1min widefield exp probs

[stardust steve (Steve)]

Hello. The other night i was enjoying some time out under the stars and decided to try some 1 min exp widefields. After a brief drift align( was close-ish but no cuban cigar) i proceeded to open the shutter for 1 min exp's.
I realized there was star trailing but that's ok for now. I seen the CA but that's ok (i was using my std 18-55mm kit lens @18mm) But after doing a quick process i found there was massive amounts of glow coming from the Adelaide side of the image (bottom right) Are filters needed to counter that glow, lower ISO? I was quite amazed at the amount there was.

pic 1- single image 1 min exp iso 1600 f3.6 This is the first time i have tried 1 min exp's. Is this normal to have that much glow?

pic 2- stacked image in DSS 11x 1 min exp iso 1600 f3.6. I noticed the image quite blurred and is this because the field drifted between frames?
Thanks for any info

[loki78 (Jon)]

I've done a bit of very similar photoraphy myself from polluted skies in Sydney so I can tell you yeah it is pretty normal unfortunately.

I can't speak to filters, but you can remove it in processing afterwards. I have done it in Photoshop with a plugin i have on trial called gradient remover, but most processing software will do it with some degree of success just google guides on removing sky gradient for whatever software you're using.

Biggest tip I can give you, apart from go to a darker location, is shoot the milky way when it is directly overhead where possible rather than lower in the sky. The lower it is, the worse your gradient will be from a light polluted location. From your picture and the foreground object in it, I would assume it was fairly low in the sky.

[LewisM]

Is that DeepSky Stacker you are using? I had some similar registration issues as on the right until I changed some of the overlay parameters etc. I find I end up using 3 programmes to edit photos - DSS to stack, PS CS5 to do most corrections of colour, and MaxIM DL to tweak it a little.

I have SEVERE light pollution where I do most shoots - 3 mercury vapour street lights (2 that destroy my SW completely, almost ruling out the Sombrero and omega centauri), sports ground floodlights about 5 km away that seem to last till 11pm or so to the SE, and "city" haze lights to the east. I have NO view north except for a SMALL amount above my house roof!!! That limits my targets somewhat, but thankfully by the time Orion rises, the town lights are reduced significantly, the sports field is shut down and the heat has dissipated. So, I photograph m42 a LOT TRIED on the Horsehead, but no matter how hard I try to fool myself, I can't see even a whisp of nebulosity around Alnitak

I limit my exposures to 2 minutes MAXIMUM on a good night, but usually 25 seconds at ISO800 or 13 seconds at ISO 1250. I end up with over 30 subs of Orion usually - should do even more - will try tonight to add to my collection already and do a MASSIVE stack session.

I should show my pre-process shots - green haze from tree reflections, orange glow from mercury vapour lamps or red wash from having to use ISO 5000 to grab a hint of NGC 253

[CapturingTheNight (Greg)]

Not really sure about the glow issue Steve (the darker the skies the longer you can expose for). What really strikes me about that first image in particular is that you mention you drift aligned so I am assuming you were using a tracking mount but the star trailing is of a length that I would expect from a fixed tripod and that camera/lens combo. Are you sure you were actually tracking? Even a very basic plonk down the mount facing south should give you nice round stars at that focal length and 1 minute exposure time as long as the mount is tracking.

[stardust steve (Steve)]

Thanks Loki. The aerial is the internet on my roof and a quick check of sky safari says the Milky Way was around 50 deg in the sky at around 9.30 pm.
I will look into these plug in gradient removal programs

I was really excited to be capturing 1 min exp for the first time on to discover the shocking LP

Thanks for the info

[loki78 (Jon)]

No prob mate I will try later on to dig up an example of one of mine before and after the gradient removal for you

[stardust steve (Steve)]

hi and thanks Lewis. Yes it was a freshly downloaded version of DSS. I will have a look at the settings. thanks for the tip. it sounds like you suffer greatly from LP and good on ya for persisting with it.

Originally Posted by LewisM

Is that DeepSky Stacker you are using? I had some similar registration issues as on the right until I changed some of the overlay parameters etc. I find I end up using 3 programmes to edit photos - DSS to stack, PS CS5 to do most corrections of colour, and MaxIM DL to tweak it a little.

I have SEVERE light pollution where I do most shoots - 3 mercury vapour street lights (2 that destroy my SW completely, almost ruling out the Sombrero and omega centauri), sports ground floodlights about 5 km away that seem to last till 11pm or so to the SE, and "city" haze lights to the east. I have NO view north except for a SMALL amount above my house roof!!! That limits my targets somewhat, but thankfully by the time Orion rises, the town lights are reduced significantly, the sports field is shut down and the heat has dissipated. So, I photograph m42 a LOT TRIED on the Horsehead, but no matter how hard I try to fool myself, I can't see even a whisp of nebulosity around Alnitak

I limit my exposures to 2 minutes MAXIMUM on a good night, but usually 25 seconds at ISO800 or 13 seconds at ISO 1250. I end up with over 30 subs of Orion usually - should do even more - will try tonight to add to my collection already and do a MASSIVE stack session.

