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06/16/2005 02:54:46 AM · #1 |
| I'm relatively new to photography. I've been trying to do some night shots...but I can't get my Canon 20D to focus on anything...whether the subject is close to the camera or far away (landscapes). I've had several people tell me to set the camera to "infinity focus," but I don't know what that means or how to do that with my particular camera. Can anyone help me out? Maybe there is an online tutorial that talks about infinity focus. I have 2 sigma lenses...mabye that's why the shots will not focus. Thanks a lot. |
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06/16/2005 03:13:43 AM · #2 |
In my limited understanding, infinity focus virtually means that everything in the picture is in focus, and is often used for shots covering extensive space such as landscapes. There's probably much more to it, but there's my two cents.
If you are focusing your lens manually, set it to the infinity sign, it looks like a sideways 8. I hope that makes sense.
Message edited by author 2005-06-16 03:18:49.
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06/16/2005 03:23:41 AM · #3 |
Google - "Hyperfocal distance" if you want a wider range of your landscape type pictures in focus.
Message edited by author 2005-06-16 03:25:20.
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06/16/2005 03:29:33 AM · #4 |
Try not to use th auto-fucus as it tends to act funny when it can't focus. Are you trying to do timed exposures for night???
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06/16/2005 08:20:12 AM · #5 |
Originally posted by justin_hewlett:
In my limited understanding, infinity focus virtually means that everything in the picture is in focus |
No, you're thinking of hyperfocal distance as faidoi said. The only time you'd want to use infinity focus on landscapes is when you ONLY want things very far away to be in focus, not your foreground.
Also, i find the 20D's af is very good at locking on to lights at night - just set it to use the centre af point and aim it at a light in the plane where you want it focused, it'll get it right away unless there's something really wrong with your lens.
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06/16/2005 08:24:49 AM · #6 |
Originally posted by riot:
The only time you'd want to use infinity focus on landscapes is when you ONLY want things very far away to be in focus, not your foreground. |
I don't understand why you say that? At 18mm for example and f8.0 focus at 8 feet will put everything in focus from 4 feet to infinity...so why wouldn't you want to focus to infinity in that landscape example?
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06/16/2005 08:43:54 AM · #7 |
Originally posted by deapee:
Originally posted by riot:
The only time you'd want to use infinity focus on landscapes is when you ONLY want things very far away to be in focus, not your foreground. |
I don't understand why you say that? At 18mm for example and f8.0 focus at 8 feet will put everything in focus from 4 feet to infinity...so why wouldn't you want to focus to infinity in that landscape example? |
No you misunderstand, that's exactly the point i was making. You're talking about setting the focus to 8 feet. I'm talking about why you WOULDN'T want to set the focus to the infinity mark.
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06/16/2005 09:25:10 AM · #8 |
I tried some landscape night shots this past weekend, a LOT harder than it seems! The landscape was just faintly visible to the eye as it was really dark where I was, and seeing through the viewfinder was impossible. I set the focus to infinity, and through trial-and-error adjusted the focus and composition in tiny bits after looking at the results on screen.
Focus was only part of the scenario though. Using tripod, remote, and mirror lock-up I tried different length exposures (20-60 seconds) and different ISO's (800-1600) with different combinations. The longer exposures not suprisingly had more noise and a few hot pixels (small red or blue bright dots), and the ISO 1600 shots at long exposures were pretty useless due to noise. I shot in raw and bumped the brightness and contrast up a lot (which gave it even more noise) before processing in Photoshop. I used NeatImage to clean up the noise, but that only worked so far. There's a full-moon in a few days, that will help a lot and give you more detail in the landscape and less noise. I only had about 1/4 moon to work with so I was pretty limited. Take your time and try different things. Hope this helps some. |
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06/16/2005 09:44:20 AM · #9 |
Originally posted by Telehubbie:
the ISO 1600 shots at long exposures were pretty useless due to noise. |
Why on earth would you use such a high ISO for long exposures? The whole point of long exposures is so you can use a nice slow ISO and get a smooth image...
