Night sky pictures - how to focus?

AlexandL

New member
Hi All,

I'm very new to DSLR and have the D3200 kit with the AF-S DX VR 18-55mm f:3.5-5.6G lens. I've been having a problem trying to take pictures of the night sky and the stars. I can't figure out how to set the focus properly. In Manual mode if I use the auto focus it just whirs back and forth, stops, insists I use the flash, and I can't take a picture. "Subject is too dark, cannot adjust exposure, use the flash". It seems rather silly when I'm using a long exposure up to 8 seconds. In Live View I can take a picture but I get the red box and the picture is blurry and out of focus. If I go to manual focus, it's too difficult to set looking through the view finder or in live mode. There's not enough of anything for me too see to set the focus. Tiny points of light, even setting on a larger brighter star (or planet) doesn't help.

With the camera on a tripod and using a remote, my basic settings are:

Manual Mode
Lens - 18mm (with clear filter attached)
f:3.5
Shutter speed: varying from 4 seconds to 8 seconds
VR - Off
Auto Servo AF
Dynamic area AF
Matrix Metering
ISO - 100 - 400
WB - Auto

I tried using various combinations with the Focus Modes, AF Area Modes, Metering, and ISO. If I go above ISO 400 I get too much noise, even with the NR on. I tried setting the shutter speed to bulb and timing the shot myself, which didn't work out any better. I feel like I'm missing something but don't know what it is.
 

BackdoorArts

Senior Member
Take a walk through the Low Light & Night photography forum under Learning Photography. This has been asked and answered many times.
 

Mike150

Senior Member
Hi Alex and Welcome.
Try this trick. While it's still daylight, focus on a distant object (to get the infinity point). Mark the lens with two pieces of blue painter's tape. One on the barrel and one on the focus ring. Make an alignment mark on both pieces of tape with a fine point sharpie.

Later that night, set up your camera and tripod Switch to Manual focus on the lens. Using a flashlight, align your two marks and you're done.

I suggested painter's tape because it can be removed easily. I generally remove the tape after each shot.
 

nickt

Senior Member
For your night sky scenes, put lens in manual focus and adjust to that infinity point that Mike described and leave it there. Automatic scene and meter modes will rarely get your night shots correct. The camera doesn't know what you want. You might want a clean shot of the moon in a black sky or you may want to see some clouds and hints of colors from sunset. Its up to you to find the exposure to give you the results you want. Another tip, the moon is a sun lit body. Its a big rock sitting out in the sun with a lot of black around it. You can spot meter it, or guess at it. But it's not going to be a very long exposure for the moon as the main subject. If no moon in your shot, just go for the exposure that looks best. Stars are similar to the moon, but you won't be after detail, so whatever exposure makes them look nice is good. Don't let the camera meter, it will try to make something of the blackness and it will be noisy. Back in film days, you would need to think a little harder, but with digital, you can experiment at no cost. Try different apertures and different shutter speeds to get the stars to look the way you want. Just keep your lens on that infinity point.
 

WayneF

Senior Member
Setting the lens to infinity is not necessarily very accurate focus, at least for stars.

What I do is to set Manual Focus. Then I use Live View, and the LCD zoom button to greatly magnify the view. Focus manually on the magnified stars (or moon), for smallest brightest dots. Then take it out of Live View mode (battery) and shoot away, with that same fixed focus.
 

AlexandL

New member
Setting the lens to infinity is not necessarily very accurate focus, at least for stars.

What I do is to set Manual Focus. Then I use Live View, and the LCD zoom button to greatly magnify the view. Focus manually on the magnified stars (or moon), for smallest brightest dots. Then take it out of Live View mode (battery) and shoot away, with that same fixed focus.


Well, this is embarrassing. I had the feeling I was missing something, I just didn't realize it was something so obvious. I had no idea I could zoom the lcd screen in live view mode. I didn't come across that function in the manual. Here I am trying to set the focus with nothing but a tiny pixel dot of light on my screen. The last couple of nights have been perfect with clear skies and moonless, and I've been pointing my camera at the darkest part of the sky. I was hoping to get some nice star field shots, and catch a few shots of the Persieds at peak but I'll have to wait and try again. I've gotten a lot of useful info for the next try.
 
Now start reading all the posts you can here even if you don't think you might need the info right now. You never know when I might come in handy. I learn something new almost every day here. When I see something interesting that I did not know I will go out and try it for myself.
 

