In order to calibrate film development times one needs to measure the resulting densities on the negative. How do you guys do this? I was wondering if there is an economical path. Is a densitometer the only way to go? What do most people use? They seem expensive, can these be rented?
Thanks in advance,
-alan
If you are talking about using the "Zone System", it is actually possible to do what needs to be done without a densitometer. You just establish a standard way to make prints and then you draw conclusions from visual examination of such prints. I'll leave it to others to explain how to do that or to give references which explain it. But, it is easier if you measure densities. A densitometer would certainly be helpful in doing that, and you may be able to find one for a reasonable price at ebay. You can also, in principle, use a negative scanner. The RGB values you get from such a scan are not very helpful because they are the end of a process of fitting the dynamic range in the negative to the values in the range 0..255. The same density values in different negatives will generally give you different values in that range. But some scanning software allows you to read the the actual densities. I use Vuescan which has such an option, and I check densities regularly. I haven't ever compared the readings with those from a densitometer, but they seem to be plausible. Also, it doesn't really matter since you just need some consistent way to produce readings which are coherently related to the actual densities. You have to relate everything you do to visual inspection of prints or scans in any event.
I use a light table and my spotmeter. Definately not a rigorous method, but the results are repeatable and it gets me in the ballpark for development times, which I then fine tune visually.
Alan,
If you have a good light meter, as Ron says, you can get yourself in the ball park.
IIRC, the difference between film base plus fog level of developed film and the zone I exposure of .1 above film base plus fog level, is 1/5 of an f/stop.
Try this, it is a simplification of Fred Pickers approach that Steve and I happened upon independently some 25 years ago. It has worked for me.
http://www.viewcamera.com/pdf/2006/VC_Getting%20Started.pdf
Thanks,
Kirk
at age 73:
"The woods are lovely, dark and deep,
But I have promises to keep,
And miles to go before I sleep,
And miles to go before I sleep"
It's possible to pick up a respectable older but still good used transmission densitometr on ebay for $50 - $100 with a little patience. If you're looking make sure to look for "transmission" densitometer, they're the ones that will be relatively inexpensive because they're tied to film. Reflection densitometers are useful in digital printing so they've tended to hold their value better.
Brian Ellis
Before you criticize someone, walk a mile in their shoes. That way when you do criticize them you'll be
a mile away and you'll have their shoes.
Maybe I should clarify my goal, which is to scan the negatives. So I guess fundamentally I want to tune my development times for the best scanning potential and not a specific scanner per se as I have a 4990 and would like to have negatives that are applicable for other scanners in the future. So I am guessing that for example a high contrast scene would benefit from a N-1 development to draw down the highlights in a range manageable. Please note that I am new to the arena and maybe way off base. So given this, how do I determine what development time will achieve this. How do you define what N-1 is in terms of scanning and that being a generic scanner?
Thanks again for your input. Hopefully I will get to the point where I can contribute at some point.
-alan
I develop my film the same way for scanning and traditional printing. That way I am covered. I use the test Kirk referred to above. The goal for both uses is to make the best use of the tones availabable with that film and developer.
steve simmons
www.viewcamera.com
As Steve said.....Since I print both digitally and traditionally, I want my negatives to service both possible mediums. Generally what services for a silver print will scan well too. I.E. the above suggestion works well for both.
next question....are you using Silverfast with the 4990? i am working on a method that looks promising for determing proper dev via a scanner, but it requires SF. It looks promising.
Thanks,
Kirk
at age 73:
"The woods are lovely, dark and deep,
But I have promises to keep,
And miles to go before I sleep,
And miles to go before I sleep"
I scan using an Epson scanner. For b/w negative film, you don't really have to worry too much about which scanner you use since the maximum density any modern scanner can handle is high enough to handle what you are likely to encounter with a b/w negative developed in some reasonable way.Originally Posted by ageorge
But, as I indicated before, you want to measure the actual desnities with your scanner/scanning software combination rather than the RGB values. As I said, Vuescan can do that, and other software may also be able to do it. I like Vuescan a lot and would recommend it anyway. (You do have to enable that capability; it is not there by default. but then using the Ctrl key will show the densities.)
So let's assume you have figured out how to measure desnities with your scanning software. You first task is to determine what you actual film speed is using your equipment and with the film devloped in what you expect your normal way to be, including your development method, developer and time-temperature combination. There are a variety of ways to do that. If you have a spot meter, take a picture of scene with a variety of light intensities ranging over a fiarly wide range, and make sure you measure the EV values carefully. That may require getting fairly close so that the field measured by the meter is uniform in each case. Take the picture so some of the regions should be dark enough not to show any detail. Develop the film normally, scan it, and read the densities, starting with the density of the clear film base. That way you can determine the EV at which you begin to see somethig above base. That should be your Level 0 (or perhaps I).
if you scan, it is not quite as important to worry about N+ or N- developement. As long as you make sure there is sufficient detail in the shadows, the film latitidue and the dynamic range of the scanner should be able to handle you maximum density. But, if you find by experience that such is not the case, you can adjust development approriately. The point is that since you still have considerable freedom to adjust the range in the scan by choice of white and black points and "gamma" (in Vuescan called birghtness), the degree of over or under-develpment won't be critical. So the kind of testing needed for conventional processing using the Zone System is not necessary.
If you want to use densities for more precise control, photograph a scene containing a variety of EV values which would take you from Zone I to Zone VIII. Again make sure you read these values carefully using uniform fields to do so. Then measure the desnity values of these different fields in the developed, scanned negative. Adjust your development until these values are what is typically recommnded. But remember those recommendations are usually for some specific method such as using a condenser enlarger and printing on normal paper. You may find that other values work beter for you with your method.
In all of this, the RGB values in the final scan are what will determine what happens in the print. No matter what the density values are, you can adjust the RGB values quite a lot when scanning and then afterwards in photoediting software such as Photoshop, useing the curves tool. (I use the Gimp under Linux, myself.) So you need to do some testing to determine which RGB values correspond for your equipment to which Zones. Here is a rough outline which works for me:
O, 0; I, 25; II, 50; III, 75; IV, 100; V, 130; VI, 165; VII, 195; VIII, 225;, IX, 245; X, 255.
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