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Tuesday, 24 January 2012

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A long time ago, I wanted to buy a basic transmission densitometer. The X-Rite 331 was my choice. It has been 100% reliable over the years and extremely accurate when occasionally compared to very expensive, frequently calibrated lab units.

If in the market again today, I would not hesitate to purchase X-Rite's current version, the 341C:

http://www.xrite.com/product_overview.aspx?ID=1453

It appears to have changed only by using flat panel switches instead of mechanical ones on top and employing nickel-metal-hydride batteries rather than nickel-cadmium. I've had no issues with either of those things, but think the improvements are worthwhile nonetheless.

An on-line search turns up retailers offering the 341C for $125 below list price.

Ahhh...sensitometry & the old Macbeth TD-502...I remember them well. Running the Ohio University Film Production Laboratory, I built a simple Sensitometer, which combined my favorite things--machine shop work & electronics--to provide calibrated exposure
strips. Then we'd monitor our processing results with the Macbeth, for which I'd built a separate, calibrated power supply, allowing us to "dial in" the printer lights on the expanded scale voltmeter, as needed. One of the best real jobs I ever had!

A couple of propellerhead comments: surely there is someone out there who could do a port to the new mac environment in their sleep assuming the original source code is available and there was interest ( but that someone ain't me ). Alternatively, looks like the job could be handled in Excel, no programming required.

Very dilute developer behaves a bit like water-bath development where you take the film (sheet, most often) from developer to water bath and back. In both cases, the deal is that it holds back development in the highlights due to exhaustion of the developer there, while giving the developer LOTS of time to work on the shadows.

So, basically, this is a primitive form of HDR; you're taking a brightness range exceeding that of the film, and compressing it down.

Ansel Adams used water-bath development on the negative for the famous moon rise over Hernandez, and still just barely managed a printable neg.

Mike, a great expansion of your 2002 article (http://luminous-landscape.com/columns/sm-07-14.shtml). It's not a good thing if becoming familiar with your materials takes so long that some of the materials go off the market.

David,
As with many things in B&W photography, that's a nice theory, but it doesn't really work--it hardly changes the shape of the curve at all, and the differences are below the threshold of noticeability to the eye. To test it you need to develop one neg that way and one with a more standard dilution to the same density range, then plot their curves against each other.

There are lots of things in B&W that are popular because they sound plausible. A number of them are in effect harmless placebos--they don't hurt, but they don't help, and if they make people feel better, well....

Water bath development doesn't work any more either. It worked with the old thick-emulsion films, but those are long gone. The thin-emulsion films of today don't hold any developer to speak of so the water bath idea doesn't (wait for it) hold water. (Sorry.) But by all means try it for yourself.

Again, as the article says, it's best not to fight the materials. Just pick an FDP combination that raises the shadow detail, or that allows you to place the shadow detail higher on the curve, and there you are--no further special measures needed (unless they make you feel better).

Mike

Can the old software be released? I still have some old macs running os7 - 9 that could run that probably....

Ah, yes; current weird films break lots of old stuff. Haven't developed any B&W film since 1985.

Mike,
As long as we are talking about stand developing, water baths, and things that sound plausible, but aren't factual:
Is it in fact the case that n-1 exposure AND development is workable for B&W negatives that are only for scanning?

And...

Have you known anyone to use HC-110 for stand development?

Sensitometry also reveals that Ilford contrast filters for enlargers are mislabled in sequence. While I haven't checked their filters for a few years, all samples that I checked until then showed the problem. The filter samples spanned many years of production.

I pity the poor darkroom worker who assumed that the Ilford #4 filter produced more contrast that the #3-1/2 filter. In reality the #4 just about matched the #2-1/2, and there were some other errors in the sequence.

