help with filters pls

[firefox]

This is a two part question,

Background info, I live in Builth wells, very close to the Brecon’s, so, I am not blest with complete dark skies, but there again it’s not a city. I am migrating to; two in filters the only 1.25 filters is the 7 colour set that seems to be the standard starter set. Once I gain the knowledge I will be attempting planetary as well as deep space photography, my cameras are Nikon D2X and the Celestron 1.25 webcam, and my scope is a Celestron cpc 9.25.

The first question is what other filters do I need, at the moment I have the following in 2 inch:

Optics UHC Filter, Variable Polarizing filter, Baader Contrast Booster, and a Baader narrowband oiii nebula filter 8nm hbw ( still learning when to use them) also can you combind filters

The second part is do i still need the colour filter set, as i have found them in 2 inch, Many thanks for your help

Clear sky’s

Dave (Firefox)

[Zul]

Don't know about other filters but light pollution filter isn't very helpful for visual observing. I live near city center so i bought LPR filter but i'am not happy with it.

[newman]

It's easy to get carried away with this, but no you really don't need the color filter set You already have an impressive collection of filters, your time would be best spent learning when to use each than getting anything else. If and when you decide you need a specific color filter, you can easily just get the one you need. Getting a full set would more than likely result in most, if not the entire set never being used.

UHC and OIII will be very useful on certain DSO's. UHC will probably get more use as there's a wider selection of targets that work best with it, but that's not to say OIII won't be useful on specific targets. The rest you'll need to test and see if an when they're useful. The contrast booster would make most sense if you had an achromatic refractor, not entirely sure if it will be of much use on your SCT. Maybe I'm wrong though, try it out on the Moon and the planets and see if it's useful. As far as I understand it it will eliminate a certain amount of CA on achromats. I suspect you'll find either the contrast booster or the variable polarizing filter as redundant. The variable polarizer might be useful on very bright targets, such as the moon or planets. You went a bit gung-ho on the filters there, best approach is to try things without, then see what you need and get one at a time.

Also, yes you can stack filters, but you need to know which combinations will produce desirable effects. Also bear in mind that a filter's function is somewhat opposite to that of a telescope; while the scope is designed to collect as much light as possible, the filter is designed to reduce the amount of light that gets to the eyepiece. Specific wavelengths, yes, but overdo it with filters and you'll just get too dim results to be useful. So be careful with stacking. Also, some filter names can be misleading. I can see how buying a "contrast booster" may seem like a great idea, but that filter will do very specific things, in specific situations, on specific telescope designs. Without understanding what a filter actually does, it's easy to get a piece of glass that will essentially be useless to you - the baader contrast booster will not boost contrast on all telescopes and on all targets! Always research and understand what a specific piece of equipment really does before buying..

Don't know about other filters but light pollution filter isn't very helpful for visual observing. I live near city center so i bought LPR filter but i'am not happy with it.

The "light pollution" filter is one of the most often misunderstood ones, thanks to the misleading name they gave it. They should have really called it a "nebula filter" or something like that instead.. anyway, this filter will make the sky a bit darker, which can be useful on enhancing contrast and visibility on faint targets such as nebulas. However, for it to be useful from a light polluted area, you'll need a scope with sufficient aperture. Even then, it can't replace dark skies - this filter darkens the sky background and makes a nebula stand out, so it will be just as useful on non-light polluted skies. I would call this filter completely useless on smaller aperture scopes, though - especially under light polluted skies. I suspect this is why you're unhappy with it, your scope doesn't collect nearly enough light for faint fuzzies, and the filter just cuts away too much to see any benefit. When you find yourself under really dark skies, locate a faint nebula that you can just barely see in your scope and try the filter again. Wouldn't bother with it from a city..

[jmdharkness]

Hi Newan,

You seem to know your stuff about these filters. I was just going to ask you a quick question, Ive been into photography for many years but am now trying to convert that over to astrophotography. I was looking at these LP filter (Nebula filters) to help get longer exposures in light polluted skies. I was looking at getting either the Astronomik CLS for eos cameras or the the UHC.

Both found here:

Astronomik CLS Filter

Astronomik UHC Filter

Im leaning towards the UHC as its the most highly recommended, but I was just looking for more experienced view on the matter. I know you recommended the UHC for visual observation and was just checking if the same held through for astrophotogrpahy ?

Thanks alot

[newman]

Unfortunately, I haven't dabbled in the dark arts of astrophotography so I don't feel comfortable handing out advice about that. I hope someone else with actual hands on experience might give you a proper advice though - I honestly don't know which to recommend

My experience with filters is limited. I have tested some, yes, but most of my knowledge about them is theoretical, gathered from books and discussions with others, more experienced members. I do tend to do extensive research on stuff that interests me, never relying just on forum discussions and always reading up on subject material written by experts. But that isn't exactly a substitute for hands on experience either, so I really can't honestly help you with filters for astrophoto. Sorry!