Life without a densitometer

[gainer]

The trouble is, the most useful use of a densitometer is for analyzing the results of usine a step density wedge. If you have that, you can get along without the densitometer for finding contrast index, etc.

 

[Kirk Keyes]

That is of course true, and in fact my later sentence in which I suggest that you can use a 47B filter in Visual mode to read the stain contradicts my own statement. Sandy

yeah - just making sure we are not putting the cart before the horse.

I'll look into the second part of your post later.

Kirk

 

[Maine-iac]

Im about a week away from getting my frist 8x10 camera. I plan to start trying out pyrocat-HD and AZO/Amidol. Ive never had a densitometer, but I have looked extensively for a local one that I could gain access to. No luck whatever. After I get started with 8x10, I wont have enough left to buy a densitometer. My question is this: Is it absolutely necessary that I purchase my own. If it is a good idea to buy my own, which brand/model? I would really love to refine my technique and start producing better contact prints than I am now..

In addition to purchasing the Stouffer Step Wedge which others have suggested and which, I agree, is very useful, try to look at your process as a whole system with individual parts that can be tweaked to your satisfaction.

1. Film speed test to determine your personal ISO. I find that a .10 Neutral Density Wratten filter is helpful here. I use my spot meter on a lightbox to measure the density of clear film base+the ND filter. This is film-base plus fog (FBF). I then run a film speed test for a Zone I (4 stops down from meter of a Kodak gray card) and try to match the density of the exposure to that of the FBF.

2. When I've got that, I expose several sheets for Zone VIII (3 stops over the meter of a gray card) of an even-toned subject (out-of-focus untextured surface) and do a development time test. Using a print time arrived at by test strips to produce the shortest exposure time for maximum black through a clear piece of film (FBF), I test the first sheet. If the development time is right, there should just be a hint of density that is distinguishable from the pure white of the unexposed paper border. If you can't distinguish border from the exposed part, increase your development time 20% or so and try again. If there's more than a very slight difference, decrease your time accordingly. You should get it on about the third or fourth try. Once you've got it, this will be your basic exposure/development combo for that film and paper combo. Your contact prints should then give you a maximum black (if your subject had one) and your brightest highlights should still be discernible.

I've managed to survive 35 years without a densitometer, and except on very rare occasions, have never felt the lack of one.

Larry

 

[noseoil]

Efke 100 is far superior to J&C 200 if azo is the choice. It has the ability to build density and contrast, both of which are helpful when using this paper. It also is one of the best films available with respect to expansion or contraction of contrast.

Efke 25 is also a good film, but is a bit more touchy with respect to exposure and development. This is a great film for showing off metals or hard paint, but lacks some of the easy expansion and contraction potentials inherent in Efke 100. Short development times or increased dilutions are the key to using it.

 

[sanking]

The trouble is, the most useful use of a densitometer is for analyzing the results of usine a step density wedge. If you have that, you can get along without the densitometer for finding contrast index, etc.

Well, I disagree a bit on this. I find the densitiometer very useful in making initial decisions with a new negative about printing speed and the type of contrast control that will be required. I measure the shadow values, which tell me how long exposure should be, and then the highlights. Substracting the shadow from the highlights gives the negative DR which I can then used to determine how to control contrast.

If you are working with an alternative process such as platinum this way of working can save a person a lot of time and expense over trial and error. I know that some people claim that they can just hold a negative up to the light and immediately know how long to print and what the contrast will be, but unfortunately I am not that talented.

Sandy

 

[Kirk Keyes]

I'll look into the second part of your post later.

Kirk

Sandy - I flipped through my Wratten filter book, and there were no good filters fo this.

However, I do have some dichroic, narrow bandpass filters that I picked up last year. They are not mounted in retaining rings, just the glass. They are about 3 mm thick and either 12 or 25 mm diameter. I have them for several wavelengths - from memory they we something like 365, 385, 400,... If you would like to borrow one to try, let me know.

The main problem I see is that for the shorter wavelengths, the tungsten bulb in the densitometer if going to be loosing energy in those wavelengths, so that even if the photocell is still sensitive (which it may well be), then you will have a noisier signal and less precision in your readings.

 

[gainer]

May even need a bulb in a special UV transmitting envelope.

 

[gainer]

Well, I disagree a bit on this. I find the densitiometer very useful in making initial decisions with a new negative about printing speed and the type of contrast control that will be required. I measure the shadow values, which tell me how long exposure should be, and then the highlights. Substracting the shadow from the highlights gives the negative DR which I can then used to determine how to control contrast.

If you are working with an alternative process such as platinum this way of working can save a person a lot of time and expense over trial and error. I know that some people claim that they can just hold a negative up to the light and immediately know how long to print and what the contrast will be, but unfortunately I am not that talented.

Sandy

Yes, but without a densitometer you can still print the step wedge and the negative of it tohether on the paper you plan to use and count the visible steps of each. Divide one by the other to get DR. Even if you have a densitometer, you may not be able to match the response of VC paper to pyro negatives.

I, of course, made my own densitometer. It is of a type that I can use it on the enlarger easel. I can calibrate it to use as an exposure meter for prints, or to measure projection density, and I can change the sensor to read reflection density. It has a digital readout.

Don't look at me that way. I also grow my own cane for oboe reeds and made my own gouging machine for cutting the cane to the proper thickness. Saved me $1500 30 years ago. Who knows how much that is worth now?