Disassembling and cleaning an eyepiece for the first time, eek!

[IB20]

I noticed a large piece of debris on an Ortho last night (first time using it on the moon) and it quickly became apparent that the debris was between lenses, which was incredibly frustrating. 

Whilst not being a very expensive eyepiece it wasn’t something I was willing to write off or was happy to carelessly damage either, so I decided to try and clean it…

Unscrewing the barrel and two retaining rings was very easy but what I wasn’t really prepared for were two lenses and another ring falling out! First lesson, note the orientation of the items that come out of the EP housing. A gentle wipe of both lenses with a micro fibre cloth and then to reassemble. 

The two lenses were flat on one side and convex on the other and checking lens schematics online didn’t clarify which way round they went; orthos are supposed to have three lenses, nightmare! Reassembling was fairly frustrating and carefully dropping the lenses and diaphragm ring into position usually ended up on their side. Eventually after all being reassembled I checked the EP in my scope and although correctly orientated, I could see fibres trapped in the lenses. 🙄 Lesson two work in a super clean area! 

Cue about 10 dis/reassemblies later I have finally got it to a place where I’m happy with it and it’s showing nice terrestrial views, there was a point I thought it was cream crackered for good and a time I thought I’d lost a lens - all very stressful. 

To summarise, I don’t recommend it if you can avoid it especially if it’s an expensive eyepiece, send it to an expert! By all means if you’re interested, take apart one of the cheapo lenses you get included with SW products. 
 

 

 

Edited November 16, 2021 by IB20

[John]

Well done !

Simple designs such as orthos and plossls with their 4 elements in 2 groups designs are not too bad but the lens elements are small with the shorter focal lengths so the process can be fiddly.

If the one you did is one of the Starbase orthos, I think they are a 2 + 2 design more like a plossl, as you found. The "classic" abbe ortho design is a 1 + 3, ie: a single element eye lens and a triplet field lens. A 2+2 design can still be orthoscopic though, as I understand it. With the 2 + 2 designs generally the convex lens surfaces face inwards, towards each other, and the flat surfaces face outwards but it sounds like the elements in yours were concave on one side ?

The older Vixen made "Or." eyepieces are also a 2 + 2 design I seem to recall when I took some apart to clean many years back.

I think I would be very wary of taking apart one of the more complex designs !

 

 

 

Edited November 16, 2021 by John

[IB20]

3 minutes ago, John said:

Well done !

Simple designs such as orthos and plossls with their 4 elements in 2 groups designs are not too bad but the lens elements are small with the shorter focal lengths so the process can be fiddly.

If the one you did is one of the Starbase orthos, I think they are a 2 + 2 design more like a plossl, as you found. The "classic" abbe ortho design is a 1 + 3, ie: a single element eye lens and a triplet field lens. A 2+2 design can still be orthoscopic though, as I understand it.

The older Vixen made "Or." eyepieces are also a 2 + 2 design I seem to recall when I took some apart to clean many years back.

I think I would be very wary of taking apart one of the more complex designs !

 

 

 

Ah it was a 1 + 3 lens design VT Ortho, so an abbé design, makes sense now! Thanks for the info, maybe I should’ve asked SGL before I decided to disassemble it! 

Edited November 16, 2021 by IB20

[Franklin]

If you ever have to take an eyepiece or objective apart again a little trick is to, once the retaining ring is removed, support the lens with a lens cloth and invert it. So you are in effect sliding the lens housing away from the lens/lenses as opposed to removing the lens/lenses from the housing or cell. That way the lenses remain in the correct order so you can clean them in reverse order and re-stack them as they were, before re-housing. No dust, linnen gloves, bulb blower on every element before reconstruction.

Best way to avoid all of this hassle is to remember 2 things. Always keep them capped when not in use. Always use the bulb blower before and after use. I only find I need to use fluid on eyepieces with short eye-relief because of the inevitable contact with the eye and all its gunk!

[fireballxl5]

Sounds like good advice @Franklin

I have a similar big bogey in my TV 8-24mm zoom.  It's been left in place owing to my concern with having to put it back together again!

Anyone have advice for dealing with this?

CS, Andy

[Franklin]

The Zoom is a different thing all together. Not only is the eye lens a multi-element lens but there is also a multi-element field lens which acts like a variable barlow lens. There is also the mechanics of the zoom movement itself to think about as well. I personally would leave it well alone and live with the bogey. But if the culprit is in focus then it must be at the field stop I would imagine, so it may pay to give the outer field lens a good bulb blowing and clean with Q-Tip and Baader fluid. It might just be lodged dirt and this may just do the trick. The TV 8-24 zoom is a rebranded Vixen LV zoom I think, I used to have one and I wouldn't be confident in dismantling it.

[Don Pensack]

There is a lens tool you can buy on-line (it's cheap)--it's a small suction cup with a bulb attached.

You can attach it to a lens to pick up the lens and place it in the eyepiece barrel without touching it with anything that will leave lint or a mark.

Here is an example:

https://www.amazon.com/SE-EL-VP6-7-Piece-Vacuum-Interchangeable/dp/B00XSDHPEK/ref=asc_df_B00XSDHPEK/?tag=hyprod-20&linkCode=df0&hvadid=309811990469&hvpos=&hvnetw=g&hvrand=15807450112636400556&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9030974&hvtargid=pla-570530083398&psc=1