Long delay between multiple long exposure shots

dh photography

Senior Member
I just picked up a timer remote shutter release to ease in long exposure shots and for playing with star trails and such. I set it up earlier this evening to try my first star trail shot.

I have the remote set on 30 second exposure and 150 shots. My D7000 was set to bulb mode, infinity focus, and f2.8. The problem I ran into seems to be that after each 30 second exposure, them timer is wanting the next exposure to immediately begin again; however the camera itself is taking quite a while to internally process the exposure before allowing another to be taken. Also each of those delays are actually showing up as basically black exposures. When I processed the images into a trail you can see the delay in the shot as very dotted trails rather than more of a group of solid streaks.

Is there any way to reduce the cameras necessary internal processing for long exposures? Maybe a way to have the timer taking 30 second exposures but also delaying it's command for the next shutter release? Amyone familiar with taking star trails that might point me in the right direction??

star trail 1.jpg
 

Vixen

Senior Member
One thing that will help is to get the fastest SD cards you can. I use SanDisk Extreme Pro which read/write at 96mb/sec. I don't have to wait very long at all after a long exposure. Also...turn off the in camera noise reduction.
 

Blade Canyon

Senior Member
Yes, turn off long exposure noise reduction if you want faster shots. The way that feature works is that the camera takes an internal photograph that is just as long as the one you just exposed, then it subtracts the noise from the "black" shot from your exposed shot. It effectively doubles the length of time for each shot.

You still got a pretty cool pic, though.
 

dh photography

Senior Member
Good morning! Thank you both for the quick replies. Never thought about the internal noise reduction setting. Bet that's the culprit. I'll set up again this evening (if the clouds stay away) to give it another go. I stepped up to the 32g high speed cards just a couple months ago when there was a deal on. I think one is the Extreme and the other one is the fast PNY version.
 

aroy

Senior Member
Yes most of the bodies will expose a "dark frame" after each long shot. That is done to detect; and subtract; primarily thermal noise which affects sensors as they heat up during long exposures. The best method is to switch the NR off, but to take a "dark frame" at least once before first shot and once after the last shot. Use any of the free software available on the net to use the dark frames.

The thermal noise is one of the reasons that most astrographers use cameras which are cooled. The cooler the better, and some dedicated cameras use liquid nitrogen for very low noise.
 

dh photography

Senior Member
Yes most of the bodies will expose a "dark frame" after each long shot. That is done to detect; and subtract; primarily thermal noise which affects sensors as they heat up during long exposures. The best method is to switch the NR off, but to take a "dark frame" at least once before first shot and once after the last shot. Use any of the free software available on the net to use the dark frames.

The thermal noise is one of the reasons that most astrographers use cameras which are cooled. The cooler the better, and some dedicated cameras use liquid nitrogen for very low noise.


Excellent info. Thank you. Definitely learning something new every day. Never crossed my mind about sensor heat. Something to pay attention too; especially during summer shoots. I would hope with the temp near freezing, that's a non factor now.
 

aroy

Senior Member
Here in India, we have to be careful, as the ambient may cross 45 degrees centigrade in summer. Even indoors without AC it will hover around 40. As yet my D3300 has had no problems in the heat, but the battery lasts only 300 images in summer. It is now increased 450 as the temperatures have come down.
 

dh photography

Senior Member
Here in India, we have to be careful, as the ambient may cross 45 degrees centigrade in summer. Even indoors without AC it will hover around 40. As yet my D3300 has had no problems in the heat, but the battery lasts only 300 images in summer. It is now increased 450 as the temperatures have come down.

Now that's some heat; especially with humidity added in. We're regularly in the 35 range a lot during the summer, but I haven't seen 45+ since my time in the Middle East.
 

dh photography

Senior Member
Update:

Turned off the internal NR and it worked like a charm. Rattled off 150 consecutive 25 second shots without a hitch. Also threw in my dark shots when running my stacking. Much much better results! Now I just need to set up in a more interesting location with something striking in the foreground.

Thank you for all the help!!
 

Scott Murray

Senior Member
Hi yes long exposure NR and high ISO NR can be the culprit.

My mate took his cough 'Canon' in to some reps as it was taking ages to process some images. They informed him it would need to be sent away for repair as it was most likely the processor. I told him to let me have a look at it first. After doing a test shot it was taking 25sec to process a 20 sec shot. I turned off NR for both high ISO and Long exposure and hey presto it was fixed. Needless to say he was very happy about it.
 

dh photography

Senior Member
Hi yes long exposure NR and high ISO NR can be the culprit.

My mate took his cough 'Canon' in to some reps as it was taking ages to process some images. They informed him it would need to be sent away for repair as it was most likely the processor. I told him to let me have a look at it first. After doing a test shot it was taking 25sec to process a 20 sec shot. I turned off NR for both high ISO and Long exposure and hey presto it was fixed. Needless to say he was very happy about it.

Yessir. Once I turned both of those off, she clicked away right on que every 25 secs. I must say I'm pretty happy that it was operator error rather than the alternative. I was kind of thinking my $13 import remote could have been the culprit. Now; I'd say that was a pretty good $13 spent.
 
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