[pure-silver] Re: compensating timers (RELATES TO: Re: Aristo VC 4500 enlarger head)
- From: "Frank Filippone" <red735i@xxxxxxxxxxxxx>
- To: <pure-silver@xxxxxxxxxxxxx>
- Date: Sat, 1 Apr 2006 17:04:21 -0800
Ok.. Let's try to se-state what Rei wants to know...
Why do I want to use a compensation timer with a 1 or 2 tube Cold light
head?
Because the light output is not consistent over temperature ( the bulb does
heat up) or voltage or time. The compensation timer makes the light
constant OVER TIME. Yes, it integrates the light output, collects the data,
and makes corrections. ( By stretching or shortening time base .... clock
speed shifting.).
Yes, your Aristo head is notorious for this issue.
No it is not required to fix, there are work arounds.
Yes the Metrolux timer is a quick fix that works. Yes, it works.
Yes there are 2 channels ... one for each bulb.
Now the question of adjusting contrast by using 2 tubes. You know the
theory, % of Blue to % of Green gives differing contrasts.
Now if the green bulb varies over its output, then the contrast is different
then what you predicted. Back to square 1.... you need the compensation.
Now the practical.... I split grade print. One bulb at a time. Not both
tubes on at 1 time. Now you can use the 2 bulb head in several ways.....
Full on green followed by full on blue Time ratio gives contrast.
Partial green followed by partial blue ( yes, the order makes a difference,
use the soft tube first) for the same time. Typically folks use the same
time, and vary the tube % and make it a quick and easy 1 exposure. This is
where your compensation goes a bit haywire.... which bulb is hotter? which
is responding to he voltage change more?
But there is no reason that you could not expose twice.. once for green for
its time, and then again for blue for its time: either the same time or
differing times... and this is where the Metrolux comes into its own.... 2
memories, 2 compensations.. separate.... makes sense?
There were several variations of Aristo 4500 heads. It seemed to depend on
when it was made.... talk to us more, and we can help you ( before the
frustration creeps in.....)
Ask more questions...you have time.....
I no longer use an Aristo head on a D5 like I had a few years ago.. I now
split grade print on a Saunders 4500. Is it better? Probably not. It is
my favorite for now.....
Frank Filippone
red735i@xxxxxxxxxxxxx
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