Thermometer for Color Processing?

[mweintraub]

"Accuracy: ±0.1 °C ± 0.4 Operating"

It is not an easy task to build a cheap and accurate digital thermometer....

Yeah, you get what you pay for. I've also read that the "over the counter" home C-41 kits aren't as temp sensitive as the large machine ones.

 

[DREW WILEY]

You still get what you pay for. Do you believe everything you read? Or do you honestly think that a dirt cheap HVAC thermometer is going to be any good in a darkroom?

 

[pentaxuser]

Or do you honestly think that a dirt cheap HVAC thermometer is going to be any good in a darkroom?

What's a HVAC thermometer and is this a reference to one that has been referred to in the posts, if so which one?

Thanks

pentaxuser

 

[DREW WILEY]

HVAC is the kind of trade that fixes your wall heater or air conditioner. Ducting etc. Hot air, cold air. Different application, different temp ranges, and even in that trade any real pro spends several hundred dollars on a meter, not thirty bucks. Worthless in a darkroom, unless you
are just trying to warm your butt.

 

[Truzi]

HVAC = Heating, Ventilation, and Air Conditioning

 

[mweintraub]

You still get what you pay for. Do you believe everything you read? Or do you honestly think that a dirt cheap HVAC thermometer is going to be any good in a darkroom?

It might be. I also don't run a professional darkroom.

 

[pentaxuser]

HVAC is the kind of trade that fixes your wall heater or air conditioner. Ducting etc. Hot air, cold air. Different application, different temp ranges, and even in that trade any real pro spends several hundred dollars on a meter, not thirty bucks. Worthless in a darkroom, unless you
are just trying to warm your butt.

Thanks for that info from yourself and the other poster on HVAC. What's your view on the suitability of the Jobo thermometers or those that are certified to be accurate within what appears to be close enough limits for both B&W and colour work?

I have both Jobo thermometers allegedly suitable for colour and another for B&W. They agree with each other and both seem to work fine. The Jobo's advantage is that it's liquid is blue which makes reading easy.

pentaxuser

 

[pdmk]

"Accuracy: ±0.1 °C ± 0.4 Operating"

It is not an easy task to build a cheap and accurate digital thermometer....

For color film processing I am using Rollei digibase chems. Critical is Dev which requires 37,8deg and has tolerance +-0,3 deg (mentioned in manual http://www.macodirect.de/download/C41_InstructionManual.pdf). Never had any problem with temperature control with this thermometer. But as somebody else mentioned I am not a professional film lab and for home usage it works. But of course I am not trying to convince anybody that this is the best thermometer just saying I have it and I am happy with the performance.

 

[AgX]

Or do you honestly think that a dirt cheap HVAC thermometer is going to be any good in a darkroom?

As already said there are dirt cheap high precision thermometers (though not very practical to use for processing):
clinical thermometers (analogue and digital)



There are wide-range technical digital meters with a readout of 0.1°C and a deviation of +/- 0.2°C at 40°C for about 70$.

https://greisinger.de/files/upload/en/produkte/kat/k14_011_EN_oP.pdf

 

[Roger Cole]

"Accuracy: ±0.1 °C ± 0.4 Operating"

It is not an easy task to build a cheap and accurate digital thermometer....

I don't even know what that means. Is the (claimed) accuracy +/- 0.1C or +/- 0.4C?

And I'm not as skeptical as Drew - it may not be accurate to .1C but it doesn't need to be, even for color. For black and white they don't really even need to be accurate at all, as long as they are consistent.

 

[JaZ99]

I don't even know what that means. Is the (claimed) accuracy +/- 0.1C or +/- 0.4C?

I think it means +/- 0.1°C display precision and +/- 0.4°C metering accuracy.

And I'm not as skeptical as Drew - it may not be accurate to .1C but it doesn't need to be, even for color. For black and white they don't really even need to be accurate at all, as long as they are consistent.

The problem is that +/- 0.4°C is not consistent enough. You can heat up the FD to the constant 38.000°C and get one reading at 38.4°C and second one at 37.6°C. So, when you are getting the reading 38.3°C you have no idea if the temp is within the specs or not. It may be good enough for home development, though. Especially for C-41, when many deviations can be corrected later on.

I'm using DT-1 thermometer, very similar to this one:
Dead Link Removed

 

[mweintraub]

I don't even know what that means. Is the (claimed) accuracy +/- 0.1C or +/- 0.4C?

I wonder if it's suppose to be .1C and .4F

 

[AgX]

No, it is 0.1°C for readout (display) resolution and max. deviation of that readout of 0.4°C from actual temperature.

See also post #35 for a similar case (though with less deviation).