Some more info here:
http://www.ohio.edu/people/schneidw/vico222/ISO-paper-contrast-grades.pdf

[Mike replies: Not true, and the experiment at the link is fatally flawed, at least for showing what it purports to show: cold light heads don't work as intended with variable-contrast paper because they emit too much blue and too little green light--blue and green being the two colors of light that the emulsions in VC papers are sensitive to, and that the yellow and magenta filters are meant to modulate. Not only that, but the spectral output of cold light heads changes with temperature. If I recall correctly, there was attempt made to market a cold light head that would work with VC papers, but it didn't yield as consistent results as enlargers with ordinary dichroic-style heads.

The linked chart is however the most precise illustration I think I've seen of what goes wrong with VC filters and cold light heads! —MJ]

As I read this post, I had moments of nostalgia for my old darkroom, with its D2 Omega, film tanks, paper trays, etc., etc. But not many. Somehow, I really don't miss the wet darkroom. True, the learning curve on PS5, and the like can be long, but I sure seem to get better results, and in color too, as well as B&W. Nope, even though I still shoot some film, I'll scan it and print digital. Digital isn't perfect, but what is??

Mike

I did the Rodinal diluting and stand development thing partly due to time constraints. I could start the development process put the kids to bed and then finish the development thus saving myself a few minutes and not being precise meant it could be 45 or 90 mins and still get the results i wanted.

Craig

Mike, I had to laugh about your phrase "APUG-type B&W photographers". I guess since I own a Heiland densitometer and understand all this BTZS stuff, AND visit APUG that I fall into this category.

But what exactly does that say about me? I have always been suspicious when I have been slotted into some readily identifiable category, and it makes me wonder if I need to adopt some counter-typical signifier such as a funny hat, or a second hobby of, oh, I don't know - maybe ham radio operator specializing in arranging helicopter rescues of stranded livestock to ensure I am not pigeonholed.

The hat thing is probably the easiest.

D,
But don't forget, the phrase "outside the box" is very inside the box.

Mike

Only got a X-rite 8xx type (and which local Hong Kong X-rite dealer still selling parts which I got just in case). Also got a set of all these. Due to some family issue, I have to wait but this view seems align with my experience.

The only one particular thing I learn from his book is to use incidence meter to do this. A bit odd and would try later.

A few notes from my perspective, for film testing. The most difficult thing for me to get my head aroud was setting the personal speed point. If you are familiar with BTZS you know what I'm talking about. Long story short, besides a desitometer, acquirig a sesitometer is a god send for testing.

With the help of a couple of kowledgable friends, I discovered the EG&G MK VI &VII are the preffered units. Hard to find, but if one is serious about film testig these gizmos will simplify the tasks. Look on ebay for used models.

I have the Eseco Speedmaster, sourced directly from the factory as factory refurrbed unit (this was after receiving 2 DOA from ebay sellers). The price was very reasonable.

I also have a Xrite 810 which allows direct capture from a serial port input but now most computers no longer support RS232 connections.

The Matcher program really works though groking the software was a bit difficult for me at first.

I do wish 31 step-step tablets were supported. And getting the data package that Phil and Fred created is also very worth while and istructional.

BTZS IS very gear intensive and may not suit everyones demeanor for gizmo-stuff or computer phobes. My best advice if one wishes to stick their toe in the BTZS pool is to contact Fred or Dennis at the View Camera store.

A friend of mine uses highly-dilute stand developing for just the reason that you mention. He can get his negatives soaking and never has to worry if the baby starts crying or someone rings the door-bell. 45 mins... 55 mins... he still gets pretty consistent results. He's a multi-tasker.

For me, I just can't help but stare at that little tin can, waiting for the sound of the buzzer.

Hello Mike,

As an FYI, the former online magazine,Magna-Chrome (not to be confused with this company http://www.magnachrome.com/), published an article several years ago explaining BTZS and offered a freely distributibed PDF and Excel spreadsheet.

MC is now defunct but I have copies of the PDF file and spreadsheet utility. If you would like a copy of each, e-mail me and I'll e-mail you a YouSendIt link so you can download them.

