UHC/LPR Filter Advice

[vvsloan]

Hi again,

Having done a little bit of reading on different types of filters and their functions I have a couple of questions I hope someone can help me with.

Firstly we're definitely in need of some kind of Light Pollution Reduction filter- There is a factory near our house that has several massive flood lights that it turns on every night flooding the sky with bright white light. Now, the Skywatcher one I'm looking at says it is designed to block out mercury-vapour light and other common causes of light pollution. Do you think this would include the type of light emitted by floodlights or is it just the more common yellow street light glow? I'm not up on types of light...

Secondly, would a UHC filter perform its function in addition to combating the type of light pollution emitted by flood lights? And if so, how efficiently compared to the simpler LPR filter? Also, same question for an OIII filter and if so which would be best for performing its function as well as combating the bright white light flooding our sky most effectively.

Many thanks for any help or advice on this would really be much appreciated,

Victoria.

[swamp thing]

Hi Victoria

You will see it written that the best purchase for those under badly LP skies is a tank full of gas. Never a truer word written.

The narrow band UHC works very well on emission nebulae as do the O-III & H-Beta line filters. The problem is they all work best from dark skies.

Filters work by blocking light. This gives better contrast between object and sky background. The more aggressive the filter, the blacker the sky background. The trouble is, to see this increase in contrast one needs good dark adaption. The aggressive line filters need better dark adaption than the UHC. This is difficult to achieve from urban sites.

Some even report the O-III and H-Beta make things "too dark" for them to make out much at all through the eyepiece. This is often because they are using them from sites where their own eyes can't get properly dark adapted.

I personally don't find the LP filters are up to much at all.

No filter is a substitute for dark skies, they are a tool to be used from them.

[vvsloan]

Thanks for that Steve.

I selected this particular scope for my mum (its actually my mums that I bought her for xmas, but which I intend to get as much use out of as possible myself:) on one of the basis that it wouldn't need moving from her home. She would not be able to carry such a heavy scope and lives alone. She effectively lives in the middle of nowhere so I was expecting the skies to be permanently dark for her to enjoy her new hobby in her retirement from her own home (actually, from her own massive balcony on top of the house, which was supposed to be perfect and where the heavy scope wouldn't need moving from. It was only on night 1 of trying out our, I mean her new scope, that I discovered the only other building for miles around, a factory just over half a mile away, turns on several massive floodlights when the sun goes down, completely ruining the sky. I do not drive and live 25 miles away from her alone with 2 pre-school children so I cant even drive her out on occasions!

I'm pretty gutted about after all the hours of reading, learning and research that went into selecting that particular scope for her. Had I known the factory floods the night sky every night I would have bought her a different, more mobile scope so she could at least drive it out herself.

I'm left trying to find the best filter I can to at least try to combat those horrible, ruinous floodlights....: (

[CodnorPaul]

Sorry to hear that Victoria - a neodymium filter works OK on LP, but it is not a difference between light and dark.  As stated the best option is to get to darker skies - then you will be wowed - could you not plan in a couple of trips together a quarter to somewhere really special, to get some really great time in, and then in between go for the brighter sky objects from the house?

There are people who observe in Birmingham, the Greenwich Obsy is in London, New York, etc. so it is possible to observe from home - and your skies I bet are a LOT darker than all of those

[Sandancer10]

Hi Victoria, I have the same problem on one side of my house with lots of glow from the town I live in and street lights.  The other side faces onto the North Sea, so that's the side I view from. I do use a LP filter and find that it helps a bit - I wouldn't give up on being able to sort your problem out.

There are other posts on here that I have seen where they have overcome a lot of light pollution, but unfortunately I can't find the link. You could try one of the forums on here that help with setting up your kit - there might be something there to help you.

I also have a problem in carrying my kit around, hence I went for the SW 150, which is okay for me if I only have to carry it for a short distance.

