Filter factor calculations question in manual

Hello,
I bought some ILFORD SFX 200 to be used with a dark red filter with filter factor 16 in a clearance sale. I know that filter factor 16 means 4 stops correction. I plan on using a TTL reading without the filter and then correcting either the aperture or exposure time on manual.

Am I correct that if I measure 1/250th with an aperture of 22, that I can use the filter with an aperture of 5.6 with that same 1/250th on manual? But what if I want to keep the aperture and want to change the exposure time? I have a remote control with time, so I can use the camera in Bulb mode with a long exposure. Does that mean the exposure gets 4 times as long, i.e. 1 second?

4 stops from 1/250 is 1/15. 1 sec is 8 stops from 1/250th.

Cheers Kris

Thanks!
I see: 1/250 --> 1/125 --> 1/60 --> 1/30 --> 1/15
Makes sense, I must have had a complete brainlock ^_^;;

Exactly. That's the advantage of my MX or LX. Four clicks of the shutter dial = four stops!

Cheers, Kris.