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Old 22-03-2009, 06:05 PM
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cookie8 (Vincent)
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Can I do DS imaging from suburban backyard?

I would like to start DS imaging using DSLR through an ED80. Driving 1.5hrs to a dark site will be quite an effort. I have read somewhere that one can add a skyglow filter or purchase a software then the result will be the same as from a dark site. Anyone has any experience to share?
Thanks in advance.
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Old 22-03-2009, 06:23 PM
TrevorW
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Yes
yes
yes

All my imaging is done from my backyard in a suburb of Perth and I have a street light in my frontyard and as yet I haven't purchased a LP filter

you can see my set up

http://www.lulu.com/content/6111968

and some of my images at

www.flickr.com/mylotian

Cheers
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Old 22-03-2009, 08:44 PM
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seeker372011 (Narayan)
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Vincent:

I live about 2 Km from you and the vast majority of my images(see Flickr link below) are from my backyard
sure you would benefit from going to to a dark site but its simply not practical most nights
Narayan
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Old 22-03-2009, 08:46 PM
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PS I did try a CLS filter but now don't bother-I shoot in H alpha and (RGB with no filter)
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Old 25-03-2009, 10:21 AM
pjphilli (Peter)
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Hi Vincent
I image in a Sydney suburb backyard and my site suffers from light pollution from sodium lights on the highway, mercury street lights and neighbor's fluro lights (why do they leave them on half the night?).
I use an Idas LPS-P2 light pollution filter as a permanent attachment.
I found that this increases exposure times by about twice but the advantage of getting nice dark sky images as against the milky pre-filter images is a definite advantage. Also I find that the use of a pier on which my HEQ5-Pro mount is permanently attached saves a lot of setting up and polar alignment time. Go for it!
Cheers Peter
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Old 11-04-2009, 12:46 PM
Robbie
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I live in suburban Perth and use a lumicon deep sky filter with very good results on an ed80 so yes you can do it,
Of course a dark site with no moon will always be better but life wasnt meant to be easy.
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Old 11-04-2009, 03:23 PM
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I have my 20" CDK in a suburben crap zone (Sydenham), and i seem to be getting good results so far. I expect better with a IPAS filter when i get around to finding one..

Theo.
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Old 11-04-2009, 04:14 PM
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Sky glow can be reduced by simply taking longer (more) exposures, signal always increases faster than noise, although it can get silly, diminishing returns on a log scale etc
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Old 16-04-2009, 10:48 AM
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That's OK for a little noise in the background, but doesn't work for skyglow from LP in a suburban setting.

In our case (most of us are in the same boat to varying degrees), the skyglow is signal, unwanted signal, but signal nevertheless. Increasing exposure times is useless, if the background is drowning out the signal, it'll always do so.

The only solutions are;
  1. wait until the object is nearer zenith, or away from the LP, incidently this is the main reason most of my DS stuff is a couple of months behind everyone else's, I'm waiting until the object clears the Melbourne LP
  2. Use an LPR filter, after much research I chose the IDAS filter from Hutech. It works, but I still get LP gradients.
  3. go on a rampage and destroy all of the external lighting that's poorly designed, or simply pointing straight up. This is pointless as they'll replace it faster than you can destroy it.
I'd only advise 1 and 2. The last one may get you locked up.

There is a fourth option, to lobby your local politicians to drop the amount of external lighting used after dark, but I wouldn't hold your breath...

Cheers
Stuart
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Old 16-04-2009, 05:02 PM
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Yes you can. Have a look at the posts of Peter_4059. He uses a DSI II Pro from very light polluted BrisVegas with no light pollution filters.
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Old 16-04-2009, 06:19 PM
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Increasing the exposure time will help only if F number is bigger.. because LP IS a signal (as stated by Stuart). And it will help ONLY with stars (point sources of light).
So for DS's, only options are filters and going out to dark sites.
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Old 18-04-2009, 04:53 PM
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cookie8 (Vincent)
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Thanks guys for your tips. I guess a LP filter is an option but not solution.
Quote:
Originally Posted by bojan View Post
Increasing the exposure time will help only if F number is bigger.. because LP IS a signal (as stated by Stuart). And it will help ONLY with stars (point sources of light).
So for DS's, only options are filters and going out to dark sites.
Bojan, any magic combination of F number and ISO for a 50mm lens?
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Old 19-04-2009, 04:57 AM
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Well.. I do not think there is anything like this, especially for 50mm..
Smaller F number the better :-) But not too small, because the lens faults will show (CA, coma in corners etc). I am using F2.8 - 4, this is giving me the good star images in corners of frame (50mm Canon FD, F1.4)
And I am using ISO 1600. Noise is dealt with by stacking (5-10 frames).
However, all this applies to dark sites, away from city lights.

In the city (at my home), well, LP almost saturates sensor after 30 sec at F4, ISO1600.
I (still) do not have any filters.. but for 50mm I think it does not make much sense to take pics from polluted areas anyway. 50km away and you are much better off, and camera with that lens (with mount, like barndoor or small equatorial) is not a problem to carry and set up on site.

However, for stars, I was using my MTO1000-A (1000mm, F10.5) at ISO1600 and at 30s exposure LP background was pretty much OK.
I could reach <13m without a problem, even for reliable photometry.

Last edited by bojan; 19-04-2009 at 05:09 AM.
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  #14  
Old 25-04-2009, 08:47 AM
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If you like to go for lunar and planetary images there is no problem with imaging from the city. Look at the wonderful planetary and lunar images taken by Eric Ng from a roof-top in Central Hong Kong!
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