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DPChallenge Forums >> Tips, Tricks, and Q&A >> long shutter speeds/night shooting
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05/10/2010 08:37:02 PM · #1
is there a sure-fire chart for what settings work for night shooting? like, if i want to do a hr-long shutter for a star photo, what would iput my other settings on?
i know i learned this at one point but really cant remember how it works. could someone explain?
05/10/2010 08:49:29 PM · #2
Originally posted by LadyK:

is there a sure-fire chart for what settings work for night shooting? like, if i want to do a hr-long shutter for a star photo, what would iput my other settings on?
i know i learned this at one point but really cant remember how it works. could someone explain?


Basically you need to point your camera at the stars with a pretty high ISO and wide-open aperture, then leave the shutter open (usually at bulb setting and via a remote so you don't need to touch the camera) and walk away for an hour.

At the end of the hour you should have some decent star trails.

You can always experiment with 1-, 5- and 10-minute exposures first. Good luck snaffly!
05/10/2010 08:54:50 PM · #3
First. LENR (long exposure noise reduction) is your friend..

Second, set your aperture as wide as you dare (remembering that a wider aperture means less DOF)

Third, think about what the light looks like, is this a full-moon, or is it a crescent? Is it pitch black? That all affects what you'll get.. Essentially a full moon will make it look like daytime with a black sky and stars, a crescent will provide detail, and a black moonless night is excellent for photographing star trails without any landscape.

I'm sure that I could come up with "rules" to about #20... But, I think it would be more helpful to simply say this: Take plenty of batteries, and turn on LENR...

Just so you don't think I missed your original question as to the exposure chart... I haven't seen one, and I doubt it would be very accurate - due to the complexity of night shooting, essentially everything changes because of ambient light, moon phase, landscape dynamics, etc..

One thing to keep in mind, is that if you want to get star trails, the wider your lens is, the longer you'll need to expose for equivalent length trails.

Oh, did I mention, turn on LENR? :)
05/10/2010 08:56:31 PM · #4
Originally posted by snaffles:

Originally posted by LadyK:

is there a sure-fire chart for what settings work for night shooting? like, if i want to do a hr-long shutter for a star photo, what would iput my other settings on?
i know i learned this at one point but really cant remember how it works. could someone explain?


Basically you need to point your camera at the stars with a pretty high ISO and wide-open aperture, then leave the shutter open (usually at bulb setting and via a remote so you don't need to touch the camera) and walk away for an hour.

At the end of the hour you should have some decent star trails.

You can always experiment with 1-, 5- and 10-minute exposures first. Good luck snaffly!


Forgive me snaffles, but I disagree. I feel that noise quickly becomes unmanageable with higher ISOs... I would suggest shooting at no higher than 200, and I would likely stay at ISO 100..

However, the remote release is a spot-on recommendation, if you don't have one, you'll need one :)

Message edited by author 2010-05-10 20:56:57.
05/10/2010 10:44:20 PM · #5
You can also take 20 or more 20 second exposures and use this to composite them together. This avoids the crazy noise issues but doesn't eliminate it totally so I would suggest using in camera noise reduction for better results.

Message edited by author 2010-05-10 22:44:50.
05/10/2010 11:21:25 PM · #6
Originally posted by Jac:

You can also take 20 or more 20 second exposures and use this to composite them together. This avoids the crazy noise issues but doesn't eliminate it totally so I would suggest using in camera noise reduction for better results.


Was there ever a consensus reached on the legality of stacking star trails? I never saw a final weigh in...
05/11/2010 12:35:52 AM · #7
Originally posted by spiritualspatula:

Originally posted by Jac:

You can also take 20 or more 20 second exposures and use this to composite them together. This avoids the crazy noise issues but doesn't eliminate it totally so I would suggest using in camera noise reduction for better results.


Was there ever a consensus reached on the legality of stacking star trails? I never saw a final weigh in...


I assume it's likely to fall in the same category as HDR.
05/11/2010 03:17:41 AM · #8
Read the tutorial on DPC, it will show you the light.
05/11/2010 03:34:26 AM · #9
Originally posted by spiritualspatula:

Originally posted by Jac:

You can also take 20 or more 20 second exposures and use this to composite them together. This avoids the crazy noise issues but doesn't eliminate it totally so I would suggest using in camera noise reduction for better results.


Was there ever a consensus reached on the legality of stacking star trails? I never saw a final weigh in...