I should show my pre-process shots - green haze from tree reflections, orange glow from mercury vapour lamps or red wash from having to use ISO 5000 to grab a hint of NGC 253

[stardust steve (Steve)]

Originally Posted by obsidianphotos

Not really sure about the glow issue Steve (the darker the skies the longer you can expose for). What really strikes me about that first image in particular is that you mention you drift aligned so I am assuming you were using a tracking mount but the star trailing is of a length that I would expect from a fixed tripod and that camera/lens combo. Are you sure you were actually tracking? Even a very basic plonk down the mount facing south should give you nice round stars at that focal length and 1 minute exposure time as long as the mount is tracking.

hi Greg. I was doing my version of what I thought was tracking haha that was to press the 8x RA drive on the hand controller then hit the shutter. I tried both the left and right RA directions including 4x and 2x speeds. I also tried doing the same in DEC to see if that would change anything...it didn't. I have never tried tracking imaging really before and I believed that was how it was done. Maybe not . The mount is a eq3 with RA and DEC motors and I was using just the rings with the piggy back thread to mount the camera. I have read people guide by looking through the EP and counter the drift that way. I may try that way? So I thought I was tracking but no matter which speed I used, the results were the same ? back to the old drawing board haha

[stardust steve (Steve)]

Originally Posted by loki78

No prob mate I will try later on to dig up an example of one of mine before and after the gradient removal for you

That would be great Loki. It would be good to see the differences. It's looking like I may be need to that that soon as soon I will be heading back to my dark site and would like to be doing everything right including tracking correctly lol....that's another issue lol

[CapturingTheNight (Greg)]

Originally Posted by stardust steve

hi Greg. I was doing my version of what I thought was tracking haha that was to press the 8x RA drive on the hand controller then hit the shutter. I tried both the left and right RA directions including 4x and 2x speeds. I also tried doing the same in DEC to see if that would change anything...it didn't. I have never tried tracking imaging really before and I believed that was how it was done. Maybe not . The mount is a eq3 with RA and DEC motors and I was using just the rings with the piggy back thread to mount the camera. I have read people guide by looking through the EP and counter the drift that way. I may try that way? So I thought I was tracking but no matter which speed I used, the results were the same ? back to the old drawing board haha

Not familiar with the Eq3 but the hand controller sounds like it might be similar to one that I have on a second hand Eq5. Is there an N OFF and S switch up the top left? If so. Simply flick it to S and it should be tracking (as long as you have it plugged into power). The 2x 4x 8x and those other buttons are for manually moving the mount around. When you flick it to S if you put your ear up close to the mount you should hear the motor very slowly moving. You wont notice any movement by eye. It is very slow. Hope that helps....

[stardust steve (Steve)]

Originally Posted by obsidianphotos

Not familiar with the Eq3 but the hand controller sounds like it might be similar to one that I have on a second hand Eq5. Is there an N OFF and S switch up the top left? If so. Simply flick it to S and it should be tracking (as long as you have it plugged into power). The 2x 4x 8x and those other buttons are for manually moving the mount around. When you flick it to S if you put your ear up close to the mount you should hear the motor very slowly moving. You wont notice any movement by eye. It is very slow. Hope that helps....

Yes there is a S, off and N. Wow thanks. I often thought of trying that but never did assuming i had to move it faster with the speeds and have heard that noise you are talking about. Woo so happy i am going to try it out now.

[loki78 (Jon)]

Not the greatest example but one of the only ones I could find to show you a comparisson. This one shows how low the milky way was as you can see trees and bushes in the foreground, there is light pollution and crap off the plants that was roughly eliminated. With more time spent, I could have tidied it up even more, but ideally now I don't shoot when it's low, directly overhead and you are more or less guaranteed an even background.

[stardust steve (Steve)]

Originally Posted by loki78

Not the greatest example but one of the only ones I could find to show you a comparisson. This one shows how low the milky way was as you can see trees and bushes in the foreground, there is light pollution and crap off the plants that was roughly eliminated. With more time spent, I could have tidied it up even more, but ideally now I don't shoot when it's low, directly overhead and you are more or less guaranteed an even background.

Thanks for posting a comparison Loki. I can certainly see the difference. That info will come in handy for my future night sky adventures

[stardust steve (Steve)]

Just a quick update on the results from the following night. After trying again to drift align, i think i got closer but i still had trails. I then realized i had the controller plugged into the DEC motor
With great anticipation i plugged in the RA motor, could hear the motor ticking away, but alas still trails.
Yesterday after thinking about what Greg had said, reading a few forums and thinking where i was going wrong.... it dawned on me to check the tiny grub screws that lock the RA motor onto the RA drive shaft on the mount. Sure enough they are loose, almost to the point they have nearly fallen out.
So that's where i am at now. I am pinning all my hopes that the RA motor was just spinning and not griping the RA shaft.
Of course the clouds have rolled over so i will do a test soon and mark the shaft with a texter, tighten the grub screws and see if i can turn this mount from being a tripod into it's former glory

To be continued....
Edit- and the glow that was in the image's bottom right corner was not there on the following night