I hope you get sorted shortly as the joy of using a scope to see detail in the sky is worth the perseverance.

Brenda  

[vvsloan]

Many thanks all.

I guess I will purchase a neodymium filter then and as CodnorPaul suggests above, hopefully be able to organise the odd trip out (from her totally secluded house)...

I'm still scouring the forums for the best type of filter available for this problem Brenda, but after nearly 40 pages, seems the neodymium is the best thing going short of moving to darker skies.

Thanks again all,

Victoria.

[swamp thing]

The trick with observing from LP locations is to be realistic in your expectations.

Your not going to observe faint diffuse nebulae or galaxies but there is plenty of other stuff up there to keep your mum happy.

Clusters, double stars, the moon, and planets are all observable. As are the brightest galaxies and nebulae.

When I'm local to home (London very bad LP) I stick to the brighter DSO's. It's still fun I just rule out hunting down low surface brightness objects as it's a waste of time.

Leave the filters for now and start working with the bright objects first. Work your way to progressively fainter stuff.

[LukeSkywatcher]

The trick with observing from LP locations is to be realistic in your expectations.

Your not going to observe faint diffuse nebulae or galaxies but there is plenty of other stuff up there to keep your mum happy.

Clusters, double stars, the moon, and planets are all observable. As are the brightest galaxies and nebulae.

When I'm local to home (London very bad LP) I stick to the brighter DSO's. It's still fun I just rule out hunting down low surface brightness objects as it's a waste of time.

Leave the filters for now and start working with the bright objects first. Work your way to progressively fainter stuff.

Sound advice. You could invest in filters which will help a good bit, or just start off observing the brightest objects and work your way down to the faintest objects (you may need filters by that stage).

Without filters, there is plenty up there to see,even from LP locations.

[Moonshane]

I think that a baader neodymium filter would be a good choice as it is very good on Jupiter, Mars and the moon which are all unaffected by light pollution. also, it will certainly reduce some types of LP.

a UHC would be great on the brighter nebulae like the Orion Nebula and it is for me at least, pretty much reserved for that object.

for an 8" scope an Oiii would work pretty well on the classic objects (veil nebula for instance) although as Steve says, everything is better from a dark site.

I have to say though that an 8" scope is a very capable instrument and there are literally thousands of objects that will be visible even from light polluted sites so please don't lose enthusiasm. sometimes you just have to work a bit harder for the objects.

[scarp15]

An Orion Ultra Block filter works quite well on planetary and brighter emission such as the Orion, nebula in gaining some contrast accentuating structure and blocking some of the sodium light.  Fit a dew shield as this will help to block out some stray light, depending on the type of scope, consider flocking and select the object to be observed when it is close to, or has reached its highest point. 

[vvsloan]

The trick with observing from LP locations is to be realistic in your expectations.

Your not going to observe faint diffuse nebulae or galaxies but there is plenty of other stuff up there to keep your mum happy.

Clusters, double stars, the moon, and planets are all observable. As are the brightest galaxies and nebulae.

When I'm local to home (London very bad LP) I stick to the brighter DSO's. It's still fun I just rule out hunting down low surface brightness objects as it's a waste of time.

Leave the filters for now and start working with the bright objects first. Work your way to progressively fainter stuff.

Very sound advice indeed. However if I can get a second hand Baader Neodymium Filter, I really would like aquire one. Do you think this copy Neodymium Filter on ebay would perform ok? It doesnt mention anything in the description about advanced 'phantom' coatings or mutli coatings on both sides like the Baader one, but still do you think it would do the job ok? 

http://www.ebay.co.uk/itm/370852458604?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2649

I have to say though that an 8" scope is a very capable instrument and there are literally thousands of objects that will be visible even from light polluted sites so please don't lose enthusiasm. sometimes you just have to work a bit harder for the objects.

 I had felt like that after that first night but I'm raring to get back up to my mums house now for another session. (We only had about 3/4 hour before the cloud kicked in..)