Star shots

[tstrub]

Hi there, I've been struggling with several attempts to do some night photography - working with my Sony A6, I took a number of shots of the starry sky this past weekend using a number of different settings, and while I did get results, unfortunately the stars were not crisp, but rather each was a little bit of a blob (looked more like raindrops on a dark window rather than sharp starpoints) - the shots were taken via a tripod on a timer, so motion was not the problem. Wondering what I may need to do in future to correct this?

Thanks for any advice!

 

[photo1x1.com]

Hi, it seems your shutter speed was too long and the stars were moving (we all know the earth was rotating ) enough to leave a star trail on your image.
Can you post some details of your shots (shutter speed, aperture, ISO and focal length) along with a sample image (full size, or a 100% crop)?

 

[NancyMoranG]

Welcome. You are not alone with this problem
There are a lot of posts on this subject as you get the time to read the forums.
I would help, but there are better experts here to guide you.

 

[tstrub]

Hi there, I've been struggling with several attempts to do some night photography - working with my Sony A6, I took a number of shots of the starry sky this past weekend using a number of different settings, and while I did get results, unfortunately the stars were not crisp, but rather each was a little bit of a blob (looked more like raindrops on a dark window rather than sharp starpoints) - the shots were taken via a tripod on a timer, so motion was not the problem. Wondering what I may need to do in future to correct this?

Thanks for any advice!

 

[tstrub]

 

[tstrub]

This is a representative example of the photos - the shutter was somewhere around 20-25 sec., so I suppose there could be some amount of drift, but dunno ...

 

[photo1x1.com]

I´m afraid your images are out of focus. Both, the sunset and the star shot. Does that happen with your daylight shots too? If yes, you need to go to Sony service. If no, better use manual focus for star shots. Usually that works pretty well, if you use the loupe function of your monitor. If it doesn´t work for you for whatever reason, focus on something that is bright enough to help you focus and is at least 5m away, 10m to be on the safe side. On a wideangle lens like the one you are using, everything beyond a certain distance is infinity focus - so the stars are well focussed if you focus on an obect that is in a distance of 10m.

I checked your image data on the star shot

16mm (equal to 24mm full frame)
30sec (is just about right, google "500 rule for astrophotography")
f4 (lower is better for astrophotography, but this is as good as it gets for your lens - don´t think about buying a new one yet though, get the best out of the equipment you have before upgrading)
ISO400 (You have to ramp up ISO quite a bit to see more than the brightest stars on your image, even when it is well focussed ISO 1.600 or 3.200 should give you better results).

One more thing to consider when photographing stars is light pollution. If there is too much light at night in your area, blacks won´t be black enough to give your stars the contrast that is needed for great pictures. There is great website that gives you an idea of how much light pollution is in your area and helps you find great spots: Light Pollution Atlas 2006

 

[table1349]

Beginners Tips for Night Sky and Star Photography
Once you understand the basics.
From Prep Work to Post-Processing: An In-Depth Star Photography Tutorial

 

[Peeb70 6]

Not pretending to be an expert, but I was pretty pleased with this recent shot.

16mm lens at f/2.8 for 25 seconds at ISO 1600.

I used an app to determine the location of the milky way and used a flash to capture the moving blades of the turbine, as an interesting foreground helps skyscapes, to me.

 

[table1349]

Not pretending to be an expert, but I was pretty pleased with this recent shot.

16mm lens at f/2.8 for 25 seconds at ISO 1600.

I used an app to determine the location of the milky way and used a flash to capture the moving blades of the turbine, as an interesting foreground helps skyscapes, to me.

I likie likie.

 

[tstrub]

I´m afraid your images are out of focus. Both, the sunset and the star shot. Does that happen with your daylight shots too? If yes, you need to go to Sony service. If no, better use manual focus for star shots. Usually that works pretty well, if you use the loupe function of your monitor. If it doesn´t work for you for whatever reason, focus on something that is bright enough to help you focus and is at least 5m away, 10m to be on the safe side. On a wideangle lens like the one you are using, everything beyond a certain distance is infinity focus - so the stars are well focussed if you focus on an obect that is in a distance of 10m.

I checked your image data on the star shot

16mm (equal to 24mm full frame)
30sec (is just about right, google "500 rule for astrophotography")
f4 (lower is better for astrophotography, but this is as good as it gets for your lens - don´t think about buying a new one yet though, get the best out of the equipment you have before upgrading)
ISO400 (You have to ramp up ISO quite a bit to see more than the brightest stars on your image, even when it is well focussed ISO 1.600 or 3.200 should give you better results).

