Filters???? what are they????

[EzyStyles]

I'm struggling to know what different type of filters do to different objects?? still a newbie. IR Filter is for? UV Filter is for? etc etc..

I keep noticing that many people uses the baad filter?

What filter is use for neb? galaxies? what are the effects and does it really make a huge difference when imaging? :shrug: :shrug:

Currently i'm using the Meade DSI for imaging. Should I take the IR Filter off all the time or just leave it? Many thanks all.

[Starcrazzy]

Hi ezy,
Must be a tricky question, no-one wants to play.. :shrug: .I'm not right up on them either but i do have a nebula filter which specifically targets the light emmited from street lights and general light pollution, if you live in a light polluted area i'd sy get one of them for a start...i took the ir filter out of my dsi, havn't put it back in yet i was working off the assumtion that a filter of any type would block stuff out and while i was learning to use the dsi i wanted to see as much as possible, i will put it back in soon mabye amd see the differance...sorry i can't help you more...surprised none of the guns are responding...awelll.
ps..:help:.What method did you use to drift allign your scope??i am still trying to get mine alligned...grrrllll.
ch

[ving]

baader? = brand name (apparently a pretty good one at that)

on the aoe website they have a description of what various filters do, try this link: http://www.aoe.com.au/filters.html
:)

[janoskiss]

Narrow bandpass nebula filters are the only ones that will do anything spectacular for astrophotography. Not much will help with galaxies AFAIK. A general purpose nebula filter like the DGM NPB (you can order from dgmoptics.com) is where I'd start. Baader/Lumicon UHCs will do a similar job (so I've read) and you can buy them locally. Then later on, if you want to get serious with nebula photography you might invest in filters aimed at emission lines of specific elements. This way in one shot you can image oxygen, in another hydrogen, for example. Theoretically you could even distinguish between different states of ionisation, but I'm not sure if that is something amateur equipment can do...

IR = infra-red. Whether you need it or not depends on camera + filter characteristics (the infra-red spectrum is very broad compared with visible). Try without and see what happens.

Grain of salt: the only bit of astrophotography I've ever done is stick a film SLR on a tripod and point it at the Moon.

[Robert_T]

I know very little about filters except for their use in planetary imaging and even then not much. For colour webcam imaging of planets (as you might do even with your DSI) an IR/UV blocking filter is useful it blocks the longer red and shorter blue wavelengths of light that might "smear" your image a little as they arrive from the same feature at your CCD sensor slightly offset from each other. Baader as Ving points out is a brand name and they make a version on this filter (I use this one). The usefulness of this seems to depend on the basic colouration of the planet you're imaging too such that for example this filter is more useful/essential on say red Mars than on Jupiter or Saturn.

cheers,

[Starkler]

There is a big difference between filters for visual use vs photography.

Many in light polluted skies swear by using a broadband filter for photos, whilst their benefit in visual use is marginal. This is the only one you should be using to photograph galaxies.

[EzyStyles]

Thanks Starcrazzy. What brand/type of filter are you using? does it make a difference in light poulluted subbie area? i'm situated around very bring suburbian lights 30 minutes drive to melb city. Sometimes i wish im in the country.

I don't drift align my scope at all. no need i figured out. Think because i have a fast scope F/4 so therefore less exposure time. I just do a very accurate polar alignment matching up the octan's region from the polar scope.

[EzyStyles]

Thanks for the link Ving. It really helped me out. Exactly what im looking for :thumbsup:



Thanks for your reply Steve. Took the IR Filter out (as seen in my Centarus A post). doesn't really do that much actually.

[EzyStyles]

Thanks Rob. I tried imaging planets with the DSI but no go. so i guess the IR Filter is mainly used for planets?



Thanks starkler! nowdays, i don't really do any visual stuff. rather see it in an image instead, much bigger and clearer :P might get myself a broadband filter :)

[Robert_T]

yeh ezi, I reckon the IR filter is primarily used for planets.

cheers,

[sheeny]

G'Day again Ezy,

A couple of links that you may get some info from as well...

http://www.astro-tom.com/download/filters.pdf

http://www.sas.org.au/filters.htm

Al.