Leitz binocular microscope - 1 damaged prism.

[alpal]

Hi All,
a friend of mine gave me a Leitz Wetzlar microscope.
You could see nothing through the right hand prism but the left one is OK.
It had been knocked off a shelf 4 feet high on to carpet many years ago.
I took the inspection plate off the binoviewer and found the right hand prism
had broken away from its mount.
I pulled the binoviewer apart and found the right hand prism was badly damaged as well and
there were tiny bits of glass inside the housing.
I cleaned that out & I found that the prism had telltale marks of where 12 spots of glue had
been used to glue it before.
I glued the prism on with 2 tiny drops of Araldite as close as possible to where it was previously
so I could check the alignment of the 2 eyepieces.

continued on next post.

cheers
Allan

[alpal]

I attach some more photos.
I had a many goes at moving the prism by hand -
from outside the inspection plate but that was impossible - the plate is too small.

After my second go at gluing the prism in position -
I then focused in on some dust on a microscope slide and took some pictures
with my mobile phone into the left and right eyepieces.
You can take the side on Y piece of dust as reference and you can see
that the right hand side shows that piece moved to the right and also upwards.
Also nearly half the frame is blacked out - caused by the broken prism properties.

I did find that if I move the prism further away from the eyepiece
the darkened area gets smaller because the damaged area is less inside the optical path.
It's possible that it could be glued on to a slightly better place.
However there is no way I could align the binoviewer even if I had a spare good prism.
The inspection plate hole is too small to a get fingers in to adjust it.

I thought of drastic solutions:
(1) drill 2 holes in the right hand side of the binoviewer and attach 2 straws via silicone
to the prism so I could move it from outside the case to an ideal position.
(2) use a hacksaw and cut the whole right hand top off the housing -
glue it back later if successful.
(3) make a custom L bracket out of thin Aluminium which would go in from the top
of the inspection housing and attach via silicone to the bottom of the prism
so it could be moved and aligned while looking through both eyepieces.
Remove the L- bracket if successful.

None of those are worth my time considering the prism is history but
even if a new prism turned up it still looks dubious as to whether it could ever be aligned?
I don't know how they did it in the Leitz factory?
Maybe it was pre-aligned on a jig outside the binoviewer?
Is this how they normally make binoviewers?
It would have been much nicer if the prism was held in a cage with adjusting screws.
The glue they used is very hard - it looks like epoxy resin.
It seems like an awful solution that after making a precision microscope
that it's only working because of some glue on the prisms.
I suppose binoculars and many other devices only have glued prisms too?

Anyway I've learnt a lot as this was my first time opening up a binoviewer.
Any comments?

cheers
Allan

[xelasnave]

Hi Allan
I have had a microscope where a prism came unstuck ( in the post so no idea of the impact that caused it) but happily I glued it back and all way ok. You may have more to worry about ?...I dont know but like you I found it a great learning experience. Maybe the EP holding so try rotating it maybe.
Alex

[alpal]

Originally Posted by xelasnave

Hi Allan
I have had a microscope where a prism came unstuck ( in the post so no idea of the impact that caused it) but happily I glued it back and all way ok. You may have more to worry about ?...I dont know but like you I found it a great learning experience. Maybe the EP holding so try rotating it maybe.
Alex

Hi Alex,
it's been a great learning experience for me.
Maybe your microscope had only one prism?
There are parts and whole microscopes on the German Ebay:
https://www.ebay.de/itm/374557940673...item5735649bc1

cheers
Allan

[xelasnave]

Originally Posted by alpal

Hi Alex,
it's been a great learning experience for me.
Maybe your microscope had only one prism?
There are parts and whole microscopes on the German Ebay:
https://www.ebay.de/itm/374557940673...item5735649bc1

cheers
Allan

It is a dual eye piece unit and only the prism on one side dislodged.

Thanks for the link.

I have two...the one mentioned which I run a small camera thru one eye piece leaving the other to check things but also another with the dual viewing set up and a seperate path for its camera...both cameras are only 5 meg but are totally adequate .... I also have one of those small digital units which is surprisingly good and very handy as you can view using your phone.