One more thing to consider when photographing stars is light pollution. If there is too much light at night in your area, blacks won´t be black enough to give your stars the contrast that is needed for great pictures. There is great website that gives you an idea of how much light pollution is in your area and helps you find great spots: Light Pollution Atlas 2006

 

[photo1x1.com]

I´m afraid your images are out of focus. Both, the sunset and the star shot. Does that happen with your daylight shots too? If yes, you need to go to Sony service. If no, better use manual focus for star shots. Usually that works pretty well, if you use the loupe function of your monitor. If it doesn´t work for you for whatever reason, focus on something that is bright enough to help you focus and is at least 5m away, 10m to be on the safe side. On a wideangle lens like the one you are using, everything beyond a certain distance is infinity focus - so the stars are well focussed if you focus on an obect that is in a distance of 10m.

I checked your image data on the star shot

16mm (equal to 24mm full frame)
30sec (is just about right, google "500 rule for astrophotography")
f4 (lower is better for astrophotography, but this is as good as it gets for your lens - don´t think about buying a new one yet though, get the best out of the equipment you have before upgrading)
ISO400 (You have to ramp up ISO quite a bit to see more than the brightest stars on your image, even when it is well focussed ISO 1.600 or 3.200 should give you better results).

One more thing to consider when photographing stars is light pollution. If there is too much light at night in your area, blacks won´t be black enough to give your stars the contrast that is needed for great pictures. There is great website that gives you an idea of how much light pollution is in your area and helps you find great spots: Light Pollution Atlas 2006

Did you want to ask a question, it seems in your reply there is no text

 

[TCampbell]

All astrophotography requires manual focus and here's the technique I find most helpful.

Crank the ISO to max and set the shutter speed to 30 seconds. This is not the exposure you'll use when you take the shot, but Sony supports "exposure simulation" (I think all of their alpha cameras support it) which means it will make faint stars brighter. You can now (hopefully) see the stars (or at least the brighter stars) to allow you to manually adjust focus until you get the stars down to a pinpoint size (zoom the display to max to help you determine when the stars are as well-focused as possible.)

Also, the focus for everything in the night sky is the same... so if you see a bright star but it's not in the part of the sky you plan to photograph it doesn't matter... go ahead and focus on that bright star, then turn the camera back to the area you plan to shoot. Focus will still be fine.

After focusing don't forget to return the exposure settings to something more reasonable.

Next you'll need to select a shutter speed... assuming you do want pinpoint stars and not elongated stars, multiply the focal length of your lens by the crop-factor of your camera sensor (which I think is 1.5x for your model). In other words if you had a 20mm focal length then you'd multiply that by 1.5 to get 30. Divide that into 500 (e.g. 500 ÷ 30 = 16.6.) That's the number of seconds that you can safely expose without getting any elongation on the stars (caused by Earth's rotation). Some people push that and use 600 (which would get you 20 seconds). Most cameras wont let you just set any arbitrary shutter speed... pick the nearest speed that the camera will allow.

You'll typically want to use the lowest aperture your lens will allow to avoid having to crank up the ISO too much (thus avoiding getting too much "noise" in the image).

If you plan to do a lot of astrophotography then I'd suggest investing in a focusing mask ("Lonely Speck" makes a focusing filter called a "SharpStar2" which works just like a Bahtinov focusing mask but instead of slots cut into a card it's an etched filter and it lets in more light). The masks cause stars to throw three diffraction spikes. When the spikes converge at a common center point you have achieved focus.

A "tracker" head for a photo tripod well let you take much longer exposures because you no longer have to worry about the rotation of the Earth. But these things start at about $300 and go up from there. So I wouldn't suggest one for an occasional astro-photo. If astrophotography becomes an area of serious interest then I'd invest in one.

 

[BananaRepublic]

View attachment 129078

Its not drift/rotation of the Earth its the image isn't focused right,.if you have live view turn that on and try to focus manually on the stars as best you can/ point it towards something big, bright and fare away focus on it, make sure auto focus is switched off

 

[GeorgeMStadler]

Not pretending to be an expert, but I was pretty pleased with this recent shot.

16mm lens at f/2.8 for 25 seconds at ISO 1600.

I used an app to determine the location of the milky way and used a flash to capture the moving blades of the turbine, as an interesting foreground helps skyscapes, to me.

This is awesome! great work