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Old Dec 4, 2006, 10:46 PM   #1
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I'm trying to take a photo of the trees around my house that are covered in ice after a recent winter storm with the full moon lighting up the tree. I'm having trouble getting my D50 with the kit lens to focus on the tree and get a good photo. I've tried all the different focus modes and both spot and center-weighted metering. Does anyone have suggestions?
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Old Dec 5, 2006, 1:48 AM   #2
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In real low light, it could take a second or two to lock (steady green light) after a half press of the shutter button. If you can't get a lock, use manual focus.

You're also getting a touch of flare from it shooting wide open at f/3.5 with the overexposed moon in the frame. If you're using any filters, remove them (as it can be a contributing factor).

You may want also to consider using manual exposure and stopping the aperture down a tad to see if that helps it or not (which will require even longer shutter speeds to expose the tree without increasing ISO speed, which you don't want to do for this type of shot).

I'd probably go down another stop or so (around f/5.6 on the wide end of the lens for starters, using a longer exposure for the tree).

Please don't take offense if you are already doing this, and I doubt it would be that good without one.

But, I'll ask this question anyway, just to make sure... You are using a tripod, right?

If so, how is the wind? With an exposure that long, if the tree limbs are blowing around in the wind, you're going to get some motion blur, even with a tripod.

Unless you really want an overexposed moon in the frame, you may want to consider shooting from the other side of the tree, too. Or, expose one for the moon and the other for the tree and merge them using software.
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Old Dec 5, 2006, 12:29 PM   #3
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I'm using a tripod, an have removed the UV filter.Wind is dead calm too.I'm even using the remote shutter release to minimize tripod movement. I just can't get a focus lock on the tree and because of the low light I can't see well enough in the viewfinder to get a good manual focus. If I were to use a flashlight to illuminate the tree to get an AF lock and switch it off and set the exposure manually would that work? I think I may have one more night to try to get a good capture with the ice on the trees before it melts. I'm planning on using software to get a properly exposed moon with the tree properly exposed as well. I was just playing around in my front yard so I could quickly go back inside and look at the results on my PC monitor until I get a good technique down.
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Old Dec 5, 2006, 1:14 PM   #4
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Why not just focus on the moon (it's pretty bright) then switch the camera to manual focus and re-frame?

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Old Dec 5, 2006, 1:33 PM   #5
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If you stay on the wide end of a wider zoom (which it looks like you're were doing), you've got lots of room for error using manual focus shooting a tree like that.

Use Manual Exposure and select around f/5.6 with it at 18mm or there abouts. The shot will be sharper if you're not shooting with the aperture wide open like you were doing at f/3.5, and you'll have even more depth of field that way.

Then, try different shutter speeds till you get the brightness the way you want it, using the histogram as a guide.

Keep your ISO speeds set low. You'll get better results at lower ISO speeds using longer exposures versus higher ISO speeds using faster exposures if wind is not an issue in most cases.

You should be able to set the focus ring for almost anything past 10 feet shooting a tree like that and get a good photo as long as you're not focusing past infinity (which some lenses will do).

Hyperfocal distance would only be around 9 1/2 feet with those settings. So, just set it so it would be in focus at something at that range or further on the wide end of the lens at around f/5.6 and you should be able to get a good photo once you get the exposure right. Forget the Autofocus and use the focus ring.

Go here:

http://www.dofmaster.com/dofjs.html

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Old Dec 5, 2006, 2:10 PM   #6
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P.S.

You'll need longer exposures at lower ISO speeds with the aperture stopped down more and might get some hot pixels.

Try it with noise reduction turned on first.

It's probably turned on by default (on long exposures it takes a dark frame exposure immediately after the main exposure so it knows where to remove hot pixels in your image, based on where it finds them in the dark frame exposure, replacing them with values interpolated from surrounding pixels).

Then, try it with noise reduction turned off (and you may see some hot pixels on longer exposures with it off).

Then, immediately take a photo using the same settings with the lens cap on.

That way you'll know how many (if any) hot pixels are causing an issue and can use the dark frame to do your own dark frame subtraction and see if you can do a better job compared to the camera's noise reduction system at retaining detail on long exposures.

It may have a threshold set too low for what's really a hot pixel versus noise and cause more reduction in detail than desired compared to doing it yourself if needed at the desired viewing/print sizes. Try it both ways to see what works best.

See How to Subtract Dark Frames with Photoshop, Photoshop LE, or Photoshop Elements (and you can apply this technique some other products with layers, and even get software like PizelZap that can work with or without the dark frame). There are more sophisticated ways of doing it, and some raw converters can even support hot pixel coordinates and interpolate them out of the final image.

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Old Dec 5, 2006, 3:11 PM   #7
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How do you focus a lens in the dark at the hyperfocal distance if the lens doesn't have a distance scale?

Keith.
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Old Dec 5, 2006, 3:23 PM   #8
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Put in somewhere in the ballbark and you don't even need a distance scale for a tree like that with a wide lens.

Heck, you can figure out how much you'd need to move it to get somewhere near it just by playing with the lens in good light. lol

It really doesn't make much difference where you put the focus ring past the middle shooting a tree at that range (unless it's closer than I think) at 18mm and f/5.6, unless you're going past infinity (which a number of lenses may do using Autofocus).

See the DOF calculator, I posted a link to, plug in 10,000 feet and you're still going to be fine shooting a tree like that with a wide lens like that, even without stopping down much (which is why I suggested f/5.6). Put it the focus ring past the the middle of the range somewhere. You should be OK with it at almost anywhere for that shot. ;-)

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Old Dec 5, 2006, 3:32 PM   #9
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JimC wrote:
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Put in somewhere in the ballbark and you don't even need a distance scale for a tree like that with a wide lens.

Put the focus ring past the middle of the range somewhere. You should be OK with it at almost anywhere for that shot. ;-)
It clearly isn't that easy - hence the original poster's question. That is why I suggested focusing on the moon. With a reasonal DOF the tree would be in focus as well.

Keith.
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Old Dec 5, 2006, 6:02 PM   #10
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Thanks a lot everyone, I'll try some more tonight (hopefully not everything melted today) and post up some results later.
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