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up vote 13 down vote favorite

alt text I used a tripod and remote shutter release. ISO:1600, F/3.5, Exp 46". I expected the flare and halo, but the ghosted spheres surprised me. Can you tell me what caused this and how to adjusting my settings? Thank you

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I see your not able to yet post a picture, but could you link a picture or something? That would really help... Also, any other information, camera type, lens type, etc would help. – PearsonArtPhoto Jan 10 '11 at 18:49
What were you trying to achieve? Were you trying to use the moon to light a landscape, or were you taking a picture of the moon itself? – drewbenn Jan 10 '11 at 20:08
I've taken dozens of night shots recently (still experimenting) because of the clear starry sky, so my objective has been to get pictures with lots of stars. Last night my objective was to get the moon with stars - I was not trying to capture details in the moon (if only I could attach the photo to this). Last night's photos are good and the few with the moon aberration are unique looking. I just don't know what caused this - no, it's not overexposed or out of focus or dust on the lens and doesn't look like lens flare. – sej Jan 10 '11 at 21:51
sej: I think you might have enough reputation now to post an image, give it another shot. – PearsonArtPhoto Jan 10 '11 at 21:53
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I think you've captured genuine evidence of extra-terrestrials there! Well done! – Matt Grum Jan 11 '11 at 19:31
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6 Answers

up vote 16 down vote

I'm going to guess... you have a filter on your lens. Probably a UV filter? In my experience, that's the number one cause of ghosting in nighttime photography.

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Yes, I do. Also, did not take this into consideration!! Thanks so much. – sej Jan 11 '11 at 16:35
up vote 6 down vote

I suspect what's happening is one of the following things.

  1. Lens flare. This occurs usually when you have a bright source of light off to a side, and makes some usually hexagonal shaped images appear in your light, as seen below. The cure is to keep the light from said external sources from reaching your lens, and to keep your lens clean. Using a lens hood is usually a good idea.
  2. It could be dust on your sensor or lens. Cleaning each of these is the solution.

Sun Lens Flare Example

I really do like the way your picture turned out. I'm guessing that it is dust in some way or another, so I'd start there. Good luck!

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point 2, don't think you'll get out of focus stars in a moon image, the distance to the moon ought to exceed the hyperfocal distance for any lens settings you could be using! Plus if you expose for the moon you wont get stars in your image as they're much much darker... – Matt Grum Jan 10 '11 at 19:08
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It'd be a little less appearant if the moon was out of focus, but I'm aware that if the moon is in focus, so will the stars. You'll note he used a long time to expose for the moon, I think he's exposing the current moon, which is more of a crescent moon. That will be in the range of stars being visible. – PearsonArtPhoto Jan 10 '11 at 19:22
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Actually, yeah at 46 seconds he must be massively overexposing and getting lens flare. Anyone else really looking forward to getting to actually see the photo now?! – Matt Grum Jan 10 '11 at 19:48
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I'm guessing now it's lens flare. I can't see what else it could be really... Hmmm. – PearsonArtPhoto Jan 10 '11 at 23:47
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The flare does not need to be hexagonal; it should follow the aperture shape. Dust on the sensor would be dark (and only visible at small apertures. – Joey Jan 11 '11 at 12:21
up vote 5 down vote

Exposing the moon for 46 seconds is an EXTREMELY long time. The moon is going to track across the sky during that whole time, creating a trail as it goes. Unless you have a tracking mount (either alt/az, which will track accurately for short periods of time, or a German equatorial, which will track for indefinite amounts of time), you can, at most, expose for about 1 second or so before the moon will start to blur due to its motion across the sky (both imparted by the rotation of the earth, as well as the motion of the moon on its orbit around the earth.) The length of time you can expose will also shrink as your focal length increases.

Additionally, if you are using a lens with image stabilization, you should make sure that IS/VR has kicked in before you actually trigger the shutter. If you have IS enabled, and fully trigger the shutter without giving IS a moment to kick in first, you will often get a ghost due to IS activating while the shutter is open. This is a fairly mild effect, however, compared to what it sounds like you are describing.

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Please help me understand regarding IS/VR: I'm not sure what "kicks in". The camera is set to manual focus. Canon Rebel XS, 18-55mm lens. – sej Jan 10 '11 at 21:57
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@sej: If you have an IS lens, switch IS to "off". – che Jan 10 '11 at 22:45
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@sej: IS = Image Stabilization (Canon), VR = Vibration Reduction (Nikon). There are other terms used for other brands. Image stabilization done in the lens is usually accomplished with a floating element group, and when IS actually "kicks in", that lens group moves to counteract any camera/lens shake. If it kicks in after exposure has started, that movement will usually result in a ghosted image. For long telephoto lenses, I recommend keeping it on so you can properly frame and focus. Either make sure IS is activated before exposing, or turn IS off before taking a shot. – jrista♦ Jan 10 '11 at 22:49
I didn't take the IS function into consideration and therefore did not toggle to off. Thank you very much. – sej Jan 10 '11 at 23:28
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@Tom: With longer focal lengths, there can be plenty of camera shake when trying to focus. Despite mounting my lens to a tripod, I often have trouble with camera shake when trying to focus my 100-400mm lens @ 400mm. Using IS in these situations is a godsend, as it allows you to focus without your subject jittering and wobbling such that you can't tell if you have it in focus or not. – jrista♦ Jan 11 '11 at 2:25
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up vote 3 down vote

The moon is a very bright object. Your image seems to be waaaay too exposed for capturing details on the moon.

EDIT: seeing your posted image now, I believe that the "ghost" spheres are lens flare due to extremely brightly exposed moon, and maybe a nearby star.

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Do you think that a lens hood would help in this situation? – sej Jan 11 '11 at 0:47
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@sej - since the bright object is in your frame (as almost in the dead center of it), a lens hood will be of no help here. You need a lens of a higher quality (read: price) which is more immune to flare. – ysap Jan 11 '11 at 1:52
Yes, I figured so. Thank you again. Your advice is much appreciated! – sej Jan 11 '11 at 16:34
up vote 1 down vote

Well it looks like you've said that you did a 46 second exposure. If thats true, the moon moves much to fast for that slow of an exposure. You'll need to make your shutter speed faster.

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Yes, the moon moves fast, your exposure time should not be more than a few seconds. – decasteljau Jan 10 '11 at 20:11
up vote 1 down vote

You've got at least two different things going on in this image.

  • At ISO 1600 and f/3.5, 46 seconds is WAY too long an exposure for the moon. To get details of the Moon's surface I start at ISO 200, f/8, and 1/125 second. That is 12 stops faster than your exposure! The moon is 4,000 times too bright for your exposure setting. The green orb in the middle appears to be lens flare.

  • The brightest sources in your photo are causing ghosting. This is an inverted and reversed reflection caused by light reflecting off the surface of your sensor (actually the IR filter covering your sensor) or a rear lens element, bouncing back forward through the lens, and then reflecting off a poorly coated rear surface of a forward optical element. Using non-coated UV or protective filters at night when there are a few sources of bright light in the picture will almost always cause ghosting. In your case, the purple orb appears to be a reflection of the moon in the opposite quadrant at the same distance from the center of the frame.

Here is an example of ghosting that is easy to see because the pattern of bright lights is near the upper left edge of the frame and the obvious reflection is inverted and reversed in the lower right quadrant.

Parade

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