 

[DREW WILEY]

What you need to do to understand advertisements like that is to get your little calculator out (unless it is also to cheap to work properly),
determine the ratio of expense to a real thermometer - in this case about 10% of the real deal, then calculate the BS coefficient, which would be, in this example 10X, then multiply that times the accuracy. Now if you're smart enough to do that before wasting your money, you might also be able to figure out that HVAC thermometers are not optimized for the relatively narrow range of water temps characteristic of darkroom work. While HVAC thermometers might or might not come with a liquid probe for things like water heater testing, their main usage is for hot air, right up the alley for accuracy claims minus the critical BSE (bullshit coefficient). Like I already implied, something like this might
be adequate for repairing the forced air heater that helps spreads dust and lint all over your darkroom; but it won't be of much value for
processing film or paper.

 

[AgX]

Drew,
Kodak advise keeping a max.deviation of 0.15K for C-41.

Considering a digital thermometer with a max. deviation of 0.2K seems very reasonable to me, especially as there always is the chance to check it easily against a Hg-thermometer of higher pecision.

Advocating a much more expensive thermometer seems to include a high bullshit factor (to keep within your repeated drastic wording...)

 

[DREW WILEY]

Digital thermometers in general read slow. You can typically buy a second-hand Kodak Process thermometer for around fifty buck if you hunt around. And it's extraordinarily naive to believe that published rating on outsourced junk are anywhere remotely near the truth. I sell equipment for a living. The junkier the product, the more ostentatious the claims. That's what I call the BS Coefficient. Snake Oil. Lead-into-gold solutions. Perpetual motion machines. Lose weight without diet or exercise. Get something for nothing. A proper digital thermometer for darkroom work would be specifically optimized for a given temp range, just like a mercury thermometer. A large roll of color paper cost around a thousand dollars here. People routinely spend a thousand or two thousand dollars for some lens or camera body they don't really need, but then go skinflint in the darkroom? Doesn't make sense. All those little things add up, and you're only going to be as good as your
weakest link.

 

[Ken Nadvornick]

Kodak Type 3 Mercury thermometer?

Relatively available (used on eBay). Relatively inexpensive (~US$50). Calibrated at multiple set points. Possesses natural provenance (expansion/contraction of elemental mercury governed by the laws of nature, not by software and batteries). Rugged stainless steel encasement.

And best of all, they are exquisitely beautiful instruments in and of themselves. Precision engraved capillary glass encased in a brilliant stainless steel sheath beats computer chips any day...



Ken

 

[DREW WILEY]

Let me explain a bit ... You want to start out rather exactly with any color solution because it's going to drift somewhat during the development cycle, during fill and drain, ambient air issues, column convection, whatever. Being out of step a couple degrees at the start might mean you actually have no latitude left as the process progresses. Maybe you can't even calibrate your temperature correctly to begin with, for whatever system you are using. I have thermoregulators which will easily keep temps within plus/minus 1/10th deg F. Overkill for ordinary black and white printing, but essential for making things like color separations, critical masks, etc. I've had expensive true darkroom digital thermometers, and found them to be a pain in the butt. But these kinds of instruments are just like electrical multimeters in terms of what you get for your money. No licensed electrician would use a thirty dollar instrument. In the long run, a person dependent upon a cheap
thermometer for color printing would probably waste a hundred times as much money on spoiled print paper than would be saved on a dicey thermometer purchase. With RA4 in particular, people can go downright nuts trying to figure out color balance and chem issues which are actually due to temp drift. Not worth it.

 

[pentaxuser]

Would the Jobo color thermometer known as the 3321, supplied with the Jobo processors and as far as I know guaranteed accurate to within 0.2C do the job?

When other manufacturers such as Kodak and Paterson say that their thermometers are guaranteed to within 0.2C but these thermometers cost well short of $50 are they just lying and making things up without any basis?

I had always assumed that to state such a guarantee in writing they had to have their thermometers tested by a recognised procedure and be certified by some kind of professional body.

Presumably it follows from what you are saying that any drift in temperature of the kind that is impossible to stop in say a non thermostatically and very accurately controlled process such as a kitchen water bath will result in problems that cannot be solved in printing.

I am still unclear what price cut-off point($20, $30, $40 etc) constitutes the minimum price for a reliable thermometer nor what deviation from the correct temperature is acceptable.

Finally I presume that those development processes such as Digibase and Tetenal in which a range of temperatures can be used are inherently flawed and any success with these kits at other than 37.8C is largely the result of chance?

