using a step wedge

[coops]

I have a 31 step wedge. Using an Omega color enlarger with the filters off, I expose the paper for 10 secs under the high light setting and cannot see a separation between 1 and 2, and 19 and 20 wedges. The wedges between 21 and 31 are all white. Am I supposed to be able to get separation on all 31 wedges? I tried a different light and aperture setting, but with similar results.
I am looking to merge wedges 1 and 2, but I though I needed to merge 30 and 31 also. I am porobably doing something wrong, so any help appreciated. Thanks

[jeroldharter]

Why not do contact prints?

[coops]

Why not do contact prints?

Actually this is a contact print. Forgot to mention that.

[Mark Woods]

Lower the contrast.

[CG]

It's not supposed to demand you print all densities. All it does is give you a clear set of equal gradations of exposure. You can chose materials and processing: paper, film, chemicals, exposure and development to get more steps or fewer steps between the black and white.

[Greg Blank]

Two potential errors to check, given that your filters are off and your time seems about right. The errors are related to not enough light or not enough development.
When I was doing paper tests I standardized on 25 lux out put at the base board and used a development time of 90 second at 75 degrees standard dilution of Dektol.

You will get the densest areas of the negative (like 7 wedges-white) as well as the low densities - being all black. Then mid tones will print with gradation.
You can use filters to check the contrast actually produced for that filter "BTW".


I have a 31 step wedge. Using an Omega color enlarger with the filters off, I expose the paper for 10 secs under the high light setting and cannot see a separation between 1 and 2, and 19 and 20 wedges. The wedges between 21 and 31 are all white. Am I supposed to be able to get separation on all 31 wedges? I tried a different light and aperture setting, but with similar results.
I am looking to merge wedges 1 and 2, but I though I needed to merge 30 and 31 also. I am porobably doing something wrong, so any help appreciated. Thanks

[Brian Ellis]

You'll never get all 31 steps visible with silver paper. You can increase or decrease the contrast as much as you want and all that will do is shift the portions of the wedge where you can see separation towards the shadows or the highlights but not both. As you increase contrast you'll see excellent separation at the lowest end but very few steps above that will be visible. If you decrease contrast you'll see more steps but less separation at the lowest end.

If you have access to Ctein's book "Post Exposure" Chapter 4 contains an excellent discussion about the limited tonal range of silver paper and reading it will help you understand what's going on as you increase or decrease contrast when making a print. I think that printing a step wedge at various contrasts from 1 to 5 (or as high as you can go) in 1/2 stop increments is an invaluable exercise that can be done in just a few minutes.

When printing a step wedge using the Van Dyke brown alt process I've been able to create a print that shows 21 distinct step but not with silver paper.

[ic-racer]

31 step? If it is a 21 step wedge then each one is 0.15 apart or one-half stop.

So your ISO(R) contrast is easily determined by counting the number of gray steps (discounting the first off-white and the first off-black), and multiplying by 15.
So if you have 8 gray steps your ISO(R) is 120 which is around a grade 2 or so (which is a likely value to obtain with 'white light' on Ilford MG)

If it really is 31 steps then you need to know how far the steps are apart to determine your paper contrast grade.

[Brian Ellis]

31 step? If it is a 21 step wedge then each one is 0.15 apart or one-half stop.

So your ISO(R) contrast is easily determined by counting the number of gray steps (discounting the first off-white and the first off-black), and multiplying by 15.
So if you have 8 gray steps your ISO(R) is 120 which is around a grade 2 or so (which is a likely value to obtain with 'white light' on Ilford MG)

If it really is 31 steps then you need to know how far the steps are apart to determine your paper contrast grade.

I believe a 31 step wedge is just like a 21 step wedge except that the increments are in thirds of a stop rather than half a stop.

[coops]

You'll never get all 31 steps visible with silver paper.a few minutes.



Now I can stop trying lol. Thanks

[Chuck P.]

The advice of Steve Anchell is that if you primarily enlarge vs. contact print, then you should put it in the negative carrier and enlarge it; if you do mostly contact printing, then contact it.

Also, he states that "there should be at least three paper-based white steps before the first signs of density change. If there are less than three pure white steps, decrease the exposure time. If there are more than five, increase the time." He states that there should be "two or more inseparable maximum black steps at the other end."

[Greg Blank]

That brings up an important point, wedges typically have a over all value. There are two types of wedges calibrated and uncalibrated. Both type wedges should be read on a densitometer prior to use. Usually though the cumulative value for any increments is a total of about 3.0 your printed paper scale will in general run about 2.0


I believe a 31 step wedge is just like a 21 step wedge except that the increments are in thirds of a stop rather than half a stop.

[PViapiano]

Brian Ellis' first response is very accurate and great advice.

You do want at least two steps to merge on the black end, to ensure you have reached paper black.

Alan Ross' column on variable contrast printing, now available through View Camera magazine as a pdf reprint on CD, is another invaluable tool for calibrating your printing materials.