Alex

[alpal]

Originally Posted by xelasnave

It is a dual eye piece unit and only the prism on one side dislodged.

Thanks for the link.

I have two...the one mentioned which I run a small camera thru one eye piece leaving the other to check things but also another with the dual viewing set up and a seperate path for its camera...both cameras are only 5 meg but are totally adequate .... I also have one of those small digital units which is surprisingly good and very handy as you can view using your phone.

Alex

Hi Alex,
I don't quite understand you.
Are you saying that you re-glued a prism in
a binoviewer and it all lined up perfectly?
Were you able to move the prism and find the best collimation?

cheers
Allan

[xelasnave]

I re glued the prism matching it to the remaining glue marks..I did not look thru the EP ( probably could not but it did not occur to me) and line it up but merely matched the glue marks...I was careful to make the glue layer very thin to minimise issues and made sure there was nothing like a "grain of sand" or any material that prevented a perfect fit..I recall I removed a small part of the old glue because at the edge it seemed to grab..I glued the old glue...I guess I was lucky ..I was very careful and inspected the surfaces with a decent glass ...but I had no problems....a contributor to my sucess was I noticed the problem early ( within 24 hrs of arrival) and started immediately to pull the thing apart.

In any event if you cant fix it you can have lots of fun with one Eye Piece.. get a cheap 5 meg camera and watch via your computer screen.
If its like astronomy for you in no time at all you will want another...thats the way it goes.

Pity I had photos that I only deleted last week....I think I posted them here...


Alex

Alex.

[alpal]

Originally Posted by xelasnave

I re glued the prism matching it to the remaining glue marks..I did not look thru the EP ( probably could not but it did not occur to me) and line it up but merely matched the glue marks...I was careful to make the glue layer very thin to minimise issues and made sure there was nothing like a "grain of sand" or any material that prevented a perfect fit..I recall I removed a small part of the old glue because at the edge it seemed to grab..I glued the old glue...I guess I was lucky ..I was very careful and inspected the surfaces with a decent glass ...but I had no problems....a contributor to my sucess was I noticed the problem early ( within 24 hrs of arrival) and started immediately to pull the thing apart.

In any event if you cant fix it you can have lots of fun with one Eye Piece.. get a cheap 5 meg camera and watch via your computer screen.
If its like astronomy for you in no time at all you will want another...thats the way it goes.

Pity I had photos that I only deleted last week....I think I posted them here...


Alex

Alex.

OK thanks Alex,
you were lucky.

yes - I've done some focus stacking at prime focus with my Eschenbach microscope:
https://www.flickr.com/photos/247194...in/photostream

https://www.flickr.com/photos/247194...in/photostream

https://www.flickr.com/photos/247194...n/photostream/

At least you don't have to worry about cloudy nights as with astronomy.

cheers
Allan

[xelasnave]

Wow great work...I have not focus stacked as the software was terrible but looking around everything was just too expensive...medical stuff.

I bagged a " water bear" after days of hunting and days seperating it from the rubbish...but it was only a single frame.
Alex

[alpal]

Originally Posted by xelasnave

Wow great work...I have not focus stacked as the software was terrible but looking around everything was just too expensive...medical stuff.

I bagged a " water bear" after days of hunting and days seperating it from the rubbish...but it was only a single frame.
Alex

Nice - both sources of stacking software have a 1 month trial and they are excellent -

Zerene
https://zerenesystems.com/cms/stacker/softwaredownloads

Helicon Focus
https://www.heliconsoft.com/software-downloads/

[xelasnave]

Thanks Allan ..that is reasonable.
Alex

[alpal]

Originally Posted by xelasnave

Thanks Allan ..that is reasonable.
Alex

Good - try it.
You need to use a DSLR at prime focus so that the microscope objective
focuses directly on to the camera sensor for maximum sharpness.
I use a T -piece on my Canon EOS 1000d DSLR.

