rotary agitation and sharpness

laptoprob

laptoprob

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Hi, I recently started doing my own film processing. Using D76 and a JOBO rotary processor. Now what amazes me is a Tmax3200 roll exposed at 1600 with full strength D76 is lacking any sharpness. It is not in focussing, the sharpness is just absent.
Is it the rotary agitation? Searching the web I get contradicting reports.
I will shortly have a look at some rolls of Ilford FP4+, developed in D76 1:1.

Any experience on this?

cheers, Rob.
 
For years already I use a Jobo CPE2 for all my films (from 35mm up to 4x5 sheets). Never noticed your problem.
Th only problem that I had, was that the minimum quantity indicated on the tanks is not enough when using a Jobo processor with a lift.

Wim
 
I haven't been keeping up on developing for many years, but I seem to recall that Tmax wasn't supposed to do well in D76. That said, I wouldn't expect it to cause a lack of sharpness. D76 is listed in the Massive Development Chart so it should be usable. Hopefully some here who do more developing can comment.
 
First scans from Ilford FP4+ show a similar result. This is not the reason for going into this way of photography! Slides and especially Scala is way better.
So, could it be the continuous agitation? Should I try a heavier dilution like 1:2 (D76 to water) and the same development time?
Seems to me the even way of rotation is very good to get an even degree of development all over. But could continuous agitation cause loss of sharpness?
There have been a lot of discussions about this on Pnet with varying outcome.

Any experience appreciated!

Rob.
 
Rob the latest pictures I put in my gallery are the result of development in the CPE2.Even after scanning the sharpness is (for my eyes) very good.
In the past I developed Tmax in Tmax or AM74 (cheap, good and a Dutch product) in this processor withput any problem.

Wim
 
I owned a MERZ twin rotary tube machine for about thirty years and used a colenta rotary machine too. There is absolutely no way this can effect sharpness. Sharpness is a function of focus or motion at the time the image is made. Acutance which is the transition between black and white at the edges of detail is a function of film and developer. You probably can not recognise acutance in what you are doing. The net result of rotary processing is less chemistry and much much more even developement. This is particularly true in sheet film but also applies to roll and 35mm. Consistency is also a big plus for rotary processing. A machine agitates exactly the same every time.


http://www.rangefinderforum.com/photopost/showgallery.php?cat=500&ppuser=2450
 
It's most likely the dilution, IMHO. D76 full strength is a pretty strong solvent developer. It'll reduce grain, but at the cost of sharpness. It can look quite nice and creamy for portraits, but for those that are seeking sharpness the lack of it is quite glaring.

Try 1+1 first. If you aren't happy go to 1+3. If you're still not happy, go to a more active acutance developer. Rodinal is the "classic" example, but there are a lot of others, too.

allan
 
Thank you all. I think the answer is in the dilution and the time. I will try those one after the other.
Point with the Tmax 3200 (EI 1600) is the full strength reccommendation with about 11 minutes rotating development. That put together is probably too much.

Attached is one of the sharpest scans of the 3200 film, reduced to 400 pix wide.

What times and dilutions are you using? Not necessarily for fast film like EI 1600 but for regular EI 100.

thank you all.

Rob
 
Well, I don't think anyone can _really_ tell anything from that scan. It's just too small. if you want to send up a 100% crop that would be more useful. But, if it's not sharp enough for you, then it's not.

I use ID-11 myself, but the times are usually the same for D76 (they are basically the same developer, except that D76 has a bit more buffering and they've figured out how to make it in one pack rather than 2). I use 9:00 1+1 with FP4 @ 100. That's for scanning and for a condenser enlarger. You'll want to extend dev time a bit for a diffusion enlarger.

I haven't done FP4 with D76 1+3 yet, but the MDC lists it at 20:00 for EI 125.

allan
 
From "The Film Developing Cookbook" by Anchell and Troop...

