Re: Scanner as densitometer?
Quote:
Originally Posted by
false_Aesthetic
Ok,
So the school's densitometer is wack! (Literally, if you wack it, the readings change significantly. . .it happens when you barely touch it too.) I'm assuming this isn't normal (I wouldn't know because theres no one here who's used it in **YEARS** and Photronics doesn't seem to exist anymore).
That said,
I've got access to a V750 (with the cheap included Silverfast software) and a Imacon 646.
Is there a way I could use either one of these scanners as a densitometer?
I'm thinking that I'd have to scan the image with no adjustments applied. Do I do it grayscale or color? In the case of the imacon do I do it with the film profile (TXP), Neg rgb standard, saturated, b/w standard etc.
Finally, where do I get the density reading from?
This whole film testing densitometer thing is way new to me. Any insight would be awesome!
T.
I don't know about Silverfast software but Vuescan can allow you to use your scanner as a densitometer. In my experience the accuracy of the densitometer feature isn't perfect but it will be close. Also the maximum log density value may be somewhat less than what can be measured with a densitometer.
Don Bryant
Re: Scanner as densitometer?
Silverfast does it too. I will look at it tonight, but first you have to turn off all the auto functions and then use the K screen in the desitometer window. I will look at it later. It will at best give you values relative to each other rather than absolutes from your negative FB.
Re: Scanner as densitometer?
Yep ... old thread.
Just thought I'd put in my observations here (March 14th 2016)
I cannot see any reference to a densitometer in the Vuescan software. There is a button on the Epson Scan software though ... (but at least my version of Epson Scan is creating a busted tiff file that Photoshop can't open) I don't think Epson envisaged the scanner to be used for big LF files ...
My experience with Vuescan is showing that in a tiff output, Vuescan is sampling the B&W negative and is assigning the most dense parts a value high towards 255 (say 225). I think it is possibly making a linear interpolation from there. My highest value is 225 ish and my lowest is 4 but my densities range from 0.25 through 1.45 or so.
I have a calibrated densitometer, Stouffer tablets, etc. and have calibrated the scanner to Wolf Faust targets etc.
I have taken a photo of a frangipane recently. It is a tree with a pure white velvety flower whilst the leaves are a dark green. The shot is close enough for me to put the darkest portion (on the neg!) of a flower petal under the densitometer. It reads in the vicinity of 1.45 or so whilst the f+b is around 0.25. This leaves a density range of around 1.2 which is pretty contrasty.
I can also take a scan of the Stouffer step tablet which has densities ranging to 3.0. So I know the scanner will go well beyond my neg density of 1.45 ... In fact, I've posted the results on this site before I think.
The raw scan from Vuescan is worse than the tiff mode in that the values of the flower are nearly at 255 - just under at 252.
I'd like to be able to 'calibrate' to a step tablet honestly. What I want is a scan that does not interpolate information. Perhaps if I could tell Vuescan to give me a value of 255 for a certain density I'd feel better.
I can understand what is going on though. The Vuescan software is making the call that the brightest parts of an image, if they are dense enough, must be 'white' or close to it. This means the digital range of 0 to 255 is spread evenly across the image. The problem with this is that there is no objective reference point so there is no way the scanner software can be used as a densitometer.
What if I wanted a really low contrast image where there was no white ?
My goal originally was to use the scanner to evaluate the negative with optical processes in mind. It has failed miserably - or I'm exhausted trying to figure it out !
The densitometer does not lie.
Re: Scanner as densitometer?
Something to check: my Epson 700 has uneven density across the width of the scan. So did the old 2450.
Re: Scanner as densitometer?
On Vuescan, go to the Prefs tab. Scroll down an be sure "Enable Density Display" is checked. After that, scan the negative, hold down the control key (cmd on Mac) and move the cursor over the scan - below the scan it will show the density of all, the R G and B channels of the point where the cursor is.
You say you can't find a reference to densitomoter in Vuescan. The above gives you one. If you are not following that process, I'm not understanding what you are doing to get the numbers you are giving.
juan
Re: Scanner as densitometer?
What school are you associated with?
Andy
Re: Scanner as densitometer?
Quote:
Originally Posted by
j.e.simmons
On Vuescan, go to the Prefs tab. Scroll down an be sure "Enable Density Display" is checked. After that, scan the negative, hold down the control key (cmd on Mac) and move the cursor over the scan - below the scan it will show the density of all, the R G and B channels of the point where the cursor is.
You say you can't find a reference to densitomoter in Vuescan. The above gives you one. If you are not following that process, I'm not understanding what you are doing to get the numbers you are giving.
juan
Thank you, that is something to try. and I did try it. Not ideal, is the sample size adjustable?
I have been frustrated for years about how to use V700 for 'density comparisons', words chosen carefully, I don't think I need calibrated absolute values traceable to a standard. ymmv
Seems to me relative density measurements should be easily done and method easily explained for EPSON xyz models.
Nothing I have read is simple in description.
Re: Scanner as densitometer?
Are densitometers that expensive? Every once and a while, one will surface that can purchased for a very reasonable price.
I think that I purchased a Tobias for something like, under $75. Years ago, when vendors were selling Fuji film and print processing stations right and left, some really excellent, high quality densitomters were selling for under $200.
Re: Scanner as densitometer?
I keep looking for one but most seem damaged and like all electronics prone to age failure. I'd rather use what I have. There is no reason a scanner cannot give relative data especially if we 'calibrate' to a step wedge.
