Request For Help With Night Sky Photography

JK1231

Hi,

In anticipation that the comet ISON hopefully putting on a show later this fall, I have been experimenting with taking night sky pictures and I’ve been sorely disappointed in the results. Back in the day (that is, too many years ago to mention), I did a lot of night sky film photography, and got good results with a cheap range finder camera, so I’m having a problem understanding why my DSLR is underperforming my expectations.

My night sky pictures end up with an almost-daylight brightness to the horizon, but I’m only capturing a very few of the brightest stars. I’m going far away from city lights and I have a dark, very visible, moonless night sky to shoot. So, I’m wondering what I’m doing wrong with my DSLR that is giving me crap for the night sky. I’ve looked at other posts in the forum and I think I’m using reasonable settings... so I’m not sure what’s up.

With this week being the new moon, the next clear night, I’m going to try again using a different location to see if that makes any difference, thinking that the little distant light on the horizon may be overwhelming my sensor and causing it to ignore the sky. But, before I do that, I thought I’d ask for some advice, and maybe someone can give me a clue what I’m doing wrong.

Here’s what I’m shooting:
Nikon D7000 with 24-85mm f/2.8-4D at 24mm and f/2.8
Nikon D7000 with DX 10-24mm f/3.5-4.5G at 10mm and f/3.5

Camera settings:
Manual Program
Manual Focus (camera and lens)
Focused at infinity
ISO 6400
Exposure times tried: 1, 5, 10, 20, 30 secs and time w/ remote: ~1min, ~2.5min, ~5min
Auto White Balance: Normal
Picture Control: Standard
RAW + JPEG fine-large
Active D-Lighting: Off
Long exposure noise reduction: Off
High ISO noise reduction: Off
Mirror Up (and on a solid tripod)

Suggestions appreciated.

JK

PB_PM

First step, lower your ISO. Second, turn on low exposure noise reduction. The latter really helps to reduce the ambient glow (heat on the sensor) that happens with long exposures longer than a few seconds.

Golf007sd

Welcome to NRF. Please have a look at the following conversation and I'm hoping it will help you with your current issue.

Lens Suggestion for Night Photography

Please note the chart regarding your lens focal length in relation to exposer timing.

Parke1953

Here is a link in the thread Golf007sd has suggested. http://500px.com/blog/738/tutorial-photograph-the-night-sky. Good reading. Not sure if it will work.

p.s. Tried it and it works.

proudgeek

I've been doing a lot of this type of shooting, along with another member, Beso. A lot depends on what effect you're trying to get. If you're trying to get star trails, the longer the exposure the better. What I've been going for is as little movement as possible. Here's what I've been shooting:
D800
17-35 @ 17mm
f/2.8
ISO 1600-3200 (the D800 does a pretty good job with noise at those higher ISOs, can't speak to the D7000)
Long exposure NR on
At those settings, I find I can shoot at about 25 or even 30 seconds before seeing movement.

Here's a sample of what I've been getting, but to be truthful Beso has done far better: http://www.flickr.com/photos/gdanford/9599490490/

Your shutter speed will depend on your focal length. In general, with a DX sensor you can divide 400 by your focal length to get optimum exposure without movement. So in your case if you're shooting with a 10-24 @ 10mm, you should be able to keep the shutter open for up to about 40 seconds. I'd start there and work your way down to shorter exposure times. The technique you've described is right; just make sure to cover the view finder while the shutter is open.

Symphotic

Where are you located? Dark skies are essential to make this work well. If you can see the Milky Way, you should be well on your way with the advice above. We used to have dark skies in my back yard, but no longer. Some call it progress. I call it a new auto dealership down the road. So I am left with Moon and Planet shots.

If you are really keen, you can invest in a clock drive as well.

autofocus

For a no moon, dark night I start at ISO 3200, 10 sec, widest aperture, noise reduction Normal, D lighting OFF, with both the D800 and D4. I'll adjust exposure time to add ambient light or lower ISO to reduce ambient light. I also set WB to Kelvin 3300 and work from there to get the color temp I like. I have so much light pollution in my area that if I use Auto WB the sky turns orange. I take a shot, check, adjust, and keep working towards the exposure and color I want. I also import to PS ACR and will start processing by hitting the auto function and then adjust to taste before moving into PS. It's just trial and error for me.

JK1231

I went out last night and found a new dark spot -- best I've found so far, but lousy horizon view and still a lot more light pollution than I think reasonable.

Well, I found my major problem -- not covering my view finder. When I did that, most of my problems went away. However, I'm not sure I understand why it was even a problem to begin with: If I am manually setting ISO, aperture, and shutter speed, why does the view finder light leak make any difference? I don't understand!

I still have a well-lit horizon -- that's orange -- so the next time out I'm going to try the above advice and set WB to 3300. Lowering ISO to 3200 helped some with the horizon, but also made a noticeable difference with the number of stars included in the same exposure -- not sure whether lower ISO is help or hindrance.

