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Where can I get a refractor objective lens recoated?

Astronut1982

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ronin

ronin

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About 6 or 7 years ago I was looking to have a lens repaired, I contacted a company called kvoptical, who I think are Kingsview Optical.

I say "think" as at the time they were, or appeared small, and had an email at/on aol.com

Looking at Kingsview now they seem somewhat bigger and have their own emails, but that may simply be a consequence of time and progression.

Still have the old email and the price then was £130 for the repair and AR coating. The repair being tooling etc to remove a scratch and then recoating at whatever wavelength I requested. The coating may not have been multi-layer. Which is what the WO's will have.

That is about the only one I have: http://www.kingsviewoptical.com/

Still assuming that KV = Kings View and honestly not 100% sure for some odd reason.

Person I was in contact with was a Shaun Elliot, but that was some years back now.

One possible problem is you are in Mussleburgh and they are in Rye East Sussex, about as far apart as you can get in the UK.

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Astronut1982

Astronut1982

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The present coating has been smeared.

I was cleaning my lens & camera chips the other day & had just finished cleaning the Camera chip with pure acetone & thought I had put the lid back on. As I was giving the objective lens a blow to remove the dust on it, I knocked the acetone which wasn't actually secured on tightly & some spilt onto the lens. I tried to soak it up with a paper towel but couldn't but smeared it a bit.

I'm worried that it will the performance of the scope. Not only that, I was looking to sell it a few months back although I ended up keeping it but I may look to sell it again in the future & this will probably put buyers off.

I've included a pic which hopefully shows the problem along with an image of M42 I took the after this had happened to see if it has affected things but I'm not sure if it has or not.

If anyone could give their opinion as whether I need to recoat or not.

As an aside, I received a reply from WO last night saying that the lens can't be recoated but I'd like a second opinion on this before deciding what to do.

Jeff

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HD-AP

HD-AP

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Hi jeff

I've had simular problems in the past with objective coatings .The problem may be no problem at all unless you have damaged the objective's coatings .

Cleaning with acetone which is a very strong pure solvent will leach impurities from wipes q tips paper towels etc and leave a white slightly opaque residue on the objective surface .

 It adds to and alters the reflective wavefront ,hence you can see it.

I corresponded with roland christian of astrophysics  on this and he said that although objectionable to look at the smearing on the objective front surface would have no impact on the image quality of the objective . Agreed it might put off a prospective buyer though.

I would suggest a careful clean using baader optical wonder fluid .If this dosen't remove the residue ,you need a very clean residue free wipe like opto wipes these can be used with acetone and leave no residue .

Also whilst some objective coatings can be removed  ,most cannot as they fuse with the optical surface and the objective has to be refiguired and then recoated ,making it uneconomical to repair as a new objective could be bought for the same price or less.

hope this helps ,p m  me if you want a detailed  description of the cleaning process.

kind regards

clive

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Astronut1982

Astronut1982

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Hi Clive,

Thanks for the advice, I will give the optical wonder fluid a go & see how I get on.

That sounds promising on the performance front as well, hopefully it isn't going to affect anything after all. I also remembered that the evening I took that image there, was lots of high haze I was imaging through which has probably affected image & may explain why it isn't as sharp as I would like.

Jeff

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ronin

ronin

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Acetone is a bit strong but I doubt it will dissolve the AR coating.

Actually when cleaning any glass it is not cleaning it that I find the problem but removing the smears/residue afterwards. Generally find I can clean the surface in 2 minutes then spend the next 10 getting rid of what the cleaning process leaves as "smears". You will put more effort and time into the smear removal.

I suspect a slightly damp cotton wool bud (OK 10 of them) and you simply sit there going over it getting rid of the surface smears. I use IPA on the optics. Acetone gets used for cleaning rods for rod building.

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Astronut1982

Astronut1982

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I wasn't using anything on the lens apart from one of those blower things for cameras. I was just trying to blow the bits of dust & what I assume were hairs from the objective as I'm still getting little artifacts even though I have a Gerd Neumann flat panel & can get good flats.

The acetone was for my CCD chip, I just spilt the bottle with an improperly tightened lid onto it. Was still pretty stupid though!

Thanks for the tip ronin, I'll try the IPA first as I think I actually have some already.

Jeff

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Astronut1982

Astronut1982

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Just wanted to say thanks to those who offered advice on how to clean my objective.

It would appear that you were correct Clive & the coating itself hadn't been affected, the acetone had with whatever I used to soak it up had caused the smearing. I used IPA as suggested by ronin & this has left the lens spotless.

Thanks very much guys, I was thinking I had really messed up until you offered some great advice.

Jeff

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Astronut1982

Astronut1982

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Thanks, that link does put my mind at ease.

I was very worried that I'd damaged the coating so I'm delighted that it hasn't been as bad as I'd thought.

I'll be keeping the bottle of acetone well away from it in future though, just to be certain!!

Jeff

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Dave In Vermont

Dave In Vermont

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Some advice from Dave the Chemist:

In basic laboratory-safety-protocols, you are trained to always keep the cap of a jar or bottle in your hand - preferably the same hand you are using to hold the jar/bottle. You never put it down so you are ready to securely replace it on the container immediately following use.

Practice makes perfect,

Dave

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mikeDnight

mikeDnight

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I've cleaned many an objective lenses including my FS 128 & FS 152 which both have their fluorite elements at the front. I always used isopropil alcohol and lenses cleaning tissues and every time, not that I did it that often, the lenses would streak. It usually took a good few minutes to eliminate the streaking, but at no time was there ever any damage to the coatings.

Don't lose sleep over it at this stage, there's probably nothing wrong with the coatings, they are seriously tough. Only don't use cotton wool balls as these can contain contaminants that may scratch the coating. Lenses tissues are purpose made and are pure. Most camera shops will stock them along with the isopropil.

Mike :-)

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