I have a Nikon D50 and apparently these new cameras/lenses can focus beyond infinity. With my old film SLR, I used to be able to take perfect pictures of star trails by focusing on infinity. Now if I try to do that, they just turn out blurry. Even after a lot of trial and error, I still couldn't get them in perfect focus. Anyone know why lenses are built like this now, and more importantly, does anyone know any tricks for focusing on stuff like this better? I also had the same problem when trying to photograph the moon. Thanks!

would shutter speed be the culprit by any chance?

No. I can actually see as I'm focusing the moon, for example, how it comes into focus and then goes out of focus as you turn the lens toward infinity. It actually is possible to focus "beyond infinity".

is it maybe the auto focus 'helper' beam .. could you turn that off? .. or .. auto focus completely if your camera can focus manually

Photographing Star Trails .. @ danheller.com

Meteor Shower Photography @ space.com

Meteor Showers @ luminous-landscape.com

Might not address your issues .. if not I'll give you your money back

Look for the infinity marks of the focus ring. Line them up in manual focus mode and away you go.

I just thought the title was catchy "Unable to focus on infinity". I know ya'll know what you's is talkin' about, but to a dumb-dumb like me...I dunno!! Seems like if you focused on infinity then what you've got focused on really wouldn't be infinity, now would it?

Cheers!!

Please continue on..don't mind my silliness!!

BUZZ LIGHTYEAR: .. to infinity .. and BEYOND !!!

I appreciate all the comments, but unfortunately I still don't have an answer. To Trisbert, there are no distance markings on the lens. And to Keifer...unfortunately none of those articles address the infinty problem. If anyone else has any ideas, I'd love to hear them.

would new glasses be in order..? maybe the wrong lenses are being blamed....

I think that you solved your own problem a few comment up: "... it comes into focus and then goes out of focus as you turn the lens toward infinity." I think that the issue is that you are expecting "inifity" to be at the full extent of the lens' travel, but due to some play in the movement you can actually go a bit farther. This doesn't mean that you can't just set it at whatever location produces the farthest focal plane. For all intents and purposes the moon is at infinity, so setting it so that the moon is in focus will give you the desired result.

Caedes - I understand that, but the problem is that I can't get the moon into perfect focus like I used to be able to with my old film SLR. Do they just make the digital lenses different? I guess I was wondering if anyone had any magical tricks to help me out, but I guess it's just going to take a bunch of trial and error, and even then it might not work. Or I guess I could just use my old camera and scan the pictures!

I actually think they do make digital lenses diff. I dont know if this is true, but b/c the chip size [image sensor thing] in a DSLR is usually about half the size of a 35mm film, you're only getting half the picture that you would normally get with a film camera (if you use the same lens). Good for zooming in, bad for wide angles.

However, i dont think that has anything to do with your "focusing on infinity" problem, but just thought it would be good info. If your lens has a "limit" setting, i guess that might work?

Try just using your hands to focus around, but this has been said a million times, seems like it would work tho. :-S

Maybe it's too dark for autofocus? Does this only happen at night?

Lens is broken?

Lens doent work on your DSLR [diff lens type, etc]?

Not holding the camera still, no tripod, too slow of a shutter speed, train passing by, etc. ;-)

Just thought of another one, if your looking through the viewfinder, and you have, lets say 20-20 vision with contacts on...and you know how viewfinders have the focus little thing on the side for ppl who wear glasses and take pictures...maybe that is at the wrong place?

That was a whole bunch of nonsense i just threw out, but hey, your despirate for answers. :-)

Ok, I thought that you meant that you _could_ get the moon in focus. What camera and lens are you using?

another attempt .. I can't imagine a lens that can't focus at infinity .. but maybe try a hyperfocal setting .. where you are using the aperature setting to take you to infinity ... try to avoid MAX aperature .. since most mfrs fudge the qualifications of their lenses


where to focus on for landscapes @ dsl-reports

Hyperfocal Chart @ DOFMaster

Hyperfocal Distance Guide @ DOFMaster

lol, the stars will start to circle around the north star, which would be a totally different picture. (b/c of the longer shutter speed)

It's a Nikon D50 with the 18-55mm kit lens. I just googled this and I see that I'm far from the only one with this problem, so I guess I'll just keep practicing. Hmmm...I always thought that infinity meant infinity...I never realized there was a point beyond infinity. Anyway, I'm curious if anyone has a DSLR where this is NOT a problem.

