Filters: Baader vs. Celestron?

[andrei23]

Does anyone have any experience comparing a Celestron UHC/LPR filter against a Baader UHC-S? Reading the descriptions they are very similar (makes you wonder if the same Chinese factory makes both) - 97% transmission, 99% across the H-Alpha band at 656nm, and a moderate 60nm passband overall.

I guess any difference (if there is one) would be in the quality of the coatings and reflection absorption, which is why I would love the input of anyone with some experiencing either viewing or photographing through these. (My main application would be CCD imaging of nebular and other DSOs using a10" reflector in fairly dark rural skies.)

Also, while I'm at it... in addition to getting a 1.25" version for my DSI II, should I also spring for a 2" version for viewing in my nice 82 FOV EPs, or will it not make that much difference given the "exposure time" of the human eye?

[andrei23]

Astronomik? Lumicon? TV? Seems the Astronomik passes all 3 critical bands at 100% (96% for H-Alpha), and is water-tight to prevent humidity and age distortion. Worth spending a little extra? It says "for viewing", though - Baader makes separate viewing and CCD versions - or is that just marketing hype (for this kind of filter, I know it makes a difference in RGB photography due to the narrower band). Thanks!

[j.gardavsky]

Does anyone have any experience comparing a Celestron UHC/LPR filter against a Baader UHC-S? Reading the descriptions they are very similar (makes you wonder if the same Chinese factory makes both) - 97% transmission, 99% across the H-Alpha band at 656nm, and a moderate 60nm passband overall.

I guess any difference (if there is one) would be in the quality of the coatings and reflection absorption, which is why I would love the input of anyone with some experiencing either viewing or photographing through these. (My main application would be CCD imaging of nebular and other DSOs using a10" reflector in fairly dark rural skies.)

Also, while I'm at it... in addition to getting a 1.25" version for my DSI II, should I also spring for a 2" version for viewing in my nice 82 FOV EPs, or will it not make that much difference given the "exposure time" of the human eye?

Hello Andrei 23,

I have some filters from Baader, they are on polished substrate, most of the other filters (China) are on flame-"polished" glass.

The UHC-S has got very broad bands, good for the astrophotography, but I do not use this filter frequently for the visual observation.

Baader is well known for its OIII 8.5nm filter (one of the best on the market) and for the RGB interference filters - all the premium make. The blue(RGB) covers 400nm up to 510nm with a very high transmission.

Another filter made in Germany is the Astronomik. Their UHC is possibly the best filter on the market, and their H-Beta profi can be used on bright nebulas with as small as 6" apertures. The company is run by Gerd Neumann, the inventor of their special technology.

Regarding the "CCD" - those filters have some extra layers to cut the wavelength above 660nm.

The basic difference of the German filters from the others cheap ones on the market is, they do not have spurious transmission bands outside their specification. They are hard coated, and most of them free from the deposition of dew. You can stack the Baader blue(RGB) with the Astronomik UHC to obtain a band-pass H-Beta through OIII, resulting into an excellent visual filter. (The H-Alpha does not contribute to the visual observation unless you have a very large sized scope)

Check out also Astrodon (USA), run by Don Goldman, a guy who understands very much of filters. They have extreme narrow-band (line) filters down to 3nm, and balanced for the SII/H-Alpha/OII astrophotography. I have the OIII 5nm filter for visual observation - it is excellent.

In the past I have spent money on the cheaper filters, but forget it, all are gone.

Hoping to have helped you

JG

[andrei23]

Vielen Dank, Herr Gardavsky!

I am so glad I asked - you see I almost did it in the opposite order (Astronomik for astrophotography, Baader for viewing)

This forum is an amazing resource, and in my short time here I have already made a rule not to go "shopping" until seeking the advice of the more experienced members.

Something I am unclear on with SII/H-Alpha/OIII photography is if it is meant to be a more precise way of doing RGB with a monochrome camera, or stacked on a one-shot instead of the UHC? In other words, if I am using the Baader B and Astronomik UHC for viewing, and the Baader UHC for my photography, under which circumstances would I need to switch to the SII/H-Alpha/OIII? (I use a 10"/254mm scope.) Seems in the viewing comparison in the article the author preferred UHC over OIII in most cases. And is H-Beta really needed considering what we have above?

