Jump to content

sgl_imaging_challenge_banner_31.thumb.jpg.b7a41d6a0fa4e315f57ea3e240acf140.jpg

Soduim light reflections off rim of newt.


Recommended Posts

Hi Guys,

Here's another one.

I live near a roundabout with sodium lights. If I point my Newtonian in an Easterly direction (towards the roundabout) the yellow light catches the rim of the telescope, which then reflects down the tube.  See here, M36:

m36.thumb.jpg.405575b3a79b10ff7e5fc5ce35016ec3.jpg

My question is, has any one had this problem and can I add something like a dew shield or similar to cut out the reflection.  Do I need to flock* the tube? (* initially I had baffle here when I meant flock).

Regards,

Steve.

Edited by SteveBz
* initially I had baffle here when I meant flock
Link to post
Share on other sites

Flocking your scope will help, you can get some cheap stuff from wilkos. 

A dew shield, homemade or store bought, will help. But my main solution would be a decent light pollution filter sucks as an idas p2 lps filter 

  • Like 2
Link to post
Share on other sites
26 minutes ago, geordie85 said:

you can get some cheap stuff from wilkos

I'll check it out.

27 minutes ago, geordie85 said:

A dew shield, homemade or store bought, will help

I have one, but I stopped using it when I got a heater.  Maybe I'll try again.

Link to post
Share on other sites

Can you rig a shield to prevent the light reaching the tube?

I have a street light that shines into my back yard.  I purchased some black builder's plastic ( it comes on a roll ) and a few poles that I use to hold up the plastic between the light and the telescope.  It has cured my problem, perhaps something similar may work for you.

 

  • Like 1
Link to post
Share on other sites
1 minute ago, MikeODay said:

Can you rig a shield to prevent the light reaching the tube?

I have a street light that shines into my back yard.  I purchased some black builder's plastic ( it comes on a roll ) and a few poles that I use to hold up the plastic between the light and the telescope.  It has cured my problem, perhaps something similar may work for you.

 

It's an excellent idea and I do have some plastic sheet hanging around.

I'll have a think how I can rig it up without it looking horrible and upsetting everyone.

Link to post
Share on other sites

Mine is temporary ( I put it up before a session and pull it down and pack it away straight after ).  

My fence is metal so I purchased a couple of large magnets and two elastic straps and I use these to hold two of the poles against the fence.  The end of the third pole I place in a shade umbrella stand and move the stand out into the lawn until the plastic sheet is tight.  The poles are wooden and about 30mm square by 2.5 to 3m long.  The plastic sheet I cut off the roll to make it maybe 4m long and I folded it along the long axis and taped the ends to create an approx. 4m x 1.5m double sheet that is closed on both ends and open at the bottom.  I place the poles up into the opening - one at either end and one at the corner I create at the fence by shifting the umbrella stand out into the garden. Sorry for the long explanation, a photo would be more informative but I am away from home at the moment :)

 

  • Like 1
Link to post
Share on other sites
1 minute ago, MikeODay said:

Mine is temporary ( I put it up before a session and pull it down and pack it away straight after ).  

My fence is metal so I purchased a couple of large magnets and two elastic straps and I use these to hold two of the poles against the fence.  The end of the third pole I place in a shade umbrella stand and move the stand out into the lawn until the plastic sheet is tight.  The poles are wooden and about 30mm square by 2.5 to 3m long.  The plastic sheet I cut off the roll to make it maybe 4m long and I folded it along the long axis and taped the ends to create an approx. 4m x 1.5m double sheet that is closed on both ends and open at the bottom.  I place the poles up into the opening - one at either end and one at the corner I create at the fence by shifting the umbrella stand out into the garden. Sorry for the long explanation, a photo would be more informative but I am away from home at the moment :)

 

It's great. Does it solve the problem completely?

I don't have a metal fence. Instead I have my neighbour's wooden fence and several sheds, one of which doubles as an observatory.

Link to post
Share on other sites

Yes it works to completely block the light.  The builder's plastic I use is the thickest I could find and doubled over is completely opaque. 

A wooden fence should work fine.  Easiest if the uprights are on your side as you can attach brackets to these; although I suppose you still could if they are on the other side by drilling and screwing into them from your side ( as long as this does not upset your neighbour :) ).

In my case the light is on the other side of the fence and shines over the top.  The fence then blocks most of the light and the sheet only has to show about a 1m above the fence in order to block the rest.

  • Like 1
Link to post
Share on other sites
3 hours ago, MikeODay said:

Yes it works to completely block the light.  The builder's plastic I use is the thickest I could find and doubled over is completely opaque. 

A wooden fence should work fine.  Easiest if the uprights are on your side as you can attach brackets to these; although I suppose you still could if they are on the other side by drilling and screwing into them from your side ( as long as this does not upset your neighbour :) ).

In my case the light is on the other side of the fence and shines over the top.  The fence then blocks most of the light and the sheet only has to show about a 1m above the fence in order to block the rest.

I just followed your link.  Nice photos.  Lots of detail.  What is your sky like?  Given our discussion I don't imagine it's very dark, but then I Googled your location and it's a National Park :)

So you must have dark skies near even if it's not your back garden.

Regards

Steve

Link to post
Share on other sites

might want to check the bottom of your scope too - I was getting similar patterns to yours when doing my set-ups with the low level patio lights still on before going dark for the session - figured out that my light spill was getting in around the primary of my 200PDS.

I got some blackout blind material off Amazon and now wrap that round the bottom of the scope with a bungey cord of the right length after I've collimated

  • Like 1
Link to post
Share on other sites
1 minute ago, glowingturnip said:

might want to check the bottom of your scope too - I was getting similar patterns to yours when doing my set-ups with the low level patio lights still on before going dark for the session - figured out that my light spill was getting in around the primary of my 200PDS.

I got some blackout blind material off Amazon and now wrap that round the bottom of the scope with a bungey cord of the right length after I've collimated

Thanks I will.  I think there is a whole list of jobs to be done for surplus light:

  • flocking
  • sheet barrier
  • check primary mirror
  • New LP filter??

Regards

Steve

Link to post
Share on other sites

I put up a retractable clothes line across the side of my garden and when I'm observing, I hang a pair of old curtains over it.

When I'm finished I told the curtains up and retract the line. Takes literally 60 seconds and totally blocks the light from that single pesky street light up the road 

  • Like 2
Link to post
Share on other sites
19 hours ago, SteveBz said:

I just followed your link.  Nice photos.  Lots of detail.  What is your sky like?  Given our discussion I don't imagine it's very dark, but then I Googled your location and it's a National Park :)

So you must have dark skies near even if it's not your back garden.

Regards

Steve

Thanks.

As for dark skies ... directly above is not too bad but from around 20deg down I am impacted by sky glow from near and distant artificial lights ( the lights from the Sydney basin effect the sky way beyond me and out in to the distant rural west ).  The darksitefinder website shows me sitting in the border region between green and yellow.

  • Like 1
Link to post
Share on other sites
12 hours ago, nicks90 said:

I put up a retractable clothes line across the side of my garden and when I'm observing, I hang a pair of old curtains over it.

When I'm finished I told the curtains up and retract the line. Takes literally 60 seconds and totally blocks the light from that single pesky street light up the road 

Very cool idea.  Best so far.

Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. By using this site, you agree to our Terms of Use.