Bulb Exposure Metering?

I never got into night shooting that requires the bulb mode. I'm not doing star trails but I'm wondering how you meter for those extra a long exposures.

cdifoto wrote in post #16271947
I never got into night shooting that requires the bulb mode. I'm not doing star trails but I'm wondering how you meter for those extra a long exposures.

I see that many exposures in this sub forum are 30s or under with high ISO, so maybe non-bulb expsure and just chimp it?

Agree with the others, you don't want to use the meter as it would be ineffective. Set your aperture and shutter and try. Also turn off the lens IS, and most turn off long exposure noise reduction and high ISO noise reduction in your custom function menu. This is especially true for astro photos. Try different settings, experimenting is part of the fun and learning process.

Thanks. I know how to do long exposures via trial & error. I just prefer to not do it that way if I can help it. I don't want to experiment and play, I want to set up a shot and take it the first time around.

cdifoto wrote in post #16273678
Thanks. I know how to do long exposures via trial & error. I just prefer to not do it that way if I can help it. I don't want to experiment and play, I want to set up a shot and take it the first time around.

The problem with that is most long exposure shots, at least night shots, proper exposure is a subjective thing. Do I want a totally black sky, do I want the lights on the bridge to blow out while I save the cables against the dark sky, or do the lights take precedence over the cables? Its not like there is an 18% gray in those scenes, if you have that then you can spot meter with a handheld meter.

gonzogolf wrote in post #16273704
The problem with that is most long exposure shots, at least night shots, proper exposure is a subjective thing. Do I want a totally black sky, do I want the lights on the bridge to blow out while I save the cables against the dark sky, or do the lights take precedence over the cables? Its not like there is an 18% gray in those scenes, if you have that then you can spot meter with a handheld meter.

Right, but the fact that you can make night look like day with a long enough shutter speed tells me that there's got to be a way to measure it without taking a photo first. Not many scenes have an actual 18% grey target in them even during the day...you just have to find a known value and adjust for it (find something white, something black, or use the grass to get closer).

I'm hoping to take the guesswork out of knowing exactly how long to hold that button down. My handheld meter won't read anything that low.

the jimmy wrote in post #16273351
and most turn off long exposure noise reduction and high ISO noise reduction in your custom function menu. This is especially true for astro photos.

Why is this?

cdifoto wrote in post #16273737
Right, but the fact that you can make night look like day with a long enough shutter speed tells me that there's got to be a way to measure it without taking a photo first. Not many scenes have an actual 18% grey target in them even during the day...you just have to find a known value and adjust for it (find something white, something black, or use the grass to get closer).

I'm hoping to take the guesswork out of knowing exactly how long to hold that button down. My handheld meter won't read anything that low.

Just raise the ISO and then count stops, or use a chart. For each stop in ISO double the time.

gonzogolf wrote in post #16273767
Just raise the ISO and then count stops, or use a chart. For each stop in ISO double the time.

Do you mean use live view to judge exposure? That's a good idea. So if you want to shoot at ISO 100, and a 30s exposure at a given f-stop requires that you shoot at ISO 400 according to live view, you would set exposure time to 120s and bump ISO down again, right?

frugivore wrote in post #16274026
Do you mean use live view to judge exposure? That's a good idea. So if you want to shoot at ISO 100, and a 30s exposure at a given f-stop requires that you shoot at ISO 400 according to live view, you would set exposure time to 120s and bump ISO down again, right?

No, what I meant was set your meter to iso 3200 or whatever so that it might possibly at least read the existing light within the time parameter limit that your meter will work at. For instance is your meter ceases to work at times longer than 30 seconds or a minute. By raising the ISO in the meter you can get the time value to at least read in the meter. Then you can do the math and extrapolate for longer times.

gonzogolf wrote in post #16273767
Just raise the ISO and then count stops, or use a chart. For each stop in ISO double the time.

That's a good idea. Let's see if I get this right. If it meters 10 sec at ISO1600, I need 20 sec at ISO800 or 40 sec at ISO400 and so on, right?

morph2_7 wrote in post #16274314
That's a good idea. Let's see if I get this right. If it meters 10 sec at ISO1600, I need 20 sec at ISO800 or 40 sec at ISO400 and so on, right?

Correct

gonzogolf wrote in post #16274229
No, what I meant was set your meter to iso 3200 or whatever so that it might possibly at least read the existing light within the time parameter limit that your meter will work at. For instance is your meter ceases to work at times longer than 30 seconds or a minute. By raising the ISO in the meter you can get the time value to at least read in the meter. Then you can do the math and extrapolate for longer times.

OK. I was assuming that we were metering a scene below the camera'metering limit (i.e. under 1 EV).

Mesmer wrote in post #16273757
Why is this?

The camera is trying to reduce the noise, which most people prefer to do themselves in post processing, and if you're going to be stacking photo's then this process doubles your exposure time. Say if you're shooting at 20 sec, after the exposure the camera takes another 20 seconds to process the pic. If you're taking a number of exposures then this can add in a lot of time. Nothing is written in stone here, try and experiment for yourself, you may prefer your own technique.

I do this.
http://www.thenightsky​e.com …/images/High-ISO-test.pdf