O III & UHC Filter ?????

[spaceboy]

Hi All

Reading through this months Sky at night 50 Deep sky wonders and came across recommending for OIII & UHC filters on some Nebula. Are they worth having? I have a celestron LPR which I have found helps with CCD imaging but can be a little over kill (darkens image) with visual. Would this be the case with OIII & UHC or are the a necessity if you want good views of DSO's. I will be in dark skie... will this make any difference?

Also what kind of prices are worth paying out as they seem to vary quite a lot considering they are supposed to do the same thing.

Thanks

SPACEBOY

[Moonshane]

hi mate

I have the Castell Oiii and for the price it's really good. it allowed me to see the Veil really well from my site near Manchester so cannot be too bad. they definitely darken the sky a lot (Oiii and UHC). the UHC is more general use that the Oiii and most people recommend getting that first. on the basis of the Oiii I have, I'd recommend the Castell UHC. at £48 for a 2" filter, it's worth it and allows you to see if it will be one that works for you. if you love it you could then pay more for eg an Astronomik but I am not sure how much better they'd be - I may be able to confirm soon as I might be able to compare the two directly.

http://stargazerslounge.com/equipment-reviews/108143-review-castell-2-oiii-filter.html

[spaceboy]

Thanks Shane

Curiosity again.... can the two be combined? as some times two colour filters can.

P.S good review of the Castell filter.

[MikeWilson]

I think if you combined the two you'd see nothing but OIII.

My understanding is that UHC allows OIII wavelengths through (in addition to a bunch of other wavelengths) and OIII only allows OIII wavelengths through. In other words, it's totally unnecessary to combine the filters.

I think I'm right, but maybe someone more knowledgeable will come along in a moment to correct me if needed?

[Moonshane]

I'm sure you are right Mike

these filters don't make things brighter, just other wavelengths they emit duller so that some elemnets stand out more.

[spaceboy]

I'm assuming they can both be used separately with web cams? Would it still be necessary to use the IR/UV filter?

[MikeWilson]

It's necessary to have an IR filter. It depends if your webcam already has one or not.

Although web cam + DSO isn't a particularly good mix since you can't (to my knowledge anyway) perform long exposures with webcams.

[mark7331]

I agree with Mike.

Filters let through "bands" of light. Some bands are "wide" like my Red, Green and Blue filters. Each of these wide bands let through tons of light(100s of nano meters). My Hydrogen Alpha (Ha) filter is "narrow" - it lets through just 7nm of light at 656nm (red). If I combined my Red and Ha all I would see is the 7nm of red at 656nm.

Some filters, like a LP or UHC filter, let through groups of "bands".

Combining filters just "selects" the light from the narrowest of bands being passed. So you should use a single filter of the narrowest band you want.

I hope that makes sense.

[Chris H]

Another filter worth looking at is the Orion Ultrablock it gets very good reviews Orion UltraBlock Narrowband Filter - SCS Astro and came out ahead of the Lumicon in S@N mag test last year.

[MikeWilson]

Hi Kris,

The Ultrablock is sold as 'not suitable for astrophotography', but I couldn't see an emissions line chart anywhere on the page.

I'm guessing that this doesn't block IR, but can't be sure.

Hopefully tonight I will have my first use of the Astronomik CLS-CCD filter. I'm really excited and looking forward to it!

Best,

Mike

[spaceboy]

Another filter worth looking at is the Orion Ultrablock it gets very good reviews Orion UltraBlock Narrowband Filter - SCS Astro and came out ahead of the Lumicon in S@N mag test last year.

how much? Little out of my budget. Decided to go with the SW UHC filter from scope and skies £36 delivered. When funds allow I will get the OIII filter also. (£39 delivered)

Thanks for all the info guys

[smulx]

Is there really that much difference between a UHC and OIII? Definitely worth buying both?

[MikeWilson]

My understanding is that UHC = OIII + Ha + Hb + SII + IR.

[spaceboy]

Well guys I can certainly vouch for the UHC filters. What an improvement it makes. I can't wait to get out to dark skies and really put it to the test. Think I will definitely be investing in a OIII filter.

Thanks for the Help

SPACEBOY