Don Bryant

the all important FDP

Yeah, but there are a few other variables as well. The enlargers optical system makes a pretty huge difference. What is a unprintable highlight in a collimated point source enlarger due to the callier effect is just fine in a cold light enlarger. I believe the shape of the response curve changes as well.

I once had the experience of working in a darkroom with an old safelight that was just an incandescent bulb painted red . We upgraded to a Thomas Duplex and all the highlights in the prints became chalky. It turned out that the old safelight had been fogging the paper just enough to add some density to the highlights without reaching the threshold of noticeably fogging the borders of the print. The guy who shot halftones of them had a memorable WTF moment when all our prints went weird on him.

Right out of school I worked very briefly for a guy that insisted that enlargers needed to be "broken in". One enlarger would "print by itself" and the new enlarger would require much fussing about, hand waving, and burning in. After a while the new enlarger and lens would be "broken in and printing by itself". Of course he was chain smoking the whole time and his FDP was calibrated for a lens and condenser coated with a film of cigarette smoke. Apparently one of his previous workers employment was terminated when "he broke the old enlarger" by "doing something weird to the condensers or the lens or something when he cleaned it" hence the new enlarger that needed to be broken in.

Rule of assisting: Don't clean any gear until you have seen if and how the photographer does it. Don't offer to fix the bent reflectors , busted softboxes, and obviously too long power cables .
And don't dare even think about that busted up umbrella that looks like the dog peed on it or it was used to serve fried chicken out of and I can't believe he's shooting the main light through it and does he know that there is a hole in the compendium where the gel fits?

Oh, and developing to completion rocks, modern thin emulsion films not so much. I fondly remember a college photo class where one assignment involved developing Pan-X for 12 hours. In retrospect I think it may of had as much to do with all the photo students going to classes whacking those little Nikor tanks every five minutes. In the art history slide lectures. Whack! Photo student here!
Does diafine still work on modern films?

That's a really cool app: I've always understood those curves but never thought about combining them into the FDP chain like that. Simple and functional.

Just wondering, is the raw data publicly available? (I would assume yes since most tech sheets are on the Internet now... so why not share the values behind the app)

I mean, if so -- we should go about building a web based version of this!

Pak

"When scanning you don't get the paper curve"....

Mike, of course you don't but if you scan using SilverFast (as my expirience goes) you do get to the point where you can adjust the scan for the film being used. My credo is simple, I always use the film developer of the company that made the film. I use Ilford Pan F Plus and Delta for B&W and use DD-X as a developer and develop using the standards given by Ilford. If my exposure was correct I should get the result that Ilford imagined (more or less) and thus when I scan using the Ilford Delta and Pan F Plus profiles in SilverFast I should wind up with evenly matched negatives, no matter what (and I'm pleased to say, I do).

But I was wondering, SilverFast has a little densitometer build in.....Have you (or any of the readers) checked that and is it any good.....e.g. could I use a scanner as a densitometer?

Greetings, Ed (http://blogger.xs4all.nl/stomoxys)

"But even then they were basically lost when it came to replacing old materials they liked with a new substitute, when, for instance, an old film or developer or paper was discontinued," as for example in the case of the Ilford Delta 400 sheet film cited above. Today it's only available in 35mm and 120.

Many thanks, Mike: this throws a very revealing light on some vividly recalled darkroom frustrations. In your third screen shot the bar graphs on the right give an immediately comprehensible explanation of what's happening. It's a bit like the ZoneMapper control in Lightzone, perhaps.

so can we adapt this to digital scanning and determine what contrast index for various films yields the best scanning neg? Dense negs don't scan well - they look grainy in the highlights.

Can we just use the same methods we used in zone system practice to get the longest tonal range out of a neg and assume that is the best scanning neg, or is it really something else?

Crikey Mike, you have taken me back 30 years or more!

