Light pollution filters

What are people's thoughts on the Orion Skyglow filter? Any good or
should I avoid? I want to reduce general light pollution to help find
objects like M33 rather than anything specific like an OIII filter.

Thanks.

Jim
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laws of right and wrong break down; beyond those metaphysical
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Hi Jim,

I've no experience specifically with the Orion Skyglow filter, but I do have
some general experience and advice.

I think the old adage, "there's no substitute for dark skies" always holds
true, but having said that, general LPR filters can make a small difference,
but often not as much as we would hope for.

My advice would be for you to join a local AS (if you're not already a
member of one), and try to "borrow" someone's LPR for a bit of observing and
see what you think. That way you could avoid spending the money and
regretting it later.

For galaxies, and remember M33 is difficult in many scopes visually, even
with dark skies, I've always tried to observe from a dark site and found
this makes much more difference than a LPR filter.

LPR filters I tried are the Baader Contrast booster (which is designed to
remove blue from achromats and air skyglow, along with some of the sodium
glow), and a SCT Neodymium (sp?) filter on a friends SCT. The Baader CB
filter does make the sky background slightly darker, so can help a little,
but only if the object is already slightly brighter than the sky. In
moderate Moonlight, or light pollution conditions, I could not see any
difference with faint galaxies. The SCT LPR filter did help with the Orion
nebula, but less so with galaxies, so I think it was designed as more of a
broadband nebula filter rather than a general LPR for stellar objects such
as galaxies and GCs.

The filter I use the most is my Astronomik UHC (obviously on Emission nebula
and planetary nebula only as this filter only lets through the 2 OIII lines
along with H alpha and beta), and I feel it was excellent value for money,
with the huge contrast boost and highlighting of detail it provides on these
specific types of objects.

Hope this is useful advice for you.


Best wishes and clear, dark skies.

--

/Paul B, York, UK.
http://homepages.tesco.net/paul.buglass/astrohome.htm





"Jim" wrote in message
m...
What are people's thoughts on the Orion Skyglow filter? Any good or
should I avoid? I want to reduce general light pollution to help find
objects like M33 rather than anything specific like an OIII filter.

Thanks.

Jim
--
AIM/iSight:JCAndrew2 - Log in and say 'hi'
"We deal in the moral equivalent of black holes, where the normal
laws of right and wrong break down; beyond those metaphysical
event horizons there exist ... special circumstances" - Use Of Weapons

Paul B wrote:
M33 is difficult in many scopes visually,

Indeed. It is one of several objects that can be a good deal easier in,
say, 10x50 binocs. In a small-ish telescope it sometimes only appears as
slight brightening of the sky.

Best,
Stephen

Remove footfrommouth to reply

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In message , Jim
writes

[apologies for swapping the order but they are best answered this way
round]

I want to reduce general light pollution to help find
objects like M33 rather than anything specific like an OIII filter.

Almost nothing will help make continuum objects more visible unless you
have very special circumstances like pure monochromatic LPS light
pollution. Otherwise there is no way to distinguish between the good
light from your object and the unwanted light pollution.

What are people's thoughts on the Orion Skyglow filter? Any good or
should I avoid?

But which one do you mean ? For visual use or photographically ?

Orion US SkyGlow filter is broadband and optimised for US style mercury
street lighting. It is next to useless in most of the UK. Their narrow
band UHC is good.

Orion UK Sodium light filter is moderately broadband but kills the worst
excesses of both the LPS and HPS street lamp emissions.

Baader Neodymium or my own Nonad filter will work if you have almost
exclusively low pressure (pure orange) sodium street lights. But it
isn't very impressive visually - the contrast improvement is largely
masked by loss of light. I recommend Nonad mainly for photographic use
where is effective (though I know a few keen folk do use it visually).
Visually M1 shows up better, galaxies are sometimes helped, star
clusters are always worse.

Photographically you just have to increase the exposure time by about
50% to make up for the filters losses and you can still have a dark sky
on even longer exposures. The eye doesn't allow this so visually you see
fewer stars.

For visual use I reckon the Orion UK Sodium light filter is your best
bet since it copes with mixed sodium lighting and gives significant
visual improvements. But even so it really only works well on nebulae.
YMMV

There is no substitute for dark skies.

Regards,
--
Martin Brown