FILTER KITS

[Darthdad8409]

I am wanting to build up a small filter kit of 4 or 5 filters. I already have a lunar filter. I am thinking about getting a 82a light blue filter. My scope is only 90mm appature with a focal ratio of about 1400 mm. Is there even a point to getting an more filters or should I wait until I have a larger scope?

[Darthdad8409]

Sorry the focal length of my scope is 1250 not 1400 if the makes a difference

[ronin]

After 12 years I still cannot find a reason to buy a filter, certainly not a straight forward coloured one. An IR or OIII maybe one day. Just cannot think of a use for a light blue, or any other, coloured filter.

Now I expect others to leap forth and suggest a yellow one in preference to a blue one, or similar.

[LukeSkywatcher]

I have in the past used coloured filters with a 90mm scope and have to say that i found them useless (i gave them away). I am led to believe that they work better on larger scopes. Moon filters are really a bit of a waste of money. They work, but really only when the Moon is full..............which is the wrong time to observe the Moon as there is little to no contrast to allow you see features like shadows in craters etc. 

I do have and use a light pollution filter, but in my new house, i dont think i need it as my skies are much darker then before. I also have an OIII and a UHC filter which really work well on different types of nebulae. 

P.S.~~~in big scopes, different colour filters work on different planets. Yellow for Saturn and Jupiter, Red for Mars (i think). I cant remember what a light blue one works with..............probably Neptune and Uranus, which in a 90mm scope will just look like stars anyway.

If they do work best on larger scopes as people report, it may be best to wait til you have a larger scope.

[Stu]

This link has some useful information about which filters work for which applications.

I've never really used coloured filters but plenty of people of find a benefit with them.

http://agenaastro.com/choosing-a-color-planetary-filter.html

For me, the most useful ones are as follows:

Baader Neodymium - good general purpose filter which works well on Jupiter, Mars and the Moon.

Outside this, a UHC and or OIII work very well for emission nebulae such as the Veil or objects like M27 and M57. I think for a smaller scope, a UHC might be best and I do find they work best when under darker skies with good dark adaptation.

Ultimately it does depend what you like observing and what your skies are like.

Stu

[Charic]

There are various links on the internet explaining how the Wratten numbering system works regarding filters, which is now a standard.  I've used filters in the past when I developed and printed my own pictures. I mainly used FP4 35mm format and still love Black & White photography. I also used filters to enhance and trick the final image for special/macro and when using Ektachrome slide film. We didn't have Photoshop that far back? 

Because of the way in which filters work, some will actually fair better with telescopes that have a better grasp of the light, i.e.  bigger apertures/objectives.

I have one filter at present, Its a cheapish Moon/LP filter, and to be honest not certain if it works that well( still needs further assessment) Normally when viewing the Moon, I often replace the aperture cap or wear sunglasses, or even view the moon through light cloud?  Viewing the Moon at high magnifications does mess up my pupils for a while, although no lasting damage is done. If you purchase any filters, I would suggest that you buy metal framed filters. Its possible to cross-thread plastic framed filters in the dark. Also, one filter = one eyepiece, unless you buy a filter tray, that fits in the focuser, so that you can 'Dial in' the required filter.

I wouldn't just go out and buy a complete full set, until you have tried one or two first. If they work for your eyes, then fine get some more, but if they don't, then heed that advice, and save your money. Finally, I've had a terrific view of Jupiter's, Io (Eye-Oh!) Moon transit. The conditions were just perfect that night.The Moons shadow was sharp as a tack, yet I still find it hard to see Jupiter's GRS (Great Red Spot). Three reasons I suppose for me. 1, its not a true dark red spot, more like the red,orange and browns its mixed with. 2.My eyes have compound myopic astigmatism, and lastly the size of Jupiter in my 8" telescope isn't enormous, so image scale could be increased by using a bigger telescope, which may help the older eyes see a bit better, which may discern a little more detail between reds and browns, but I'm not colour blind. So with all that aside, there maybe one or two filters that could help me, but it will be a personal choice, and what suits me, may not suit you.

[rwilkey]

Filters have different applications, in my opinion if you are just starting out, stay clear of them, cetainly wouldn't buy a filter kit to start off with.  When buying filters you need to target them at specific objects, so until you know what your preferences are it is better not to spend the money yet as it will be a waste of time.  Preferences include planetary/Moon/nebulae and so on, there are specific filters for specific types of objects.  Colour filters have never been of any use to me, they just colour up the whole image and diminish certain aspects of the object whilst enhancing others.  A good all-round filter if you want to try one is the Baader Neodymium Moon & Skyglow filter.

[Darthdad8409]

I decided to stay away from filters for a bit. I'd like to get into imagining. Particularly DSO and planetary imagining but I don't know how well my scope can resolve DSO objects yet. Once I figure that out, I will take a second look at filters.

[Dave In Vermont]

I will assume that your scope is an achromat - 2 lenses up front - which gives you an F/13.9-ish scope. Not fast enough for chromatic-aberration (CA) to come into play. If it were a faster (say about F/8 or faster) I'd suggest a Baader Fringe Killer filter to cut off the blue-purple halo effect on bright objects. So with a 90mm refractor the only filter I would suggest is a variable-polarizing filter for use on the Moon and other very bright targets - like Venus. A variable-polarizing filter consists of two separate filter-cells. Depending on how you orient them to each other, they will dim your target from between being 40% as bright, down to 3% as bright. Your Moon filter that came with the scope, no doubt, dims by 13% usually.

I am a certified filter-nut.

Clear & Dark Skies,

Dave