Here's a question for you and I can't find an answer on Google.
I have found that all microscopes that I've measured have
eyepiece barrel diameters of 23.2 mm or 0.913 inches.
Telescopes are generally at 1 1/4 inch = 31.75 mm.
Of course telescopes can even fit 2 inch eyepieces.

Question:
why are microscope eyepieces so small in diameter?

cheers
Allan

[xelasnave]

Originally Posted by alpal

Good - try it.
You need to use a DSLR at prime focus so that the microscope objective
focuses directly on to the camera sensor for maximum sharpness.
I use a T -piece on my Canon EOS 1000d DSLR.

Here's a question for you and I can't find an answer on Google.
I have found that all microscopes that I've measured have
eyepiece barrel diameters of 23.2 mm or 0.913 inches.
Telescopes are generally at 1 1/4 inch = 31.75 mm.
Of course telescopes can even fit 2 inch eyepieces.

Question:
why are microscope eyepieces so small in diameter?

cheers
Allan

Originally there was duty on larger optics and by making them a little smaller the duty was avoided and the practice carried was still carried on even after the duty was dropped after WW2..no hang on thats not right as I just made all that up..

.I really don't know why the difference ..probably just following the original leader in the field and as with so many things " we do it this way because we have always done it that way".
There could be a reason based in optics.

Who was the leader way back? Maybe the EPs were similar to those in a sextant or something and pirated...

I wont sleep tonight of course.

Alex

[alpal]

Originally Posted by xelasnave

Originally there was duty on larger optics and by making them a little smaller the duty was avoided and the practice carried was still carried on even after the duty was dropped after WW2..no hang on thats not right as I just made all that up..

.I really don't know why the difference ..probably just following the original leader in the field and as with so many things " we do it this way because we have always done it that way".
There could be a reason based in optics.

Who was the leader way back? Maybe the EPs were similar to those in a sextant or something and pirated...

I wont sleep tonight of course.

Alex

I can think of a good reason but I'll reserve it till tomorrow.

[alpal]

I think I have an answer.
the Royal Microscopal Society (RMS)

https://www.sizes.com/tools/microscope.htm

Eyepieces
The RMS established a standard for the inner diameter of the tubes into which eyepieces fit in 1882, revised in 1889.
The standard eyepiece has an outer diameter of 23 mm.

It's handy that you can mix and match different eyepieces ( and objectives) from
different microscope manufacturers.
Still - if there was some advantage in making larger eyepieces I'm sure that they would have done it.
My guess is that wider eyepiece design would only have the detrimental effect
of increasing optical aberrations seen in the eyepieces.

cheers
Allan

[xelasnave]

Now I can sleep.
Thanks Allan.
Alex

[alpal]

I did a comparison with images taken with my other microscope - at prime focus -
an Eschenbach model back in 2015 with my latest Leitz microscope.
I think the Leitz is a little clearer than the picture I'm posting.
Still they are nothing compared with what I see for daisy pollen online:

https://www.facebook.com/photo/?fbid...pollinated-the


https://microscopyofnature.com/pollen


Maybe I should take some prime focus pics with the Leitz?

cheers
Allan

[Huey (Michael)]

Allan,
When/if you use the oil method you can put some nail polish around the coverslip to make it even more durable.

https://microscopyofnature.com/pollen

Huey

[alpal]

Originally Posted by Huey

Allan,
When/if you use the oil method you can put some nail polish around the coverslip to make it even more durable.

https://microscopyofnature.com/pollen

Huey

Thanks - I have the original slide that I made in 2015.
I have proper immersion oil and yes it
does seem to work better and the oil needs to get under the coverslip.
As I said - I had a look last night through both microscopes
and the Leitz was giving me better views with oil.
I can now mix and match eyepieces and objectives -
I also used the 100X objective from the Eschenbach on the Leitz.
Still they are not as good as the link pictures I posted.


cheers
Allan

[xelasnave]

I found a photo which shows the old glue to be worse than I remembered but probably the sucess I enjoyed with re glueing can be attributed to the old glue being just so ruff as it sure made positioning a snap in retrospect.
Alex