Need 28mm eyepieces

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vichighmathguy
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Joined: Sat Apr 24, 2021 9:48 pm

Need 28mm eyepieces

#1 Post by vichighmathguy » Sat Apr 24, 2021 9:58 pm

Hello everyone,
First time post here. I am a retired teacher who (a long time ago) used to use stereo microscopes in the lab. The make I have is Erma Optical Works (Tokyo), the objectives are 2x/4x and the eyepieces have tubes which are 28mm (1.10") in diameter. The eyepieces are WF10X.
In the (hobby) work that I do, I need to examine diamond or sapphire phonograph styli from a hundred years ago, but the 40x power I can achieve is somewhat less than I need for determining the wear on the styli. I think it likely that changing the eyepieces out to perhaps 20x would do the job, but I am having a difficult time finding 28mm eyepieces. Would someone on this forum be able to direct me to where I might be able to get the higher power eyepieces? This is only a hobby, so I'm hoping to find the sweet spot between cost and quality, and used is OK.
Thank you very much for any advice you may be able to offer.
Don Mayer

PeteM
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Location: N. California

Re: Need 28mm eyepieces

#2 Post by PeteM » Sat Apr 24, 2021 11:02 pm

Assuming the 28mm is some odd internal diameter -- the simplest thing might be to buy 15x or 20x eyepieces that fit the standard 23mm tube and hold them in a bushing. Aluminum adapters (black anodized) are readily available to go from 30 or 30.5mm to the 23mm of standard eyepieces. These could be turned down on a lathe - or made entirely from plastic or soft metal on even a wood lathe. Or, the part could be 3D printed. You could test they'd work just by wrapping them (around and around) with tape.

Greg Howald
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Re: Need 28mm eyepieces

#3 Post by Greg Howald » Sun Apr 25, 2021 12:22 pm

Posted in Hand made adaptations on the forum find the post entitled Have 3d printer will Print .
Ask how much it would cost to make a set of matching adaptors to go from 28mm to 30mm Eyepieces so you can use 30mm Eyepieces in your scope. This would help greatly with a binocular microscope as the size of the adaptors would exactly match making focus much easier. You will have to provide exact measurements for it. You have to have a tiny bit of slack. You can put a 30mm eyepiece into a 30mm hole but you need a hammer to do it. It would be too tight. If it is a monocular scope you can make such an adaptor with just about anything including a cardboard toilet paper roll .
Greg

vichighmathguy
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Re: Need 28mm eyepieces

#4 Post by vichighmathguy » Sun Apr 25, 2021 4:04 pm

PeteM:
Thank you for that suggestion. My current plan is to buy some inexpensive 23.2 to 30mm adapters and turn them down on my metal lathe so they will fit my microscope. (The 28mm I had posted is the O.D. of the eyepieces that came with it). I needed to order a live centre that will support the end while turning, but that will be just another tool in the drawer.

Greg: Thank you for your reply as well. I'm not sure I understand the up-sizing that would allow the microscope to take larger (30mm) eye pieces than it does now (currently only 28mm). That would necessarily involve a long extension to achieve the necessary diameter, but would that throw a bunch of optical (focal length) considerations into question?

Has anyone tried those inexpensive 23.2mm eyepieces available on that auction website? Are they serviceable or is there something I should be forewarned of? Here is an example link:

https://www.ebay.ca/itm/203181990348?ha ... Sw7YtfsUTI

Thank you for your opinions!

Don

MicroBob
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Re: Need 28mm eyepieces

#5 Post by MicroBob » Sun Apr 25, 2021 4:17 pm

Hi Don,
with 20x eyepieces you will get into empty magnification, bigger but not better resolved. To get twice the magnification and twice the resolution at half the free working distance you could install a 2x lens under the objective if this is possible on your model. Often there is a mounting thread for this.

Bob

vichighmathguy
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Re: Need 28mm eyepieces

#6 Post by vichighmathguy » Sun Apr 25, 2021 4:23 pm

Interesting comment, Bob. My microscope has a sliding 2x/4x objective (photo attached). Does your comment suggest that I would be better getting 15X eyepieces rather than 20X? A fellow who is knowledgable about microscopes (a collector/repairer) suggested that 80X is a good magnification for examining the styli that I have in mind, hence my 20x eyepiece thought.
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Hobbyst46
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Re: Need 28mm eyepieces