Now that I have some decent star shots, I see a new issue: not sharp focus. Both the lens I use will focus past infinity, and I had focused the best I could through the view finder -- and focus indication on the lens showed it split the infinity symbol -- so what's the best means to sharpen my focus?

And that leads to a more general question: Why do the lens have the ability to 'focus past infinity'? What would be the focal point when the focus setting was moved past infinity?

Thanks all for your help! It's been very useful!

JK

Symphotic

I have that problem with focus myself. My solution is to focus on a bright star or planet first before moving to the part of the sky you want to photograph. I also use a magnifying right angle viewer. I find live view doesn't work as well as focusing using the viewfinder.

Yetibuddha

I think night photography is really neat JK. But takes some work to produce good images. The recommendations above are all within my experience. Not sure why when you reduce ISO below 3200 why you are still not getting lots of stars. I shoot with a D800 and 20mm F.8 and get very good results. Perhaps your sky is not as dark as you think. In terms of focusing, I set focus before the sky gets dark and avoid touching the lens during set up.

Also, try a series, a couple of hundred if possible, short, about 20sec or so exposures consequetively and use startrails.exe to put them together at least as a start, to produce nice start trails. Have a good object in the foreground to enhance interest.

Have fun.

autofocus

Ok, this may sound crazy but I focus by setting the lens to infinity, take a shot with something in the distant foreground and check image. If it's not in focus I'll bump the ring incrementally until I reach a focus I'm happy with. After doing this so many times I now have a mental mark for each lens and can set it pretty close for the first shot. I also find each lens / camera combo has a different setting. I never wind up dead on the infinity bumper. If I'm going to be out for a long period of time I'll use gaffer's tape to lock the ring. Helps out when I'm going to be moving the camera around for different compositions.

@JK1231, can you post one of your photos here?

JK1231

Hi,

Here's two photos. They were taken from: 32.592042,-80.468583 -- which is about 20 miles as a bird files from any civilization, in the middle of the ACE Basin south of Charleston, SC. I have not had a chance since this night to try again, as it has been either foggy or overcast every night since I shot these.

This image is facing approximately ESE:


This image is facing approximately S:


The best I can figure is the light on the sky in the latter image is from I-95 -- about 20 miles to the west.

There is a small pier at the area where I shot these from which would have eliminated the trees, but quite honestly, I wasn't comfortable heading out there in the middle of the night when I was by myself (except for the wildlife, which was in great abundance, from snakes, field mice, opossums, and racoons, to foxes, coyote, and deer -- not to mention mosquitoes).

I'm looking for somewhere darker and that has a better view of the eastern horizon, but that will appear to entail adding another couple hours to my drive from home.

Thanks for all the feedback thus far. Any comments on what I can do better are appreciated.

JK

Fred_B

From what I've heard some of the new glass is somewhat temperature sensitive. This is probably why most of the newer lenses don't have a hard infinity stop.

I have my best luck when I'm running the longest exposure I can get without star trails. The long exposure will help get the dim stars to show up again and still allow a reasonable ISO setting (3200 is still on the high end for me). Long exposure noise reduction is a must. Also, the sharpness (focus) may improve if you use a slightly higher aperture.

With a fast lens I can sometimes get my D800 to focus on a star if I have spot focus turned on. Doesn't always work but it's worth a try.

Golf007sd

Here is a good example for those of you that like to shoot the stars to consider.

Image Setting & Spec's:D800 14-24 2.8 25 second ISO 2000 @ f/2.8
Photographer: Daniel Cheong

dissent

Just saw this at Petapixel; thought it worth it to post the link here -
http://petapixel.com/2014/01/29/picking-great-lens-milky-way-photography/#more-129143

Article has a lot of other links from Ian Norman to other interesting night sky stuff he has available.

Elvishefer

Hi,

Here's two photos.

My $.02:

20 miles isn't enough. The amount of light a small town or even a large industrial building can push into the atmosphere is amazing. Add some moisture in the air and you get a giant diffuser. I would say the light in both those images is pollution from some source.

To get super clear night time images you have to work a bit outside your camera's settings. Travelling to an official dark zone helps. Shooting in the winter or in a desert where temperatures drop well below zero also helps. This can reduce a lot of the moisture in the air.

Knowing where your subject will be located at different times of night will help you shoot when your subject isn't under the influence of light pollution 'blooms'.

Also, it's not always a bad thing to have some trees or other foreground interest in your night sky shots. They can help frame the image and give it some context.

spraynpray

Hi,
Here's two photos.
JK

What colour temperature did you shoot these at? Look like that is more the problem than the light pollution as the orange is everywhere in the image not just near the ground. try tweaking it cooler.

Twenty miles is OK IME (limited) for from a few houses to a small village, but if there are a few lit streets the light pollution starts to creep up.