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Date: 20 Jul 2006 08:13:01
From: DWilson
Subject: Focusing Nikon D50
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Hi - I recently purchased a Nikon d50 and tried some shots of the sky using
a camera tripod. The stars all came out looking like little donuts, in other
words out of focus. Can someone tell me how to get this in focus? I had it
set for manual focus...should I have used auto focus? Any advice would be
appreciated.
Thanks
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Date: 20 Jul 2006 16:14:56
From: Sam Wormley
Subject: Re: Focusing Nikon D50
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DWilson wrote:
> Hi - I recently purchased a Nikon d50 and tried some shots of the sky using
> a camera tripod. The stars all came out looking like little donuts, in other
> words out of focus. Can someone tell me how to get this in focus? I had it
> set for manual focus...should I have used auto focus? Any advice would be
> appreciated.
> Thanks
>
>
Critical focus changes with temperature... at least in my Canon lenses,
so presetting is not a guarantee of good focus... I use a 2.5x angle finder
on the camera to aid in focusing--essential really.
Similarly with the camera at prime focus on the telescope, the 2.5x angle
finder is essential... again focus can change with temperature.
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Date: 20 Jul 2006 10:32:24
From: S. Caro
Subject: Re: Focusing Nikon D50
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DWilson wrote:
> Hi - I recently purchased a Nikon d50 and tried some shots of the sky using
> a camera tripod. The stars all came out looking like little donuts, in other
> words out of focus. Can someone tell me how to get this in focus? I had it
> set for manual focus...should I have used auto focus? Any advice would be
> appreciated.
It depends on your camera and lens.. I have an old Canon 10D and find
that Jupiter is generally bright enough for the camera autofocus to
work.
I put the lens in Auto Focus, then focus on Jupiter. Once proper focus
is obtained I switch the lens to Manual Focus so it doesn't change.
Now I can shoot all the stars and have them in sharp focus. The moon
is another good subject for obtaining focus on 'infinity'.
If Jupiter or the moon aren't around, I usually focus on distant lights.
I live in the country so it's pretty dark. There are a couple of yard
lights about a mile or so away. I find if I focus on them, it's just
as good as focusing on Jupiter.
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Date: 20 Jul 2006 09:35:49
From: John Steinberg
Subject: Re: Focusing Nikon D50
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DWilson wrote:
> Hi - I recently purchased a Nikon d50 and tried some shots of the sky using
> a camera tripod. The stars all came out looking like little donuts, in other
> words out of focus. Can someone tell me how to get this in focus?
If you were using manual focus and did not have it set to infinity,
there's a potential problem in the optical train.
(The train consisting of the camera optics and your own visual acuity.)
Actually, more input is needed. For example, exposure and shutter
speed settings, was it mounted on a sturdy tripod, etc?
--
-John Steinberg
email: not@thistime.invalid
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Date: 20 Jul 2006 13:34:12
From: Chris L Peterson
Subject: Re: Focusing Nikon D50
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On Thu, 20 Jul 2006 08:13:01 -0400, "DWilson" <dwilson577@comcast.net >
wrote:
>Hi - I recently purchased a Nikon d50 and tried some shots of the sky using
>a camera tripod. The stars all came out looking like little donuts, in other
>words out of focus. Can someone tell me how to get this in focus? I had it
>set for manual focus...should I have used auto focus? Any advice would be
>appreciated.
You generally can't autofocus on stars. There are several manual focus
techniques you can try. During the day, carefully focus on a distant
scene and then place marks on the focus ring (which probably won't quite
be where the lens shows infinity to be). Position the lens here when you
shoot stars. Another trick is to focus on some very bright point source,
if one is available. Depending on the lens, you might be able to see a
few bright stars, planets, or distant streetlight. Finally, you can buy
an attachment to the viewfinder that magnifies the view. This will let
you see dimmer stars and focus on them more accurately.