Stacking star trails is illegal IIRC as that falls into the time lapse .... hdr is fractions of a second apart and you are not capturing movement

@LadyK For star trails the biggest issue is ambient light. One way is to put the ISO to max, apperture wide open and take a shot in av. Once you are happy with the exposure of the stars you can calculate approx what settings you need by dropping the ISO to 100 and setting the apperture correctly. Or just try by starting at about f8 or f5.6 and ISO 100 and take a 10 min exposure and see how it looks. You really want minimum ISO for noise as you are going to get lots of noise from the long exposure anyway. You could do much short 30s exposures and stack them, set the camera to burst and use the remote trigger to hold the shutter down ... fairly certain this is not legal for dpc though
05/11/2010 06:45:55 AM · #10
Originally posted by spiritualspatula:

Originally posted by Jac:

You can also take 20 or more 20 second exposures and use this to composite them together. This avoids the crazy noise issues but doesn't eliminate it totally so I would suggest using in camera noise reduction for better results.


Was there ever a consensus reached on the legality of stacking star trails? I never saw a final weigh in...


You're talking DPC legal, right? I didn't think it was for a challenge, she didn't mention it was for one.
05/11/2010 06:53:40 AM · #11
Originally posted by Jac:

Originally posted by spiritualspatula:

Originally posted by Jac:

You can also take 20 or more 20 second exposures and use this to composite them together. This avoids the crazy noise issues but doesn't eliminate it totally so I would suggest using in camera noise reduction for better results.


Was there ever a consensus reached on the legality of stacking star trails? I never saw a final weigh in...


You're talking DPC legal, right? I didn't think it was for a challenge, she didn't mention it was for one.


Yes, I was talking DPC legal
05/11/2010 08:14:18 AM · #12
I think y'all better poll the SC about the legality, you may in fact find it's legal. Check with them.
On the subject of long exposure noise reduction, *no*, don't use it. There are too many disadvantages. If you expose for an hour, you will have to wait *another hour* for the dark frame exposure, and you risk running out of battery and losing the entire exposure. Using it with shorter exposures and stacking the results is also not recommended. You will get gaps, specifically, your trails will look like dotted lines with 50% missing. Not good.
Best practice is to use shorter exposures, say a couple minutes, and stack at the end. You can also shoot a manual series of dark frames before and after the main series, stack those, and subtract from the main image. Doing all this does take patience and practice, and a lot of reading on procedure and technique. But the results are worth it.
05/11/2010 08:16:19 AM · #13
Originally posted by kirbic:

I think y'all better poll the SC about the legality, you may in fact find it's legal. Check with them.
On the subject of long exposure noise reduction, *no*, don't use it. There are too many disadvantages. If you expose for an hour, you will have to wait *another hour* for the dark frame exposure, and you risk running out of battery and losing the entire exposure. Using it with shorter exposures and stacking the results is also not recommended. You will get gaps, specifically, your trails will look like dotted lines with 50% missing. Not good.
Best practice is to use shorter exposures, say a couple minutes, and stack at the end. You can also shoot a manual series of dark frames before and after the main series, stack those, and subtract from the main image. Doing all this does take patience and practice, and a lot of reading on procedure and technique. But the results are worth it.


I've seen discussion about making a "catalog" of dark frame shots, with it being noted that you need to have different dark frames for different temperatures and humidity and specific to different apertures. However, I've never seen an explanation of what sort of interval you need to do. Any insight?
05/11/2010 08:33:53 AM · #14

I've heard of people stacking, but I have also found something that I have used for longer exposures that works quite well.

First thing to do is take a picture with your ISO at 1600 and put your f number as high as it will go for that lens and your focal length (f22 or f32). Next you have to play around with the exposure length until you get a picture with enough light in it so you are happy with the result. (for this example lets say it's 30 seconds) Next you have to do a little math (NO!!!!! NOT MATH!!!!!) Don't worry it's simple math. Take your ISO number and divide by 2 and take your exposure time and multiply by 2. Do this until your ISO is at 100. SO.....

ISO 1600, 30 sec
ISO 800, 60 sec
ISO 400, 120 sec
ISO 200, 240 sec
ISO 100, 480 sec

I have done this for a few pictures and they always come out really nice. You will have to do some tweaks in PP, but they usually come out pretty good and the noise is super low.

Just a note, I have never done this with star trails (never take a shot like that before), but I really want to try to get some. To any of you who have, is there an amazing secret, or do you basically go out and take a 10 minute exposure?

