Film calibration newbie question

[Matthew Cordery]

Never done film calibration before but now that I have the equipment at home I'm giving it a try. Dumb question #0001 (note possibility for 9999 dumb questions):

I'm sure this is obvious but when you are making a contact print of a 4x5 negative using your enlarger, are you metering first off of a grey card placed under the light source to get the exposure correct? Any other gotchas? At this point, I've acquired a slosher tray from Summitek (fine piece o' plastic that is) and have a tempering bath set up for my developer using a fish tank heater and pump (seems to work well in getting the temp right). My Zonemaster should handle the densitometry part right.

Some might say that densitometry is unnecessary (like Barnbaum) but I want to run through it for no other reason than my own edification and the fact that I don't have B.B's decades o' experience....

[Ron Marshall]

Do you want to calibrate film, or are you trying to find the correct exposure for the paper?

[Matthew Cordery]

I realized after I took off to the shower that I wasn't quite clear there. I'm looking to put a step wedge into my enlarger and get the density curves as a function of development time etc for my setup, proper speed rating, that sort of thing.

[Eric Pederson]

I suppose you could try to meter the light from the enlarger and factor in the base+fog of the step wedge. You would also need to worry about bulb warm up to calculate the exposure correctly.

Or you can just make an exposure as a best guess (e.g. 1/2 second, f16, medium height enlarger, low bulb setting). You might need to make a corrected second exposure, but probably not a third. The exposure is far from critical because many of the steps will be pure white or pure black. Which steps you use for the calibration doesn't matter because they are equidistant values and as long as your exposure gives you a couple black and a couple white at the extremes of the step wedge (with at your initial development time), all the other developments at the same exposure should still work for plotting curves and estimating relative film speeds at the different development times.

[Shen45]

Never done film calibration before but now that I have the equipment at home I'm giving it a try. Dumb question #0001 (note possibility for 9999 dumb questions):

I'm sure this is obvious but when you are making a contact print of a 4x5 negative using your enlarger, are you metering first off of a grey card placed under the light source to get the exposure correct? Any other gotchas? At this point, I've acquired a slosher tray from Summitek (fine piece o' plastic that is) and have a tempering bath set up for my developer using a fish tank heater and pump (seems to work well in getting the temp right). My Zonemaster should handle the densitometry part right.

Some might say that densitometry is unnecessary (like Barnbaum) but I want to run through it for no other reason than my own edification and the fact that I don't have B.B's decades o' experience....

Hi,

I use BTZS as my test methodology.

It requires [1]

Test paper with a step wedge projected onto the paper. This accounts for your enlarger's light source.

[2]

Test film with step wedge in contact with the film.

Both are done under the enlarger.

For more info contact BTZS.org

[steve simmons]

There is a straight foward set of instructions on the View Camera web site in the Free Articles section. You can use a densitometer if you want to but you shoud still calibrate to your paper. Even Ansel felt this way. The BTZS is one way to go but not the only way.

If you are a newcomer to large format there may be several articles that will be helpful to you.

steve simmons
www.viewcamera.com