Baader Filters

[Yamez]

Hi everyone,

i was looking for narrow-band filters and i came across the Baader UHC and the Baader OIII. I was reading up about these filters and it says they're "stackable". I wasn't to sure what this meant so i came here to ask. Does this mean that you can physically put a filter on top of another filter and if so would it be advisable with these two filters (Baader UHC and the Baader OIII)?. My telescope is a Skywatcher 130p Synscan GoTo if anyone needs to know. Thanks

[cloudsweeper]

Stackable just means you can screw one into an eyepiece, and another into that first filter.  You might for example use a Baader Neodymium with a Moon filter.

Not sure what you'd gain by using both of these emission nebula filters.  The UHC (which I have) is I believe considered a good all-rounder.

Doug.

[Yamez]

Ok thanks for getting back, ive heard good things about both the UHC and the OIII i will try out stacking them, dont know what will happen but if nothing really happens then i will still have 2 good filters. There in my price range to!

[cloudsweeper]

Good plan - try things out and see what works and what you like.  (Without spending a fortune!)  Try them individually and together, although I doubt there'll be a huge difference.

Doug.

PS: For starting with filters, a Moon filter would perhaps be a more useful accessory.  A variable (polarising) version would be even better.

Edited May 16, 2016 by cloudsweeper

[Yamez]

When i purchased my telescope it came with a moon filter and i have also purchased an LPR filter for views on galaxies and overall to reduce the light pollution in my area. Annoyingly there is a mercury vapor street lamp right near my garden which never use to work but as soon as i got my scope they fixed it haha.

[cloudsweeper]

They should be sufficient for starters.  I'd think about nebula filters once you start to find your way round perhaps.  There are plenty of other interesting targets to try - clusters are quite easy, and very beautiful.  And you'll soon be wanting to extend your eyepiece collection!

Doug.

[Dave In Vermont]

UHC and OIII filters work by isolating various bands of light to bring out more detail in certain deep-sky objects like nebulae. Using both a UHC and a OIII together will cut out too much light and you'll likely wind up seeing very little. So this is inadvisable.

Here's a link to a good article by David Knisely on which filter works best for which objects:

http://www.prairieastronomyclub.org/resources/by-dave-knisely/filter-performance-comparisons-for-some-common-nebulae/

Have fun with filter. I have 36+ of them.

Dave

Edited May 16, 2016 by Dave In Vermont

[Yamez]

47 minutes ago, Dave In Vermont said:

UHC and OIII filters work by isolating various bands of light to bring out more detail in certain deep-sky objects like nebulae. Using both a UHC and a OIII together will cut out too much light and you'll likely wind up seeing very little. So this is inadvisable.

Here's a link to a good article by David Knisely on which filter works best for which objects:

http://www.prairieastronomyclub.org/resources/by-dave-knisely/filter-performance-comparisons-for-some-common-nebulae/

Have fun with filter. I have 36+ of them.

Dave

Thanks for the reply, funnily enough i read that article this morning on the train, was very interesting and this is why iv'e settled with the UHC and OII

[YKSE]

David's article is an excellent guide for for these nebula filters.

You can test to stack the filters, my prediction is that you would find it worse than using the OIII filter alone. This is how I see it:

UHC filters let through light in both OIII (496nm and 501nm) and H-beta (486nm), and blocks most light ouside 486nm-501nm range.

OIII filters let through light in only in OIII (496nm-501nm) range.

Therefore the stacking result will be light in OIII range with less tranmission because of light loss through the addtional UHC filter.