Hope this helps.
05/11/2010 12:28:28 PM · #15
And remember Mirror Lock Up is you friend to avoid those wobbly starts on your star trails.
05/11/2010 01:35:02 PM · #16
Stacking several identical star trail images to reduce noise is DPC-legal (Advanced).

Piecing together several star trail images to make longer trails is not.

Another program to stack images (to improve exposure and reduce noise) is RegiStax.
05/11/2010 02:15:07 PM · #17
Originally posted by GeneralE:

Stacking several identical star trail images to reduce noise is DPC-legal (Advanced).

Piecing together several star trail images to make longer trails is not.

Another program to stack images (to improve exposure and reduce noise) is RegiStax.


So, as per this... See my post above... Turn on LENR, and make sure you have a big-assed battery. 21.gif KevinSLR's math is accurate, and 21_N.gif BrennanOB's comment about mirror lock up is very good advice to listen to.
05/11/2010 02:23:49 PM · #18
Originally posted by spiritualspatula:


I've seen discussion about making a "catalog" of dark frame shots, with it being noted that you need to have different dark frames for different temperatures and humidity and specific to different apertures. However, I've never seen an explanation of what sort of interval you need to do. Any insight?


A catalog of dark frames is feasible, however bear in mind that as the sensor ages, things will change and you'll eventually need to re-do the frames. The following variables affect the dark frame results:

1.) Exposure time
2.) ISO setting
3.) Temperature of the sensor*
4.) Sensor and electronics aging
* This is why it's desirable to take dark frames both before and after an exposure series; you average the effect of temperature as the sensor heats during use

Humidity and aperture have no effect whatsoever on dark frames.

Remember that dark frames compensate for "fixed pattern noise," that is, a pattern that is the same from frame to frame. Stacking several dark frames is required so you don't reintroduce random noise, which is noise that is different from frame to frame.
05/11/2010 02:30:04 PM · #19
Originally posted by GeneralE:

Stacking several identical star trail images to reduce noise is DPC-legal (Advanced).

Piecing together several star trail images to make longer trails is not.

Another program to stack images (to improve exposure and reduce noise) is RegiStax.


ROFL, that just makes *no* sense at all! you cannot "stack star trails to remove noise" unless you rotate the camera in between exposures to bring the stars back to the starting position... and then the foreground would rotate, so arguably the composition is changing, and that would not be allowed; yet you are saying this perverse case is legal.
Conversely, if I keep the camera stationary and just record the scene, it's illegal. :-P
Gawd, now I remember why I left SC.
05/11/2010 02:32:42 PM · #20
Originally posted by GeneralE:

Stacking several identical star trail images to reduce noise is DPC-legal (Advanced).

I may be missing something, but how does combining multiple exact copies of an image reduce noise? It seems that you are just copying multiple images that have the same noise in the same places and therefore the noise should not be reduced at all be stacking multiple copies. I was under the impression you gain benefit when you overlay multiple images that are not the same exposure so that the noise (random) can be cancelled out.


Message edited by author 2010-05-11 15:05:41.
05/11/2010 09:01:04 PM · #21
Originally posted by kirbic:

Originally posted by GeneralE:

Stacking several identical star trail images to reduce noise is DPC-legal (Advanced).

Piecing together several star trail images to make longer trails is not.

Another program to stack images (to improve exposure and reduce noise) is RegiStax.


ROFL, that just makes *no* sense at all! you cannot "stack star trails to remove noise" unless you rotate the camera in between exposures to bring the stars back to the starting position... and then the foreground would rotate, so arguably the composition is changing, and that would not be allowed; yet you are saying this perverse case is legal.
Conversely, if I keep the camera stationary and just record the scene, it's illegal. :-P
Gawd, now I remember why I left SC.


LOL- this exchange is IDENTICAL to the previous one in another thread, and the reason I asked for clarification ;)
the more things change, the more they stay the same...

About the darkframes, I didn't think the aperture made sense either, so that confirms it. I was pulling that from something I read ages ago and it was hazy.

Using mirror lockup is dubious in this situation as any vibration induced is over before an actual image is being captured due to the exposure length. But of course, it's not like it does any harm.
05/11/2010 10:20:38 PM · #22
Originally posted by spiritualspatula:

LOL- this exchange is IDENTICAL to the previous one in another thread...


