Isolette III w. Solinar 3.5/75 collimation

[ginquo]

Hi everyone, I recently bought an old Isolette III with the plan to get it into working condition again. I removed the dried up Agfa grease, cleaned the shutter and replaced the bellows etc.


Photo here: https://drive.google.com/open?id=1hJ-0HZ5I0s_3J2Uq4uTOfQ-p8G_v5d1z


But there's one thing that's giving me a bit of trouble: When trying to collimate the lens using another camera focused to infinity I can barely focus the lens to infinity if I turn the front group all the way in. I also tried to focus on closer objects and this barely seems to work. It's a Solinar 75mm f/3.5.
From what I can tell the Solinar, being a Tessar clone should focus with its front element only, but the two front elements seem to be one combined unit. Is that normal? I keep wondering if they're still somehow glued together with agfa grease, but I can't seem to find any seam.


Maybe I'm worrying to much.. I'll put a roll of film through it on the weekend and see how that turns out.

 

[Solinar]

When you removed the glass elements from the shutter - were there 3 groups?
-
* rear group located behind the shutter - which is really two elements cemented together
* middle element - which is concave.
* front element - which is convex / it is the focusing cell.

If the front focusing cell and middle element came out as a unit, then you would have only seen two lens groups.

 

[ginquo]

When you removed the glass elements from the shutter - were there 3 groups?

They came out as two groups. One group in the back and one larger unit in the front.

Here's a photo: https://drive.google.com/open?id=1owEXOWowm7NzHpSHSZNZ6pIVwL8TdXuI

The front unit is convex in front and concave in the back. As you'd expect from the two front elements of a tessar.


EDIT: I might be messing up terminology a bit. The rear group is a group, yeah. But the two elements in the front came out as seemingly a single unit that's more or less fused together.

 

[Solinar]

Okay - I know what your issue is.

The reason that you claim only two groups is that the front focusing cell is firmly stuck within brass ring of the middle element. Two separate the two, you need glass jar that seals really well. Place the stuck elements in the glass jar, along with enough 90% Isopropyl alcohol to fully cover the elements and then some. Screw the lid on the jar and test if leaks. If leaks get another glass jar.

Now comes the dangerous part. On an electric stove - boil water in a pot that is large enough to hold the glass jar with room to spare. Turn the stove to its absolute lowest setting and place the glass jar in the hot water for about an hour.

After an hour remove the glass jar and allow it cool for about five minutes. Remove the two stuck together lens elements from the alcohol - while wearing cotton or leather gloves unscrew the two elements by grasping the outer threads of the middle element's brass mount with one hand and the front most collar of the focusing element with your other hand. If you want to chance using a pair of pliers on the front cell - be very careful. I've been able to finger loosen the first two elements on multiple Agfas, just by heating them as described.

What you have done is to heat the dried out, solidified 65 year old grease that Agfa used as a lubricant. The water bath keeps the temperature under 212°F / 100°C.

 

[ginquo]

Alright, that confirms my fear. I'll probably try your procedure tomorrow if I get all the supplies. I'll let you know about the results.


I assume soaking the elements in isopropyl alcohol or naphtha overnight is unlikely to work?

 

[Solinar]

I assume soaking the elements in isopropyl alcohol or naphtha overnight is unlikely to work?

I've tried a naptha overnight soak without much success as opposed to the above method. The naptha is good to have when comes time to clean the helical threads with the tips of wooden tooth picks. That dried up, solidified Agfa grease is tenacious stuff. It has green tinge from reacting with the brass on the two lens mounts.

 

[hanskerensky]

You might give this a try :

Agfa Jsolette Lenses Fused Together (03) by Hans Kerensky, on Flickr

 

[ginquo]

Alright, many thanks for both of your help.


Hans, the hose thing sounds like a good idea. Just to be 100% sure, the top part should come off if I turn it counter-clockwise from your photo's point of view, right?


What kind of threw me with my lens was that there seem to be no notches for a lens spanner on the middle element's brass ring like in your picture.

 

[kaffefant]

I would not heat isopropyl alcohol in a sealed container under any circumstances. I would only heat any alcohol if I have acces to a active ventilated work area, such as a fume hood or similar.

The heat alone is very effective, and I have had succes with baking a sealed Agfa lens in the oven. Set the oven to 60-70 C (160 F) and put the lens in the cold oven to avoid temeprature chock. Heat it for may be 30 min. As you are working on the front part, there should be no risk of decementing your lens (no cemented elements in this part).

 

[Solinar]

I would not heat isopropyl alcohol in a sealed container under any circumstances. I would only heat any alcohol if I have acces to a active ventilated work area, such as a fume hood or similar.

Good advice - which is why I stated that it is dangerous. I say that from past construction and use of an alcohol camping stove, called a spirit burner.

With that said, I use the following:

* A Mason brand canning jar - which is intended for home-made fruit preserves.

* A cast iron cooking pot that is much larger than the Mason jar.

* The cooking pot has nice heavy lid to keep the water bath from evaporating.

The reason I use this method is the the two lens groups/elements unscrew from each other with just finger power.

But back to safety issue - this is not a safe procedure.

 

[ginquo]

I have a large temperature-regulated brewing kettle, so I should be able to control the water temperature quite precisely. I'll probably leave it at around 70C. IPA boils at 80C so that should still be in the safe area.

 

[kaffefant]

You don't need the IPA, the heat is enough. If it isn't, you can try with the IPA later.

Warm/hot solvents like IPA will give off way more fumes than just at room temperature. You should in general use solvents as little as possible. Your brain cells will thank you. 🙂

 

[hanskerensky]

Alright, many thanks for both of your help.


Hans, the hose thing sounds like a good idea. Just to be 100% sure, the top part should come off if I turn it counter-clockwise from your photo's point of view, right?


What kind of threw me with my lens was that there seem to be no notches for a lens spanner on the middle element's brass ring like in your picture.

Indeed CCW.


btw For gentle heating I often use the electric hairdryer of my wife. Turn the lens in the airstream. Then let cool again. Might take several times but you just have to be very patient.

 

[ginquo]

Last night I tried to heat it up by putting it in an empty mason jar and placing that in a water bath. Slowly heated the water up to 70C and kept it there for half an hour so it can slowly heat through.
No luck. The front element wouldn't budge. I wore some rubberized cotton gloves like Andrew suggested. I'll give this a few more tries over the weekend. Guess there's no point in rushing this.

 

[Solinar]

My method took the temperature a little higher to almost 100°C

In deference to safety concerns, place the two elements on a plate and then into a cold oven on a middle rack - with out any alcohol - Adjust the oven temp to 100°C and leave it there for about 45 minutes. - Then handle with leather gloves.

 

[ginquo]

Ah well, time to give the IPA bath a go.

 

[Solinar]

Whoa - that's not a kettle - it's a modern day Russian electric samovar.

I have no room to comment, because as mentioned, I used a heavy-duty cast iron stew pot to hold the hot water bath at near constant temperature.

 

[ginquo]

Whoa - that's not a kettle - it's a modern day Russian electric samovar.

Hah, yeah. I used it for brewing beer. It has an internal colander with a flat bottom, so it's pretty much ideal for water baths.

Anyways, I didn't have much success. 🙁 Had the IPA in the mason jar boil for a good 45 minutes, but the front element still wouldn't budge.


EDIT: I'll probably try Hans' method with the rubber stopper and mat next. But first I'll have to get the supplies which might take some time. Hans, did you unscrew the lens when hot or cold?

I'm starting to worry that my constant fiddling with the lenses is starting to mess with the lens coating.