Densitometer and Kodak Projection Print Scale

[ederphoto]

I just bought a densitometer and i need to calibrate it . I'm planning on using a Kodak Projection Print Scale for the job . In order to do that , i need help .
Could one of you masters out there with a Desnsitometer and a Kodak Projection Print scale read the density of each sector of the Kodak scale and post the results ?I would apreciate that and i know for a fact this is going to help hundreds of people looking for a way to calibrate their recently bought Densitometers as well .The pic posted along is of the Kodak Projection Print scale i have .
Thank's guys !

 

[John Shriver]

This is a simple matter of math. If there was a 60 second wedge (totally clear), that would be a density of 0.0. A 30 second wedge would be a density of 0.3 (one stop). So you can call the 32 second wedge 0.3. You can call the 16 second wedge 0.6, the 8 second wedge 0.9, the 4 second wedge 1.2, and the 2 second wedge 1.5.

With some division and logarithms, you can compute the exact "nominal" density of every wedge. Of course, it's not nearly as precisely manufactured as a Stouffer step wedge! Another major limitation is that the highest density is 1.5, and you really want to calibrate your densitometer out towards 2.5.

 

[Mike Wilde]

but that does not account for the density of the base plus fog. Measure the transmission with nothing in the densitometer, and zero the machine. Then measure a clear area. You should have something between 0.09 and 0.17, as I recall. Add that to the computations as suggested above, in setting the gain, and then go though the iterations of zero and gain again.

I use a non-calibrated stouffer step wedge with an old macbeth td-501 or 504; I cannot recall at the moment. It is close enough for my purposes.

I have never had to set any technician related potentiomenters since I got it, but I am not looking forward to the day when the bulb burns out. I was going to source a spare bulb, but thought that the photomultiplier tube might burn out first, and then the money spent on the spare bulb would have been a total waste.

Before the densitometer came into my setup I would estimate maximimum density by enlarging the neg, and putting the probe of my analyser over the densest section as projected onto the baseboard. Then without moving the probe, or enlarger head height or changing the aperture, I would slide a 21 step 1/2 wide stouffer wedge mounted into a peice of cardboard into tthe enlarger and move the wedge into postion over where the analyse probe was sitting.

When the exposure time needle matched what the original neg showed, I would look up the density of the step to figure out what the maximum density was.

The result would be used to fine tune development time for the next time that film and developer combination came together again.

I would aim to develop a negative to print well on grade 2 or 3 paper, to give me room to manipulate the image to higher or lower contrasts for the purpose of artistic manipulatiom via multigrade filtration.

 

[RalphLambrecht]

but that does not account for the density of the base plus fog. Measure the transmission with nothing in the densitometer, and zero the machine. Then measure a clear area. You should have something between 0.09 and 0.17, as I recall. Add that to the computations as suggested above, in setting the gain, and then go though the iterations of zero and gain again.

No need. John was right, only the delta between step wedges needs to be considered. It's the difference between relative and absolute density, here turning into exposure.

 

[RalphLambrecht]

I just bought a densitometer and i need to calibrate it . I'm planning on using a Kodak Projection Print Scale for the job . In order to do that , i need help .
Could one of you masters out there with a Desnsitometer and a Kodak Projection Print scale read the density of each sector of the Kodak scale and post the results ?I would apreciate that and i know for a fact this is going to help hundreds of people looking for a way to calibrate their recently bought Densitometers as well .The pic posted along is of the Kodak Projection Print scale i have .
Thank's guys !

My advice: Stay away from these projection scales other than using them as a very rough guide to start making test strips. They cannot be used for determining the final print exposure, because they evaluate different areas of the print. The preferred practice is to make a test strip for the highlights to get the optimal exposure and then adjust paper contrast to get the best shadows.

 

[ic-racer]

My Kodak pie was far from expected when tested with my densitometer. Its still OK for doing prints with my kids (5-7 year old) but it is NOT a 'calibrated step wedge.'

 

[RalphLambrecht]

My Kodak pie was far from expected when tested with my densitometer. Its still OK for doing prints with my kids (5-7 year old) but it is NOT a 'calibrated step wedge.'

That's a good use, because it is a good educational tool. I'll keep mine for that and as a good example of how not to do it.

 

[Martin Aislabie]

Fred Newman sells an uncalibrated Step Wedge for not a lot of money - Dead Link Removed

Martin

 

[John Shriver]

Another approach is to buy a 0.3 gelatin neutral density filter, cut in 9 pieces, and then stack 1, 2, 3, ... to 9 of them.

 

[RalphLambrecht]

Fred Newman sells an uncalibrated Step Wedge for not a lot of money - Dead Link Removed

Martin

This is a good choice. This is another:

http://www.stouffer.net/

They got all you need plus friendly service!

 

[RalphLambrecht]

Another approach is to buy a 0.3 gelatin neutral density filter, cut in 9 pieces, and then stack 1, 2, 3, ... to 9 of them.

Works, but buying a good transmission step tablet is simpler and works as a projection test tablet as well.

 

[Kirk Keyes]

Another approach is to buy a 0.3 gelatin neutral density filter, cut in 9 pieces, and then stack 1, 2, 3, ... to 9 of them.

That going to be pretty expensive if you are using Wratten filters. Just buy a Stouffer step wedge instead.

 

[ederphoto]

I used this method and it worked well .

 

[ederphoto]

I'll be ordering a Stouffer step wedge as well ,it is a good tool to have for many applications .