LOMO 90x 1.25 Oil

[smollerthings]

Hi All,

I was playing with my shiny new vintage LOMO microscope and tried the 90x oil which I hadn't tried before. I don't have oil right now but have glycerin and saw that they have similar refraction indices so I gave it a try. It works pretty well on some of the slides I prepared myself but not on some the ones I bought (can't focus further, bumping against the cover slip).

I have noticed that some of the prepared slides have very thick medium. Is that the cause of the inability of the lens to focus? I saw on aliexpress that a 100x's working distance is 0.13 mm, so not a whole lot. Maybe the slides were prepared too thick...

This lens is also stuck (no spring action at all). I wonder if this could play a role?

Thanks!

[MicroBob]

Hi,
these 33mm LOMO objectives are old pre-WWII Zeiss Jena designs - good but old fashioned. At this time one expected the user to be acceptably competent in handling a microscope to get along without a sprung front element. As long as the objective is about 33mm long and you get a sharp image with 0,17mm cover slips I would expect the objective to be working as it should. I think that late 40:1 and 90:1 objectives by LOMO had spring loaded front elements, the older Zeiss Jena not. In some cases springs are visible when looking into the objective from the back.

Bob

[Lomonaut]

Yes, I guess some of these slides are just too thick.

The 60x/0,7-1.0 oil I just sent to you also has a tiny working distance and isn't spring loaded (or is it stuck?), and don't count on parfocality. It's much shorter than 33 mm, very bulky. These Lomo objectives are so tiny compared to my Nikons!

I never tried glycerin instead of proper immersion oil. I remember when the 60x arrived (1986) I went to the local apothecary and wow, the owner happened to have a Zeiss microscope and gave away 5 ml of immersion oil for free in a small dropper bottle, even printed a sticker for it. Still use it today

[Leitzcycler]

Dismantling and cleaning the 90x objective is very easy and straightforward. It only takes a minute or two. The structure of 40x objective is the same. Just unscrew the cover cylinder. If it is tight, use e.g. rubber sheet around. Unscrew the upper top cap with a pair of slots. You may use a specific tool for that or use your imagination selecting a tool if youd don't have a specific one. Unscrew the little black screw in the side of the objective barrel. Then just push the objective barrel out, obviously taking care not to touch the front lens. Clean the barrel and put the parts back. I don't know what the experts here think but would it be better not to add any new grease? Is the grease necessary in spring-loaded objectives?

I dismantled mine and took pictures for you.

[smollerthings]

Thanks Leitzcycler. This is awesome.
The issue is that I don't have the tool to take the top cap off. Can you give me the name of the tool? I can't seem to find it.
Also I think the inside barrel is seized (just like the rest of the microscope was), this part looks like it is designed to receive some oil. Is there a risk of damage if I put a drop of W40 in there?

And what will be really good is that I will be able to fine tune the parfocality that way!

[MicroBob]

Hi together,
this is a newer version of the objective. To decide whether to grease or not to grease I would suggest to clean it and try it without grease - if it it possibel to get it to move freely I would leave the grease away. Better no oil as it could seep into the lens barrel. If it doesn't move freely check for burrs around the slot. WD40 has far fewer uses than most people think , probably a case of successful marketing! It can be used to prevent rust and to loosen screws but little else. Putting it into the objective would lead to th need for total dismanling of the objective. A project we would follow with lots of interest of cause!

Bob

[smollerthings]

Mmm... this sounds risky then

Does the spring have a purpose other than protecting the sample slides? If not, I think I am just going to leave the objectives as is because they are really seized.

[Leitzcycler]

Here is an example: https://www.ebay.com/itm/313575222672?_ ... %3A2334524

A very useful tool if you do DIY repair a lot. However, I just used tweezers this morning as I was too lazy to go to my workshop. Of course, this is not recommended as you may broke or scratch something is there is not enough adherence with you tool. The cap is not necessarily very tight though...

I am afraid you can't do anything to the parfocality. Switching to 40x to 90x needs a lot of refocusing according to my experience.

[Leitzcycler]

I have used WD40 (CRC45), but just a small drop. You could first spary it into some cup and then rise a drop with a toothpick.

I think the spring action is very usefull as you will easily touch the slide anyway.

[Leitzcycler]

Sorry, CRC-56. Practically the same as WD40. The idea, of course, is to use it so little that it will not penetrate into the lens system. This should be possible if you work carefully.

[smollerthings]

Quick question: where is the moving seam? 1 or 2?

90.jpeg (66.31 KiB) Viewed 5974 times

[Leitzcycler]

2

[smollerthings]

Ok, that sucker is not wanting to move at all. Damn the soviet grease/glue!

[Leitzcycler]

And you did remove the spring already?

A drop or two WD40, let it penetrate some time and then apply force to the objective head around the front lens (edge no. 1).

[smollerthings]

I did not. The cap is stuck as well. I put a little bit of wd40 on both. We will see how it goes after a couple hours.

[MichaelG.]

Does the spring have a purpose other than protecting the sample slides? If not, I think I am just going to leave the objectives as is because they are really seized.

That’s fine, as long as they’re seized in the fully-extended position
… which is, of course, very likely.

