Scanning Film Speed Test/what's your favorite film testing method?

[Bob McCarthy]

With a scanner I don't use the same process to evaluate ISO and development times as I did with optical enlargement, thought the general principles hold true.

I do include some of the clear film edge in my cropping box with my scanning software. I adjust scanner density by using the eyedropper on the clear edge to set DR = 0.

That pins the lower end. If you use a piece of film shot at zone I it should read base + .1 if your software has a densitometer function.

As for development time, I shoot for log 2.5 as normal. If I have a ++ scene I found I am still inside the capability of this scanner (a pro level flatbed).

If I have a minus scene then off to photoshop, or tweek in the scanning software.

I owe Fred Picker my inspiriation for testing of film speed from 20-30 years ago. I think of my scanner as a funny looking enlarger,and proceed appropriately.

bob

[Bob McCarthy]

I miswrote DR=0 and should say, Z=0 (Zone 0)

Sorry for any confusion

bob

[sully75]

still working on all this stuff, thanks for your help everyone.


Peter, do you think there's much difference in use between a 21 step wedge and a 31 step wedge? The price difference is quite severe.

Thanks!
Paul

[Peter De Smidt]

Hi Paul,

The 21 step version should be fine, as long as the densities go up fairly high.

[sully75]

Hello all,

Still dubbing away on all of this.

So I have a sort of test thing in my head that I'm planning to do. Was going to run it over with you before I do it.

I was going to shoot 5 copies of two negatives:
1) A high contrast scene with a mix of bright highlights and dark shadows, that's sort of horizontally even in composition
2) a low contrast scene

But my trick idea was that I was going to take an incident light exposure with my meter, set the aperture at that reading. Set the shutter speed 2 stops down and pull the dark slide out 1/5 of the way. Take a shot. Pull it another 5th, take a shot. Another 5th, now I should be at correct exposure. Take a shot. Etc...for two more shots.

Then...develop at my current time, -1, -2, +1 and +2. Scan all the negatives and then I should have a good idea what development time will work for a good negative for scanning?

Any gigantic holes in this method? Will this pulling the darkslide thing work?

Thanks
Paul

[BetterSense]

Is there a used densitometer that's usually recomended to someone on a budget?

A photographer needs a densitometer like a fish needs a bicycle.

The amount of creative control you have over exposure dwarfs any tiny film speed differences you might find out by doing elaborate film speed testing. Besides, the manufacturer already does elaborate film speed testing for you...it's written on the box.

Look, this is what I do: I take pictures. Sometimes I even use a meter to measure the light. Then I look at the pictures. As a photographer, I know what I want the pictures to look like. If they don't have enough shadow detail, and I can't get said detail out of the negative because it's too thin in the shadows, then I expose more. If I can.

It's not that complicated. Go take pictures. Make sure you expose your film enough, if you have enough light to do so.

[Henry Ambrose]

Hey Paul,

I, other sheet film users and especially the film makers really appreciate you keeping sheet film alive by shooting lots of tests. <grin>

Seriously, its become generally accepted practice to make negatives for scanning that are essentially normal or normal minus for scanning. And there is a good bit of lee way as long as you don't make a negative with a density range that your scanner can't see all at once. Do a search for this subject and you will find many, many pages of discussion on this subject.

You're kinda re-inventing the wheel but I'm sure that it'll help hone your personal process, which is a good thing. There's nothing like knowing something is right as opposed to thinking its right. Be sure to report back with your test results and add to the knowledge base here.