What happens if your camera runs out of batteries in the middle of LENR?

Hey guys...

So yesterday in the middle of a 40+ minute star trail shot, when I realized that the fresh battery I meant to put in was still in my pocket and the camera had the well-drained one in it. It finished the shot (about 1.5 hours with LENR), but that got me thinking...

What happens if your camera runs out of juice in the middle of doing the LENR? I mean once it's finished taking the actual picture, but before the whole thing is complete. I sometimes take shots that take over an hour, plus the LENR, so this is a bit of a real concern for me, especially as the nights get colder and battery performance declines.

Thanks!
Tamas

LowriderS10 wrote in post #15160680
Hey guys...

So yesterday in the middle of a 40+ minute star trail shot, when I realized that the fresh battery I meant to put in was still in my pocket and the camera had the well-drained one in it. It finished the shot (about 1.5 hours with LENR), but that got me thinking...

What happens if your camera runs out of juice in the middle of doing the LENR? I mean once it's finished taking the actual picture, but before the whole thing is complete. I sometimes take shots that take over an hour, plus the LENR, so this is a bit of a real concern for me, especially as the nights get colder and battery performance declines.

Thanks!
Tamas

I have had this happen before, but I can't remember the results. That experience made me turn to a way better system than long exposures. Many short exposures stacked together. The pictures turn out way better that way too.

Raylon wrote in post #15160691
I have had this happen before, but I can't remember the results. That experience made me turn to a way better system than long exposures. Many short exposures stacked together. The pictures turn out way better that way too.

I agree with that. Download free ware "startrails" software and stack your 30 second exposures to get you fantastic results. Way better than one super long exposure and a lot more forgiving if there is a slight bump or you need to change a battery ... Plus I don't know for sure but I'd assume super long exposures would be really hard on your camera sensor.

30 second stacks are fine if you only want the bright stars.... for the less bright stars, 30 seconds doesn't cut it. For deep sky shots, 30 seconds doesn't cut it.

I'm assuming if he's shooting star trails and not DSO's, he'd only really want the brighter stars. Plus with a single 30 second exposure with a bit higher iso,s you can get A LOT of the dimmer stars as well with out any problems.

To test, I opened the battery door on my XSi's grip during the dark frame portion of a 30 second exposure. The image was not recorded.

Thanks for the test (and being the only one to actualy answer my question haha), oldvultureface...and that sucks!!! It'd be kind of cool if the camera would temporarily write the image onto the card, then do the dark frame and overwrite the image once that's done. That way, if there's an interruption, you still have the original frame.

Now, the next big question is (I might ask that in a new thread)...how long of a shot + LENR can I take on a freshly-charged LP-E6...

Why ask the question when you can test yourself? Or is it better to let other people use their cameras to satisfy your curiosity........

LowriderS10 wrote in post #15162497
Now, the next big question is (I might ask that in a new thread)...how long of a shot + LENR can I take on a freshly-charged LP-E6...

I'll charge my 7D's battery and get right back to you.

jwp721 wrote in post #15162524
Why ask the question when you can test yourself? Or is it better to let other people use their cameras to satisfy your curiosity........

Ummm...no...I'll give you 10 seconds to think of another possibility...
9
8
7
6
5
4
3
2
1...

Give up?

I thought that perhaps someone might already know the answer.

oldvultureface wrote in post #15162527
I'll charge my 7D's battery and get right back to you.

haha thanks...hoping someone will chime in with the answer before you go to all the trouble haha...

You can skip LENR if you have a darkframe sitting around and subtract it in post. Lets you use battery power spent capping the back of the shutter on more interesting things.

Also, if your camera runs out of battery during a bulb exposure, it'll save the picture and shut down prematurely.

Some good tips on star photography here...http://photoextremist.​com/star-trails-tutorial.

Also, Popular Photography just recently recommended the Satechi Wireless Remote ($60 for Canon) for this type of work. You can find it on Amazon or go to the link at the bottom. Among other things it can work as an intervalometer automatically taking a series of 30-second exposures for stacking. A key difference to more expensive units is its range of 15 feet. Some "pro" units will work at several hundred feet but set you back about $400. I'm dying to get one but the better half wants to put it on the Christmas gift list. I might just have to request Christmas come early this year.

http://www.satechi.net …y-compatible-with-rs-80n3

evilr00t wrote in post #15162578
You can skip LENR if you have a darkframe sitting around and subtract it in post. Lets you use battery power spent capping the back of the shutter on more interesting things.

Also, if your camera runs out of battery during a bulb exposure, it'll save the picture and shut down prematurely.

Thanks, that's great to know! It would definitely help things, if nothing else, it would allow me to take twice as many pictures while I'm out (going from 1 or 2 shots to 2 to 4 haha)

How do I do this dark frame thing in post? Also, the camera matches the dark frame's exposure time to the real image's exposure time...obviously that won't happen with using a pre-saved dark frame in post...won't that present potential problems?

You can find software via a search: http://deepskystacker.​free.fr/english/index.​html
You have a dark frame for each exposure time you use, of course.

The in-camera method of dark frame subtraction is probably the worst way to do it, as read noise is doubled (from two exposures: dark frame + new frame) and you will end up with lower image quality. For astronomical imaging, it's common to take many dark frames and average them to reduce the read noise component.

You really only need dark frame subtraction if you have a camera that suffers from ampglow, which most modern DSLRs don't have: this will manifest as purple corners on most older Canon DSLRs. Try a ten minute exposure and push the levels to see if your camera has it.

So what do you do if all you want to do is remove hot pixels?
Take a dark frame to find hot pixels, and map them out (see http://www.pixelfixer.​org/ )

Also another tip: use ISO 1600 for optimal dynamic range and read noise characteristics on 1.3x / 1.0x, 800 on 1.6x cameras.

Still looking for a wireless remote and found the hahnel remote at http://www.hahnel.ie …motecontrols&id​=80&pId=80. This one works at a much longer range than the satechi and has some expanded capabilities. B&H has it for $99.