Filters with B/W and GT camera

[Fiatgusto]

Hi: I am trying to understand the affect a filter will have when using B/W film in my GT.
The manuals say to increase f stop,( +8 with red filter) but in doing so, does anything really change as we cannot control shutter speed?
And to increase by 8, does this mean 8 stops which way from f8 or f5.6? Not sure what to do.
😱
A novice's question, but I would appreciate any help.

Thank you,
Dennis

 

[ColSebastianMoran]

You are correct; changing the f-stop will just cause the camera to change the shutter speed.

To use a filter with your GT, change the film speed.

The typical adjustment for filters is usually described as a Filter Factor. Indeed, a deep red might have a filter factor of 8 which is 3 stops. Change the film speed to 1/8 of the number on the box. More typical a yellow filter might have a filter factor of 2; divide box speed by 2.

Look at Wikipedia article on "Filter Factor"

Some Yashicas (e.g. the GX) have the meter on the lens, metering through the filter. For these cameras, just mount the filter and shoot; no adjustments to ISO are needed.

 

[Fiatgusto]

WOW: Great help. Thank you.....

 

[Fiatgusto]

One more thing. (I think) When I develop the film, what changes in my normal times do I make?
Thank you again,

 

[Larry H-L]

No change required.

If you are consistantly in a bright sun and deep shadow situation, the red filter may cause the shadows to look slightly darker, so you then might want to further decrease your ISO by another 1 stop, which will give more exposure for the shadows. Then take about 20% off your developing time.

But this gets tricky. Red and orange colors will be relatively unaffected by the filter, and blues will darken significantly. Really depends on the scene.

 

[Fiatgusto]

Thank you all!!!!! Great forum especially for we challenged seniors.