Astrophotography questions

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eurotrash

Senior Member
So as many of you may know by some of my pictures, I'm an avid backpacker. I hate bringing my gear with me on account of the extreme added weight, but when you can't shoot these things living near D.C, when you get the opportunity you take it:) On Friday morning, I'm leaving for a 4 day in the backcountry of West Virgina and want some advice on astrophotography, namely using the interval timer.

I'm shooting for this effect, (at around 35 seconds in.) I'm not looking for TRAILS, i'm looking for singular stars that move around the frame:

Startrail Timelapse Compilation - Nevada Nights - YouTube

As if it weren't confusing enough to do this, Nikon an others seem to substitute words like "picture" with words like, "interval" and the like.

Now, I know posting a question like, "What settings should I use?" is a bit silly, but that's honestly what I'm asking. I really need the most help on what interval to shoot for, how long to shoot for etc. I know I'll likely end up using the wide end of the lens and that
I'm going for a smooth video in the end, preferably longer than a minute and a half, with upward of 1,000 and preferably more photos to increase the length a bit. (You may also know that the last one I did was comprised of 200 shots and lasted ten seconds, LOL) I'll be using my f3.5 16-85 and a tripod obviously but I also have faster glass available. I just find that the wider the better in this scenario.

Thanks everyone!
 
E

eurotrash

Senior Member
So, if I'm to understand this correctly:

INTERVAL is the time in between shots, i.e., if you set it to "00:00:05", it will take your shot and wait 5 seconds before taking the next shot.
NUMBER OF SHOTS well...obvious? The number of shots to be taken in total?
X I don't know about this one. I assume that it could theoretically take muiltiple shots at the same time?
 
Scott Murray

Scott Murray

Senior Member
eurotrash said:
So as many of you may know by some of my pictures, I'm an avid backpacker. I hate bringing my gear with me on account of the extreme added weight, but when you can't shoot these things living near D.C, when you get the opportunity you take it:) On Friday morning, I'm leaving for a 4 day in the backcountry of West Virgina and want some advice on astrophotography, namely using the interval timer.

I'm shooting for this effect, (at around 35 seconds in.) I'm not looking for TRAILS, i'm looking for singular stars that move around the frame:

Startrail Timelapse Compilation - Nevada Nights - YouTube

As if it weren't confusing enough to do this, Nikon an others seem to substitute words like "picture" with words like, "interval" and the like.

Now, I know posting a question like, "What settings should I use?" is a bit silly, but that's honestly what I'm asking. I really need the most help on what interval to shoot for, how long to shoot for etc. I know I'll likely end up using the wide end of the lens and that
I'm going for a smooth video in the end, preferably longer than a minute and a half, with upward of 1,000 and preferably more photos to increase the length a bit. (You may also know that the last one I did was comprised of 200 shots and lasted ten seconds, LOL) I'll be using my f3.5 16-85 and a tripod obviously but I also have faster glass available. I just find that the wider the better in this scenario.

Thanks everyone!
Click to expand...

Try here - Lets Go Streaking, a Guide to Star Trails : Liquid in Plastic – Photography and Words by Dan Newton
 
BackdoorArts

BackdoorArts

Senior Member
Funny, but I was just reading this post yesterday and I believe it will contain most of the information you're looking for. The rule, to eliminate any trails, is to divide 600 by the focal length of the lens, which will give you the maximum exposure time in seconds before you get trails. So, if you're shooting with a 16mm lens you need to limit the exposure to under 37 seconds (figure 30 since it's the programmed max). From there it's all getting the exposure right on a single frame and then setting the intervalometer as described above.
 
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PhotoAV8R

Senior Member
eurotrash said:
So, if I'm to understand this correctly:

INTERVAL is the time in between shots, i.e., if you set it to "00:00:05", it will take your shot and wait 5 seconds before taking the next shot.
Click to expand...
I'm not so sure. I believe INTERVAL is the time between each shutter actuation - i.e., the beginning of each exposure. Of course, this definition is dependent on the equipment you're using. (Intervalometer in the camera, a remote unit, TIMEX on your wrist, etc.)

As I understand the issue, the INTERVAL has to be greater than the shutter speed by enough time to allow for the buffer to clear enough memory for the next shot. For example, if you set the INTERVAL for rapid-fire shots, you'll eventually miss shots as the buffer is full. One's camera buffer speed/size, obviously, has a lot to do with what settings are going work in each case. (A D800 will have less limitations than a D40.) Google is your friend.

BWTHDIK, YMMV, etc.
 
BackdoorArts

BackdoorArts

Senior Member
What PhotoAV8R said. Interval is the amount of time between shutter actuations, not the amount of time allowed to pass after the shutter closed on the previous shot. This is less of an issue during daylight, but certainly a factor with long exposures.
 
E

eurotrash

Senior Member
Oh, gotcha. I think..

So If I used

INTERVAL: 00:00:01
NUMBER OF INTERVALS: 999 x 001

That would grant me 999 pictures, taken with my chosen settings (just for example, say, shutter priority @25 s and appropriate ISO)? Also, it would take 1 extra second for the mirror to raise when taking an exposure?
 
BackdoorArts

BackdoorArts

Senior Member
Almost. You're interval is 1 second. If you are shooting a 25 second exposure this isn't going to work. What you want, if you truly want 1 second in between shots, would be an interval of 26 seconds. If you are using a 1 second delay on the exposure then you need a 27 second interval. If you have long exposure noise reduction turned on then that tacks on another 25 seconds to the process so you would need to set it to 52 seconds.

In other words...

MINIMUM INTERVAL TIME = ((SHUTTER SPEED (in seconds) * (1 if Long Exp NR is OFF, 2 if Long Exp NR is ON) + SHUTTER DELAY) * NUMBER OF SHOTS PER INTERVAL) + 1
 
E

eurotrash

Senior Member
Ahhhh. So the interval needs to be longer than the actual exposure length is?
It's working now with a 17 second interval shooting at 15 second exposure. So I guess that solves the mystery! Thanks Backdoorhippie for clearing that up!

Now, on to the question of getting a shot like that where as many stars and the milky way is viseable. That's probably the hardest part now.
 
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bhaskarv87

New member
Hi, Ideally speaking we cannot have 1 sec difference between two shots when Shutter speed is greater than >1 sec. I mean if shutter speed is 25sec, we need to keep 26sec interval time so that after every 26 sec , one shot would be taken.


I think interval should be greater than shutter speed as minimum requirement.


interval >= shutter speed.(Considering long Exp NR OFF)


Correct me if i'm wrong.
 
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