AlexandL

New member
Now start reading all the posts you can here even if you don't think you might need the info right now. You never know when I might come in handy. I learn something new almost every day here. When I see something interesting that I did not know I will go out and try it for myself.


That would be quite an undertaking, I doubt I would have the time to read that many posts and I'm no spring chicken. :) It's enough to keep up on what replies I can get out. It'll be a few more days before I get around to filling out all the profile info. I've only had this camera for 3 days but so far I'm liking it and getting some really nice pictures. Before that I was using a Canon Powershot SX 150 IS. Some things are familiar and a lot of things are new and will take time and practice. I'm waiting until I know more and can better handle this kind of camera before I go out and buy more lenses. But my first one will be a nice macro lens.
 

sOnIc

Senior Member
Myself, I recommend you find one of the brightest stars in the sky (Vega in the Summer, UK, or Sirius in the Winter - the most obvious bright star you can see) and zoom the lens in; say 55mm for the kit lens, this allows you to manually focus on that bright star with great accuracy, then zoom back out and compose your shot, being careful to not mess up your focus. As the lens gets colder it might move a tiny bit; so its worth checking the focus occasionally during a session to be safe. I do have a right-angle 2x viewfinder extension as well but I rarely need to use it, it maybe useful if there are bright lights around and you cannot dark adapt your eyes enough to see; or you have less-than-ideal eye-sight.

​Live view is a good idea; but it will destroy your dark adapted night vision - likewise using a star-map app on your mobile phone; even in red mode; will completely ruin your dark-adapted eyes. By this I mean that for viewing the night sky you want at least 10 minutes of darkness to get your eyes adjusted; looking at any form of backlit screen will put you back to square one.

EDIT: Before somebody points this out - of-course this does not help if you're using a prime lens; I'll worry about that when I get one .. but thankfully the thread was about the kit lens!
 
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AlexandL

New member
Myself, I recommend you find one of the brightest stars in the sky (Vega in the Summer, UK, or Sirius in the Winter - the most obvious bright star you can see) and zoom the lens in; say 52mm for the kit lens, this allows you to manually focus on that bright star with great accuracy, then zoom back out and compose your shot, being careful to not mess up your focus. As the lens gets colder it might move a tiny bit; so its worth checking the focus occasionally during a session to be safe. I do have a right-angle 2x viewfinder extension as well but I rarely need to use it, it maybe useful if there are bright lights around and you cannot dark adapt your eyes enough to see; or you have less-than-ideal eye-sight.

​Live view is a good idea; but it will destroy your dark adapted night vision - likewise using a star-map app on your mobile phone; even in red mode; will completely ruin your dark-adapted eyes. By this I mean that for viewing the night sky you want at least 10 minutes of darkness to get your eyes adjusted; looking at any form of backlit screen will put you back to square one.



Night vision isn't a problem for me. I can see incredibly well in the dark and my eyes adjust fairly quickly without much difficulty. My problem they just don't focus that well, not as well as they use to. :) I wear bifocals but more often I wear contacts for long distance and reading glasses for up close. Full manual focus can be a little tricky for me but with the diopter set correctly and through much practice I'm able to properly set the focus manually and get a nice sharp in focus picture. My problem was using live mode in standard view and trying to focus on a tiny point of light, even the larger brighter objects were too difficult. Until it was pointed out that I could zoom the viewscreen, which I've been experimenting with. But I haven't had the same excellent conditions again yet, and it's not always easy romping around in a dark place late at night. So it may be a little while longer before I can make another attempt, though I'll be sure to post the results.
 

sOnIc

Senior Member
Yes good conditions are hard to come by, I'm waiting for the Moon to go away .. but my most recent experience was for the Perseid meteor shower a few weeks ago; I focussed using Cappella which is the brightest star in the northerly direction, I zoomed in to 55mm and very carefully adjusted the focus back and forth until I was sure I'd got it right, then pulled back to 18mm - and it was in perfect focus for the whole session. But I just realised this would not be possible if using a prime lens, so maybe Live View is the best way to do it in that case...
​Clear skies ...
 
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nickt

Senior Member
My problem they just don't focus that well, not as well as they use to. :) I wear bifocals but more often I wear contacts for long distance and reading glasses for up close.
I hear you on that. Its been really frustrating for me the last few years with needing reading glasses over contacts and sometimes just wearing plain distance glasses or bifocals.
 
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