light meter for extreamly long night exposures?

[chihiro]

Hello

I am looking for a light meter for extreamly long night exposures ( i have only found a few that can go to upto 30 min). and i dont want to be calculating manually as a I need accurate readings and that why i hope to find quite sensitive light meter for longs exposures please.

Could you tell me which meter do you think you could recomend me please?

Thank you

 

[tirediron]

What sort of work and how long are the exposures you're dealing with? While some meters may have scales which go up to 30 minutes (I'm not aware of any that go longer... Helen?) the real world practicality is that even exposures over a few minutes often can't be accurately metered simply because conditions change. The moon comes out, gets hidden by cloud, a street light comes on....

 

[480sparky]

"Manually calculating" is really quick and simple. If you're shooting at, say, ISO 400, set your meter to, for example, ISO 6400. That's a 4-stop difference. If the meter says 2 seconds, multiply it by 4..... 8 sec exposure. Always use the same two ISO setting, and you'll always use the same multiplier.

However, I typically find most meters don't do well at night anyway. It's usually at "Take a shot and check the histo" method.

 

[Derrel]

Take a meter reading off of a piece of white typing paper at night. Multiply the exposure about 20-fold.

 

[Big Mike]

Just a guess...but I'd guess that light meters were never really designed for long exposures because of the reciprocity failure characteristics of film...and how one film would differ from another.

Reciprocity failure is a breakdown in the normal/expected relation ship between shutter speed/aperture and exposure.

 

[Helen B]

The Gossen Profisix SBC (also called simply Profisix in some countries) goes to 8 hours. It also happens to be one of the most sensitive meters around. It works down to EV -8 at ISO 100. The only meter I have that is more sensitive than my Profisix is the Sekonic L-508 with the Booster II attachment (made by Minolta). That is a stop or two more sensitive than the Profisix, but is more cumbersome to use. The L-508 only reads to 30 seconds, however. The later Sekonics in the same line (L-558 and L-758) do not accept the Minolta Booster II.

Take a meter reading off of a piece of white typing paper at night. Multiply the exposure about 20-fold.

Metering off a piece of white paper only gives you about two and a bit stops more than metering off a grey card - ie a factor of about 4.5, not 20. It is a useful technique, however.

"Manually calculating" is really quick and simple. If you're shooting at, say, ISO 400, set your meter to, for example, ISO 6400. That's a 4-stop difference. If the meter says 2 seconds, multiply it by 4..... 8 sec exposure.

Er, your maths is wrong there Sparky. Multiplying the exposure time by 4 is a 2-stop change, not a 4-stop change. Not a great example of how "quick and simple" it is?

Are you going to be using this with film (remember reciprocity failure) or digital?

Best,
Helen

 

[Derrel]

Metering off a piece of white paper only gives you about two and a bit stops more than metering off a grey card - ie a factor of about 4.5, not 20. It is a useful technique, however.

Your reply seems to indicate that I am implying that the white piece of paper has a factor of 20x more than a gray card...not sure where you came up with that...apparently you were reading something in to my post something that I never said.

My suggestion was to take a reflected reading off of a white piece of paper, because at night or in dim light, it is much,much,much,much more reflective than say, a nearly black night sky...and to multiply the resulting reading by a factor of about 20. As a general starting point for determining the exposure of most night scenes, using a d-slr,and not film.


Maybe next time you can read what was written a bit more carefully...before trying to correct something that was not even "said"...who the hell brought up a fricking gray card in my post????? Did I mention a gray card in my post? Why the hell would anybody try and meter off of a gray card at night?

 

[Rephargotohp]

Are you trying to reverse calculate this? Meaning I want to shoot for 5 Hours what ISO and Aperture?
Because the reason that no meters go past 30minutes is there is no need to based on metering the existing light.
The lowest possible night light condition is Starlight only, No moon, No city Lights (desert conditions) and that woulod be f/8 ISO 200 and 32 Minute exposure. There is nothing beyond that.
If you are looking to do star trails, you are better off, because of noise from sensor heat on long exposure,s to do Multiple exposures and stack the image in a star trail program

 

[480sparky]

Er, your maths is wrong there Sparky. Multiplying the exposure time by 4 is a 2-stop change, not a 4-stop change. Not a great example of how "quick and simple" it is?

Best,
Helen

Er, the idea is what counts, not the piddly details. 32 seconds then. How hard was that?

 

[Helen B]

Er, your maths is wrong there Sparky. Multiplying the exposure time by 4 is a 2-stop change, not a 4-stop change. Not a great example of how "quick and simple" it is?

Best,
Helen

Er, the idea is what counts, not the piddly details. 32 seconds then. How hard was that?

It wasn't hard, and it wasn't hard to make quite a significant mistake, write it down and not notice that there was something strange - even though the ISO ratio (400 : 6400) should be the same as the exposure time ratio (2 : 32). It happens with even the simplest calculations - it's no reflection on you personally.

Metering off a piece of white paper only gives you about two and a bit stops more than metering off a grey card - ie a factor of about 4.5, not 20. It is a useful technique, however.

Your reply seems to indicate that I am implying that the white piece of paper has a factor of 20x more than a gray card...not sure where you came up with that...apparently you were reading something in to my post something that I never said.

My suggestion was to take a reflected reading off of a white piece of paper, because at night or in dim light, it is much,much,much,much more reflective than say, a nearly black night sky...and to multiply the resulting reading by a factor of about 20. As a general starting point for determining the exposure of most night scenes, using a d-slr,and not film.


Maybe next time you can read what was written a bit more carefully...before trying to correct something that was not even "said"...who the hell brought up a fricking gray card in my post????? Did I mention a gray card in my post? Why the hell would anybody try and meter off of a gray card at night?

Wow. I think that you are doing exactly what you accuse me of. Maybe next time you can read what was written a bit more carefully. I made a comparison to a grey card reading because most people will understand that that is a good guide to exposing the scene - the landscape, for example - if you don't already have a grasp on how a white card reading compares. The brightness ratio between a white piece of paper and, say, leaves (or grass, or bricks, or rock or whatever), does not change as the overall illumination level changes. If you take a white card reading and open up two stops (ie quadruple the exposure) or so, you will get a a fairly good exposure. Open up another two stops (ie 16x the exposure) and the scene will look very bright - midtones will become white. (This assumes either digital imaging or film imaging after reciprocity failure has been taken into account.)

I've used both white card reading opened up two stops and the equivalent of grey card readings (incident metering; reflective metering of the palm of my hand; normal scene average reflective metering) many times at night in the last four decades. Taking pictures in dark situations has been something of a speciality for me.

Best,
Helen