Recirprocity and Bellows factors question

[blue4130]

So this could be a dumb question, let me know if I am a complete dunce...

What should the order be? Should I read my meter, adjust for reciprocity and then add the bellows factor OR should I meter, adjust for bellows factor and THEN deal with reciprocity?

Still learning this LF thing out...

Vance
www.vancelester.com

[baro-nite]

As a fellow LF beginner, my thought is make the bellows factor adjustment first. That way it doesn't matter whether you make the adjustment by adding time or by changing the f-stop. Whereas if you adjust for reciprocity first, and then want to adjust for bellows factor by adding time, you'd need to adjust for reciprocity again.

[Doremus Scudder]

So this could be a dumb question, let me know if I am a complete dunce...
What should the order be? Should I read my meter, adjust for reciprocity and then add the bellows factor OR should I meter, adjust for bellows factor and THEN deal with reciprocity?
Vance
www.vancelester.com

Reciprocity failure corrections should always be done last.

Read your meter, figure in all your filter and bellows factors, etc. and arrive at a base exposure first. Then see if you need to correct for reciprocity failure.

And, you're not a complete dunce

Best,

Doremus

[Jim Noel]

Calculate in this order: filter, bellows extension, reciprocity

[Heroique]

The calculations might allow enough time for the initial light to change, so stay alert!

[Andrew O'Neill]

What Jim said.

[Patrick13]

And to make Jim's sequence more visual, for those of us who think that way:

Light comes in through the Filter first, then through the Bellows, then hits the Film last.
So apply the Filter first, and then the Bellows, and then the Film's reciprocity.

[blue4130]

Thanks all, now that I slow down and think it through, it makes perfect sense.

[ImSoNegative]

This how I learned how to figure bellows factor. Say you are shooting with a 125 5.6 lens and your bellows is racked out 10 inches round the 10 to the nearest f stop which would be f11. Then figure the difference between 5.6 and 11. 2 stops is what you would increase your exposure by. Works like a charm

[fishbulb]

This how I learned how to figure bellows factor. Say you are shooting with a 125 5.6 lens and your bellows is racked out 10 inches round the 10 to the nearest f stop which would be f11. Then figure the difference between 5.6 and 11. 2 stops is what you would increase your exposure by. Works like a charm

I'm not sure you have that quite right? The aperture of the lens doesn't matter for bellows extension.

It'd be more like: "Say you are shooting with a 110mm lens. Your bellows is racked out to 220mm (measured between the front and rear standards). Drop a zero from both numbers, and you've got f/11 vs f/22. The difference is two stops, which is what you have to increase your exposure by vs. what the meter is telling you."

So if the meter is telling you ISO 100, f/16, 1/60th second ... you really need ISO 100, f/16, 1/15th second (two stops more light by means of a longer shutter speed).