#7 Post by Hobbyst46 » Sun Apr 25, 2021 4:41 pm

My experience with unbranded WF20x/12, 30mm OD inexpensive eyepieces is negative - the view feels "weird" and most of the FOV is blurred or distorted. The best combination IMHO is a 1.5x Barlow lens (if the scope in the picture has this option) with 10x or 15x eyepieces. Together with an on-scope 4x objective, that will yield an overall mag of 60x-90x.

vichighmathguy
Posts: 9
Joined: Sat Apr 24, 2021 9:48 pm

Re: Need 28mm eyepieces

#8 Post by vichighmathguy » Sun Apr 25, 2021 5:49 pm

Hobbyst46 wrote:
Sun Apr 25, 2021 4:41 pm
My experience with unbranded WF20x/12, 30mm OD inexpensive eyepieces is negative - the view feels "weird" and most of the FOV is blurred or distorted. The best combination IMHO is a 1.5x Barlow lens (if the scope in the picture has this option) with 10x or 15x eyepieces. Together with an on-scope 4x objective, that will yield an overall mag of 60x-90x.
I appreciate your feedback as I don't have the opportunity to "try before you buy". I just read up on Barlow lenses but I suspect my objective lens configuration does not provide that option. Please feel free to tell me otherwise.

On a related note, if I cannot use a Barlow lens, should I assume that I would be better off buying a used set of eyepieces that are of better quality? For example,

https://www.ebay.com/itm/254573152574?h ... ondition=4

or

https://www.ebay.com/itm/254573096730?h ... ondition=4

Thank you,

Don
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Hobbyst46
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Re: Need 28mm eyepieces

#9 Post by Hobbyst46 » Sun Apr 25, 2021 6:28 pm

I hesitate a little to suggest, if the magnification is inadequate, and turning of eyepieces is considered, would it not be better to look for a used stereo microscope that has alreay the appropriate eyepieces and an optional Barlow lens ? and just add some inexpensive external light source, since the scope in the picture does not have one anyway ? I happen to use a very old zoom Olympus that delivers beautifully; and I find that zoom is not so important, two magnifications are usually adequate. There are 30mm eyepieces (like the Olympus) and 23mm (certain AO) microscopes, for which eyepieces are abundant.

vichighmathguy
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Joined: Sat Apr 24, 2021 9:48 pm

Re: Need 28mm eyepieces

#10 Post by vichighmathguy » Sun Apr 25, 2021 7:12 pm

No, your suggestion is a good one and one which I have considered. In fact, I have had an eBay search in the works for a few months looking for something like this one which a microscope collector/phonograph rebuilder has:
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The advantage of the swing-away body is that I can more easily place a reproducer below for examination. Alas, none has shown up thus far so I thought I would adapt my existing microscope in the meantime without putting a lot of money into the project, and waiting for the better alternative to appear. Then there is the issue of not quite knowing enough, but enough to get into trouble with a wrong turn somewhere in the process. There is a fellow on my island who has a box with 30-50 eyepieces so I might see if there is a pair in there that I can press into service. The tinkering aspect has some (non-redeemable) value until the one in the photo turns up on that auction site.

I agree with your assessment of zoom not really being necessary. Thankfully, the need is not urgent and the learning curve is manageable.

Thanks very much for your thoughts,

Don

apochronaut
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Re: Need 28mm eyepieces

#11 Post by apochronaut » Sun Apr 25, 2021 7:17 pm

Microbob is almost 100% correct in suggesting that your image resolution would not be improved by adding 20X eyepieces and thus raising the magnification to 80X. Even 60X is stretching it with microscopes that were up the ladder from yours from the same era. A 15 or 16X eyepiece would be a better choice and the improved resolution, brightness and contrast you would get compared to the 20X would be very obvious.

Are you measuring the eyepiece or the tube to get 28mm? If the fit is a bit loose and or the tube is close to 29mm, eyepieces from the older 29mm Reichert stereo microscopes might be made to fit by trimming the barrel on them a little, or swaging the tube a bit. Possibly not either. My recollection too is that they are not a full 29mm, maybe just over 28mm. They show up on ebay sometimes and there were 16X available.

