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DPChallenge Forums >> Tips, Tricks, and Q&A >> Long Exposures (not fireworks related) :-)
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 07/04/2004 08:06:17 PM · #1
Hi, all. I've just ordered the Canon Timer Remote Controller.

What's the longest exposure you've taken? I love long exposures but am wondering how the 10D handles anything over 30s. If you have any shots, please share! Be sure to include your settings. I've seen shots with exposures that are hours long, but am curious how long digital will handle (without using stacking software).

Do you know of any sites that specialize in long exposure shots? Please share! :-)

Thanks a bunch!

--
Jen

07/04/2004 08:55:36 PM · #2
Longest exposure that I ever made was just over 3 hours, but that was inside a garage using a 4x5 film camera.

I this was just 30 sec, but still, I like it a lot.

07/04/2004 10:27:22 PM · #3
6 minutes on a D60, using the timer remote and reciprocity to work out the correct exposure. Other shots in that folder show the impact of the long shutter over time on the sensor - later shots show more noise on the side of the chip near the sensor power supply which is warming up. There's a 100% crop at the end to show the noise too.


07/04/2004 10:42:02 PM · #4
Originally posted by Gordon:
6 minutes on a D60, using the timer remote and reciprocity to work out the correct exposure.


I was under the impression that reciprocity was largely a film phenomenon with long exposures, but I have not done much with really long digital exposures.
 07/04/2004 11:26:19 PM · #5
Forgive my ignorance, but what is reciprocity?

-Terry
 07/04/2004 11:52:37 PM · #6
Originally posted by ClubJuggle:
Forgive my ignorance, but what is reciprocity?

-Terry


Terry, the following link actually discusses reciprocity failure, but it also gives a good definition of the Law of Reciprocity as well.

//www.parkwestcameraclub.org/tips/reciprocity.html

It describes the reciprocal relationship between light and time. For a given exposure, you can close down a full stop and double the exposure time, or open up a full stop and halve the exposure time and and achieve the same exposure. Aside from the time of the exposure, the biggest change will be DOF.

Message edited by author 2004-07-05 00:55:48.
 07/04/2004 11:54:46 PM · #7
I know my camera starts to show the bright noise from the pixels getting too hot (sometimes even before 30s if I have the ISO too high) I'm impressed at the 6 min shot on the D60. Did you use any noise reduction filters on the shot etc?

The lower ISO your camera goes, the better the results will be for this.
 07/05/2004 07:35:22 AM · #8
Reciprocity is just the term used for idea that you can double the shutter speed and half the aperture and get the same exposure - or that you can half the ISO and double shutter time and get the same exposure and so on. The basic principle that doubling one of the 3 of ISO, aperture and shutter time can be compensated for by halving one of the other quantities.

Reciprocity failure is the term used to describe how this relationship breaks down when using film, at longer shutter speeds. Typically you need to increase the exposure for film, as it behaves non-linearly beyond about 30 seconds or so. Digital as a media is different, and doesn't really suffer from reciprocity failure - so you can use reciprocity, as is, to calculate exposures even up in the 6 minute range - as the response is still essentially linear.

The reason I mention it here is that I didn't have a spot meter, and my camera meter gives up at exposures longer than 30 seconds. So for these shots, I meter the scene at a wide open aperture, and if needed a higher ISO. This gives me a base exposure for the scene, say at f4, ISO 800. I know I want it to appear dark, so I first compensate that with a -1.5EV adjustment, over the base reading. I then use reciprocity to convert that to an ISO 100 exposure reading, at f22 - which worked at at 6 minutes. This then gets set on the timer and used as the shutter value.

I also used some flash, dialed down to -1.66EV, to fill in the foreground and tree, but using E-TTL, that doesn't effect the ambient exposure value at all.

360s f/22.0 at iso100
180s f/16.0 at iso100
90s f/11.0 at iso100
45s f/8.0 at iso100
24s f/5.6 at iso100
12s f/4 at iso100
6s f/2.8 at iso100
6s f/4 at iso200
3s f/2.8 at iso100
3s f/4 at iso200
3s f/5.6 at iso400
1.5s f/4 at iso400

All the same exposure and also derived (roughly) from each other.


