Long exposure of clock face challenge!

[Alan_Silvester]

I've been set a task to use photography to demonstrate the changing of time. I shoot a lot of long exposure but never really with reference to specifically showing a shift in time, more just using the technique to bring out hidden elements etc. I'll be shooting on digital for this.

My idea is to shoot 3 shots of a clock face across three differing exposures. I know there must be a calculation in here somewhere but can anyone suggest a formula for showing the disappearance of the 3 clock hands across the 3 shots?

If a minute hand rotates across the frame in 60 seconds what exposure duration would just about capture the movement around the clock and still show the blurred hand? What's the limit to the exposure to cause that hand to disappear? The same question for the minute and hour hands...

Alternatively, anyone got a better idea to show the change of time across 3 images? I've been thinking of ice melting, or something with slow movement but it needs to be something with quite a formulaic progression as opposed to an organic change.

Hope that makes sense!

 

[Ces1um]

Could you just shoot three long exposures and then superimpose them? Or do a multiple exposure with each photo being a long shutter speed?

 

[jim10219]

I would shoot multiple images at one minute intervals and then overlay them in software. With a digital camera, if you have the sensor going for that long, you're going to generate so much heat and noise that the picture is going to look pretty ugly. Astrophotographers will sometimes get around this by building special liquid cooling units to draw the heat off of their sensors to reduce noise, but that would be pretty expensive for such a simple project.

When you go to combine them in software, don't try to combine them all at once. Just combine a few at a time, render that down into a single image, and then once you have a bunch of them, combine a few of them and render them into a single image, and so one until you get all of them together on one image. If you try to do them all at once, you'll likely lock up the computer and crash it.

I've actually done this, though I used film. I used a large format camera to do this, which allowed me to stop my aperture down quite a bit without having to worry about diffraction. And instead of using just an ND filter, I used a red, green, and blue filter (plus and ND) and recorded the image on B&W film. I then combined them in the print stage to create cyan, magenta, yellow, and black separations for a 4-color process image. By using slow film in a low light environment, and colored filters, I was able to make exposures that were several minutes long each, without having to worry about sensor noise. Reciprocity failure actually played to my benefit here. I actually took that photo over the course of several weeks, allowing several days to pass between each exposure, to get the flowers in the vase to die. I have a digital render of the scanned negatives of it looks quite a bit more detailed, but that's buried in my computer somewhere deep, and I don't feel like looking for it. I do, however, have this scan of a Gum Bichromate that I made from it (my second gum print, so I didn't exactly do a great job on it), but while it lacks the detail and precision, it does give you a rough idea of what I'm talking about.

 

[Theo Sulphate]

...
If a minute hand rotates across the frame in 60 seconds what exposure duration would just about capture the movement around the clock and still show the blurred hand? What's the limit to the exposure to cause that hand to disappear? The same question for the minute and hour hands...
...

It is the second hand that moves once around the dial in 60 seconds ... but you knew that.


So, for just this hand, I would try a technique that film shooters would use to show car motion (where you see the blur of the car in motion and at the end of the blur is a somewhat sharp image of the car). That's made with flash and second- curtain sync: what you do is trip the shutter and it stays open while the car (clock second-hand) moves. That produces the blur. Then, when the second (rear curtain) starts to close, the flash fires. The result is a sense of blur which terminates with the frozen car (clock-second hand). But you have to use second curtain sync and not first curtain.

https://www.understandphotography.com/front-and-rear-curtain-sync-on-your-flash/

You'll have to experiment to see how much blur you can get to produce the effect you want. Just showing even 5 seconds of blur would give a sense of the passage of time.

 

[Sirius Glass]

O remove the hands from the clock

 

[Alan_Silvester]

Thanks for all the suggestions. I think I might have failed to explain myself properly however.

I appreciate there are many ways to achieve an image to look like the passage of time has, well, passed. I could Photoshop the image and manipulate it to look as I wanted. However, this project is intended to demonstrate time, to show time change in an image. I need to make it real or there's no point in making the work. It's so that an audience can see three images and understand that within a single frame there can be a passage of time. I think most people see photography as a freeze frame and this project is one element of a larger project to show people how time can be inbuilt into things that they'd perhaps not considered. Maybe the clock face image is a bit too literal and wont yield the best result but it's a clear way to demonstrate time, plus movement (hands rotate). I therefore want to be able to show these images with a clear figure next to them (60 seconds, 1 hour, 12 hours for example) and show the change in the image as the time has passed.

If I had the time (no pun intended) I'd shoot a decaying flower or something that changed very slowly over time but I'm a little up against it with turnaround. One idea I had was to use a clock with phosphorous hands, and shoot the exposures in a dark, enclosed case. The resulting light painted circles would be quite visibly different across three differing exposures times.

 

[Sirius Glass]

Exposing half an hour should do it.

 

[MartinCrabtree]

A snail in the foreground clock face in background with rear curtain sync flash.

 

[jim10219]

The problem with showing clock hands moving over a single exposure is in order have the exposure run long enough to show the motion of the clock hands, you'll likely overexpose everything else in the scene. And if you used some ND filters. small apertures, and very slow film (like maybe a paper negative), you likely won't get enough exposure from the moving clock hands to show their movement. I'm not saying it's impossible, but it would be pretty difficult.

The root of the problem is the slow speed at which a clock moves. Since the beginning of photography, people have been trying to make films faster and more light sensitive, not slower. So you might be better off choosing something that doesn't move so slowly.

You might consider shooting things in a dark room using strobes to light objects in motion at various points in time. Lots of photographers have used this approach in the past to show the passage of time in a single photo. Check out the work of Gjon Mili for some beautiful examples of this.

 

[alanrockwood]

Could you rig some kind of system to put light sources on the ends of the hands of the clock, LEDs for example?

 

[Sirius Glass]

Take a long exposure of a digital clock. A sun dial?

 

[John Koehrer]

Long exposure and an hourglass?

 

[KN4SMF]

It's only the clock that appears to be slow. As for time, I've found it gets away like greased lightning.

 

[choiliefan]

The passage of time could be shown as a long linear scale with tic-marks denoting passage of time in seconds, minutes or hours.
The image could be arranged in a fashion similar to step-less darkroom test strip progressing from very dark to very light.

 

[MartinCrabtree]

A dark room using a dim flash every so often time exposure?

 

[flatulent1]

Three photos of a person walking past the camera: one entering the frame, one in the middle, one leaving the frame. Not a brilliant example perhaps. Or three photos of a scene where the shadows are moving, changing the character of the scene.