Star Trail Help

Hi,
I was practising getting the right Shutter speed/ISO/Aperture settings last night for stacking star trails in my garden. I decided on ISO 400, 120 seconds, F4.5 which seemed OK.

I took 18 photos and after stacking them, I noticed there was a glitch in the trail, I found it was the 5th photo, and was about the first 1/4 of the trail on that photo where the star had move down for about 30 seconds then reverted back to the same line it was previously.

The tripod I use is a Manfrotto MT293A4, with a 494RC2 Head, the tripod wasn't fully extended, it was on solid wooden decking, there wasn't any wind.

Does anyone know what might cause this, I had a problem at Christmas time doing a Star trail of Mount Teide in Tenerife where the trail wasn't smooth.I assumed that was because the ground was sand/dirt(although there wasn't any wind then so there was no reason for it to move).

Star trails take a lot of time, and the only way to find out if its OK is after stacking , so I'm hoping to avoid this happening again.

Here is the photo that was wrong.

View attachment 39157

This was as part of the trail(not sure how easy it is to see in this photo)
View attachment 39156

If the trail moved slightly and continued on a different line, then I would think the Camera/tripod moved. But as it reverted back after about 30 seconds to the original line I don't see Camera/ tripod movement could cause this(unless it moved twice)

I have noticed the MC2 quick release on the tripod, when screwed to the camera doesn't have a great contact area on the camera. I intend to replace the head with a Manfrotto 498MC4 which has a larger quick release plate. Although I don't see any slight wobble would cause this in a star trail.

Is it possible anything in the camera mechanism, or Lense might cause this, is there anything that could move a small amount and slightly move the image? ( Vibration control on the lense was turned off)

Any help in what might cause this would be appreciated ,I'm hoping for some clear skies tonight so I can try some more Star trails.


Thanks,
Andy

The only thing that makes sense is that something hit the tripod during this exposure. The good news is that you can easily fix it using clone stamp or healing brush (as well as other ways)

thanks for the reply, There wasn't anything to hit the tripod, when I was changing settings to get the right exposure, and getting the focus right, I was going out to the camera and making adjustments. But once I started doing the star trail photos, I was sat indoors with my laptop which was connected to the camera with USB cable(and 5m extension) looking at the photos as they were sent to my laptop. One possibility is the USB cable might have tugged on the camera, I can't be sure but I don't think I moved it.

I'm thinking maybe ,as it was at the start of an exposure. It was the action of the shutter release that caused a slight movement, and stayed stuck in that position for 20/30 seconds before returning to it's original position.

It would make sense if a small bird landed on the lens, for 20/30 seconds then flew off, but you don't get many birds flying at midnight.

I think you have to wait a certain amount of days for the pictures to show up. Admins, is this correct? Doesn't show up for me either. But on long exposures.. anything from a little gust of wind can move the tripod. Calm days are the best.

You get birds flying... you just don't see them. haha.

andy1read said:

thanks for the reply, There wasn't anything to hit the tripod, when I was changing settings to get the right exposure, and getting the focus right, I was going out to the camera and making adjustments. But once I started doing the star trail photos, I was sat indoors with my laptop which was connected to the camera with USB cable(and 5m extension) looking at the photos as they were sent to my laptop. One possibility is the USB cable might have tugged on the camera, I can't be sure but I don't think I moved it.

I'm thinking maybe ,as it was at the start of an exposure. It was the action of the shutter release that caused a slight movement, and stayed stuck in that position for 20/30 seconds before returning to it's original position.

It would make sense if a small bird landed on the lens, for 20/30 seconds then flew off, but you don't get many birds flying at midnight.

Click to expand...

I think we have to rule out anything within the camera since it didn't do it with the other images. And we can also rule out the shutter release stuck theory since light did indeed make it to your sensor (something that wouldn't occur if your mirror/shutter were stuck somehow). And mirror-slap is out of the question since this occurred well into your exposure and not at the beginning. After the mirror is up there's no other moving parts in the camera during the exposure process that would account for any movement. That leaves only camera shake of one form or another as the cause. Now whether it's from your USB cable or wind or even the focus ring on the lens slipping, that's a tough call. But the good news is that it happened to only one of your images which means it's a fluke rather than a reproducible problem. Try repeating the star trails shot and weigh down your tripod set up with a bag of sand or do like I do and hang a bag of pennies to your tripod (assuming you have the weight hook on the center post) and see if this issue repeats itself.

Btw, welcome to Nikonites.