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06/16/2005 09:58:39 AM · #10 |
Originally posted by riot:
Originally posted by Telehubbie:
the ISO 1600 shots at long exposures were pretty useless due to noise. |
Why on earth would you use such a high ISO for long exposures? The whole point of long exposures is so you can use a nice slow ISO and get a smooth image... |
Ya, I found that out the hard way. I didn't do my homework before trying it. I was trying out different things as I've never done that before. But was almost totally dark, and I didn't want to have a REALLY long shutter speed for fear of too many hot pixels. |
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06/16/2005 10:15:21 AM · #11 |
Originally posted by Telehubbie:
Originally posted by riot:
Originally posted by Telehubbie:
the ISO 1600 shots at long exposures were pretty useless due to noise. |
Why on earth would you use such a high ISO for long exposures? The whole point of long exposures is so you can use a nice slow ISO and get a smooth image... |
Ya, I found that out the hard way. I didn't do my homework before trying it. I was trying out different things as I've never done that before. But was almost totally dark, and I didn't want to have a REALLY long shutter speed for fear of too many hot pixels. |
I find generally on the 20D most of the hot pixels will crop up in the first two minutes of exposure. If you can live with that, you can extend the exposure to five or six minutes without any noticeable deterioration in quality - and if you're not entering for basic editing, you can always just clone out the hot pixels. Much better result overall than having to run noise reduction on your image (and you can experiment with nice traffic light trails as well).
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07/17/2005 07:28:46 PM · #12 |
(Im a rookie) I got night shot problems of my own....
Not only is my focus pretty guess and check at night, but I seem to get this wierd effect with my long exposures. I cant get distant lights (stop lights, neon signs, burning people, etc) to look sharp. Instead i get this (still pretty cool looking) glowing light beam-hard to describe so I'll post a pic effect.
How do I rid myself of this during my long night exposures?
[thumb]241839[/thumb]
Message edited by author 2005-07-17 19:30:41. |
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07/17/2005 07:34:19 PM · #13 |
lol a few hot pixels after 2 minutes? Try the 1D over 1/4 second!
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07/18/2005 01:02:07 PM · #14 |
Hyperfocal distance depends upon the focal length of lens, and aperture. For a standard lens (equivalent to 50mm in 35 mm format), the hyperfocal distance is given by formula 50/f. i.e., the H=6.2 metres approx, for an aperture of f8.
If you focus at Hyperfocal distance (6m), everything from 3m to infinity will be in focus.
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07/29/2005 02:31:54 AM · #15 |
Originally posted by Pedxer:
I seem to get this wierd effect with my long exposures. I cant get distant lights (stop lights, neon signs, burning people, etc) to look sharp. Instead i get this (still pretty cool looking) glowing light beam-hard to describe so I'll post a pic effect. |
Could be due to Aperture. I don't know if it happens on all cameras, but I have an FZ5, so it might be similar. I've noticed that on long exposures, a small aperture (5-8) will give a 6-point star around bright points, and sometimes ghosting, whereas overexposing with a large aperture (2.8-4) tends to give more of a glowing ball effect. I'm not totally sure of the cause of the small aperture star, or whether it happens on other cameras, but my suspicion is that it might be caused by internal reflection of the iris or something like that. Just a guess. As for the glowing ball, just reduce the exposure time to account for the large aperture.
What do people say? Does it happen on other non-panasonic cameras? Does it happen on SLRs?
Message edited by author 2005-07-29 02:34:06. |
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07/29/2005 02:54:05 AM · #16 |
Here is a link to a good on-line Depth of Field calculator.
//photoinf.com/Tools/Don_Fleming/Depth_Of_Filed_Calculator.html
It also calculates the Hyperfocal Distance for a given Aperture and Focal Length. When you are focused at the Hyperfocal Distance (H), everything from H/2 to infinity should be sufficiently in focus for most applications. |
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