Filter help

[alan potts]

Sorry for asking this as I am sure it is on site somewhere.

I have just gone after an Astronomik 2 inch O 3 filter, which I wanted in any case.

What filter is the best to view DSO, E.G. to help M33 stand out. I do not have any light polution (sorry to rub noses)

Alan.

[Stu]

Unfortunately I don't think there is anything which will help with M33 other than dark skies, more aperture, low magnification and good dark adaptation.

Any of the filters just cut down to specific wavelengths, and given that M33 is a galaxy they will only make it dimmer I think.

M33 is really low surface brightness so a wide field and dark skies help. My best views have been with binos at a dark site.

Stu

[swamp thing]

Your O-III filter can help with M33, not for the galaxy itself but for the large H11 regions contained within.

M33 is one of the galaxies that shows pretty bright extragalactic nebulae. I've often used mine on this object and it does indeed drag some nebs out check this map out (cheers Acey)

[alan potts]

Steve,

I was just picking M33 at random, I though there was a filter that helped with DSO in general, I know it is not a CLS filter that is for street lamps but something made me believe there was another.

Alan.

[Naemeth]

How about a UHC and a H-Beta filter? They both should be fine on their respective targets.

http://www.cloudynights.com/item.php?item_id=1520

[Plantins]

The views from a dark site of the Veil Nebula through a nice refractor and a good OIII filter is worth the price of the filter alone.

[swamp thing]

Oh! Sorry.

In that case. Not that I know of. Globs, stars and galaxies transmit light from right accross the spectrum. Filter any light and you filter them too.

Nebulae are the only DSO's that can be successfully filtered as far as I know.

[alan potts]

Steve ,

Maybe it is me that has it wrong, I tend to agree with what you say. It must have been some type of nebular filter but it was not the O3 filter and I don't thing it was the H Alpha.

It may have been an UHC filter, I tried a SW once and wasn't over impressed, seemed to make everything deep blue.

Can't you tell I have run out of eyepieces to buy.

Alan.

[Stu]

There are sky glow and Ultrablock filters which take out sodium street light frequencies so may help, but in your case you don't have LP so probably not.

One thing is that you can't generalise DSOs as such because the are different beasts. Some are emission nebulae which you can target with specific filters, some are reflection, some galaxies and clusters. My understanding was that, in general, galaxies and clusters don't generally benefit from filters as they emit across the spectrum.

Stu

[alan potts]

Stu,

I have been skipping around the sites and I think I have my wires crossed somewhat. I believe I am getting mixed up with a type of UHC filter which Televue call a Nebustar but it is a type of UHC filter. I know that HA is for targets like the Horses Head Nebular.

I may well just settle with the O3 for the moment in that area and may just give one of these Mars filter by TV a go, I know we don't get to see it often but it always disappoints me, I have never seen it that well.

Thanks

Alan.

[Moonshane]

you might have seen this Alan http://www.cloudynights.com/item.php?item_id=1646

in general I'd agree though that no filter I have used will really work as you want it to.

[Moonshane]

my main Mars (and Jupiter/moon) filter is the Baader neodymium. it provides great increases in contrast and detail to my eyes at least

[Stu]

That cloudy nights link describes something similar to what I was referring to, a fairly broadband filter which targets taking out the mercury and sodium lighting if that is what affects your viewing. The Ultrablock is similar to a UHC and won't help as it cuts too much light.

I think H Beta is the one to try for the Horsehead Alan.

Stu

[Stu]

Btw, I agree that the Neodymium is very good on both Mars and Jupiter.

[Stargazer_00]

Bit late to the show but +1 for the Baader Neodynium. A good broadband filter to boost contrast.

Doubles up as a moon filter but who uses a filter on the moon, I want to feel my retina burn with those lucious photons!