I've been playing around with capturing more data (very simple colour data) and keep coming up with one of 2 situations. Image is weak and not a lot of detail or nearly white. Telescope is constant, 90mm f5.5 refactor, 2" 10:1 focuser. Cameras are Canon 5D MKII, 450D and a Nikon D7200. I started out conservative ISO 800, 1 min subs. M45 came out ok. Then I tried M42 and was a bit disappointed, with 40 subs I still didn't get much more than the centre cluster and nebulousness. So I bumped up the ISO and all I managed to do was blow out the centre so badly I won't even show it. So I switched targets last night and tried C103, 10 3 min subs, ISO 3200. The frames were nearly white with over exposure.
So I started to think about what was happening and would like other opinions. I've attached some photos of my backyard with mount setup, one of the view to C103 and a JPEG of the image captured. Please note the street lights in close proximity. I don't need any light assistance when I go outside, its like early morning just before sunrise, all the time.
I'm thinking that all that light bouncing around in my yard and onto the house is simply overwhelming the camera sensor with long exposures, and introduces more noise than can be compensated for in short exposures, masking detail.
Kevin those street lights look like the aliens from War of the Worlds! They certainly are close. What kind of lights are they? If Sodium Vapour or Mercury they could possibly be filtered out. With some of the new low noise cmos cameras it is possible to take many fast subs that prevent sky glow saturation. Have you tried say 20 sec subs on Orion (M42). If you shoot a bunch of those you might get something useful, as Orion is so bright. However with the moon working against you it is probably impossible this week.
Are any of your cameras modded? Ie, do they have the blue cast filter removed? This opens up the camera to much more red light and could make narrowband imaging a possibility with an Ha filter - which would not be subject to most of the street light spectrum pollution.
Kevin those street lights look like the aliens from War of the Worlds!
I'll have to post a pic of the yard at night... even at f8 I get less than 1/125th of a sec and ISO 100 on the camera. Those things are as bad the aliens were in the movie!
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Have you tried say 20 sec subs on Orion (M42).
Yes I tried shorter subs, 40 at 25 seconds and the attached is what came out in the end.
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Are any of your cameras modded?
No, all stock cameras. The Nikon is suppose to have the anti aliasing filter removed but my understanding is that that is not relevant in astrophotography.
I have thought about introducing the NPB filter I got from you a few months back, not fond of narrowing my FoV from 2" down to 1.25". I'll have to get a new T adaptor.
You might be able to work with that Orion stack. Is that a stacked image or a single sub? At least your getting something out of short subs. What ISO was that? The higher the ISO you use the more skyglow your going to collect for any give sub. Short subs at ISO 400 might over come the glow better. You will still have CA to deal with but Orion is bright enough to over come skyglow in short subs, i think.
You have taken these shots when there's no moon about, right?
On the day I took the Orion images, the moon was quite a ways west. Orion was not getting above the tree to my east until around 1am. This is probably most affected by the lights of downtown Gosford.
The one of C103 was taken early on the 12th around 11:30 pm. The moon would have been past zenith, but still quite bright at over 75%, and behind me. At ISO 3200, probably a significant contributor to background light. I just find it hard to believe it would wipe out an image so badly when the object is in the opposite side of the sky.
I could see C103 quite clearly in an eyepiece in the same scope. My 8" SCT rendered it very well considering how unstable the seeing was.
It's only 2 weeks until no moon so I don't have too long to wait to try again and test out my hypothesis. If only the weather holds up...
Definitely will make comparisons and determine the level of moon light that might be acceptable at my location. Probably will be considerably less given the additional pollution from the surrounding city.
Thanks for all the feedback! Its one thing to know the theory and such, to have the practical experience is another world all together.
My old poor M42 was done with 15sec subs from light polluted suburbia, unmodded Nikon. Lots of them. My guess is you havent learnt how to tease out the faint signal from an integrated image yet and not a light pollution/setting/equipment problem. I suggest you browse you tube for tutorials on processing (regardless of program) and learn to understand a methodology to approach each problem you encounter. DSS and photoshop I consider poor choices to use, as they are limited in what they will let you do to process, thats why PixInsight, Nebulosity, Star Tools, Astro Art etc all exist and they all have the features to help, you just need to learn to understand what and when you need to use a feature.