Here's an explanation I found on another site. It seems to make sense: it's a feature of newer lenses that allows for compensation for different temperatures, e.g., what is infinity for 25 deg F might not be the same as when it's 100 deg F.

sounds like a salesman's explanation .. ;o)

Darn, I forgot that a lot of modern lenses don’t have those focus marks. You said that the moon comes into focus then out again. So the focus can’t latch onto the moon itself. The moon is a low contrast object. So the focus will have a better chance of working if you focus on the edge of the moon, which is a high contrast area. Another thing that helps is to use just the centre focus point, if your camera offers that option. Using a tripod helps too because the camera will have trouble focusing on something that is wobbling all over the place.

Isn’t photography fun :-)

Trisbert - OK, let me clarify. I've been using manual focus. When I use auto focus, the camera will lock in on the moon, but it doesn't focus sharply. So instead I use manual focus. And what I mean by "comes into focus and then goes out of focus as you turn the lens toward infinity" is...if you were to look through the viewfinder while focusing, you could see the moon start out of focus, and then as you turn the focusing ring toward infinity, at some point it would appear to be in focus, and then if you continue turning the ring slightly more to the end (what I thought was infinity), it would go out of focus again. Make sense? You might ask "why don't you just stop turning the ring when it's in focus?" That's where the trial and error comes in, and I haven't been able to get it just right. It used to be so easy with my old camera to get it spot on. Just set the manual focus to infinity and it was perfect...

Ah I see, well they all do that so that bit is functioning normally. They do that to allow the auto focus to work it’s magic under a wide variety of atmospheric / temperature conditions.

You said “but it doesn't focus sharply” which leads me to suspect that your lens needs calibrating. I just got one calibrated. It’s focus accuracy was not the same after someone dropped it down some concrete steps. After calibration it works better than it did when new. I kid you not. By the way calibrating the lens affects auto focus and has no effect on manual focus that I could see.

Just to complicate matters, the old film camera was full frame and the size of the viewfinder is in proportion to the media (film or sensor). So the old film camera had a bigger brighter viewfinder than your new camera with it’s cropped sensor. That means you get a smaller dimmer view of the world and moon than you used to get and that’s why its harder to use manual focus with the new camera.

It helps to use a fast lens. A F:2.8 lens passes twice as much light than a F:4 so the view is that much brighter with the fast lens. Those fast lenses usually come with a huge price tag though.

jeffpratt: I think that your confusion in this matter is mainly due to an incomplete understanding of exactly how the imaging system in a camera works with respect to the depth of field. I have to admit, I have a degree in physics and it is still easy for me to get confused with optics problems. would suggest looking for a tutorial on camera optics and ray tracing problems (an intro physics textbook would probably have some useful diagrams and explanations as well).

I got a better idea...dont read the quantum physics books and just take pictures anyway that works. ;-)

Physics books! Hah! I'd rather have blurry pictures. Alls I know is that what I'm trying to do worked with my old camera/lens but not my new one. I can see from googling it that a lot of people are having the same issue, so I'll just drop it now. It's obviously not something wrong with my camera. I guess that's just the way it has to be. I'll just stop my bitchin'!

Thanks everyone...

theres nothing wrong with your camera. the lenses are made so that if the ccd is slightly farther back than what it is supposed to be they can still focus at infinity. this is also the situation with lens extenders, and such. if the lens movement was such that the lens could only rotate to 'infinity' and no farther, then once the ccd is put farther from the lens all of a sudden they wouldnt be able to focus to infinity, which is in my opinion a far larger problem than having to simply focus properly, rather than simply shoving the lens all the way to the end of the focus dial. i'll admit i've done the same thing before, you just have to learn how to focus your lens well in very low light, or use higher apperatures/wider angles to make it less picky