"Many photographers like to develop film with continuous agitation on a JOBO rotary processor. Unfortunately continuous agitation interferes with the formation of sharpness-enhancing edge effects. Because continous agitation exaggerates highlight development at the expense of shadow development it also results in lower speed and a shorter tonal scale. One way of compensating for this is to use a more dilute developer. Whatever developer you use dilute it with at least 30% more water and increase your development times"

Steve
 
If you aren't happy go to 1+3. If you're still not happy, go to a more active acutance developer. Rodinal is the "classic" example, but there are a lot of others, too.

One problem with using rodinal in a rotaty machine, the developer is extremely prone to oxidation. Working with 1:100 dilutions there is just enough developer to carry out developement and if you introduce additional oxidation it might not stay active enough to complete the developement cycle. Film developement is a redox (reduction/oxidation reaction) anyway and the natural process oxidizes the developer as the silver halide is reduced to metalic silver. Any additional oxidation through agitiation can be disasterous.

For many years and thousands of rolls of film I processed my film in a MERZ or Colenta rotaty machine using HC110 1:31. Never any problems using recommended or dlightly modified times. I always print on a diffusion head so I like a little more guts. My primary films were Tri-X and Plus-X many years ago and then Agfa 100 & 25 then since Ilford Delta came out this is 95% of what I shoot. Never any issues with HC or HC 110.

http://www.rangefinderforum.com/photopost/showgallery.php?cat=500&ppuser=2450
 
Last edited:
dilution is the key?

dilution is the key?

kaiyen said:
I haven't done FP4 with D76 1+3 yet, but the MDC lists it at 20:00 for EI 125.

allan
Click to expand...

So dilution and longer times may be the key? I will check that MDC out, thanks.

This is the max. allowed JPG, still not enough acutance.

Rob
 
Well, to get more acutance from a solvent developer like D76, you need to dilute it more (thus reducing the concentration of sulfite and reducing the solvent effect in general). The more you dilute it, the longer you have to develop it.

So with D76, dilution is the key. But you have to develop longer to compensate for the dilution 🙂

Or just go to another developer entirely. But try D76 diluted first.

allan
 
Good post.

Agitation will not affect sharpness. It will however, affect grain and density since the constant agitation is akin to overdevelopment.

If you do use constant agitation processes (and there are advantages), then you should do a film exposure/process test for each type of film you use.
What you are looking for is described by Ansel Adams in "The Negative". You need to discover the lowest level of exposure/processing that just produces a density above base fog: that becomes your films ASA speed and std dev time.

I have processed film for myself and others for many years and have a set of dev charts I rely on. I almost always process in Rodinal and agitate for the 1st minute then 5 sec every minute thereafter. More importantly, you should pre wet the film before development (this does aid evenness of process). Wash it for about a minute at the standard temp then process (this also washes out most of the dyes in modern film so don't worry about the green or pink coloured water that you pour out).

Your problem sounds more like focus or movement. Put the camera on a tripod, shoot a test subject and repeat the process steps.

x-ray said:
I owned a MERZ twin rotary tube machine for about thirty years and used a colenta rotary machine too. There is absolutely no way this can effect sharpness. Sharpness is a function of focus or motion at the time the image is made. Acutance which is the transition between black and white at the edges of detail is a function of film and developer. You probably can not recognise acutance in what you are doing. The net result of rotary processing is less chemistry and much much more even developement. This is particularly true in sheet film but also applies to roll and 35mm. Consistency is also a big plus for rotary processing. A machine agitates exactly the same every time.


http://www.rangefinderforum.com/photopost/showgallery.php?cat=500&ppuser=2450
Click to expand...
 
Thank you all, I guess my development timing has been too long. That and the 1:1 dilution for the FP+ and full strength for Tmax 3200 must have been my mistake.
The developer could not have been fresher.
Next test will be a Tmax 100 with T76 1:3 and longer development time.
Before trying another developer I should try T76 more extensively. Lots of people use it so this must be a problem that can be solved.

cheers, Rob.
 
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