Use of a step wedge.

[steven_kefford2]

Hi,

 

I noticed in anothet post, somebody mentioned using a step wedge.

Whilst I know what a step wedge is, I can't find any info on how to

use it with reference to LF photography. I am sure it is used for some

sort of callibration, but any further leads would be appreciated. A

google search turned up a lot of stuff, not of much use here, but I

don't know enough about it to refine my search.

 

Steve

[nikos peri]

Stouffer step wedge. You place it in front of your sheet of film in the holder, shoot a white evenly illuminated wall, and voilຠyour complete negative for film testing.

[daniel_jolicoeur]

A Densitometer may be handy, and and understanding of the Zone system or some form of sensitometry. Suggest a visit to your local library to start. The Negative, by Ansel Adams; Beyound The Zone System; The Simplified Zone System, The Ansel Adams Guide to Photograhic Techniqes, by John ???. Stoufer also makes comparison strips if you don't have use of a densitometer. Here is there link http://www.stouffer.net/

 

Just don't get too caught up in all the testing. Excuse my spelling please.

 

Regards,

Dan

[mike_buehler]

check here: http://www.apug.org/forums/article.php?a=104

 

Mike

[brian_ellis16]

If you do your own black and white printing it's very informative to make a bunch of separate prints of the step wedge using different filters or filter equivalents (i.e. colors in a dicrhroic head or filter settings in a variable contrast head) and different exposure times with variable contrast paper to see the effect that each filter/setting has on print contrast, to see where in the print the steps cease to be seen as distinct steps (and instead merge into one (i.e. where you will lose tonal separation in a print), and how much or how little exposure is needed with various filters/settings to print a good black or a good textured white and what effect that exposure and filter/setting will have on the other areas of the print. There are other, more specialized uses as well, e.g. a 21 step wedge is needed if you use the BTZS/Phil Davis zone system testing methodology and is useful for determining print exposure times with various alternative processes.

[steven_kefford2]

Thanks guys. The APUG article was a good intro. I do have "The Negative", but have not yet read it, just skimmed it - I guess I will have another look in there. I have only just got my first LF camera, so it is probably a bit beyond me at the moment, but its good to know for future reference.

 

Steve