Mike- the reason for stand development times of an hour to an hour and a half is to let you go and watch a film or the TV, whilst you reflect on whether the shot you just took really is good enough for the Pulitzer. 18 minutes just doesn't cut it.

It's a win- win all round: Photography, TV and reflective learning!

"That tells you two things—first, you need to match your film to a paper based on the way you want your higher values to look, and second, when you expose under the enlarger, you do just the opposite of what you do with film—expose for the highlights and then adjust contrast with contrast filters."

I have the feeling that this is important advice for a darkroom novice like me. I'm just not sure how to follow it. Any posts about darkroom printing will be much appreciated.
Paul

Dear William,

Adding to what Mike said, cold light heads typically have narrow, spiky spectra, so their peak emissions may not at all match the peak absorptions of the dyes in the variable contrast filters. Furthermore, VC papers have spiky spectral sensitivity (see my section on VC papers in POST EXPOSURE) and expect to be dealing with a "white light" source, so who knows what the paper is actually seeing.

The fact that you got extremely different results for each different combination of paper and filter set you used should have been a big clue that something wasn't right.

One factor that DOES matter is the age of the filters and how much they've been used. In particular, the magenta dye used in some VC filters is relatively fugitive, so it's possible to have Grades 4 and up light-fade enough that they actually become lower in contrast than Grade 3. That big a change is readily seen with the naked eye-- when your Grade 4.5 filter looks merely rosy pink, it's kind of a big hint-- but lesser degrees of fading may not be at all visually obvious.

Careful workers keep some kind of quick and dirty reference neg & print on hand and every couple of months bang out a few quick prints just to make sure their filters are still in A-1 shape.

pax / Ctein
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-- Ctein's Online Gallery http://ctein.com
-- Digital Restorations http://photo-repair.com
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Re link from William Schneider showing apparently "mis-labelled" Ilford filters: chart states that an Aristo V54 lamp was used, reportedly this lamp does give close to proper grade spacing with VC papers without the lack of low contrast and "bunching" at the end a regular cold light lamp will give (I've only personally used the regular lamp with filters though so I can't confirm from direct experience that the V54 lamp is really any better. This link to something originally in Photo Techniques mag appears to show the V54 does work though: http://www.light-sources.com/sites/default/files/v54_lamp_color.pdf). William Schneider's link definitely would make me wonder about the filter set he tested.

If you calibrate your scanner with a standard transmission step wedge, it should be usable as a densitometer -- especially if it's CCD-based, as CCDs are among the most linear of all measurement devices.

The problem is when you're at high densities and thus near the scanner's noise floor (since high density = low transmission). On negative film you'll get the densities for the shadows right, but the numbers obtained for highlights are unlikely to be useful, unless your film is developed to give very thin negatives.

Dave,

The V54 lamp is an improvement over the older bluish lamps. I am able to get very even grade spacing using it, as measured using a reflection densitometer reading step wedges. Here's another chart showing that the V54 (with Kodak PolyMax filters) achieves a true -1 grade even in Dektol, but especially with Ansco 120 developer...

http://www.ohio.edu/people/schneidw/vico222/images/ISO_contrast_multigrade_ansco_dektol.pdf

I do want to mention one more thing. In the March/April 2007 issue of Photo Techniques magazine, Kodak scientists Dick Dickerson and Sylvia Zawadzki also mention that they discovered some mislabled filters in a story titled "Variable-Contrast Filters - Are They All They Claim To Be".

They advise spreading out the filters to check for a smooth color progression. Both of my MG filter sets fail that test, and it shows in the sensitometry data. It's hard to argue with numbers.

Yeah, Rodinal 1:100 longer than ~19 minutes is pretty useless. Agitation regimen is more important. No I haven't measured it; I'm buying a densitometer to do that.

Oh, and lon sstand development probably isn't too good for grain structure and emulsion (physical) stability on the substrate.

Dear Bill,

OK, I'm sure convinced. You're right. I'm wrong.

Looky, I lernt sumpin new!

pax / Ctein

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