Night-time Exposure Problems

N

Naad47

New member
Hi Everyone,

As it turned out, I wasted 2 hours after midnight last night taking 200 pics of the lovely night sky, only to find that when I went to my D7100 this am to process the pictures to create a star trail, I found that after the first 7 exposures, the next 30 were underexposed, then I would get one at the correct exposure, then another 30 underexposed and so on.

I was using my 18-55 lens set on manual, Camera mirror up, a user setting on the camera that has an ISO of 5000, the aperture at 3.5 and the exposure at Bulb. I then have a remote intervalometer that is set to take a 30sec exposure picture with a delay of 7 seconds between each.

Any ideas as to why after the first few, I would get only 1 in 30 ok ?

Thanks, Nige.
 
P

pforsell

Senior Member
Have you checked the EXIF of the images that every image really has the settings you think they have?

Shutter speed, aperture, ISO?
 
N

Naad47

New member
Sorry, No I didn't. I was that hacked off with the results I formatted the sd card.

I see your point though, am I correct in assuming therefore, that the camera would revert to the user 1 settings after each take, rather than keeping to any
minor adjustment I would have made before running the intervalometer ?

Nigel.
 
P

pforsell

Senior Member
Naad47 said:
Sorry, No I didn't. I was that hacked off with the results I formatted the sd card.

I see your point though, am I correct in assuming therefore, that the camera would revert to the user 1 settings after each take, rather than keeping to any
minor adjustment I would have made before running the intervalometer ?

Nigel.
Click to expand...

There are too many possibilities. It could be that the intervalometer itself acted up, and that would be evident in different shutter times. If you had Long Exposure Noise Reduction ON, that would cause all the timings to go badly off, because a 30 second exposure is followed by a 30 second black frame.

But without EXIF all we can do is guesswork. :confused:
 
B

Blacktop

Senior Member
Naad47 said:
Sorry, No I didn't. I was that hacked off with the results I formatted the sd card.

I see your point though, am I correct in assuming therefore, that the camera would revert to the user 1 settings after each take, rather than keeping to any
minor adjustment I would have made before running the intervalometer ?

Nigel.
Click to expand...

Did you just look at the images on the back LCD of your camera? That is how I am understanding this, since you said that you have formatted the SD card.
 
S

STM

Senior Member
Try these settings: 25 sec exposure @ f/11 @ ISO 1000-1200. This works well for me. The image below was composed of 75 exposures stitched together with StartStax software

 
N

Naad47

New member
Thanks STM. I'll give those setting a try next time, nice Star Trails pic. Glad to find someone else using StarStax. its a great simple to use tool that produces fine results.
 
N

Naad47

New member
Many thanks for your reply's pforsell. I'm sure you are on the right track. I'll make sure to ask here before I delete next time.
 
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