A couple more related questions, if I may...

For CCD imaging, do I still need a separate IR reducer if using the Baader UHC-S? And if so, would you recommend Baader's here as well?

I am also looking at Baader's Semi APO (combines SkyGlow and Fringe Killer plus IR into one) as a general all-around planet/moon viewer (for sharing my scope at star parties), maybe the occasional photo (though I'm more of a DSO guy). Is this a sensible choice?

Who makes a good polarizing/variable moon filter? I was looking at Antares, but am leary now that thanks to your explanation I understand where the money is saved in Chinese optics.

I cannot thank you enough for sharing your experience!

[j.gardavsky]

Hello Andrei,

my experience with filters is in visual astronomy, unfortunately not in astrophotography. I'd suggest, contact directly Don Goldman, he is very helpful. I have had lots of e-mails with him, before purchasing his filter. He can best explain the filter issue for the high end astrophotograpy, and he has a very nice gallery. Find a link below and do not hesitate to contact him,

Don Goldman, Ph.D.
Astrodon Imaging
Orangevale, CA 95662 (USA)
Astrodon Astronomy Filters - Home (commercial site)
Astrodon Imaging - Home (personal astro image gallery)
skype astrodonrgb

As far as I understand the SII/H-Alpha/OIII photography, it is a false color photography, yielding nearly the Hubble-like pics on lots of the galactic nebulas, like those in the Don's gallery.

However, most of people shoot RGB-filtered pics plus a pic in H-Alpha, and combine them later on the PC. This way works excellent on the galactic nebulas, whenever there are some reflection and dark clouds. It is also the preferable way to take pics of the galaxies. Regarding the RGB, I'd prefer the Baader filters on reasons as explained in the post before.

I have no experience with the Moon polarizing filter, I'll ramp up the magnification to reduce the brightness, or take a color filter.

Regarding myself, I am still taking pics the classical way on the Kodak slide film Ektachrome E200, and enjoy the starry night slide show on the wall of my home. In fact no filter is needed, or I take the B+W Neodymium Redhancer to enhance the cherry-like nebulas. Checkout my pic of the North America Nebula NGC7000 in "your favourite image 2010"

Your favourite image of the 2010

Hoping to have helped you, und viel Erfolg

JG

[andrei23]

Thank you so much... this has been really helpful. I was stuck on spending so much money on a (2") RGB filter set just to use the Blue for visual observation (with the Astronomik) - I wish they sold them separately! (I did some looking, and no one offers anything with nearly the transmission in just those bandwidths.)

I am still torn on whether I will eventually go LRGB vs. SII/H-Alpha/OIII for photography once I get enough practice to justify the "big" expense. Right now I am only doing one-shot 1.25" (hence my interest in the Baader UHC).

Looking at their spectral analysis (of the Baader UHC), if I am reading it right it seems no separate IR reducer is needed?

Really appreciate all your advice, Herr Gardavsky. Your photo is amazing, and I really like the idea of astro slide shows - thanks!

[Vali x]

i wanna thank both of you guys for the huge quantity of info !

[andrei23]

A pleasure... I'm learning too!

Hey, nice scope.

[Vali x]

thanks ! now makes sense what info i will use from your post ! )

[DMouse]

Hey Guys,
I have both the Baader Moon & Skyglow and the Baader UHC-S. The Moon & Skyglow is also an IR cut filter and I mostly use this one. The images look dark pink/purple on longish exposures, ie 3mins. I tried the UHC-S and upped the exposure time to 7min!!! The background came out a deep blue/green. I am thinking that the UHC-S is too harsh in the reds, for my liking and feel the Moon & Skyglow gives a better balance.
All this again depends on what you are trying to achieve, better reds or better light pollution removal? Its gonna come down to where you are imaging from and what you are actually imaging.

Just my 2 cents worth, still very much a newbie

Clear skies