uhc vs olll

[gedmac]

in medium light pollution using a 200p dob which is likely to give the best all round value?i want to look at nebulae and dso,s from my backyard and cancel out the usual street light/neighbour secutity light problem as best possible.i appreciate one filter doesnt do all just looking to decide which to buy first:rolleyes:

[Peter Drew]

I think the UHC might be the best overall filter for your circumstances. As far as I know, the O111 is rather more specific.

[pvaz]

Both of this (OIII,UHC) are not light pollution filters. They are specific for Nebula only and galaxies/clusters will be much dimmer with them.

If your problem is light pollution and you want to look at any DSO then you need a broadband LP filter such as this:

Light Pollution Reduction

I don't know how effective they are as I never used one.

If the stray light is really bad, you should use a dew shield (can be home made) to act as a light shield as well. This will increase contrast.

Another indispensable item for me is a black cloth. I got a couple of street lights near my front yard where the south horizon is visible. Without the cloth it's impossible to let my eyes adapt enough to notice planetary details such as the great red spot. I use it over my head and press it against my left eye so I can observe with both eyes open, instead of squinting.

[johnh]

What Paulo says is right the UHC is for nebula views and the OIII is for planetary nebula view, the CLS is for light pollution but first use a dew shield and use eyepieces with eyecup shields and even an eyepatch over your eye will help and putting your head under a towel is worth a try first then go for the CLS filter by Astronomik.

John.

[Doc]

I also use a piece of black out fabric about 1 metre square. For those elusive galaxies or planetaries it really helps to keep you dark adapted.

As for filters, I would go for the UHC first. The UHC will be useful on many more objects then the O111.

[John]

I agree with the other posters, get a UHC first. The contrast improvement will be seen on nebulae and planetary nebulae and super nova remnants in particular. Galaxies and clusters will not benefit - dark skies are the key to getting better views of those !.

[Martin-Devon]

For light pollution I use the Baader Neodymium filter and for nebulae I use the Baader UHC-S filter - both are available in 1.25" and 2" sizes and both are excellent filters.

[gedmac]

many thanks for the replies,looking to make a dew shield and also the black cloth idea:pwill see the effect and then decide on filters cheers guys

[Adrian]

Sorry to hijack a little, but...

The streetlights in my area were recently changed from orange sodium lights to a much whiter light (High pressure sodium?) Will a light pollution filter still be effective or will the different wavelength cause problems?

I ask because the new light is also between the houses, so shines into my back garden, and doesn't switch off overnight The old one was behind my house and the whole area shut off from midnight anyway.

[sixela]

Sorry to hijack a little, but...

The streetlights in my area were recently changed from orange sodium lights to a much whiter light (High pressure sodium?) Will a light pollution filter still be effective or will the different wavelength cause problems?

The light is whiter through absorption of the photons in the main sodium line and emittance of other photons. Sadly, one of the "new" secondary bands is smack bang over the secondary OIII line, so while the filters will still make the sky background darker, those lamps are a lot nastier to objects with an UHC or OIII filter than the low pressure sodium lamps.

In other words, you'll need what is called a "fuel filter".

[Adrian]

Thanks Sixela, I guess I'll have to venture up the hill with my scope, or set up some sort of shade.

I'm going to contact the local council about going back to switching off during the early hours anyway