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Any advice for wide angle sky shots with a bright moon?


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Greetings SGL

My name is Carl, and I've recenly become more serious in pursuing my interest of the "dark side". While deciding what telescope setup I want to use I've been running around with my Nikon D5100 DSLR (only with the standard 18-55mm 3,5 optics). I've been lurking around SGL and other swedish forums for a while but decided it was time to register and take part in the discussions.

I really like getting wide angle shots of the sky and tonight the weather seems to be nice so I'm going to go out and try to get Jupiter, the Pleiades, Alderbaran and the Moon. My question:

Since the moon will most likely drown out much of the surrounding stuff, do you have any tips to get a nice result with the moon in a wide angle star field shot? Ive seen people stacking different exposures to get detail in the moon but my first tries (and from studying) have been indicating that the moon will be too bright and bleed over when i try to catch lower magnitude stuff.

So any tips on this? Or doest it require huge amounts of difficult photoshopping (altho im not a stranger to image processing) from different images to get a result?

Many thanks

Carl

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At a guess I'd say the best results would always be obtained by blending seperate exposures. Sooting the moon will require a much shorter exposure to retain the detail, but the night sky would need longer exposures, but I think having the moon in the frame while shooting the stars will probably ruin the shot.

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Yeah I'm probably screwed since the lens will probably produce heavy lens-flaring aswell, but nevertheless I'll see if i can't take a few frames and get lucky. I'll post results later ;)

Carl

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I second Allcart. Will be very difficult to get anything decent with the Moon in the sky as it is very bright indeed. To get good star exposure, you will need long exposures ranging into seconds. The Moon will make this difficult to achieve.

Scott.

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I went out for some more experimentation a little while ago. I am once again very pleased with the results since I have only a kit-lens, and the area is light-polluted.

Moon, Jupiter, Pleiades and Perseus

The moon didnt drown everything. Jupiter is very visible right next to it. I managed to get the Pleiades, Perseus and parts of Cassiopeia in this one.

The northern sky

Here's a view of the northern sky with the square of the Plow and Ursa Minor with Polaris at its tail.

Seems I found polaris

A 10 minute exposure of the northern sky. I don't mind the dead pixels when just playing around with settings etc
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Carl, these are nice shots. The sky gets much darker further from the Moon and it is, as you say, bright! :D

I wonder, did you use any sort of tracking to keep the stars sharp, or just reasonable exposures?

Scott.

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Thanks for your kind words Scott.

I use between 15 and 20 seconds exposure with the aperture on maximum (f 3,5) with an ISO of about 400. Focus is manually set to infinite with zoomed live view. I have brightened up the exposure and contrast when importing the Nikon RAW's a bit in the last few pictures but I havent done any serious enhancements other than Photoshop standard sharpness filter. The gradient sky we see is mostly light pollution from the international airport in the moon/jupiter picture and the next town called Knivsta in the Polaris shots. Trailing is visible in 1/1 in the original pictures but less apparent since i usually scale mine down about 50% to 1600px wide.

I hope I can get some good milky way shots next time im join my astronomy club out at the club's permanent observatory outside Uppsala, but chances are I will have my new 150mm newtonian to play with then instead ;)

Carl

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Really nice images even with a bright Moon. The Moon has not messed up the images. It really has added something to them.

I just wonder if a Moon filter would help? Its designed to cut down the glare while observing the Moon, so could work on widefield images when the Moon is bright.

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Thanks Carl,

I had a very brief go at Vega last night and got my exposure down to 2 seconds at ISO 3200. Then turned my attention towards M13 and although I could get the cluster, to make it bright enough to create any sort of reasonable image, I had to expose for 15 seconds at ISO 1000 and the star trailing was obvious. I did try lower ISO and longer exposures and vice versa, but I do think the limitations of my 'scope and the fact that I was in the garden and not at a dark site had a definite effect. I will have another go later I think, but having viewed Andromeda galaxy before the clouds rolled in, and seeing how faint it was in the 'scope, I think DSO photography through the scope will be challenging.

Scott :)

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Scott, the 15+ seconds only works when I set the lens to as wide as I can (18mm). Any closer and trailing becomes a problem (unless you go for broke like I did in the 10 minute polaris shot). Tried getting some shots with my old crummy 105mm but thats too much for get a nice wide view and too little to focus on any objects in particular, unless you want to set up some nice larger targets while theyre still close to the horizon. I was thinking about getting myself a Tokina 11-16 f/2,8 to get really bright wide angel shots but I ordered a SW Explorer 150pds instead :) Still gonna give the Milky Way a go next time I'm away from the city. Also do you have a motorized EQ mount Scott? Otherwise DSO's will be a challenge as far as I understand it.

Luke, I seem to recall some sort of tunable polarisation filters for telescopes (and probably DSLRs). I'm taking a wild guess here but shouldn't one be able to cut some of the moon glare since its reflected has a different polarisation than direct, or am I making this up?

Cheers for all the replies guys!

Carl

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