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alligator · Jul 4, 2006, 11:34 PM

I had an opportunity recently to take a few photos of the stars, the moon, and venus. This is a rather unique situation since I live in a very light polluted city.

My only problem is that the photos did not turn out as well as I would have hoped. Can anyone suggest ways to fix this? I'm not very good at this, but willing to learn more.

I'm using a 6.3 MP Cannon Digital Rebel (EOS) with a Tamaron 50-300 telephoto lens (to get the close up photos of the moon). I use an infrared remotely operated shutter control (which eliminates vibration), a cheap tripod, and a lens hood. I have the film speed on 200 and the lens on manual focus.

Here are some of my results. I'm just not satisfied with any of them.

The moon is missing all of its detail.

I like the way this was framed. This shot includes Venus! But where is the moon detail?

This was a 30 second exposure of some very weak stars. How come they are all different colors? And how can I clean these up?

Thanks!

Demonhood · Jul 5, 2006, 02:26 AM

check your manual for 'mirror lockup' and 'long exposure noise reduction'.

alligator · Jul 5, 2006, 10:05 AM

Apparently my camera doesn't have the "long term exposure noise reduction" feature. I think that is found only on the Canon Digital Rebel XT and EOS 20D. Mine is the EOS 300D. I also can't find "mirror lockup" anywhere in the manual.

Help?

Knightrider · Jul 5, 2006, 11:40 AM

Originally Posted by alligator

My only problem is that the photos did not turn out as well as I would have hoped. Can anyone suggest ways to fix this? I'm not very good at this, but willing to learn more.

If you go to adobe.com web site you can d/load PhotoshopCS2 30 day try out and try playing with the image adjustments. You can also download a beta version of a program called 'Lightroom' which is a mac only version at the moment. Its valid until the end of the year and its pretty good.

K.

f1000 · Jul 5, 2006, 11:55 AM

Originally Posted by alligator

This was a 30 second exposure of some very weak stars. How come they are all different colors?

Stars are different colors. You just didn't notice it before because they are so faint.

f1000 · Jul 5, 2006, 12:04 PM

By the way, are you compensating for the Earth's rotation in any way?

Demonhood · Jul 5, 2006, 12:51 PM

dang. looks like they didn't add mirror lockup until the XT as well. sorry.

try taking a shorter exposure for the moon shot. the lack of sharpness might have been due to the moon moving (and/or the earth rotating).

alligator · Jul 5, 2006, 03:11 PM

So what I'd really need is a computer controlled telescope to account for the movement of the stars?

I already have Photoshop Elements 3.0, how is CS any different? Would Apple's Aperature help? I'm considering using that for some of my other photos (non-astronomy related).

Photo678 · Jul 6, 2006, 03:42 AM

not sure about your cam...but you will want to stop down the aperture, you will pick up a bit more moon detail. your shots are basically a bit overexposed, hence the loss of detail

good luck

alphamatrix · Jul 6, 2006, 09:46 PM

The Moon is brighter than the stars, as the poster above recommended you should stop down the aperture to the point where the moon's highlights aren't blowing out. Stopping the lens down will also produce a sharper image in most cases. If your camera has a spot metering mode you should use it when you're shooting the moon directly. The white balance should be on daylight as its reflecting the sun's light.
You have to consider ISO, shutter speed and aperture and the fact that you are shooting moving objects. If the exposure is too long then you lose detail due to the moons and/or stars movement.
As for the last photo, stars are different colors, so thats not a problem. I would have used a higher ISO for that shot so more stars are visible.
I've been able to take perfectly useable shots of the stars without anything special, just a tripod and my camera.
Here are two pictures of my own... the stars movement is somewhat visible but not to the the point where its distracting IMO.
26mm, f/2.8, 20 sec, ISO 1600 (some noise reduction done in photoshop):

50mm f/2.0, 25 sec, ISO 800:

alligator · Jul 9, 2006, 10:28 AM

Okay, for my second attempt at astrophotography:

This time I used an equal timed shot with the lens cap on as a subtraction layer to reduce inherent pixel noise in the camera. I also used a reduce noise filter in Photoshop.

And finally, a better (although slightly out of focus) shot of the moon. It's hard to focus manually on this thing!

I might have another shot at the full moon tonight. Any recommendations for better shots?

alphamatrix · Jul 9, 2006, 03:02 PM

You're still shooting at ISO 200 so unless the exposures are quite long (several minutes, which would be useless w/o a tracking system) you shouldn't need too much in the way of noise reduction or dark-frame subtraction but they are both good things to learn.
The first two appear to be in-focus but maybe should have had higher ISO, longer exposure, or wider aperture. The moon, while pretty well exposed is not in focus. The stars and the moon are so far away it should not be difficult to get them in focus. All you need to do is turn the focus ring all the way to the left so that the marker is on infinity and you should be set. I'm not sure how MF mode works on your camera, all I have to do is flip a switch and AF is disabled.