Enlarger Timer - Inner numbers meaning?

[Sim0n]

My recent acquisition of printing equipment included a Viponel S15 timer.

The operation seem fairly straight forward - start, stop, lamp, 1x 10x etc

However inside the number dial of 1 - 6 is another group of numbers from 1-22, the 1 is at the .5 second mark and the 22 at the 5.6s mark.

I get the feeling whatever this is could be useful but I can't work out what they mean, unless i'm just missing something really obvious.


Any assistance welcome

Si


I found a pic online that may help illustrate

 

[Hilo]

Not sure, but I imagine you can switch from up to 6 seconds exposures (outer circle) to up to 22 seconds (inner circle). Maybe by pulling out the main dial?

 

[Ron789]

Those numbers correspond with the numbering on the pillar of a Meopta enlarger. They indicate how you need to correct the exposure when moving the enlarger head up or down.

 

[Michael L.]

Thank you very much, Ron789. Your answer to Sim0n cleared up the mystery of the similar markings on my old Novex timer (see (there was a url link here which no longer exists)).

 

[henpe]

Hi,

It might very well be that you can use those numbers to correct the exposure when moving the enlarger head up or down. Additionally,...

...If you look closely and do your math, you will realize that each inner marking is a 1/6th of an f-stop. The VIPONEL is actually a f-stop timer! I used to work with this timer and used it in this way. You do need to observe, though, that most f stop timer have the following relation between "f-stop" and time in seconds:
t = 1*2^f
so that a f-stop number of f=0 correspond to a exposure time of 1 sec
whereas the Viponel instead use the formula
t = 0.5*2^(1/6) * index)
so that a viponel index of index=0 corresponds to a exposure time of 0.5 sec.


An example:
You have made a test-print with an exposure time of 20 sec. This corresponds to a inner markings index of 13. You now wish to increase your exposure by +1/3 of a f-stop, which is the same as +2/6 f-stops and therefore +2 on the inner index scale. So, you should set your dial to 13+2=15, which is rougly 25 sec.

 

[Sim0n]

Thanks for that - the f stop scale makes sense now - i'll also have a look on the enlarging scale to see if that also ties in.

in terms of the differing formula mentioned - would that only be a concern if I switched timers - i'm guessing if i'm working in seconds that both types of scale would give similar results but with slightly different inner numbers.

Would be handy to see what the manual says - i'll have a scout around for one.

thanks again
Si