When you have broken your first slide … you may wish to re-consider !

MichaelG.

[Leitzcycler]

Sorry, this is only because I didn't know how to put picture attachments into PM. Don't try this at home unless the situation is absolutely desperate. No guarantee, no responsibility from my side .

1. Remove the back cap and spring. Use some tool fitting properly to the slots, press to hold the tool inside the slots. Turn open as usual, anticlokwise. Shouldn't be tight. Has never been...

2. Remove the little black screw.

3. Add more WD40 if needed. Not too much to contaminate the lens surfaces. Press firmly downwards against a table. With fingers you can't apply too much force to break something. The inner objective barrel should now slide down. If not, I am amazed no matter how old the thing is. If you don't have enough strength in your fingers, you may drill a hole into a piece of plywood and use it as a tool and use your body weight.

4. Wipe all traces of WD40 away and clean also all traces of grace with petroleum. Again not touching the lens surfaces!

I have even used a piece of extremely fine-grain sand paper (for metal craft) to clean the surface of the inner barrel if it don't slide back properly. But don't tell this anyone especially at the forum.

[smollerthings]

Alright, after 3 days of fight, despite Leitzcycler's guidance and pep talk , I am conceding to the 43 year old Soviet grease.

I used WD40 on the black cap and barrel, several times. And still no sign of even the slightest movement. I had a pretty good grab on the black cap with a small plier, and I could feel I passed enough force (at least 2-3x normal) to unscrew it in normal conditions. I also tried to push on the inside barrel using Letzcycler's method (which should move, regardless I unscrew the top cap or not), and nothing.

I think the main issue is that this microscope, and all parts came new to me. The microscope was made in 1978 and nothing has moved for 43 years. The acidic grease froze and corroded the metal, hence the tremendous difficulty I already had with the bigger components which I had to flood with WD40 and use some percussive force on (and a lot of blunt force) to unstuck. I can't do that on this cute objective.

Oh well, I was good fun.

Thanks everyone !

[MicroBob]

The gummed up grease softens when heated to 60°C for a while. I wouldn't heat microscope optics unless absolutely necessary but before you give up you might as well try this approach.

[Leitzcycler]

In case you destroy it, I have an extra 90x objective which I can send to you. It moves freely, as you have seen the pictures. I haven't check the optical condition though...

[smollerthings]

Thanks guys. I thought about heating it up but it seems risky. Actually I thought about putting it in my fridge since it could retract the metal but I am pretty sure these cycles will have negative impact on the optics, possibly delamination.

I will just keep them (my 40x is the same) as is and be cautious.

[Hobbyst46]

These internal parts of the objective, possibly excluding the screws, are very probably made of brass.
Brass is corroded to copper salts, as shown by the greenish-bluish color.
WD40 works well on iron and steel, which really rust. Rust is brown.
Ammonia dissolves some copper salts. I never tried it, but perhaps a drop of weak ammonia (an ingredient of certain liquid household cleaners) could help some.
Solidified grease sometimes softens after a few days of contact with light machine oil (sewing machine oil). Such oil, in contrast to WD40, does not emit vapors, so is relatively safe to the lens cement.

[patta]

First WD40 ; then, sandpaper ; now Ammonia
What will be next? Fix collimation with a sledgehammer ?

[Leitzcycler]

That's correct. When everything possible is done, you will need a hammer to mold fishing net weights out of old Lomo stuff

[smollerthings]

Yep. I just ordered a new flamethrower from Aliexpress

Na, I like it, the images are of fine quality to my eye:


By the way, the optical cement, do you replace it after you take all the pieces apart?

[smollerthings]

These internal parts of the objective, possibly excluding the screws, are very probably made of brass.
Brass is corroded to copper salts, as shown by the greenish-bluish color.
WD40 works well on iron and steel, which really rust. Rust is brown.
Ammonia dissolves some copper salts. I never tried it, but perhaps a drop of weak ammonia (an ingredient of certain liquid household cleaners) could help some.
Solidified grease sometimes softens after a few days of contact with light machine oil (sewing machine oil). Such oil, in contrast to WD40, does not emit vapors, so is relatively safe to the lens cement.

Thanks for the info. Didn't know about ammonia.

[Leitzcycler]

I agree that the grease used in Lomo may be acidic and corrosive. However, I wouldn't use ammonia or other strong agents although it might dissolve the copper salts it theory. The reason I have used WD 40 (CRC 56) is that it penetrates well and softens the grease after which the parts, according to my experience, can be easily dismantled. I have used fine-grain sand paper (for metal) to clean the the barrel surfaces to remove any remains of corroded brass which prevent the proper sliding. Of course you have to clean it and remove all the dust formed, which won't actually be there as you should use a drop of water (or oil) with the paper.

I have refurbished four of five Biolams and have owned a total number around ten Russian microscopes. I have never met any part that couldn't be opened or dismantled by this method. However, it is possible that the threads of objective barrel was defective already at the factory and they just glued it...or something like that. I think it's unlikely, but possible as I have seen all kinds of strange and vague constructions.

By the way, the optical cement, do you replace it after you take all the pieces apart?

I didn't quite understand the question. However, the idea of course is to keep the lens system completely intact.