Are simple colour filters all alike?

[Ben Ritchie]

I'm looking to pick up Wratten #47 and #58 filters in 1.25" format, ideally as cheaply as possible. Visual use only, so IR leak isn't an issue.

Looking around on ebay I see there's a fair range of prices, from no-name generics at a few quid to Meade and Lumicon filters at £20+. Anyone know if there's a significant difference or if they are all much the same? With dichroic interference filters you seem to get what you pay for, but I don't know if that's still true for basic coloured filters.

edit: apologies, I meant to post this in eyepieces not scopes/whole setups, could a mod kindly move? thanks

[alan potts]

I have in the past used a good many colour filters with varios cameras and I have used very expensive 'Lee' ones and many cheaper. I can't say that I ever noticed any differences. The only time that I guess you would get a difference is with the RGB filter used in Mono CCD work there will be quality difference in the transmission and colour of these will be carefully controlled. For normal light blue filter on Jupiter or yellow for that matter I don't really see any problems as to which you buy, TS do a fair selection.

Alan

[great_bear]

I've noticed quite big differences for visual use.

The Lumicon ones are a step up from the generic ones. Better coatings and visibly sharper.

But other than a Deep Red (#29) as a moon filter, I don't see the point of colour filters for planets unless you've got a very big dob...

[Ben Ritchie]

Thanks - going to use them with a Herschel wedge, not for planetary. I've read that the #47 is useful for bringing out some details, while the #58 is the poor-man's alternative to the Baader solar continuum filter.

At a cost of a few quid each I don't mind picking them up to try out, but there's no sense if the cheap ones are intrinsically rubbish. On the other hand buying a brand-name #58 is a large fraction of the price of the Baader filter, so I might as well buy the real thing.

[hunterknox]

I used the cheapest Wratten 58 I could find with my Herschel prism and it did the job. I bought mine from Astronomica, along with a bunch of other colour filters to try. Some seemed to have condensation marks on when they arrived, which I presumed to be a result of the fact the boxes they came in were not 100% sealed. Not worth sending back but not ideal.

I've now got a Continuum, which came packaged with my 2" Herschel prism and it's a marginal improvement, but really there's not much in it.

[Astrobits]

If they are sold with Wratten filter numbers ( which using the numbers implies ) then they SHOULD have the same colour transmission as the Wratten specs. However, there is always the possibility that there are differences in the flatness, wedge and coatings of the glass which leads to the price differences, and optical performance as noted by GREAT_BEAR above.

Nigel

[rwilkey]

I have a preference for the Lumicon ones, the cells are much better engineered, but have to admit, I don't see much difference in how the glass performs.