[Aavso-photometry] Where do the professionals source

[Bill Goff]

Bob and Michael,
Yes, I checked mine as well after reading this, no crud at all, but now 
that I've looked it will probably appear tomorrow ;-).  Mine are also 
about 4-5 years old.

Like Bob, we have a dry climate during the hot months, tho the winters 
are be wet.

Bill


On Sep 23, 2005, at 6:50 PM, Bob Koff wrote:

> FWIW, I have had the same Schuler B and V filters for four or five 
> years, with no sign of any gunk.  I'm in the Denver area, with a 
> generally dry climate but large extremes of temperature.
> Bob Koff
>
> Michael Koppelman wrote:
>
>> This is, of course, not practical for a working observatory. I touch  
>> my CCD/focus as little as possible. I'm certainly not going to  
>> unmount the CCD every night. Given that this seems to be a reality it 
>>  sounds like I have to treat my V filter as a consumable resource and 
>>  just buy a new one every few years.
>>