Valuation and evaluation of these filters.

[ketans]

Shri Swami Samartha

Hi friends, scholars and starry eyes,

Can you do me some help? For a Omni XLT 102 achromat refractor, here is a list of filters-

A) Baader Planetarium - UHC-S Filter

Baader Planetarium - UV-IR Blocking Filter

C) Baader Planetarium - Solar Continuum Filter

D) Baader Planetarium - Polarization Filter for Herschel Wedge

E) Baader Planetarium - O-III Nebula Filter

F) Baader Planetarium - IR-Pass 670nm Filter

G) Baader Planetarium - Contrast Booster Filter

Neutral density and some color filters are not much to talk about.

For all around object near or far, if I want to do viewing and imaging: Please someone tell me-

1) Which of these filters serve same purpose, so that I can eleminate the other from buying? for e.g. Are filter A & G the same?

2) Which of these filters do double work? means any one filter, listed or not listed here, may do the work of two?.. so that I can save money? for e.g. Does C do the work of D also? or Will D solve both purposes?

3) Which of these filters is of less use, or almost useless?

4) I see so many 1.25" color filter sets for very much low cost. Are they all good? Celestron, OPT, Owl, Meade. Any recommendation?

5) I have read the theoretically analyzed articles, but still practically couldn't make out any sharp choices for buying. I want to understand through latest personal use of the astronomer friends. So please tell me which filter will be unnecessary for buying.

see you soon, good wishes, sincerely Ketan.

Shri Swami Samartha

[John]

Hi,

I have not used all the filters you list but I have used the Baader UHC-S and OIII filters. The UHC-S is a very useful filter and works well in smaller aperture scopes. I have found it valuable for enhancing the views of objects such as the Veil, Ring, Dumbell and Owl nebulae - in some cases making them visable in an 80mm scope which otherwise could not pick them out. In my view the UHC-S is mre effective than a standard broadband filter such as an Orion Skyglow.

The OIII filter is even more effective at making the nebulae stand out but, because it's transmitted bandwidth is narrower than the UHC-S, I found that you needed a larger aperture scope to really make use of it (say 15 cm and up). In smaller scopes the surrounding stars almost vanish which, for me at any rate, was less satisfactory.

I hope that helps.

John

[davieradio]

If I had only one filter it would be the Baader UHC-S and thats the one I have .It cuts down sodium lighting as well and it does not dim faint stars too much .

it makes the sky darker It is an all rounder The narrower the filter the more light you will lose and a bigger appature scope is needed to overcome this.

remember all filters will give you a caste the UHC-S has a blue caste ,

Dave

[ketans]

Hallo,

Thank you Dave and John.

UHC-S filter is sure, thanks. Dave did you mean the OIII will do less for 4" refractor? Can you tell me any narrow filter limits for a 4" refractor with StarBright XLT coating?

What about the low cost color & neutral density filter sets? Will they perform well? Or do I need Baader or any higher?

Anyone experienced with the other speciality filters?

Good wishes, see you, Ketan.

[ketans]

hmm,

Ok anyway I got answer thanks.

But does the 1.25" and 2" filter format makes a difference in light gathering? So if I am thinking to buy a filter for 4" achromat(f9.8), should I consider 2" size filter, once and for all? (2" after up gradation, not talking about the 1.25" stocked accessories that comes along with it)

see you, sincerely Ketan.

[John]

On the OIII filter, IMHO it will not work too well in a 4inch refractor. There are no limits as such it's just that you really need more aperture to be able to afford the light loss that the OIII filter delivers.

With regards to filter size, I would invest in a 2 inch diagonal and then you can use a 2 inch filter on the diagonal so that when you change eyepieces you don't need to mess about moving the filter from one to another. If you are atrying with 1.25 inch accessories (including the diagonal) then the 1.25 inch filters work fine.

There is loads of information on the web regarding filters and their benefits or otherwise - try the Cloudynights site reviews section for a start.

John