Astrophotography / starscape head ache

[GDHLEWIS]

Morning, afternoon good evening all,

So having bought a star tracker I took the opportunity tonight to practice my astrophotography / starscape whilst I wait for the new toy to be delivered. As you can see below things didn't turn out as well as I had hoped. I have tried changing the iso settings a few times but as I get lower I just cant get enough stars to pop out. I am around 5-7 kilometers from the nearest major light source and for some reason I'm still getting the pictured issues. What looks like over exposure and this odd red tint on the lower right hand side. I was only using ViewNX2 (Nikon standard photo software) as I am on my work computer (slow night shift day), so will have to give it another go on Elements when I get home.

Any one got any suggestions where I am going wrong? Ill list the set up
Nikon D3200, 35mm 1.8 dx lens with hood, tripod (obviously). 35mm, iso400, f1.8, 20 second exposure

 

[jesseswll]

It looks like your lens fogged up. Is that the case? Was it humid or cold outside?

 

[GDHLEWIS]

It didn't fog up and the humidity is low tonight either temp is a nice 25C as well so perfect weather to be out and about, just for some reasons the long exposures are just not happening for me today

 

[GDHLEWIS]

One thing I do remember that's just popped in to my head was the Moon is ridiculously bright tonight so maybe that was the issue

 

[KmH]

Yep. Looks like light pollution.

Pro astronomical observatories use the nights right around the full moon for maintenance.

The Nikon 35mm f/1.8G AF-S DX Lens needs to be stopped down a couple of stops to get to the start of it's sharp focus range of apertures.
Wide open the lens gives up some contrast too.
You want as much contrast as you can get when doing astrophotography.

I had one, but got fed with having to repair the chromatic aberration and purple fringing the lens delivers, and sold it.

 

[GDHLEWIS]

Thanks KMH, the moon finally decided to bugger off so have snapped a few more shots that I will post later once I get home and have had a fiddle with elements

 

[Edsport]

Most of these night sky pictures has to be processed to make them dark. If you get some reddish color in the corner of the photo it's most likely amp glow (google it) and can be removed using software. I darkened your photo using photoshop's curves and levels. Is that something like what you were trying to achieve?

 

[KmH]

That's part of the reason astronomers still used CCD's instead of CMOS.

Many astrophotographers that make deep sky images using telescopes use specialized astrophotography cameras that can chill the image sensor.
Professional observatories use liquefied gases to really chill their CCD image sensors.

 

[JosephCarter]

I'm not an expert on astro photography by any means, but I think the red tint looks like light pollution.. as far as I know, I don't think 5-7 km is nearly enough distance to escape the light pollution of a 'major light source'... depending on how bright it is of course.

A bright moon will also reduce the amount of visible stars dramatically. As far as I've learned if you can't see many stars with your eyes, you wont be able to capture many stars with your camera. If I can suggest one thing, I would try to shoot with a higher ISO, and possibly compensate with one more stop smaller aperture. but again as far as I understand, if you have a 20 second exposure at ISO 400 f1.8, and your image is overexposing, it must be from too much light pollution, either from the ground or the moon.

Again I'm no expert, just speaking from my own experience, but hopefully someone with more knowledge on the subject can help you.

 

[GDHLEWIS]

Spot on, Iv still not had a chance to clear up some of my other images that I took after the moon went down. First week on night shift makes me very un Photoshop friendly lol

 

[GDHLEWIS]

Thanks guys, much food for thought. Im going to try a few more shots tonight and process them via elements, might try my kit lens as well as its a lot wider but will have to boost the iso as its only a standard nikkor kit lens