Exposure settings for different 6x9 lenses

[Fernando]

Hello everyone. I'm new to this forum. I have a Fujica G690BL with 50mm, 100mm and 180mm lenses. My question is this: When I use my hand-held light meter, an old needle Gossen, I assume its metering angle is appropriate for the normal lens; therefore, I empirically use to open one half f/stop when I use the tele lens, and inversely, I close one half f/stop when using the wide angle lens. Is this correct, or is there a more accurate method to calculate the exact exposure ?
Thanks in advance,

Fernando

 

[StuartR]

Hello Fernando,

Welcome to the forum!
As for your question, I can't think of any reason why your angle of view should effect your metering unless it is a TTL meter, and then only if the larger scene has a different metering requirement than the smaller part of the scene that the tele would isolate. Since the G690BL has no meter at all, this should not be a problem. When metering, you should just make sure that your meter is taking a reading from the correct part of the scene. Depending on what you are shooting, this could mean that the f/stop would be the same for all lenses or totally different -- it really depends on the lighting situation of the particular scene and your light meter's metering angle.

Overall, it would probably be easiest to use an incident meter and just use the reading for the amount of light on the scene.

Finally, since there are leaf shutters in each of your 50,100 and 180 lenses, you should probably check them for accuracy. The lenses are over 40 years old now, and they are probably not that consistent. The error in the speeds is probably more important than the half stop over/under that you are using for the different lenses. I know that my speeds are off in both my 100mm and 180mm lenses -- once you know what they are off by, it is pretty easy to compensate.

Sorry for the long answer. Enjoy your G690! It takes phenomenal picutres!

 

[Doug]

Yes, there is no optical reason to give more or less exposure for different focal length lenses. F/8 lets in just as much light in a wide lens as a long lens.

 

[Fernando]

Thank you folks for your time and the quick answers. I'll follow your advice. As for the shutter speeds, I have checked all three lenses and they seem to work fine. Actually the slides and prints look great! The only problem I found is that the inner black covering tends to cast off some loose hairs that then become visible on the negative if they are near the focal plane; but that can be prevented by checking it every time you load a new roll.
Thank you again,

Fernando