Acros again...

mono · Nov 14, 2006

...and reciprocity!

As far as I understand there is no exposure correction up to 120 sec. and plus half stop up to 1000 sec.
But how about more than 1000 sec up to 8 hours?? For night exposures?

I cannot find anything about long exposures, please help!
Thank you!

André E.C. · Nov 14, 2006

Hi Folker,

A friend passed me this table:
IT----CF---CET

80---1.02--82
160--1.04--166
240--1.05--252
480--1.08--519
960--1.14--1090
1920-1.19--2288

IT- Indicated Time
CF- Correction Factor
CET- Corrected Exposure Time

I hope this help!

Cheers

André

mono · Nov 14, 2006

Thank you, Andre!
Just a little bit... ;-)

kb244 · Nov 14, 2006

mono said:
...and reciprocity!

As far as I understand there is no exposure correction up to 120 sec. and plus half stop up to 1000 sec.
But how about more than 1000 sec up to 8 hours?? For night exposures?

I cannot find anything about long exposures, please help!
Thank you!

Out of curiousity about where are you going to plan to shoot an 8 hour exposure, and at what aperture. I think 8 hours may be too long depending on where and what.

Lee L · Nov 14, 2006

Andre's data appears to be from Kit Courter.
http://home.earthlink.net/~kitathom..._gallery/technique/reciprocity.htm#acrostable
You can see the formula for the correction factor used on Kit's page.

This works out to be a Schwarzschild factor near 0.9835 when plugged into the Covington-Schwarzschild formula where:
adjusted time in seconds = (metered time in seconds +1)^(1/Schwarzschild factor)-1

Lee

(Yes, the numbers are excessively precise, but approximately correct.)

Ed Sukach · Nov 14, 2006

Same here, Andre.

Kiitoksia paljon!

Ed Sukach · Nov 14, 2006

Lee L said:
Andre's data appears to be from Kit Courter.
http://home.earthlink.net/~kitathom..._gallery/technique/reciprocity.htm#acrostableQUOTE]

Those were the days, my friend - I thought they'd never end ...

*Excellent* web site! Reminds me a LOT of the days when I was "In training" ... and came out the other end calibrating Light Energy Measuring Instruments... along with sundry other "troubles".

I would suggest that they who are new to "the game" go to this site and access "On Light and Camera Settings", and let me know how many times reading and re-reading this *wonderful* article is necessary. :rolleyes:

André E.C. · Nov 14, 2006

Lee L said:
Andre's data appears to be from Kit Courter.
http://home.earthlink.net/~kitathom..._gallery/technique/reciprocity.htm#acrostable

Yes, my friend just confirmed it was from this site he took the data!
Good choice for a source one must say!

Cheers

André

mono · Nov 15, 2006

kb244 said:
Out of curiousity about where are you going to plan to shoot an 8 hour exposure, and at what aperture. I think 8 hours may be too long depending on where and what.

as I wrote: "more than 1000 sec up to 8 hours"
.... ;-))

Acros again...

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