RH Designs StopClock Professional timer's split-grade mode

tbm · May 2, 2009

When using the above enlarger timer in the split-grade mode, does one have to change one's enlarger's filter setting to 0 for channel 1 and to 5 for channel 2? I ask becase the instruction manual for mine is not explanatory enough about performing the split-grade mode.

Terry

kraker · May 2, 2009

The timer does assume that channel 1 is the soft channel (grade 00, 0, 1, or a lot of Y for a dichroic head) and channel 2 the hard channel (grade 4, 5, or a lot of M for a dichroic head).

Whether you use grade 00, 0 or 1 for the soft, or 130Y, or 170Y; grade 4 or 5 for the hard, or 130M, or 170M: it doesn't really matter; just choose something that works for you and use it consistently.

tbm · May 2, 2009

Kraker, I must ask again, in a slightly different way: If, on my dichroic enlarger, I have the filtering set to, say, grade 3, does the split-grade feature automatically override that and move into low grades (for highlights) for channel 1 and high grades (around 5) for shadows?

Nicholas Lindan · May 2, 2009

What enlarger are you using with the timer? If it is standard dichroic - Omega or Beseler, say - then the settings on the head do not influence the timer and vice-versa. It is up to you to coordinate the head filtration and the timer channels.

jeroldharter · May 2, 2009

The purpose of the "splitgrade mode" is to tie the two channels together so that if you adjust one channel, the timer automatically adjusts the other channel to maintain the same contrast.

For example, you have determined that Channel 1 is 15 seconds at grade 0 (say 200 units yellow) and Channel 2 is 25 seconds at Grade 5 (say 200 units magenta) is the appropriate exposure for your print and you have a series of burns programmed into each channel. Then you decide that you want to print the whole thing 1/6 stop darker. In the split grade mode, you just nudge up one of the channels base exposure by 1/6 stop and the timer adjusts all the other times to maintain the same overall contrast for the print.

In the disconnected mode, the two channels are completely independent of one another so adjusting the exposure in the soft channel has no effect on the hard channel and vice versa. That is the mode I use. I might have the explanation a but wrong because I never use the split grade mode but I think I am on track.

OMU · May 3, 2009

Hi,
When using the split grade mode you must change the filters as Jerold explained.

The hard channel (channel 2) is not affecting the soft channel (channel 1)
That means that you can fine tune your contrast by the exposing time in channel 2.

When the contrast is decided by the time in channel 1 and 2, you can make your photo darker or lighter by changing the exposing in channel 1. Channel 1 is affecting the hard channel. The channel 2 will change and keep the contrast as you have decided.

So you should decide the soft expose first, then the hard expose.
(Sorry for my english)

RH Designs · May 3, 2009

The timer clearly has no knowledge of what filtration you're using. We designed the split grade mode to use ch.1 for the soft exposure and ch.2 for the hard; if used together with Ilford filters (grades 00 and 5 respectively) and a typical white-light source the notional "grade" indication on the timer will be approximately correct. Other filters, colour enlargers etc. will differ, sometimes substantially. However the basic premise will hold i.e. in split grade mode, adjusting ch.1 mostly affects the overall exposure whereas adjusting ch.2 mostly affects contrast.

RH Designs · May 3, 2009

tbm said:
I ask becase the instruction manual for mine is not explanatory enough about performing the split-grade mode.

Terry

Terry - what firmware version do you have? (Check by reading the display during power-up). If it is earlier than v8.5 then the split grade mode works slightly differently and adjusting either channel will affect overall exposure. However, the comments regarding filters are still valid, on a dichro head set max Y when using ch.1 and max M for ch.2.

tbm · May 3, 2009

Richard: Aren't these two comments contradictory?

"The timer clearly has no knowledge of what filtration you're using."
"On a dichro head set max Y when using ch.1 and max M for ch.2."

clay · May 3, 2009

Not contradictory at all. The second statement tells YOU what to do when using the timer. The timer and the head do not 'talk' to one another. It needs the mediation of your own brain to make the whole thing work.

tbm · May 3, 2009

Richard: My timer's firmware version is 8.3 and my enlarger is a dichroic Saunders LPL 670MXL.

RH Designs · May 3, 2009

tbm said:
Richard: Aren't these two comments contradictory?

"The timer clearly has no knowledge of what filtration you're using."
"On a dichro head set max Y when using ch.1 and max M for ch.2."

No. The timer does not know what filters you're using. It's up to you to change the enlarger filtration, there is no information feedback from the enlarger to the timer, nor does the timer itself control the filtration. The usual way to split print is to make two exposures, one through a soft (max Y 0 M) filter and one through a hard (0 Y max M) filter. We suggest you use ch.1 for the soft exposure and ch.2 for the hard in which case in split-grade mode the firmware prompts you when you change channels to set soft or hard filtration appropriately. That's all. The later firmware also computes a notional grade based on the ratio of the two channels and assuming you're using Ilford filters; for dichroic heads this is unlikely to be accurate but it doesn't matter, it's the result on the paper that's important. Changing the soft exposure mostly affects the exposure and is useful for setting the highlight density, changing the hard exposure mostly affects the contrast and is useful for setting the shadow density.

Nicholas Lindan · May 3, 2009

RH Designs said:
Changing the soft exposure mostly affects the exposure and is useful for setting the highlight density, changing the hard exposure mostly affects the contrast and is useful for setting the shadow density.

As far as the "mostly" goes ... the soft exposure is not much effected by the hard exposure when making a soft print (ie from a hard negative); and vice-versa with hard prints when the hard exposure is not effected by the soft exposure.

The dividing line is when the hard and soft exposures are roughly equal when using Ilford 00 & 5 filters.

If you are printing soft negatives you may want to use the hard filtration as the 'exposure control' first channel and the soft filtration as the 'contrast control' second channel. This becomes more important with softer and softer negatives.

The order, of course, makes no difference to the final print, it's only a matter of more intuitive control over split grade printing.

Most printers find this much too confusing and do all prints soft/hard and just muddle on through with the occasional very soft negative.

See 'Way Beyond Monochrome' for more information.

tbm · May 3, 2009

Richard: Can my StopClock Professional be upgraded to the current firmware version by sending it to you? If so, how much does it cost to upgrade it and can the most current user manual be sent back to me with the timer?

Terry

RH Designs · May 3, 2009

tbm said:
Richard: Can my StopClock Professional be upgraded to the current firmware version by sending it to you? If so, how much does it cost to upgrade it and can the most current user manual be sent back to me with the timer?

Terry

No need to send it back Terry, it's user-upgradeable by means of a new processor chip, and you can order on-line here. A new manual is part of the upgrade but meanwhile if you want to you can download a copy from the web site.

tbm · May 3, 2009

Richard, what is the cost of the new chip for my StopClock Professional in U.S. dollars (your site only shows it in Euro dollars)?

RH Designs · May 4, 2009

Depends on the exchange rate when you buy. Currently 25 GBP is approx $37.

RH Designs StopClock Professional timer's split-grade mode

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