views through 2 inch oIII filter with possible spores present.

[Robbos30 (Peter)]

I have had a 2 inch oIII nebular filter for about 6 years now and have only just recently noticed when held up to the light a ring of dried looking splotches on the filter.Is their anything to worry about in regards to the life of the filter and can these splotches be removed?When looking at the filter normally these splotches dont register until you look at say a bright light .Would this effect the quality of viewing?

[ballaratdragons (Ken)]

Best answer I can think of is: try it in the scope and find out.

[ausastronomer (John Bambury)]

Peter,

What make of filter is it? The reason this is important is that some filters are surface coated and some are "sandwich" filters, which are infinitely more durable.

CS-John B

[Robbos30 (Peter)]

Thanks for your responses,i have a Lumicon oIII filter.I had a look through it at Rons place last Saturday.I looked at Eta Carina through the Sdm 30 and I could not see any noticable degrading of the image.The extra light coming through may compensate to an extent perhapse?

[ausastronomer (John Bambury)]

Peter,

To the best of my knowledge the Lumicon is a "sandwich filter". In other words the filter material is sandwiched between two external layers of glass. You can clean it as you would normally clean an eyepiece. If the views are not affected, I wouldn't bother.

CS-John B