Profililng film with the Sekonic L-758 light meter

[ljsegil]

The Sekonic L-758 is designed to use user generated profiles for digital sensors or film types to enable more accurate light readings and indications of image areas out of the exposure range for the digital sensor or film. I have been able to find a lot of information on calibration and profiling of digital cameras (naturally) with this meter, but (naturally) nothing on how the procedure is done for film. Does anybody have any experience using this meter with film? Have you tried/succeeded in profiling any film types? If so, have you found it helpful, or is this tilting at windmills to try to attain such accuracy and information from a light meter? The thing does sound good on paper, and costs minimally more (new) that a Pentax Spotmeter. If it can function as touted by Sekonic, I can see it providing real value above and beyond a simpler meter.
I'd very much like to hear of anybody's experience who has actually worked with the meter, particularly with regards to usefulness of film profiling or comparisons with the Pentax or other meters.
Thanks and good day to all,
Larry

[Brian Ellis]

" . . . enable more accurate light readings and indications of image areas out of the exposure range for the digital sensor or film . . . " I understand how this would work with a digital sensor (though the camera's histogram would seem to serve the same purpose) but since film curves are affected by choice of developer, developing time, agitation, etc. I don't exactly see how it would work with film. But then I probably don't understand it very well since I know nothing about the meter.

[algarzai]

sorry to bring up an old post.
i am looking for the same piece of information. I have started using film, LF cameras, Home development, home scanning (drum) and printing all at once. the cause of all of this is a long story summarized by labs are closing and shipping is expensive and risky.
I am using sekonic 758 for metering. Instead of all the tests, chemical printing, densitometer and all I would just shoot the targets, develop, scan, then build the profile. I would know the process's zone 1 and set it as black point and zone 8 as white point.
I would then stick to my process and make very fine refinements then recalibrate.

it makes total sense to me. but i am starting to think that my sense isn't quite right because I failed to find someone to explain how to do this. i am mainly worried that the scanner would auto-something then mess it up for me.

[ki6mf]

For how to use this meter to determine film speed and development time, for Black and White film. Check out Zone system Development Test. There are a couple step by step ways of developer time, ISO setting etc. Pick a film and chemistry and change NOTHING till you finish test. Change after if you prefer other films or chemistry.
http://www.jerryo.com/teaching.htm

[dikaiosune01]

I'm reviving this thread because my question is more or less exactly the same and I'm seeking the advice of people who (in so many words) are better than I.

The wonderful thing about this meter, I thought would be the calibration. Once I've determined my metering and developing times and procedures, I will have some kind of standardization by which I can measure. My process begins once I've already determined my processing and the negatives are dry and ready to go (in the enlarger and in the scanner).

When I pop the negatives in the scanner, and the scans come out (I'm using a Epson 700). I'm not sure at what values or what settings I ought to use to get the +3, +0 and -3 exposures needed for the calibration target.
What do I need to do in photoshop? Or what do I need to turn off in the Epson scanner menu.
Anecdote: Personally, I"m in the habit of playing with the levels and curves of my scans to get the shadow and highlights I'm aiming for. However for this test, I'm not sure how to play with the levels.

[Helen Bach]

Assuming that you have used version II of the profile target: Scan the three negs with exactly the same scanner settings - black point, white point and gamma. The black point and white point should be at fb+f and DMax for fully exposed film (if you usually invert during scanning) so that the full density range achieved by the film-developer combination is recorded - but remember that the system was designed for the processed output from a digital camera, so it only covers 10 stops of dynamic range without modification of the process.

If you are happy with the 10 stop range that is all you need to do, apart from deciding where to set the end-use black point and white point - ie the values in the scans you have made of the target negs that are the onset and end of usefulness. All these values can change in subsequent, working scans but for the moment you are concerned with only the extremes that the film-developer-scanner combination is capable of.

How does that sound so far?

Best,
Helen

[dikaiosune01]

Thanks Helen. This is beginning to sound awesome.

Im doing this because i want the profile to produce a baseline target that i will use as a reference when i try special processing.

I do have a new question though. If you need to snack your head for the my silly ignorance, feel free to smack mine.
What is "fb-b"?
I can change the dmax settings? I did not know i could do that. (the scanner is new and im still fiddling with it. At the moment im getting some decent results after playing with the levels and curves.

[Helen Bach]

Sorry, my mistake for using shorthand in an insufficiently clear manner, not your fault.

'fb+f' is 'film base plus fog' - ie the minimum density of the film. This should end up as value 0 in the TIFF file (if the neg-pos inversion occurs in the Epson scan software).

DMax, in this case, refers to the maximum density of the film when processed by the method you are testing, not the scanner's DMax. You could use the density of the lightest patch of the +3 exposure, but check that it is at DMax or close - this is a limitation of using a system designed for digital on film with its greater possible dynamic range.

You can set the scanner black and white points by using the little histogram tool at the left of the row of icons half way down the 'advanced' page in Epson scan. I'm going from memory here - I don't use Epson scan very much. There's a numeric option, so the numbers should be the same for all three scans - I think that should work, but as I said I'm not very familiar with Epson scan.

An alternative is to use the scanner's limits (0 and 255 as the input, 0 and 255 as the output), then set the dynamic range points in the Sekonic software. One way or another you have to set the appropriate range points in the Sekonic software.

Good luck,
Helen

PS Have you thought about doing this in a more traditional way as well as doing it this way? I'm worried that you are going to exceed the software's inherent 10-stop limit. I'm not sure that there is a good workaround. If I get a chance I'll investigate it over the weekend.