Good, Reasonably Priced UV Densitometer?

Neil Poulsen · Nov 22, 2007

I'm about to embark on calibrating a 3800. (Soon to buy.) What's a good, reasonably priced UV densitometer that can also be used for non-uv purposes?

This isn't a want ad. It's just a query about which reasonably priced UV densitometers work well for digital negatives.

I guess I'll also ask whether or not a regular transmission densitometer can work for digital negatives used with UV fluorescent bulb lightsource.

Joe Lipka · Nov 22, 2007

I use a reflection densitometer for calibrations. (It is an X-rite. I can't remember the model number.) My densitometer will measure in per cent dot area. This number is the same as the percentage numbers measured by the photoshop eye dropper tool.

I have a step wedge file calibrated in 2% increments. When the percentage on the screen is the same as the percentage on the step wedge you have printed, your curve is correct.

It makes more sense to me to directly measure the first step (photoshop file) and the final step of your process (the print) rather than an intermediate step (the digital negative).

sanking · Nov 22, 2007

Joe Lipka said:
I use a reflection densitometer for calibrations. (It is an X-rite. I can't remember the model number.) My densitometer will measure in per cent dot area. This number is the same as the percentage numbers measured by the photoshop eye dropper tool.

I have a step wedge file calibrated in 2% increments. When the percentage on the screen is the same as the percentage on the step wedge you have printed, your curve is correct.

It makes more sense to me to directly measure the first step (photoshop file) and the final step of your process (the print) rather than an intermediate step (the digital negative).

As to what would be a good densitometer, consider the X-Rite 810/820. It has both reflection and transmission modes and will measure in either Visual light (all colors) or in Red, Green or Blue. Not sure what the going price is these days but I picked one up on ebay a few years ago for less than $100.

Although I have a densitometer that measures UV transmission I don't find it terribly useful for digital negatives because in many cases the measured density is different from the actual blocking density when your print.

Sandy King

Neil Poulsen · Nov 23, 2007

Joe Lipka said:
I use a reflection densitometer for calibrations. (It is an X-rite. I can't remember the model number.) My densitometer will measure in per cent dot area. This number is the same as the percentage numbers measured by the photoshop eye dropper tool.

I have a step wedge file calibrated in 2% increments. When the percentage on the screen is the same as the percentage on the step wedge you have printed, your curve is correct.

It makes more sense to me to directly measure the first step (photoshop file) and the final step of your process (the print) rather than an intermediate step (the digital negative).

This makes sense to me. I have an X-Rite hand-held reflection densitometer that gives me standard density units. I don't think I can ask it to give me percentages. Is there some sort of transformation I can use to obtain those percentage values?

Neil Poulsen · Nov 23, 2007

sanking said:
As to what would be a good densitometer, consider the X-Rite 810/820. It has both reflection and transmission modes and will measure in either Visual light (all colors) or in Red, Green or Blue. Not sure what the going price is these days but I picked one up on ebay a few years ago for less than $100.

Although I have a densitometer that measures UV transmission I don't find it terribly useful for digital negatives because in many cases the measured density is different from the actual blocking density when your print.

Sandy King

Sandy, Thanks for this perspective. This thread clarifies the approach for me. Are you aware of a means for predicting those "blocking densities"? Even then, would they be useful?

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I'm thinking that in silver, it's the other way 'round. One uses a densitometer to measure the negative, and measuring the print isn't all that useful. But then in silver, we're not associating the final density on the print with what we see on a screen. We're focused more on controlling contrast in the negative.

In that process, we end up calibrating ourselves as well as the negative. We condition ourselves as to what a Zone III and a Zone VII or VIII looks like, and we visualize how the printed scene will appear with respect to those shadow and highlight zones. So, it does come back to how the final print will appear, after all.

Just thinking aloud; that's all.

sanking · Nov 23, 2007

neil poulsen said:
Sandy, Thanks for this perspective. This thread clarifies the approach for me. Are you aware of a means for predicting those "blocking densities"? Even then, would they be useful?

Neil,

One can theorize in that generally red, green and yellow have good UV blocking density, but that does not help much if you want to make the best possible negative.

You can test for the best blocking density for your process using either the color palette file in PDN or the color array of MKS. What you may find is that there are several colors that block equally well. If so, you need to test further to determine which one gives the least grainy look, and which one prints with the greatest linearity.

However, before you test make absolutely sure that you have enough control of your process to repeat results. Best way to do this is to practice with a film step wedge like the Stouffer.

Sandy King

Joe Lipka · Nov 23, 2007

Now that I'm home, I have an X-Rite 400 densitometer.

Ted Harris · Nov 23, 2007

I can confirm Sandy's post on the 820. They seem to be readily available on the used market but the prices I have seen are in the several hundred dollar rage.

Neil Poulsen · Dec 7, 2007

sanking said:
Neil,

One can theorize in that generally red, green and yellow have good UV blocking density, but that does not help much if you want to make the best possible negative.

You can test for the best blocking density for your process using either the color palette file in PDN or the color array of MKS. What you may find is that there are several colors that block equally well. If so, you need to test further to determine which one gives the least grainy look, and which one prints with the greatest linearity.

However, before you test make absolutely sure that you have enough control of your process to repeat results. Best way to do this is to practice with a film step wedge like the Stouffer.

Sandy King

Again, thanks.

What is MKS? The only thing that comes to mind is Meters, Kilograms, Seconds.

Also, does it make sense to use just a broad grid of color patches. I can generate these easily with the ProfileMaker measurement tool. Or, is there something special about the collection of patches provided as part of the PDN or MKS approaches?

Joe Lipka · Dec 7, 2007

MKS is one of the forum members, mkochsh. He has done a wonderful job in creating a color array which will clearly and quickly demonstrate the appropriate blocking color needed for your digital negative. He has already done all the "smart person" work in developing the color array. All that is necessary is to print the chart out and use it for your tests.

Good, Reasonably Priced UV Densitometer?

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