Thanks

pentaxuser

 

[DREW WILEY]

Whenever you buy a legit CERTIFIED scientific thermometer, you have to first recognized the exact range and kind of substance it is certified
for in the first place. Something that might very precisely measure the boiling point of water, for example, might not be anywhere near as accurate in "room temp" darkroom applications, or the slightly higher temps typical of color printing solutions. They are all kinds of these things out there. What Kodak did is simply cut to the chase and market a Process thermometer that was practical specifically for darkroom use. And new, it cost about what certified thermometers in general then cost. The cheaper units, Kodak or Paterson or whatever, are not the same thing. Are they good enough? Just depends what you are doing. I could say the same thing about spotting brushes. I can buy them cheap at the camera store, but really really prefer the better, more expensive ones I get from a large art store. ... But regarding "room temp"
RA4 etc ... I tried that kind of chemistry once. Never again.

 

[DREW WILEY]

I should have interjected the concept of quality control. Yeah, you can get lucky sometimes with a bargain, but then go back, buy the same
thing and have bad luck. It's like buying a square from a hardware store or home center. Very few are actually square. Does it matter" Depends on whether you're just cutting a fence post or building a fine piece of furniture. I check all my squares with a true certified machinist's square first, and those simply cannot be made cheaply. Analogously, even if you're paranoid about dropping an expensive thermometer, it's a good idea to have one on hand to check your other thermometers. With complicated things like electronic thermometers, there's a distinct risk of drift. They have to be periodically recalibrated, sometimes even daily.

 

[pentaxuser]

So there does seem to be a certification process and if both Jobo and the other thermometer I have which was an English make are called colour thermometers and are certified I'd assume that there are certified in the range that applies to photographic temperatures which is important as you state.

I agree that it is important to buy the correct tool for the job but I was simply trying to establish the likelihood of colour thermometers from well known photographic equipment suppliers such as Paterson and Jobo being able to meet the temperature colour accuracy required both for myself and others interested in buying certified thermometers which do the job but do not cost anything like $50.

If someone is contemplating starting darkroom developing, especially colour then I'd hate them to be put off by believing that only a great deal of money will get them the right tools.

pentaxuser

 

[DREW WILEY]

How you manage your gear budget is up to you. I wouldn't want to discourage anyone from getting their foot in the door. I did my first one-man color gig in a spare bathroom with a total gear investment of less than a thousand bucks, and got compliments on the prints from some of the most famous photographers who have ever lived. But it was sure a pain in the butt, and once I had some spare money, I put it to serious use in terms of better gear and better digs. A certified thermometer mean that someone has physical tested it against a strict standard, and it will come with a signed certificate. New certified thermometers are typically two or three hundred dollars apiece. Ya obviously have to pay someone to do the testing, to do the quality control, blah blah. Just buying a batch of this or that and putting your brand name on it means next to nothing, specially nowadays. Lots of companies don't really make anything anymore. They just outsource it
and stick their name on it, which they might not own anymore either. I just can't see wasting time getting into color without a serious thermometer. Would you stick a fifteen buck lens on the front or your Nikon or whatever?

 

[pentaxuser]

OK. Just to summarise your position if I may: It is that if you are serious about colour work you really need a thermometer that has been individually certified and spend 2-3 hundred dollars buying it?

There may be those newcomers who will spend that amount to start colour work but I fear that most will not and if this results in them not starting at all, this is a shame for them and maybe the future of the colour film industry.

While I agree that a thermometer made for colour work is the right way to go and that the HVAC route carries risks, I have had success so far with my Jobo Processor and Jobo thermometers and other "certified" thermometers and would encourage others to try the same.

pentaxuser

 

[MartinP]

I think that there may be a slight mis-understanding of the word certification here. A certified piece of lab-gear will be individually calibrated throughout it's working range, in a way-of-use matching it's working purpose -- and will probably be expected to be recalibrated regularly, for most lab-kit. Due to the time and cost involved in this calibration process, the pieces of equipment to which the process is applied will generally be of higher quality, stay longer within spec, will often be adjustable to a specification (eg. power-supplies) and so on.

A guaranteed thermometer, like the alcohol Paterson colour-thermometers I use, will pass quality control on the production line. I have a couple of them, and check regularly the (surprisingly small) difference so that if I break one I still have a known device from which to work.

Which level of quality is appropriate for the home worker is a good question, with many factors to be considered. If you buy a twenty year old 'certified' piece of equipment which does not have an in-date certificate, then you will be buying a high-quality uncertified item. Does your process water-bath maintain a temperature within the developer tank inside the required range at all times, including filling and emptying? Etcetera, etcetera. With the limited process control available to me, I try to be as consistent as possible and accept that I can't match the perfection of the professional Q-Lab where I once worked (Edit: a quarter of a century ago!!), consistently in the top five labs in the UK on process-control figures.