Focusing a DSLR for shooting the sky is definitely a tricky procedure
that requires practice. Your experience isn't uncommon.
_________________________________________________
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com
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Date: 20 Jul 2006 16:31:03
From: Iordani
Subject: Re: Focusing Nikon D50
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Chris L Peterson wrote:
> On Thu, 20 Jul 2006 08:13:01 -0400, "DWilson" <dwilson577@comcast.net>
> wrote:
>
>>Hi - I recently purchased a Nikon d50 and tried some shots of the sky
>>using a camera tripod. The stars all came out looking like little donuts,
>>in other
>>words out of focus. Can someone tell me how to get this in focus? I had
>>it set for manual focus...should I have used auto focus? Any advice would
>>be appreciated.
>
> You generally can't autofocus on stars. There are several manual focus
> techniques you can try. During the day, carefully focus on a distant
> scene and then place marks on the focus ring (which probably won't quite
> be where the lens shows infinity to be). Position the lens here when you
> shoot stars.
If you are using an auto focus lens this probably won't work since the
focusing ring does not have a fixed position with respect to a specific
distance/focus. At least it doesn't on my lens. (18-70mm zoom)
I use following method.
At the focus ring, put a distinct mark of some sort.
I use a bit of masking tape in one of the "grooves" in the focusing ring.
On one part of the lens close to the focusing ring, I have put a strip
(some 2 inches) of masking tape, as close to the focusing ring as
possible.
Now, I turn the focus ring all the way to infinity and *then another whole
turn* until the mark in the groove lines up exactly to a distinct offset
mark on the strip. Take a test shot and check focus, move the ring from
infinity a *tiny* bit, take a test shot, and so on, until you have
reached focus.
Take care to move the ring only one way while doing this.
Now when you have reached focus, put another mark (focus mark) on the strip
exactly opposite to the mark in the groove. Next time you want to focus,
move the focus ring to infinity and then slowly continue until the mark on
the focus ring is at the offset mark, then back until it is at your focus
mark.
(hmmm... when reading this it sounds complicated, but it really isn't!)
If you use a zoom lens, this focus mark will most likely only work for the
focus length you used at the time you made the mark. So if you want to use
more then one focal length you will have to repeat this and make additional
marks on the strip.
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Date: 20 Jul 2006 14:58:01
From: Chris L Peterson
Subject: Re: Focusing Nikon D50
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On Thu, 20 Jul 2006 16:31:03 +0200, Iordani <somewhere@earth.net > wrote:
>If you are using an auto focus lens this probably won't work since the
>focusing ring does not have a fixed position with respect to a specific
>distance/focus. At least it doesn't on my lens. (18-70mm zoom)
>
>I use following method...
I've never seen an autofocus lens like this, but your solution sounds
like a good one. All of my autofocus lenses have fixed rings, but some
don't have any markings, so I need to mark both sides.
>If you use a zoom lens, this focus mark will most likely only work for the
>focus length you used at the time you made the mark. So if you want to use
>more then one focal length you will have to repeat this and make additional
>marks on the strip.
Good point. Even very good zoom lenses rarely control their focus well
enough for stellar imaging, even if they appear perfect for normal
terrestrial use.
_________________________________________________
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com
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Date: 20 Jul 2006 22:40:49
From: William Hamblen
Subject: Re: Focusing Nikon D50
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On Thu, 20 Jul 2006 08:13:01 -0400, "DWilson" <dwilson577@comcast.net >
wrote:
>Hi - I recently purchased a Nikon d50 and tried some shots of the sky using
>a camera tripod. The stars all came out looking like little donuts, in other
>words out of focus. Can someone tell me how to get this in focus? I had it
>set for manual focus...should I have used auto focus? Any advice would be
>appreciated.
Autofocus won't work on stars.
