Night time long exposure problems...

So the last time I shot anything like this was on film where the reciprocity failure thing was in play. Have shot a lot of stuff on my old 300D at 30secs where I've managed to get lovely bleeding deep blue and purple skies, so during an ill-fated trip to a village in the lower Highlands last weekend I got the camera out.

The results weren't what I expected. Despite upping the exposure times, thinking that if reciprocity failure isn't something you worry about with digital (something else I'd read on here) that the more I double the exposure time, the more the light from the sky will bleed into the image and give me those glorious colours. Instead I got dark shots, with high noise, which I'm assuming is a by-product of the longer exposure.

The shots are below, both as they came off camera and with a VERY quick levels to show how they should have looked (in my head) roughly.

So what am I doing wrong? Two questions? Why am I not getting the bleeding light and deep purples and blues in the sky (time of shots between 11:30 and 1am and on a relatively clear night, eyes seeing the blue in the sky)? And how do those of you who are producing shots like this successfully on here (and there are some I've seen them) control the noise? All shots off a 5D and on the 17-40L. Exifs intact as best as I can see.

Shot 1 off camera

iso 400 is standard for astro photography from earth - i see you used 100 which will require more exposure time to get the decent brilliance from stars etc and therefore your trails will be dimmer and your shot will be noisier

*my 5c, from what i've read recently

also, don't use jpeg/levels, shoot in raw and adjust there for exposure as lossy jpg deteriorates fast with large levels adjustments

I've got them in RAW as well, just used the jpegs as a reference for this post, but cheers.

I'd used ISO 100 as I assumed noise would be an issue so was trying to minimise it.

Definitely increase ISO. 100 is way way too low. I usually shoot in 800 or 1600 despite noise.

I would Keep your ISO at 100. Increase time to 1min. or even 2min. or even 4 min., (with niose reduction on). A 5D does a great job of this.
Then if you want the foreground to stand out you could paint it with light.

Did this one with my 20D 5min. 100 ISO f8.0, Noise reduction on.

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I can't see too much wrong with those images at all.

Remember though, that the aperture diaphram controls how much light enters the camera, and no matter how long the exposure you just won't get some details at the smallest aperture. I would suggest opening the aperture a bit, f22 isn't really necessary unless your goal is the star patterns around the lights, and even then f16 should suffice? Most lenses get a bit soft at f22 too. At the museum the other night I started at f8 which is often the sharpest spot for a lens, and worked down from there if I wanted the star patterns.

White balance is a bit off in the last couple, but should be easily fixable in a raw editor.

if you get the exposure exactly right or a little over exposed from the camera, then you won't get the horrific noise. Try shooting in raw and almost over expose by .5 -1.0 stop depending on the situation. try shooting at 200-400 and at f8. take readings from a few different sources(or no sources) and try and work out a nice balance from it.

That's quite useful guys thanks. So what you're saying is that because of the fact that digital doesn't obey reciprocity failure past a second or so, I can still trust the light meter in the camera?

*I'd love to know the science behind why this is the case with digital as opposed to film - understand why means understand how to exploit it*

Some of those shots were at like 700 secs+ but the effect I was after (in the sky) was similar to Boomer's above, or perhaps even more so. It seems to me like there just wasn't enough ambient light and all I was doing by ramping the exposure time up was increasing noise. Speaking of which, aren't there arguments for leaving NR off as well as using it?

Hey dude, I won't try and tell you how to do it, I'll just post a pic with my settings (not a brilliant image, but cool because it was taken at night).

5D
ISO - 50 @ f4
6 mins 48 seconds

First is direct from camera
Second is levels adjusted with 20% saturation

If you keep your exposures below 8 mins on the 5D, you won't get noise, (and below IS0 400)

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Cheers Aaron. Can you remember if you were using the camera's meter to get to that exposure? Or using the cameras meter to ascertain an exposure then adjust it yourself in your head via fixed stops to get your settings? (Doesn't the camera stop telling you exposure times after 30secs?)

And did you use NR or not?

NR is on 100% of the time, I never turn it off.
Yes, 30 secs is the max time the meter will read for.
Unless there are some bright lights around, at night you'll never get a 'correctly-exposed' photograph with the shutter open for less than 8 mins. Because I don't want noise, I just use a stop watch (or in this case count in my head - one thousand and one, one thousand and two. . .) and time for 7 minutes. Then levels adust afterward.

If levels comes out to bright, you can always pull the exposure back a bit.
I never get noise.

Does that help?

Just checked your exif for one of your pics. 17 secs - there the prob.

Shot 3 was like 765 secs or something like that I think, and the one I was expecting the biggest things from.

So your kinda golden rule is 7mins or so, f/8 and ISO 200 with NR on. That usually gets you somewhere near?


Edit to say the exposure times were 375, 512, 785 and 586 seconds respectively, all shot at 17mm if that's what you saw?

Generally you will get horrendous noise if you try to increase exposure in PP. The closer you can get to a correct exposure in-camera, the less likely you are to get noise. As mentioned before, slightly over-exposing will make PP much "cleaner".

I saw 1020 seconds on the one I looked at, hmmm, are we looking at the same exif - photoshop > info

But yeah, 7 minuites is good, around eight can get a little noisey (the reason is that the sensor has specs/imperfections all through it, and these come through when it's exposed for a long time).

Shoot at like f4, and don't have to much close to the camera (DOF reasons).

It gets near enough for PS to sort out with levels adjust.