Sorry but i disagree with that statement entirely too. His issues are not ONE factor and without cost or taking more photos he can get better image from the shots he has. Its up to him to learn. Watch tutorials even if they are not using the program you prefer and you also learn processing tricks that are portable. Don't try and you dont learn. Not my problem. If I was able to reveal more of M42 with shorter subs he should be able to exceed it with the longer ones.
Settle down. I know Kevin pretty well having been on dark site trips with him and we get together locally, he is just getting into trying imaging, and his frustrations are pretty much in the acquistion side of things at this point and getting that sorted. In my opinion, adding more variables, like chasing a processing solution fix is just a distraction. I am entitled to have an opinion, you certainly expressed yours. Sorry if your offended. In future i will speak to Kevin privately to express my opinion.
I'll have to post a pic of the yard at night... even at f8 I get less than 1/125th of a sec and ISO 100 on the camera. Those things are as bad the aliens were in the movie!
There's the problem - you've just described what amounts to something like a daylight exposure on an overcast day at ISO 100 !!! (The Good ol' Sunny-16 rule & its variants.)
As mentioned, I'm very appreciative of everyone's input.
The learning curve is steep with this hobby and is certainly not single faceted.
I already recognize that each of you has made VERY valid points. I'm certainly not well versed in post processing. Neither am I well versed in image taking. I have only picked up a camera seriously in the last 6 months. I didn't realize that the moon was such a major contributor to imaging, most of my experience has been visual so far. All of these things are TRUE, no one should argue these points.
Our personal relationships shouldn't even factor in. I'm a reasonably quick study and like to experiment so with this new found knowledge, I will be able to come back in a couple of weeks (or sooner) with some progress. I'm envious of the efforts being posted and want very much to satisfy my not so small ego and post a decent image or two very soon or die trying !
We all have our opinions and we should accept that as an inconvenience, lord knows I am maybe the worlds worst cynic there is, but that is life.
The information you all have is invaluable and we are very lucky that you are willing to share it. But let's keep in mind the keyword is "Share", one person's method is not wrong or right, it's what works for them. Having so many variations allows one to find that combination for themselves.
There's the problem - you've just described what amounts to something like a daylight exposure on an overcast day at ISO 100 !!! (The Good ol' Sunny-16 rule & its variants.)
Yes JA, I'm so glad my bedroom is on the opposite side of the house, it's like a day on Venus! Constant light ALL the time.
Certainly a major obstacle to overcome. Planning a trip to council one day very soon. See if they would consider some kind of shield to help control the dispersion radius. Wish me luck!
Yes JA, I'm so glad my bedroom is on the opposite side of the house, it's like a day on Venus! Constant light ALL the time.
Certainly a major obstacle to overcome. Planning a trip to council one day very soon. See if they would consider some kind of shield to help control the dispersion radius. Wish me luck!
Sorry to hear of your woes, ST.
If your visit to the council is backed up by perhaps some medical &/or psych. advice as to the effect of this on your personal health, councils sometimes are more likely to listen only because it may effect their bottom line or involve them in litigation. Street lighting can also be/is governed by the relevant road authority in your area. Your council may refer you.
For the record... here are 2 quick snaps of the backyard after twilight. I used Av mode which skewed things a bit but you get the picture... lots of light, everywhere.
Needless to say its a challenge that probably won't be easily overcome. I'm lazy at heart and would prefer to image at home, at my leisure, but I don't think this is the place to get anything useful.
Mate, if there's one thing I've learned about astro-photography, there's always a way. Your lights look like those orangy kind, and they are the type that respond well to light pollution filters if it comes to that. I have a dozen of the same ones out the front of my place, the closest within 30 metres of the house. I'll post some pics of my front nightmare later. Needless to say I don't do any deep sky out the front! (With one exception)
Actually Carl, I do! But I don't think it would even chip the glass. Would need one of those industrial hunting things that brace against your arm to break the cover lens.
I've already spoken to a nice young lady at council and gotten the contact info for the right people at RMS. Seems I'm not the first to complain about these lights.
Thanks for all the feedback! Its one thing to know the theory and such, to have the practical experience is another world all together.
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That's the solution to your problem
But I don't think it would even chip the glass. Would need one of those industrial hunting things that brace against your arm to break the cover lens. 