Message edited by author 2004-07-05 07:45:20.
 07/05/2004 07:39:47 AM · #9
Originally posted by jadin:
I know my camera starts to show the bright noise from the pixels getting too hot (sometimes even before 30s if I have the ISO too high) I'm impressed at the 6 min shot on the D60. Did you use any noise reduction filters on the shot etc?

The lower ISO your camera goes, the better the results will be for this.


I don't think I used any noise reduction after shooting on these - maybe slight neat image, but I don't remember. Edit: I went back and checked the origial RAW files. They do show a lot of single pixel noise, but downsampling to 640x480 removed them - the linked image is 'as shot' without noise reduction - though Capture One seems to do some in RAW conversion process.

It was quite cold so that certainly helped with the sensor noise - but the main thing that has helped has been reducing the image down to 640x480.

The main problem was build-up on temperature on the sensor due to taking multiple shots.


Was taken just after the previous shot - for slightly less time (345s)
and you can see the heating of the sensor on the right (red fringing) that occurs around the power contacts on the device (or it could be just being near the battery - but I think it is silicon connections)

Also, this image shows a 100% crop from that shot, under the bridge - you can see the very apparent bright pixel noise there.



Message edited by author 2004-07-05 08:01:34.
 07/05/2004 07:52:05 AM · #10
Here's an extreme example: Lens cap frame for 15 minutes after over an hour of continual use. The 10D/300D may not behave identically.
07/05/2004 07:55:45 AM · #11
Originally posted by dwoolridge:
Here's an extreme example: Lens cap frame for 15 minutes after over an hour of continual use. The 10D/300D may not behave identically.


Looks like 5 voltage pins on the sensor then.
 07/05/2004 07:59:49 AM · #12
This one was done over 30 seconds at F16.

07/05/2004 08:03:29 AM · #13
was a 30s D60 shot.

was also 30s with a D60 (both without a cable release so stuck at the 30s exposure limit)

For practical (i.e., noise) reasons, I found that 6 minutes was really the top end of useful results with a D60 and even then the noise is significant, particularly the blooming that dwoolridge demonstrated very clearly.

This will vary on the camera temperature quite a bit - you can probably get better results in a cold winter for example.

10 second exposure


4 second exposure (not very long, but I think it is cool :) )


Message edited by author 2004-07-05 08:07:51.
 07/05/2004 08:51:13 AM · #14
27 minutes, but bad orange light pollution forced me to desaturate.
 07/05/2004 11:03:31 AM · #15
Originally posted by marbo:
27 minutes, but bad orange light pollution forced me to desaturate.


First time I've seen star trails with a commercial digital camera - a lot of noise to deal with ?
 07/05/2004 02:10:36 PM · #16
Originally posted by marbo:
27 minutes, but bad orange light pollution forced me to desaturate.


Cool shot. Have you tried breaking it down into multiple exposures, say 9 - 3 minute exposures and then stacking them in PS? That is typically how astrophotographers deal with noise. I haven't done it myself, but I want to try it.
 07/05/2004 10:16:14 PM · #17
Thanks for the replies, guys!

Spazmo: It is a cool shot! I like how the lights converge and how you can see the movement in your speedometer.

Gordon: Thanks so much for showing me the series. Very interesting. I love your shot, too. It's beautiful. Thanks also for explaining reciprocity. I've never heard of it.

dwoolridge: That's weird. I never knew that happened.

brownt: Neat shot! I love light trails like that. Thanks for sharing.

marbo: I like that. Star trails is definitely something I want to try. I'm curious how much noise you had, too.

Thanks again for your replies. I appreciate it.

__

Jen
 07/05/2004 10:27:38 PM · #18
Originally posted by Gordon:
was a 30s D60 shot.

was also 30s with a D60 (both without a cable release so stuck at the 30s exposure limit)

For practical (i.e., noise) reasons, I found that 6 minutes was really the top end of useful results with a D60 and even then the noise is significant, particularly the blooming that dwoolridge demonstrated very clearly.

This will vary on the camera temperature quite a bit - you can probably get better results in a cold winter for example.

10 second exposure


4 second exposure (not very long, but I think it is cool :) )


Beautiful shots, Gordon! I really, really love that first one. Awesome reflection. Nice job! That last one is really neat. Thanks for sharing, too. :-)
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