Autofocus lenses will focus beyond infinity, so you just can't put the
lens over to the infinity stop and get good results. You probably
will have to use trial and error to find the correct setting. Here is
one method for finding infinity focus on a camera lens:
http://www.astrofoto.org/tips/focus/index.html
Bud
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Date: 20 Jul 2006 20:01:41
From: nytecam
Subject: Re: Focusing Nikon D50
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DWilson Wrote:
> Hi - I recently purchased a Nikon d50 and tried some shots of the sky
> using
> a camera tripod. The stars all came out looking like little donuts, in
> other
> words out of focus. Can someone tell me how to get this in focus? I
> had it
> set for manual focus...should I have used auto focus? Any advice would
> be
> appreciated.
> Thanks
I use my Canon Rebel/300D with standard Canon autofocus zoom lenses for
general sky shots on tripod or LX200 piggybacked. Autofocus gets close
to infinity eg point at night sky and depress shutter [to focus]. Move
focus slider from Auto to Manual and fully depress shutter to take pic.
Examine pic on LCD at full zoom - manually tweak focus slightly and
repeat 'till stars/ distant trees etc are sharp.
Note: focus is NOT held when changing the zoom setting with modern DSLR
autofocus lenses eg focus shifts too and above procedure must be
repeated!
Nytecam 51N 0.1W
--
nytecam
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Date: 20 Jul 2006 15:02:14
From: atasselli@hotmail.com
Subject: Re: Focusing Nikon D50
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DWilson wrote:
> Hi - I recently purchased a Nikon d50 and tried some shots of the sky using
> a camera tripod. The stars all came out looking like little donuts, in other
> words out of focus. Can someone tell me how to get this in focus? I had it
> set for manual focus...should I have used auto focus? Any advice would be
> appreciated.
> Thanks
With Nikons/DSLRs (I have several) the best practice (if possible avoid
zooms as they are no good for deep sky shots and more often than not
even for terrestrial photos) is to start shoting the polar star (and
surroundings) as for lengthy exposures it won't move. Set the camera
exposure dial to M (manual) e move the little lever beside the lens to
M as well. Set the exposure at 10s and center Polaris in the frame.
Start with widest aperture you have. Set the focus ring to infinity
(oo). Put a hand (or a cap or a cardboard) in front of the lens and
press the shutter release. After a couple of seconds remove the
hand/cap/cardboard from the lens' front and wait till the exposure is
completed (the hand/cap/cardboard trick is to avoid shaking the camera
while exposing). Remove the camera from the tripod and download the pic
to a PC. See if it is in good focus (look at the center portion of the
photo only). If not go back and repeat the process moving the focus
ring very very slightly toward either directions (with some lens the
focus ring won't move past the oo mark), and I mean REALLY slightly.
Once you find the best possible focus take some adesive tape (for
electrical cables and such, it will last longer), cut a small piece and
stick it so that it straddles across the focus ring and the non moving
part of the lens' body. Use a very sharp knife or balsa-wood cutter cut
the tape were the focus ring meets the lens body.Now you can return to
the best focus position any time you want and still use the lens for
daytime photography.
Andrea T.
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Date: 20 Jul 2006 21:24:56
From: DWilson
Subject: Re: Focusing Nikon D50
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Thanks everyone for the tips. I will certainly try your suggestions.
Another thing I'm wondering is how many people are actually using the d50
for astrophotography.
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Date: 21 Jul 2006 10:46:14
From: Iordani
Subject: Re: Focusing Nikon D50
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DWilson wrote:
> Thanks everyone for the tips. I will certainly try your suggestions.
> Another thing I'm wondering is how many people are actually using the d50
> for astrophotography.
Try 'astrophotography nikon d50' in Google and you'll have a lot of
reading...
Depending on how serious you are about this, following links may or may not
be of interest. (I own a D70 and the "mode 3" method really makes a
difference.)
http://www.sfu.ca/~dmunro/D50.html (check out the FAQ)
http://astrosurf.com/buil/d70v10d/eval.htm
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