Reciprocity failure of black and white films

[Thmaga]

I'm going to be shooting lots more B+W over the coming months and im wondering what the reciprocity failure characteristics are of black and white films, I've found a table here but id assume Reciprocity failure varies as much for different black and white films as it does for colour.
I'll be shooting primarily ilford film, most likely FP4 or HP5.

 

[Musicman]

Unlike Kodak, Ilford are good at publishing reciprocity data about their films.

FP4+

HP5

Both PDF

For the rest, pick up the Technical Data sheets for each here

 

[Thmaga]

Thanks!, maybe I shouldve had a browse of the website first!

Edit : anyone used them for more than 30 secs, i may need longer?

 

[colpepper]

Always worth bracketing very long exposures.

 

[excalibur2]

Always worth bracketing very long exposures.

Indeed until you get experienced to roughly judge exposure times. But some cameras should be able to make a good attempt at exposure if below 40 secs and a lit street scene at night should be easy for most cameras.

Just let a T70 sort out the exposure for this shot:-

 

[colpepper]

That's a very good exposure. Some cameras are battery hungry with long shutter speeds. Anything above a few seconds I estimate manually.

 

[Thmaga]

I may have to do some experiments, I'll need to dig out my remote shutter release for bulb shots though.

 

[excalibur2]

That's a very good exposure. Some cameras are battery hungry with long shutter speeds. Anything above a few seconds I estimate manually.

Just holiday snaps with cheap cameras:-

Nikon EM the camera did the exposure:-

Nikon EM the camera did the exposure

AV1 the camera did the exposure:-

 

[EdMoss]

The Ilford tables are a good starting point and don't use you cameras built in meter, unless you can spot meter and take an average for the scene.
If you are shooting 35mm then it's really not a problem to bracket your exposure.
At longer timed exposures, the difference between 170 seconds and 190 seconds will make very little difference between shots. Film is quite forgiving during long exposures, and if in doubt do a few tests with your digital to give you a very rough starting point.

I've never shot any long exposure B+W but here's one I shot last week on Kodak Ektar 100 (Thanks Kodak for no reciprocity help...)

St Ives

I metered 1 minute at f45 and gave it 2 extra stops to allow for reciprocity, giving an exposure of 4 minutes @ f45.
Out of curiosity I also did one at 5mins and there was hardly any difference between the negs.