Confirming Strips and all that crap...

[nickandre]

So rather than just differentiating from my color print/negative processing using adjectives like "good" or "poopy looking" I'm searching for a more scientific test. I just purchased an automatic densitometer on ebay and I'm just checking over some things here. I don't know if anybody has used these things and could help me here.

I'm just gonna throw some stuff out there. So control strips are expensive...I'm just going to have to deal with that. So the general idea is that I process my control strip using my normal method and use this densitometer to compare the reference strip to that one. I can use some sort of gigantic trouble shooting table to diagnose my problem based on which of the numbers are going which way.

Is this overkill? I'm processing in small tank with one shot use of the developer, so I assume any problems that I get are caused by temperature/agitation issues. Say my tank processes at 101. Is this going to show up on control strips? The only thing is that if I am botching the processing right now, I would kindof like to know that...

anybody have some control strips they won't be using???

 

[hrst]

My humble opinion: Don't bother, this kind of stuff is more important in continuous processors. If you do one-shot and do it as instructions say the results will be very good. 1 F error in temperature doesn't mean much in practice. Use your valuable time to shoot some pictures and have fun in darkroom! If you find that there's too much contrast for RA-4 printing, then, decrease the dev time for, say, 15 seconds. More important than following the exact specifications is that you get results you like. It may mean some variations in processing time, but eye is then better device than test strips & densitometer.

 

[nickandre]

Brilliant idea. I'll play with the densitometer and re sell it.

 

[removed-user-1]

Control strips are indeed meant for high-volume continuous processing... Of course you could always just make your own "control strip" by photographing any sort of color chart at the first frame of each roll of film. I did this once in college with a gray card and a bag of skittles. Crayola crayons also work (seriously).

 

[DanielStone]

transmissive or reflection densitometer? I was playing with an analyzer/densitometer at school last week. Even with the instructions(yes I understood them as they wrote them), I still couldn't really figure it out.

no matter. I mainly shoot 2 or 3 films for color neg, and b/w gets me going with 3 too (efke 25, acros 100 and TMY-2) all in all formats (35mm-4x5)

the real advantage of a densitometer from what I've found and heard is in more of a studio environment, where you have the same film being shot every day(generally from the same emulsion), being printed to the same paper(same emulsion), and you have 3-4 different backgrounds, all of which are somewhat color neutral, yet pleasing to the eye. You use the same rough setup for lights(2 softboxes, and a separation light or 2).

repeatable actions in every step lead to repeatable results.

but this has been eclipsed by the new generation of densitometers, ones being used to calibrate inkjet printers and the monitors used to edit on. So, instead of programming your densitometer for a film/paper combo, you're creating a profile(program) for a specific combination of paper/ink and the computer/monitor hooked up to it.

same thing pretty much, but a little more finicky IMO with the digi stuff.

-Dan

 

[nickandre]

It's an automated densitometer for use with minilab quality control. AFAIK it has pre-programmed control strip layouts and a memory to indicate trends in control strip performance. It's both reflection and transmission.

I use one film with one paper for all my serious work. Ektar 100 (i guess some 160VC now that I've started 4x5 color) but it's much the same. I'm actually thinking that some temperature loss tests along with a hydrometer might be more useful.

 

[Bob Carnie]

For one shot processing a control strip is still a good thing, It gives you a reference to aim for.
Plotting control with a densitometer is probably overkill for your situation but using one and understanding its value , could be a good thing.
Running a continuous roll processor having plots run is a must for RA4 and C41.

 

[ic-racer]

I run control strips for all my different B&W processing routines. Making the strips is easy if you have sensitometer. Knowing your gamma and relative speed is a real boon these days when one may be forced for various reasons to use a number of different types of film.

A logical way to use the control stips in a home darkroom is to first make some 'perfect prints' and work backwards. Find the gamma of the negatives used to make the good prints. Then, when an 'unknown' film comes your way, process it to that same gamma as a starting point. Then tweak from there if needed.

(After writing this I realize this is in the Color section so my comments may not apply..)

 

[hrst]

ic-racer, "make perfect prints and then work backwards" apply very well to color also; and that's just the reason why I can't find any use for a densitometer. That's because C-41 process is standardized for every film; when you have found the perfect developing time, just use it, and you should get repeatable results every time, regardless of film.

 

[nickandre]

My issue is chemistry mixing errors and temperature errors based on irregular transfer of heat to the can from the water bath during development.

 

[hrst]

If that's the case, then well, control strips AND densitometer together will only reveal the problems (not telling what's the actual cause is) but there's nothing you can do, but just to be more careful next time. And, you cannot see the problems before it's too late. The next time is a new batch so the results are useless, or they tell you only one thing: be more careful.

And again, you don't need a densitometer to be extra careful.

Only thing you can do with test strips & densitometer with one-shot development, is to find the correct time for your processing style (including agitation, heat losses etc -- everything that remains constant). Then you just maintain the process, and you can check it once in a while. But, it does not help random problems at all as you cannot take a corrective action like with continuous processors.

If you want to check for chemistry mixing error, buy a precise pH meter.

But, it's not that difficult. Just follow the instructions and your results should be very good. Probably better than from most commercial labs.