Calibrating a Transmission and Reflection Densitometer

[Len Middleton]

Just picked up a ESECO Speedmaster model TRC60D transmission and reflective densitometer for the price of gas and wear and tear on the car, so the price was really good (relatively local i.e. within the Greater Toronto Area).

It works and the fellow who gave it to me showed me how to calibrate it, as he had a calibrated step wedge for the transmission calibration and a MacBeth chart for the reflective calibration.

I am looking at using it to do some B&W film / developer testing for my own use, and frankly that will be limited in scope.

Now I am looking at calling Stouffer and getting a calibrated step wedge for transmission calibration, but wondering whether I really need a calibrated tablet for setting the reflective. Or should I just use the gray scales on my older "Kodak Color Separation Guide"? Or buy a a new uncalibrated tablet from Stouffer? Or use the developed and fixed unexposed whites and maximum black from your printing paper? OR what other options???

I guess the underlying question is do other calibrate the reflective mode for evaluating B&W prints?

And of course, I do not have a manual, although that never stopped me before. If anyone could point me in the direction on where I can get a manual on-line, it would be much appreciated.

Thanks,

Len

[ic-racer]

I have 2 sensitometers and 2 transmission densitiometers, and never had the need for a reflection densitometer. I always do test prints, so calibrating and testing reflection density on the paper materials was never an issue. Also, toning, and surface characteristics influence ones ability to record a reliable D max when reflection density testing.

Having said that, you will gain a good understanding of the paper curves by plotting them out. I'd just proceed without a reflection calibration standard and see if you will be regularly doing the reflection tests, then get a standard if you need.

As far as keeping the transmission densitometer calibrated, having a calibrated step wedge (or even a single value around 1.8) would be good.

So, I guess the guy did not give you the calibrated wedge with the unit?

Someone with a similar unit may chime in, but frequently there will be a calibration screw for the 'level' and 'gain' or 'slope'. The 'level' would be set with nothing in the light path and the 'gain' adjusted with the calibrated step (say 1.8) in the light path.

[Len Middleton]

In all fairness to the gentleman that gave me the densitometer, I did notice he had another densitometer there, so he may have retained the calibrated step wedge for the one he had left.

He did show me how to calibrate it i.e. setting the "zero" (nothing in transmission path) and range (calibrated with high D value), typical for analogue instrumentation.

Thanks for your thoughts,

Len

[Len Middleton]

I did contact ESECO Speedmaster via e-mail, and they do have a printed (versus electronic) manual available for it, as well transmission step wedges and reflection reflection calibration plaques.

With regards to the manual, is there much else one does with densitometers other than calibrate them and use them for measuring? What else is in the manuals maybe other than a listing of parts, specificaions, operating conditions, etc.?

As I need to pay for restoration of an 8x10 view camera in a couple of weeks and get film for it, I am looking at deferring as much as I can.

Thanks for the information,

Len

[ic-racer]

With regards to the manual, is there much else one does with densitometers other than calibrate them and use them for measuring? What else is in the manuals maybe other than a listing of parts, specificaions, operating conditions, etc.?


For my Tobias, the manual is like a service manual. It has troubleshooting tables and lists all the components, with schematics etc.

If the unit was recently calibrated by your friend's step wedge, you can make a 'pseudo standard' by finding a piece of exposed or fogged film with a density between 1.5 and 2.0. Get a good measurement of that and put it in a safe place and you can go back to it if you ever feel the unit has drifted.

[Marko]

Len, I have the same model as you do, I even got it the same way!

For calibration, I went with Stouffer's callibrated 21-step tablet as the original ESECO calibration chip was significantly pricier and they didn't seem all that interested in selling it anyway. It's been working fine for me.

As for the manual, someone somewhere took the time to type it up and I got it for free so I'll be happy to pass a copy on to you for the same price if you want it. Just PM-me your email address.

Marko

[Len Middleton]

Based upon the comments, maybe all I need to purchase at this time would be a calibrated transmission step wedge.

Thanks for your help,

Len