Frustrating failure . . . D7100 intervalometer issues

[qleak]

So I set my D7100 intercalometer to 120 x 30" intervals of 30" exposures and got 60 x 1' intervals with 30" exposures. Only wasted an hour. Here's a crop in of the stacked version with dashed star trails lol

the




I looked up the relevant manual section and the intervalometer doesn't take pictures if it's past its next start time. I couldn't find any reference to how much extra time is needed.

I tried doing some rudimentary calculations to guess the times like adding the CH frame rate but these estimates have been vastly too fast. So most of what I've figured out below is from trial and error.

The following two solutions appear to give adequate time to capture roughly every 30s

• T=33s per exposure 1/11~9% unexposed time.
  
• 4:50<T<=4:55 for a batch 9 exposures That's between 6.9% and 8.5% unexposed time

Which do you think will look better for an hour or longer series of exposures? I'm leaning towards T=33 single exposures because then all the blank spaces will be spread out.

Here are some things that I have verified are not the problem:

• I'm not running out of buffer space. It may be related to the shallow buffer, but I can observe the buffer go down and steadily stay at r04. The problem also happens in normal jpegs which the buffer is much deeper for.
  
• I don't have any Noise Reduction on so it's not taking a dark frame between each shot.
• I have a rather fast set of SD cards class 10 at 90MB/s so I highly doubt that's what is slowing me down.

Thought's welcome! Happy new year

 

[astroNikon]

I can't recall but whenever I use the intervalometer it's always opposite of how I think it works It takes me a few tests to get my understanding straightened away. Maybe take a few 30 second runs and figure it all out before jumping to an hour.
Sorry can't be of much more help. I'll run a test but I've never had a problem with my d7000 and d600 even on hour long runs. I just can't remember how it works lol

 

[qleak]

I can't recall but whenever I use the intervalometer it's always opposite of how I think it works It takes me a few tests to get my understanding straightened away. Maybe take a few 30 second runs and figure it all out before jumping to an hour.
Sorry can't be of much more help. I'll run a test but I've never had a problem with my d7000 and d600 even on hour long runs. I just can't remember how it works lol

Thanks for your response. So what do you think will work better for the star trails? Lots of smaller gaps or a few larger gaps?

Maybe I just need an intervalometer that can do bulb exposures.

 

[KmH]

No exposure longer than 15 seconds, small time gaps between exposures, and lots of exposures will work best.

 

[astroNikon]

If you have large gaps between exposures then you'll get the gaps between the trails.
If you do long exposures then you'll introduce more noise.
So as Keith mentions shorter long exposures with short gaps between them

experiment pointing to the North Star / Polaris to get the circular photos

It all depends upon what you want in your photo - long exposure with long delays between, or variety of other options. Here's a couple examples with different lengths of trails ==> Fixed Tripod Astrophotography - Star Trails

 

[astroNikon]

It's been freezing cold out ... but I just realized I have a radio remote release .... hmm ... i can watch from my kitchen window now !! haven't thought of that until now . duh

 

[qleak]

No exposure longer than 15 seconds, small time gaps between exposures, and lots of exposures will work best.

Thanks for your feedback

At 15" exposure time, the intervalometer only functions at a minimum of 17" per exposure. 2/3 as small but twice as often.

It appears that lower exposure times require at least 1" extra to function. 8" gives the longest exposure where the D7100 intervalometer will function with 1"+exposure. I imagine things get worse much faster than this.

The camera is clearly capable of taking the exposures more quickly than this even with longer exposures. Holding down the shutter the exif reads 16" between 15" exposures and it may be rounding up there

 

[runnah]

I would suggest an app like Triggertrap as it allows for much better fine tuning.

 

[qleak]

If you have large gaps between exposures then you'll get the gaps between the trails.
If you do long exposures then you'll introduce more noise.
So as Keith mentions shorter long exposures with short gaps between them

experiment pointing to the North Star / Polaris to get the circular photos

It all depends upon what you want in your photo - long exposure with long delays between, or variety of other options. Here's a couple examples with different lengths of trails ==> Fixed Tripod Astrophotography - Star Trails

Thanks for the link

I was going for an interesting foreground object: roche de bueof. A Native American sacred place "buffalo rock" that was torn mostly apart in 1907 to build the now decrepit bridge.

I must admit, it was very cold last night 12F and this was my first go. So I just picked a place I could park my car next to the tripod and hang out in my car while it clicked away.

There are places that would give less light polution (shooting south). But theres no parking on that side of the bridge.

Shooting towards polaris with this object would point me north towards toledo and detroit (worst possible light pollution) and would necessitate trespassing. I'm thinking I'll save this for the dark sky preserve nearby, now if only I knew some interesting objects to shoot there

It's been freezing cold out ... but I just realized I have a radio remote release .... hmm ... i can watch from my kitchen window now !! haven't thought of that until now . duh

At 12F I'd have loved to have a warm mug of tea and a toilet available. Only bad thing about living in a city

 

[qleak]

I would suggest an app like Triggertrap as it allows for much better fine tuning.

Well now I have an excuse to buy a trigger trap setup. I'd been thinking about playing with one of these but felt it was frivolous since my camera has a built in intervalometer. thanks!

 

[astroNikon]

Ohio?
I thought you lived in Nebraska?
well if you wander up to Detroit PM me and I'll give you my phone #
I'm just north of Detroit.

 

[JTPhotography]

It is a little tricky to figure and that is made worse when a mistake isn't just a little one but rather turns out ruining your whole night. I went through this a few weeks ago, we haven't had any clear nights for me to pursue it, but I had no problem making 30' exposures work, setting the intervals at around 32 seconds, make sure your autofocus is off as the shutter will not fire if it searches for focus. I am sure there are some other things that will screw it up, like mirror lockup. I think this is about 45 stacked shots taken at the setting above. The gaps are hardly noticeable and I will have to google it again but there is a filter you can run in GIMP that will smooth them out. I would have had these going all across the sky with about 150 shots but I didn't want to invest that time without knowing it would work first. Need more clear skies, BAD!!! LOL

ps: that streak in the middle is a cloud that I could barely even see.

 

[qleak]

The gaps are hardly noticeable and I will have to google it again but there is a filter you can run in GIMP that will smooth them out.

I found this for gimp (downloadable here if not already installed with your gimp). I don't think it's what you described, but it sure speeds up the layer stacking process!

 

[JTPhotography]

Cool, thanks! I did mine manually, it took a while but it came out better then with star stacker.

 

[TCampbell]

You can do this without using an inveralometer at all.... put the camera in "continuous" shooting mode. Dial the shutter speed to 30 seconds. Lock the shutter down (e.g. using the basic shutter button on your wired release to press-and-lock it.) The camera will now take images continuously... one every 30 seconds.