted: Sat Nov 04, 2017 8:22 am    Post subject: Reply with quote

Got it! Haha, he definitely didn't. I bought 2 or 3 adapters from him trying to make them work and eventually messaged him and he offered to make one with the right thread specifications. Very awesome guy!
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