My evil nature revealed. I had hoped that in the intervening time some semblance of reason may have taken hold... but no. Does no one see the irony that:
- If I *move* the camera, shifting foreground objects and changing the composition, it's legal, but if I keep the camera steady, it's illegal??
- I can take an exposure of moderate length, capturing some trailing and then *fake* longer trails in post (motion that is present can be enhanced in editing per the Advanced Rules) but I can't capture it *naturally*.
The whole business is bass-ackwards.
05/11/2010 10:36:51 PM · #23
Katherine,

Before this thread turns any more political, here are my thoughts on your original question. :)

* Night shots are unfortunately too varied to be accurately covered by a chart, but the suggestions below should hopefully help.
* If you want to capture the stars as points of light and not trails, you need to use a shorter exposure, high ISO, and the largest aperture you have available. Shooting really wide helps, since the length of any star trails will be greatly minimized and you'll have more depth of field because of the short focal length (which is good since you'll be shooting at such a large aperture). To avoid the stars turning into trails in the photo, the general rule is that the length of your exposure in seconds shouldn't exceed 500/(your focal length). So if you shoot with your 15mm fisheye, you could take an exposure up to about 33 seconds while keeping the length of the star trails not too noticeable. Compare that with only about 20 seconds for your 24-70 at 24mm. Another reason to shoot wide!

Example exposure settings: 15mm fisheye, f/2.8, 30 seconds, ISO 1600

* Twilight is a great time to shoot stars, since it's dark enough for them to show up but you get more light so you can use a lower ISO and also get some great colors. Example (and shameless self-promotion):

Copyrighted_Image_Reuse_Prohibited_860960.jpg

* Long Exposure Noise Reduction is useful, but I personally don't use it most of the time since it doubles the amount of time you wait for each shot AND increases the drain on the battery. I find that software like Noiseware Professional does a great job of reducing the noise in post and gives me finer grained control (no pun intended ;) ).
* Try and keep your exposures less than 5 minutes. After that point, your sensor heats up enough to introduce a second form of noise (amp glow - which often appears purple).
* If you WANT star trails, your best bet when shooting digital is to shoot multiple shorter exposures in succession and then stack them using one of the pieces of software previously mentioned (or by importing them all as layers in Photoshop and setting all the layers to Lighten blending mode). Combining shorter exposures will let you achieve less noise than taking one REALLY LONG exposure. I'd still recommend shooting at the largest aperture you can and as wide as you can. Remember, turn Long Exposure Noise Reduction OFF for this method for sure since you don't want gaps in your star trails. I find that Canon's Timer Remote Controller TC-80N3 works great for stuff like this. Tell it you want three hundred 30 second exposures in a row or whatever and just let 'er rip!
* You probably already know this, but your battery will drain REALLY quick doing long exposures. ESPECIALLY since you're in Montana! (I have relatives in Butte, and know how f***ing cold it gets up there. :) ) If you don't already have it, I highly recommend getting the Canon battery grip. Start your night with two fully charged batteries in there and you have a much higher chance of not running out of juice before you have your shot.
* Use a remote shutter release to reduce camera shake.
* If taking one exposure at a time (i.e. not combining several in succession), using mirror lock-up can potentially help reduce vibration even more (though the benefit will probably be negligible with most longer exposures).
* The sturdier the tripod, the better.

I could probably write enough on this topic to make a book (and might some day), but that should at least get you started. Depending on the phase of the moon, time of night, desired length of trails (or lack thereof), you'll want to play around with the shutter speed and ISO to let you achieve your creative goal. Reducing the ISO would obviously be a great thing, but the 5D MKII luckily handles noise pretty well. I have no clue what methods are DPC legal and which aren't, but there is photography outside of DPC after all. ;) <-- BLASPHEMY! *gasp*

Hope that helps! :D
05/11/2010 11:41:42 PM · #24
Thanks 21.gif cutlassdude70, much appreciated and very informational. Lots of stuff to remember on my next nighttime excursion. You've made my day, err, night. ;)
05/11/2010 11:52:59 PM · #25
I'd politely disagree with a few of the tips here.

1) Mirror lockup doesn't matter at all on a long exposure. The amount of time the mirror is wobbling about is tiny compared to the total exposure. Mirror lockup really matters on a 1/4 or 1/5 second exposure. It hardly matters at all on a 30 second exposure or a 30 minute exposure.

2) I would not use in camera noise reduction when stacking shots because your star trails are going to look dashed. You take a 20 second exposure and record the trail, then the camera takes another 20 seconds with the shutter closed (while the star is still moving). Then you take another picture for 20 seconds and the camera works for another 20 seconds with the shutter closed. Can you see how this is going to degrate the trail?

3) I cannot imagine that stacking star trails would get you DQ'd in advanced editing.
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