Can you tell me what this stepweg is and how the procidure is to calibrate your analyzer whith it?
The stepwedge is essentially a negative with predetermined densities in equal increments. You can get them here:
The version I have is the TPC4x5-31
If I was to buy a new one I would get the TPC-4x5-41. It would be nice to have 1/6th step increments.
My method for calibrating starts with a calibrated film exposure and developing plan. My target density for zone IV is 1.20. This is step 12 on my wedge. The goal is to calibrate the analyser so step 13 is paper white and step 12 is just showing density. After making several contact prints to find the correct exposure for this, I note the difference in exposure between suggested and reality and use this to input the correct exposure compensation. This is done for every grade and half grade.
The second step is to setup the contrast. This is done by counting the number of steps on the stepwedge. Convert these steps to stops. Each stop is worth 30 iso units. Add it all up and this is your contrast range for that paper.
Thanks for the reply. I'm right in saying that the stepwedge would be on the paper instead of in the negativecarrier? My enlarger does 6x6 as maximum, so 4x5 inch would not fit in the negative carrier. Thanks for the reply. I can see that working very well.
It looks like they are also available in 35 mm and other sizes to fit your enlarger. Look on the Stouffer webpage.
Originally Posted by naaldvoerder
Sorry to hear you've been experiencing problems calibrating your Analyser. Using Ilford filters and paper together with a colour head should give you results that are fairly close, but there are a number of factors which can affect your results and offsets of up to a stop are not unusual. Enlarger lamps can and do vary and this can affect results particularly with VC paper. Also, the particular density you choose to calibrate to will affect the results significantly - in particular if you choose too bright a white you're getting into the toe area of the paper curve and large changes of exposure produce small changes on the paper (as you'll know if you've ever tried pre-flashing). We don't specify a precise density to set the white point to for two reasons - first, most people don't have a reflection densitometer and second, it gives you the choice to set the unit up how you want. If you like punchy prints for example you might want to choose a lighter white point and a darker black.
Ultimately, the Analyser is a print-making tool so you can set it up fairly closely by simply examining your prints. Use the built-in test strip generator to make a series of prints from one negative and choose the exposure that gives you the highlights you want. It's important to judge exposure by [color=darkred]highlights [/color] alone. If the best result is say 1/2 stop darker than the Analyser recommends, enter -6 in the cal table (the steps are 1/12 stop) for that paper grade. If after you've got the highlights right the shadows are too light or too dark, you can adjust the contrast settings to achieve the results you prefer. Use a smaller step size at the harder grades, and a larger one at the softer grades to minimise the effort involved.
If at the end of the day you need a large offset to get the results you want, that's perfectly fine, it doesn't indicate a fault either with the Analyser or with your other equipment or technique.
If you're still having difficulty by all means get in touch, we're always happy to help, and I'm sorry if we didn't provide the best response last time!
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Thanks for your reply dr Ross, and forgive me if I was complaining in my previous post. Mr C. Woodhouse explained to me that my mail got lost in some spam-mail. As I wrote to you before, I suspect a fool can ask more than ten wise men can answer (me being the fool in this equation). I am sure, ones I get it right, the analyzer will proof to be an enormous advantage in my darkroom. Up to now I have been looking for the nearest non white strip, I.e. the first strip that I thought was descernable from paperbasewhite. Is that maybe to for down the toe-end? Secondly I would like to ask you, what you think of Dr. Phill's method of calibrating using a Stouffen stepwedge. If I understand correctly that would simplify calibrating somewhat, allthough I miss negativebase+fogg in his method. I would appreciate your thoughts.
This is all very interesting and intriguing. Unfortunately, I can not add to the general knowledge or experience, yet. I purchased a StopclockPro and ZoneMaster II from a list member through the APUG Equipment for Sale forum. ( Will probably arrive this week and I am in Denver at a seminar until Friday :-( , so I have yet to tackle the calibration and practical learning curve.)
I had been researching f-stop timers and analyzers, (I am a Jobo product fan, in general, but have never been able to receive "value" from my Comparator to move from step strip iterations). The RH Designs site is very informative and I decided that the products would meet my needs. I downloaded manuals to read and hopefully predispose aging brain cells to "get it!" quickly. Additionally the site has a user written guideline for calibration.
I emailed Dr. Ross with a question regarding pyro negs and received a prompt and courteous reply. I am excited, but, perhaps, a little daunted by the posts regarding the calibration of the analyzer, (ZoneMaster II). My experience has been that responsive vendors with websites rich in customer oriented content generally make great products. I am positive that this purchase will reaffirm that experience.
Thank you Dr. Ross for posting to the community!
Since we have Dr. Ross here, I'll post my wild dream about the Analyser. I would love a Analyser Vario. Yes, an analyser with the vario's cold light sensor!! I've noticed that the variation with my cold light head does exist. I can see as much as a half step difference with cold light head.
However, I suspect that the vario's sensor and the analyser use the same circuitry. Thus, I might be out of luck. If I had to do it over again I'd likely get a stopclock vario and a zonemaster and transfer the results manually between each unit. Currently I'm trying to decide how to manage the upgrade.
Hi Dr Phil -
Unfortunately you will have to keep dreaming about an Analyser Vario. The circuitry would indeed be complex, as would the software, because the unit would have to monitor the light level from the tubes and subtract any changes from the readings from the baseboard sensor, because otherwise the sensor would interpret those changes incorrectly as changes in negative density. It would also need an absolute reference for tube light level, so it could work out any necessary change required during the exposure. It all gets a bit difficult as you can appreciate I'm sure! The likely market for the device would not recover its development costs I don't think.
So long as you keep the tubes lit as much as possible to minimise the likelihood of output variations, you should find a standard Analyser / ZoneMaster will work OK. I know of at least one customer using a ZoneMaster together with a Vario successfully with a DeVere 10x8 cold light.
We have a method of calibrating using a stepwedge. It's available at Chris's site: http://www.ktphotonics.co.uk/pdf/pluscal.pdf and is similar to Dr Phil's.
You can either do it yourself, or we offer a service whereby you make the test print and mail it to us to make the necessary measurements and sums.