Light pollution

[Alan64]

I also blacken that portion of the drawtube that extends down into the light-path...

In that case, however, I used satin-black, slightly glossed, so as to better glide over its PTFE bearings.

The secondary-assembly, before and after...

[Space Hopper]

On 04/07/2019 at 23:42, devdusty said:

One of the reasons I wanted to buy a telescope was to observe the colourful double stars. Just read in July edition of Astronomy Now magazine that Albireo ,s wonderful colours will be washed out to some degree in a light polluted area.

it would seem pointless to buy a telescope for a light polluted back garden., If this is the case.

Chris P

If you're worried about light pollution, take a drive west to Dartmoor.

Its almost in your backyard. They'll be a lot less light pollution there.

[Rob Sellent]

On 05/07/2019 at 00:42, devdusty said:

it would seem pointless to buy a telescope for a light polluted back garden.

Chris P

I have found that LP doesn't affect planetary, lunar, double star, and solar work. So to this extent, LP needn't prohibit your enjoyment of the night sky with a telescope. On the other hand, LP not only cripples what you can see when it comes to hunting out many of the Messier objects and so on, but essentially robs you of their inherent beauty and detail.

[Nigella Bryant]

I was gobsmacked this spring when I got this image from my light polluted bortle 6 back garden. It was my first galaxy image. Even through the telescope I was blown away. So light pollution canbe overcome. I have taken most of the thing's mentioned in these posts, flocking the tube, painting items black inside the tube, etc. The only thing I've not considered was the light shade so I'm now thinking about that. 

Image is of M64, NGC 4826 the black eye galaxy and sub's of 30secs. I know I need to add flats, etc when I image in the future as light pollution causes an uneven background. 

[Nigella Bryant]

Double posted, opps. 

Edited August 6, 2019 by Nigella Bryant

[Nigella Bryant]

Opps. 

Edited August 6, 2019 by Nigella Bryant

[Nigella Bryant]

Image attached from above post, silly me. Also M42. 45sec subs. 

 

Edited August 6, 2019 by Nigella Bryant
Forgot to attach image

[Nigella Bryant]

I found this which might help.

I found this which might help.

OK I had a chance to do some very rudimentary filter comparisons. It's not all IDAS but is IDAS dominated so will put it into this thread. This is a comparison of the LPS-D1, LPS-D2, LPS-V4, HEUIB II, No Filter, and finally the STC Duo Narrowband.

There is -no- tracking, exposure is 5 mins with ISO2000, and is taken with the A7S RAW downloaded and converted to JPG. Scope is the Takahashi Mewlon 250CRS (2500/F10), therefore pardon the star trails due to gusty winds.

This was from a golf course carpark in Chiba whereby the SQM was 20.27 when the shots were made. it was 21:50 JST and ambient temps were 15.7C (although my Astro A7S cooled the sensor down to -3.9C) and humidity was approx 77%. As mentioned, it was annoyingly windy. There were some LED lights but were literally only 1 foot off the ground but a good 200-300 feet away from me. I was parked next to a 3 story building and next to my car for shielding from the wind. There was a vending machine light on in one of the rooms where my scope was approx 30-40 feet from the window. I don't think it would have contributed much light pollution seeing I'm on such a high focal length scope.

Subject was M97 (planetary Owl Nebula). 

No Filter Used

 

IDAS LPS-D1

 

IDAS LPS-D2

 

IDAS LPS-V4

 

IDAS HEUIB II

 

STC Duo Narrowband v4

Edited August 6, 2019 by Nigella Bryant

[bottletopburly]

I use Idas D2 filter and it does a nice job for me in a town /county that has 90% led street lights , would recommend if Led lighting is a problem .

image of M11 taken using 200pds  and a Idas D2  stacked in regim processed in startools flats and bias as  darks  , dithered 20 x  120 

 

[MarsG76]

I wouldn't say that it's pointless.. surely you wouldn't be buying a scope to look at only one object.

There are a lot of object to see through a scope, even from a light polluted back garden.

 

[Nigella Bryant]

4 hours ago, bottletopburly said:

I use Idas D2 filter and it does a nice job for me in a town /county that has 90% led street lights , would recommend if Led lighting is a problem .

image of M11 taken using 200pds  and a Idas D2  stacked in regim processed in startools flats and bias as  darks  , dithered 20 x  120 

 

Thanks for sharing, I've just splashed out on a D2 so hoping for better imaging when the skies darken. We'll as dark as they can be from a bortle 6 sky, lol. 

[bottletopburly]

30 minutes ago, Nigella Bryant said:

Thanks for sharing, I've just splashed out on a D2 so hoping for better imaging when the skies darken. We'll as dark as they can be from a bortle 6 sky, lol. 

If you get a halo around stars and you use DSS it’s a setting can’t remember off top of my head  something to do with hot pixels needs unchecked, I use regim now , I will look at DSS to jog my memory.

[Nigella Bryant]

24 minutes ago, bottletopburly said:

If you get a halo around stars and you use DSS it’s a setting can’t remember off top of my head  something to do with hot pixels needs unchecked, I use regim now , I will look at DSS to jog my memory.

Thanks, I would be using DSS. I have read something about halo around stars using the D2, appreciate your input. 

[bottletopburly]

10 minutes ago, Nigella Bryant said:

Thanks, I would be using DSS. I have read something about halo around stars using the D2, appreciate your input. 

Yes don’t worry about halos  I had read this too but soon found it was to do with this one setting .

[darkskyastronomy]

Double stars should always be visible, as long as you have no clouds.

A full moon is the greatest source of light pollution and many DSO hunters switch from DSOs to double stars during full moon periods, as double stars are not really affected.

Respective double star colours might be a bit blander under light pollution conditions, but the underlying colour trends should be visible, especially for Albireo.

[devdusty]

Thanks for everyone's advice and comments. Unfortunately Albireo is not visible with the naked eye even when Cygnus is overhead due to light pollution. I have tried looking for it with 8 x 40 binoculars but without success. Is it easy to find with a 90 mms refractory ?

Chris P

[DaveS]

OK, this is an image I made of the Leo Triplet of galaxies from my Bortle 8 back garden in Ruislip.

I'd have to look up the exact details but it wouldn't have been more than 7 1/2 hours. I think I didn't use a LP filter,

[John]

Some great images being posted here but I think this thread was originally about visual observing in light polluted skies ?

[DaveS]

OK, I take your point John, I was just trying to show that 'scopes aren't a total write off in cities.