All the magnifications of those eyepieces look similar, just the higher mags. are shorter. A notable unique i.d. feature is that the upper eyelens bezel is narrower than the barrel. They are all marked Reichert with W.S. and the magnification. The 16X is marked Reichert Austria 16X W.S. 143

here is a pair in Israel in a joblot. The seller is very good. I just bought a Reichert 40X planapo objective from her and she worked overtime to find more info.about it's condition and ship it really carefully. It arrived in Canada in a week with no customs involvement. I'll bet she would carve those out of the 7 eyepiece lot and sell them separately.
https://www.ebay.com/itm/284257511643?h ... Swyjpgduof

edit. I thought your microscope looked familiar and it mostly does because it is most likely a Japanese copy of the Reichert MAK GS or similar model. I'ii bet it has the same size eyepieces as the Reichert MAK series that used those roughly 29mm eyepieces. The MAK came in various models but the original basic one above the JR , the GS, had a sliding objective holder later replaced by a rotary 3 objective drum type holder. Yours looks to be a very close copy.
I may have one of the eyepieces here , so will search and measure it exactly to compare.

here is an old catalogue http://www.science-info.net/docs/reichert/ bring up the Reichert 75th cat. pdf and scroll to the very last picture of the MAK GS.
Last edited by apochronaut on Sun Apr 25, 2021 8:03 pm, edited 2 times in total.

vichighmathguy
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Re: Need 28mm eyepieces

#12 Post by vichighmathguy » Sun Apr 25, 2021 7:38 pm

Great comments, apochronaut, thank you. I was measuring the OD of the eyepiece body below the flange. I was actually getting measurements of 1.100 to 1.101" (27.97mm). The ID of the tube it slips into is 1.107" (28.12mm). I would rather not swage the tube but will check out the Reichert Austria that you refer to as it looks like it could be promising.

Thanks to everyone for doing a great job trying to get a novice on track!

Cheers,

Don
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apochronaut
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Re: Need 28mm eyepieces

#13 Post by apochronaut » Sun Apr 25, 2021 8:04 pm

have a look at my edit to the last post.

vichighmathguy
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Re: Need 28mm eyepieces

#14 Post by vichighmathguy » Sun Apr 25, 2021 8:41 pm

Thanks, apochronaut, it certainly does take its design cues from that microscope. I appreciate your power of recall. I'm looking forward to getting an accurate value of the outside diameter of the eyepieces that Tatiana (seller at the link you sent) will measure when it is morning her time. I'm keeping my optimism on low right now, but if the eyepiece fits . . . then I'll see what I can do, so to speak.

I'll keep this thread updated on the results of that measurement.

Thanks again,

Don

vichighmathguy
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Joined: Sat Apr 24, 2021 9:48 pm

Re: Need 28mm eyepieces

#15 Post by vichighmathguy » Mon Apr 26, 2021 6:54 pm

Well, that was a great try with respect to the Reichert eyepieces, but they turned out to be 28.9 mm in OD vs my sleeves which require something less than 28.12 mm. I have therefore ordered a couple of adapters for 30 mm to 23.2 mm and will turn them down to fit. Now to acquire a couple of 15X 23.2 mm eyepieces (thank you for your guidance, apochronaut and others). Is there any reason these would not work (there are 2 listed of which this is one):

https://www.ebay.ca/itm/324567749099?ha ... SwwlVgHF-S

Getting closer :-)

Don

apochronaut
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Re: Need 28mm eyepieces

#16 Post by apochronaut » Mon Apr 26, 2021 7:20 pm

It becomes guesswork when using eyepieces from a different mfg. Some of the guesswork can be based on known parameters. It also depends on how wide a field you want and how well corrected you need it. I assume as wide as and well corrected.
Older stereo microscopes required corrections in the eyepieces for lateral ca and to flatten the field because usually the objective lenses were fairly simple and relatively uncorrected. Those Nikon eyepieces are probably pretty neutral in their corrections because of the type of objectives they were made to work with but the price is sure attractive. Perhaps Scarodactyl could comment. He knows a lot more about the Nikon stuff and may even have a pair of those CFW 15X.

You would be better off looking for eyepieces that originally came from a stereo microscope of similar characteristics to yours. Most unfortunately used 30mm barrels in order to get a wider field. Some of the simpler Japanese scopes used 23.2mm . Bausch & Lomb and AO kind of pioneered using 23.2mm eyepieces for wide field stereos but again the later ones were specifically corrected.

Perhaps a look at your existing 10X would offer some clues. They look like they might just be Huygens type, which have some corrective capacity and were often used on simple stereos.
Where are you located?

vichighmathguy
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Re: Need 28mm eyepieces

#17 Post by vichighmathguy » Mon Apr 26, 2021 9:12 pm

I really must thank you for all of your input. I am located in Victoria, British Columbia, Canada. Were you thinking that you might have a set of appropriate eye pieces? Please feel free to send me a PM/DM.
Thanks very much,
Don

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