Exposure Calculator

[ernesto]

Hello,

I have this strange exposure calculator, that looks very simple and old. It is a Orange Plastic piece about 3 cm x 2 cm x 1 cm.
If you look trhough it, you will see a semitransparent numbered scale, where each number is darker than the previous, so depending on the lighting scene there will be an almost invisible number, while others will not be visible at all.
Using that key number there is a celuloid sliding table in the outside, that can be aligned to the key numbr, then you will have the possible shutter speeed, together with film speed and lens apperture.
I have never used it, because I do not know the accuracy nor the right circunstances to use it.
Any help will be greatly appreciated!
Thanks.

Ernesto

 

[wontonny]

Take a picture of it, it'll help others help you

 

[Roger Hicks]

Dear Ernesto,

This is an extinction meter. They are surprisingly accurate if you do not look through them for too long, in which case your eye adapts; you can see a dimmer number; and you tend to under-expose. Their value also varies with age (the older you are, the harder it is to see the next dimmest number).

There were even a few cameras with them built in. They are rather better than no meter at all but not always better than an informed estimate.

Cheers,

Roger

 

[denishr]

The description fits the so-called "extinction light meters". Use Google, you might find which one it is...

[Edit]: Roger beat me to it... 🙂

 

[ernesto]

Thank You all for your help!
In fact I have just found this article that shows it:
http://www.marriottcameras.co.uk/instructions/leudi_meter/with_pictures.htm
LEUDI is the brand name.
I will give it a try, and will see the results.

Ernesto

 

[ernesto]

First thing I had to figure out to use this exposure calculator, was the ASA or ISO equivalent to DIN.

In red, the scale shown in the LEUDI exposure calculator.

10 ASA/ISO = 11º DIN
25 ASA/ISO = 15º DIN
50 ASA/ISO = 18º DIN
80 ASA/ISO = 20º DIN
100 ASA/ISO = 21º DIN
160 ASA/ISO = 23º DIN
200 ASA/ISO = 24º DIN
320 ASA/ISO = 26º DIN
640 ASA/ISO = 29º DIN
800 ASA/ISO = 30º DIN
1000 ASA/ISO = 31º DIN
1250 ASA/ISO = 32º DIN

More info here: http://en.wikipedia.org/wiki/Film_speed

I have just found that this exposure calculator is calibrated for film speed of DIN 26º which is ISO 320
Then if you use 100 ISO film you should convert it rotating the cellophan two spaces.

E

 

[ernesto]

Well, I have my first roll exposed with the LEUDI calculator, and I must say it was perfect for exteriors interiors sunny days, or cloudy days, even with artificial light (not specificated in the LEUDI instructions)
Obviously it was a C41 process colour negative which has a wide exposure latitude.
I will publish some samples tomorow.

E