I think my Gossen Luna-Pro is broken...

[POSTI-Tuomo]

Something has messed up the wheels on my meter, since it won't show proper Sunny 16 settings on any given film rating. Example: I set the meter for ISO 400 film, roll the wheel to EV 15 position (Sunny 16) and it offers me this combination "Shutter: 1/125, aperture: 16) I think the correct Sunny 16 setting for ISO 400 would be f/16 and 1/500...

Quite odd, how to rectify the situation?

PS. Actually, my Gossen does show proper settings @ ISO 100 but further down the road, it doesn't. :bang:

 

[POSTI-Tuomo]

I am beginning to doubt myself... have I gotten something completely wrong about the Sunny 16 rule?

Let's see: On a bright, sunny day use a shutter speed nearest to the reciprocal of your film speed and an aperture of f/16...

Nope, I have it all right, and the Gossen doesn't!

 

[POSTI-Tuomo]

I think I am broken!

I think I am broken!



Well, it seems I didn't grasp the concept of EV correctly, after all. It seems you have to add two stops to the EV 15 when using an ISO 400 film so that the EV becomes 17. Works the other way around, naturally. And to think I thought EV was a constant value...

Example: For ISO 50, you will have to reduce one stop so that the EV becomes 14. This produces correct exposures. It is described in detail in this Wikipedia article: http://en.wikipedia.org/wiki/Exposure_value .


Live and learn, something new every day, yada yada.

 

[Rhoyle]

Also, make sure you have the correct batteries in it. If it's an old Luna Pro it may require the old 1.35 volt mercury batteries. The current readily availble one (I think it's a PX625 or some such thing) is actually 1.5 volts. You can get the correct voltage if you use the 1.35 zinc/air batteries made by Wein. If you've not already done so, check it out.

BH

 

[andcolorII]

My theory is that Light meters are like toasters. They Lie!!!

 

[Nikon Bob]

Have you tried to re zero the meter? I think there is an adjustment on the back.

Bob

 

[sjw617]

Example: For ISO 50, you will have to reduce one stop so that the EV becomes 14. This produces correct exposures. It is described in detail in this Wikipedia article: http://en.wikipedia.org/wiki/Exposure_value .

I think you are misunderstanding something. An EV value does not change because of ISO. I do not see where you saw that on Wikipedia after reading your link.

Steve

 

[Bill58]

Also, make sure you have the correct batteries in it. If it's an old Luna Pro it may require the old 1.35 volt mercury batteries. The current readily availble one (I think it's a PX625 or some such thing) is actually 1.5 volts. You can get the correct voltage if you use the 1.35 zinc/air batteries made by Wein. If you've not already done so, check it out.

BH

Gossen does indeed make an adapter for the old Luna Pro that takes two SR44 batteries. B&H (NYC) carries them:

SKU # GSLPSB

Mfr. Part # GO4145

Our Price: $38.95

My adapter works fine. Also, somewhere (here or LUG I read about some guy who repairs them-can't remember who-sorry)

Bill

 

[KoNickon]

The Wikipedia entry is very clear that EV is dependent on film speed. Take a look at the text below Table 2. This agrees with my understanding. Every time I have read a discussion of a camera's metering range, it's always based on ISO 100 -- there is no "absolute" EV. EV 17 is what my Luna Pro/Lunasix show for sunny f16 with 400 speed film.

 

[POSTI-Tuomo]

The Wikipedia entry is very clear that EV is dependent on film speed. Take a look at the text below Table 2. This agrees with my understanding. Every time I have read a discussion of a camera's metering range, it's always based on ISO 100 -- there is no "absolute" EV. EV 17 is what my Luna Pro/Lunasix show for sunny f16 with 400 speed film.

Yes, it does show the EV calculations and how different film speeds affect the EV. Check it out, it's true. The example agrees with my Gossen perfectly.

SR44 batteries are good for my meter, btw.

PS. Quote from Wikipedia: "The exposure values in Table 2 are for ISO 100 speed (“EV100”). For a different ISO speed, increase the values by the number of exposure steps by which the speed is greater than ISO 100, formally"

So, when using an ISO 400 film, the EV increases by 2 steps. Sunny 16's EV is therefore 17.

 

[oftheherd]

The Wikipedia entry is very clear that EV is dependent on film speed. Take a look at the text below Table 2. This agrees with my understanding. Every time I have read a discussion of a camera's metering range, it's always based on ISO 100 -- there is no "absolute" EV. EV 17 is what my Luna Pro/Lunasix show for sunny f16 with 400 speed film.

Which has screwed with my mind for years both with EV and flash. Remember the good ol days when camera meters and flash power were given based on ASA 25? sigh

But I thought I rememered EV -3 was 30 seconds at f/1.4. See how it has screwed up my mind!?

 

[JoeV]

Compensating Ring

Compensating Ring

Also don't forget that the Gossen Luna Pro has an offset ring that is used to compensate the meter reading in f-stops; just be sure it's in the null position.

 

[FrankS]

There is both an EV scale and a meter scale. Don't confuse the two. Use the yellow triangle as the index point.

 

[POSTI-Tuomo]

There is both an EV scale and a meter scale. Don't confuse the two. Use the yellow triangle as the index point.

Yes, I am aware of that.

PS. As far as I am concerned, this thread is now sort of pointless... A non-issue. EV isn't constant with different films speeds. The Gossen is okay after all. Thanks for the helpful comments though!