TTL metering question....

[steve garza]

Playing around with the TTL I find the meter rarely shows a "proper" exposure i.e., the single, lit dot. Typically, it shows 1/2 stop over or under even w/ a variety of shutter/aperture combinations and lighting conditions. Is this normal for a TTL? Should it be fairly easy to get that single lit dot? I know the meter is easily fooled. I am wondering if the camera is functioning properly.

 

[ch1]

Playing around with the TTL I find the meter rarely shows a "proper" exposure i.e., the single, lit dot. Typically, it shows 1/2 stop over or under even w/ a variety of shutter/aperture combinations and lighting conditions. Is this normal for a TTL? Should it be fairly easy to get that single lit dot? I know the meter is easily fooled. I am wondering if the camera is functioning properly.

Since you don't say what camera you are using I can only point something out I just read as a general comment.

In the Hicks review of the ZI in the April Shutterbug when talking about the TTL metering there is a "side comment" I found notable. Generally they say that TTL meters are optimized for chrome films and suggest slight underexposure (as read by the meter) for print film.

They gave a more logical and detailed explanation but perhaps this helps?

 

[steve garza]

George....

George....

Since you don't say what camera you are using I can only point something out I just read as a general comment.

In the Hicks review of the ZI in the April Shutterbug when talking about the TTL metering there is a "side comment" I found notable. Generally they say that TTL meters are optimized for chrome films and suggest slight underexposure (as read by the meter) for print film.

They gave a more logical and detailed explanation but perhaps this helps?

It's an M6....My concern is the proper function of the meter...

 

[oftheherd]

I don't have any RF cameras but the Canonet QIII. However, I find it quite common for it and some of my TTL SLRs, as well as my Luna Pro and Luna Pro sbc to show readings at half or third stops. My guess is that is has something to do with sensitivity of your meter and programming of the meter in the way it shows readings.

How are your shots coming out? That is the real test.

 

[ch1]

It's an M6....My concern is the proper function of the meter...

To some extent it is a "your milage may vary" kind of thing. I'd suggest side-by-side tests with a high-quality hand meter and see how much they vary under different lighting situations.

The "meter gurus" here can probably give you better advice....

 

[Les Lammers]

I don't have any RF cameras but the Canonet QIII. However, I find it quite common for it and some of my TTL SLRs, as well as my Luna Pro and Luna Pro sbc to show readings at half or third stops. My guess is that is has something to do with sensitivity of your meter and programming of the meter in the way it shows readings.

How are your shots coming out? That is the real test.

Agreed, What you are seeing is a 1/3 stop change when you move the camera. The meter is sensitive. If the snaps are good, don't worry.

 

[SolaresLarrave]

Like Les says, if the pics are good, why bother.

However... I've wondered about meter accuracy at times. And not the Leica's, but my Sekonic. Hence, I played with my toys for a while and switched lenses about and whatnot, to find that...

-Metering varies according to the focal length of the lens (a short lens gives me small openings compared to a long one, which asks for a slightly wider opening, focusing the same subject under the same light).

-Reflectivity is a big thing when using TTL, so beware of where you meter if that's not what you want prominently shown in your frame.

-My Sekonic and Leica meters work about the same way: they take a reading of reflected light, and the final decision about the photo and its metering is always mine.

Hence, if you're finding that the little dot in the VF of your M6 shows up at certain points and then the right or left arrows come up together with it, you're simply not focusing on an area with even lighting. You're the one making the call. If shooting chromes, focus on the zone you want exposed. If not, just overexpose a bit and no harm will be done.

Now go out and have fun! 🙂

 

[jaapv]

...

-Metering varies according to the focal length of the lens (a short lens gives me small openings compared to a long one, which asks for a slightly wider opening, focusing the same subject under the same light).

There is a simple explanation for that: The f-stop given on the lens is a mathematical value that does not take the light transmission loss in the lens into account. If the lens has more loss, the actual f-stop will differ from the mathematical value by up to one stop difference. Different glass types, different coatings, glass thickness, kitted or single elements,number of elements, all will influence this. Exposure meters compensate for an average lens.For instance the Leica Telyt 400 and 560 6.3 lenses could be rated half a stop faster than their nominal value because they used just one two-lens element of very clear glass. Most zoom lenses will underexpose by at least half a stop.

 

[Jon Goodman]

If you want a quick check of your meter's accuracy...not that it will be incredibly accurate, but usually pretty close...get a common white styrofoam coffee cup and cut it so that it fits snugly to the outer edge of your lens. Set your shutter speed for 1/125 and your ASA to 125. Set your aperture to 16. Go outside and point your camera lens (covered with the styrofoam cup) straight at the sun on a cloudless day. Check your meter. It should tell you everything is a "go" under these conditions. You can get an idea if your meter is over-reading or under-reading this way.
Jon

 

[steve garza]

Jon...

Jon...

If you want a quick check of your meter's accuracy...not that it will be incredibly accurate, but usually pretty close...get a common white styrofoam coffee cup and cut it so that it fits snugly to the outer edge of your lens. Set your shutter speed for 1/125 and your ASA to 125. Set your aperture to 16. Go outside and point your camera lens (covered with the styrofoam cup) straight at the sun on a cloudless day. Check your meter. It should tell you everything is a "go" under these conditions. You can get an idea if your meter is over-reading or under-reading this way.
Jon

Sounds like something I might be able to handle. I will try it. Thanks.

 

[Jon Goodman]

What you are basically doing is creating "sunny 16" for the benefit of your lightmeter...hence the 125 ASA setting, 1/125 shutter speed and aperture of 16. Good luck.
Jon

 

[FrankS]

relevent thread here:

http://www.rangefinderforum.com/forums/showthread.php?t=11120&highlight=chasing+needle