Marks on eyepiece

[jason.p]

I noticed these marks on the inside of the lens some time ago. I think its getting worse (can't be sure). Is the coating corroding?

I'm not sure what this ep is, I think it was described as a planetary TMB but find it a bit disappointing for getting more detail out of DSOs, perhaps I'm expecting too much. What would be a reasonable alternative. My other eps are the 26mm Meade 5000 and GSO 32mm (and a 2x Barlow).

Thanks

Jason

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[sologuitarist61]

Looks very much like an old camera lens of mine which has fungus growing on the inner surface; usually happens when eyepieces aren't dried enough for storage. It tends to start in numerous small areas and then grow bigger. If it is fungus infection it tends to mar the inner lens surface as well. With camera lenses there isn't much you can do about it but whether that is the same with eyepieces which are easier to take apart, I have no idea.

I hope that I am wrong!

[paulastro]

Are you certain the marks are on the inside of the eyepiece?  They look like drying/dew marks to me.  You'd have to keep an eyepiece in fairly damp conditions for a long time to get fungus on the inside I'd have thought.

[NGC 1502]

Hi Jason.  I could be wrong as it's difficult to diagnose from a pic, but that could be greasy residue on the outer lens surface.

I'd try a careful clean myself. Before starting, make sure there's no grit on the lens that could cause scratches. I use isopropyl alcohol (from a good chemist) and a freshly washed & dried microfibre cloth (photo suppliers).   Many use the Baader Wonder Fluid cleaning kit.

Put a small amount of fluid on the cloth, don't pour the fluid on the lens, it could seep inside and cause further problems.  Go slowly and carefully. You may need more than one try, using a fresh area of cloth.

Edit - link to Baader Wonder Fluid - http://www.firstlightoptics.com/misc/baader-optical-wonder-fluid.html

Hope you sort it, Ed.

[jason.p]

Oh, this is so embarassing:rolleyes: You are dead right. I had convinced myself the marks were inside, so didn't even try cleaning!! Dug out the Baader fluid and cloth and all sorted. Thanks for replies and sorry to have wasted your time:mellow:

(Just another one of those senior moments which are becoming all too frequent now!)

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[NGC 1502]

No need to be embarassed, I've been there done that (senior moment) and am certain to do a repeat performance 

Glad you're sorted, Ed.

[Moonshane]

I was about to agree with Ed that it was grease. too late again!