7 replies to this topic

[SriBri]

I have a Vixen A80mf that has been sitting on it's side, on a shelf in a closet for over a decade with no lens-cover. Dust has likely been collecting on the lens, and I'm concerned about moisture. How should I approach getting this scope ready for use again? Can I just pop the lens out and wipe it with a lens-cloth? I'd like to use the scope to dabble in photography if I can get it back in good shape.

[cookjaiii]

I wouldn't pop the lens out unless it's absolutely necessary. The only time I would consider this is if fungus has grown on the innder surface(s) of the lenses. 

 

If there was high humidity during storage, fungus growth may have occurred.  If fungus is present, cleaning will require aggressive measures and may not be feasible depending on the extent and location of the growth.  Fungus can etch the surface of glass and permanently degrade the image.

 

Assuming no fungus growth, do the following.

 

To clean the outer lens without disassembly, take off the dew shield and blow off loose dust with a rubber bulb. Stubborn dust may be flicked off with a soft brush (a make-up brush from the drug store is perfect).  Do not use canned compressed air - ever!!!.   

 

If surface haze or dirt is significant, dab the lens with a cotton ball moistened in 70% isopropyl alcohol.  Don't use a soaking wet cotton ball because you don't want any liquid to soak into the edges of the lens.  Don't rub hard as you may end up dragging tiny particles of dirt across the surface and scratch it.  Once you have dabbed away surface dirt, you can gently wipe with either cotton balls or facial tissue moistened with 70% isopropyl alcohol.(Televue recommends "Puffs" brand for their eyepiece cleaning).  Don't use facial tissues with lotion or fragrances.

 

Don't re-use cotton balls or tissues and swap out for clean ones frequently.

 

A little dust on the interior of the lens is very common and is unlikely to affect the image at all.

 

After you have cleaned the lens, find or fabricate a lens cap (plastic jar lids work if you can find the right size, find a friend with a 3-d printer, or even just Saran Wrap will keep the dust at bay.

 

If you can, post a picture of the lens before and after cleaning.

 

Good luck!

[deSitter]

I have a Vixen A80mf that has been sitting on it's side, on a shelf in a closet for over a decade with no lens-cover. Dust has likely been collecting on the lens, and I'm concerned about moisture. How should I approach getting this scope ready for use again? Can I just pop the lens out and wipe it with a lens-cloth? I'd like to use the scope to dabble in photography if I can get it back in good shape.

Post this on the Classic Telescopes forums and you'll get a dozen answers about disassembling and cleaning a classic objective. I'm sure your scope is fine.

 

-drl

[Paul Sweeney]

Second vote for going over to the Classic Telescope forum. There you will find the real experts on restoring old telescopes.

[Inkie]

At the time I see this, it has not been moved, so I will answer as best I can.  I agree, no need for now to remove anything.

 

First, aim he telescope tube (OTA, or optical tube assembly) downward so that it has at least a slope of about 10 deg...if possible.  You want the main lens up front to be at the low point so that any liquids will have to migrate against gravity to work their way behind the lens and into the tube. Make sure it cannot tip over.  If on a tripod, put something heavy against the legs for that purpose, or sling a heavy gallon jug full of water from the middle braces to help keep the center of gravity low. 

 

You can blow on the lens yourself, or use a soda straw for that, or use an optics cleaning kit's blower bulb...whatever works to get anything removable that way off of the outer surface.  Then, if you have a mister, like a plant mister if you keep orchids or epiphytes, you can give two mists, light ones, just to dampen the schmutz still present on the lens. Wait-two-three, then use a clean sheet remnant (cotton, please) dampened with Windex or a glass cleaner, or a drug store strength isopropyl/water blend, and very lightly wipe small areas, turning the cloth to a clean area after each wipe.  Repeat with another cloth remnant (only cotton, please), until the lens is obviously waaaaaay better. 

 

Lastly, cap that lens!  Cap it if you leave the scope out over night.  Cap it before you return it to an indoors location. If you can see that it has condensation on it, ever, leave the cap off, but return the OTA to that lowered front end again to keep dust off the lens. Replace the cap an hour later. 

[SriBri]

Thanks for the advice everyone. I used isopropyl alcohol and cotton balls on the lens and it improved visibly. However it appeared there were blemishes behind the lens.

 

Against some advice here, I did remove the lens and was mildly surprised to find a 2nd piece of glass directly behind it that appeared to somehow have more trouble than the exterior lens. I gave it the same alcohol and cotton treatment, and let things dry before replacing the outer lens. Unfortunately it looks like a lot of the blemishes are somehow on the rear of the inner lens(?), which I did not feel comfortable removing (it would have required removing 4 screws around the tube.

 

Attached images are: Before Cleaning, Before Cleaning, After Cleaning, and that inner lens which has not been removed.

 

I will try moving this thread to the classic camera board.

 

 

Edited by SriBri, 13 October 2024 - 05:41 PM.

[Inkie]

I'm guessing it's a substantial improvement.  If It's an 'air spaced' doublet, you probably have a decent scope on your hands.  Personally, I would have no compunction about removing the cell with the rearmost lens to see if it responds well to a cleaning, but if you're a bit put off, what you have left after your exploration and cleaning can be filed as 'good enough'.

[SriBri]

After some advice on the classic telescope forum, I did remove the lens assembly to clean the back of the doublet. I am very sorry to have forgotten to take photos, because I cleaned 2 small dead spiders and their web remnants from the inside of the tube! Again, used isopropyl alcohol to clean up blemishes on the back of the 2nd lens, and the glass was looking much nicer when I was finished. We had a clear night last night (except for the very bright moon), so I took the scope outside to give it a go at Saturn. I was able to make out the rings faintly, but there was a bit of a glowing blob around the planet which I thought looked like lens flare? Would that be caused by the moon being too bright and close to Saturn, or is that a problem with the scope that I can address?