Kostas rites:
I have my doupts on the enlarger and lens, and i cannot find any info on
the timer
the set is a MeoptaAxomat5, Schneider2.8/50mm lens & AhelC766 timer.
but the axomat is new to me.
Further reasearch shows that it differs from the Opemus in the condensing
system. the axomat has probably one lens only, the opemus a 2-lens system.
references
looking here:
http://www.vanbar.com.au/catalogue/product.php?id=31711
it suggests the axomat has two condensers
What i cannot get around are these:
1. What is the effect on the single lens vs double on print contrast?
the lens(es) are to collimate the light, and just as with a picture taking
lens, the better the optical configuration, the better the light will be
collimated. but don't forget that these aren't really true condenser
enlargers - those have point source lights and you could almost print an
image without an enlarging lens using one of them! These really are
condenser/diffusor enlargers. full diffusers as you know don't have any
lenses to collimate the light and often use a sheet of white acrylic to
provide the illumination.
As to contrast, it'll be close to what you are used to with other
condenser/diffuser type enlargers. One lens or two: with two (if they are
designed and configured properly) giving higher contrast than one lens using
the same light source.. but bulb size, bulb position and head design can
have as much effect as lenses.
2. The lamp is opaline 150W/E27 fitting with 70 mm envelope (not included).
What is the function of this envelope?
Not sure - could this be referring to the 70mm contrast filters? That's the
only thing I can think of and they would generally be bought seperately..
3. What are your impressions of the lens?
these are fine lenses. more info here with some being better than others:
http://en.wikipedia.org/wiki/Schneider_Kreuznach#Enlarger_lenses
4. Anyne knows of the timer?
Is the number correct? maybe look through google images and see if you can
spot one that looks like it, that may lead back to some information - C760
sounds like an LPL number (try http://tinyurl.com/nypz57y ) - the only Ahel
products I could locate quickly were grain magnifiers and thermometers. It
shouldn't matter too much though, as long as the timer is accurate - and by
accurate I mean consistent, so even if it's wrong (say you set if for 10
seconds and it runs for 12) - as long as it does this every time then it's
fine. If you want to check precisely how accurate it is, you can always use
a computer soundcard to check it :) *
5. what are the detaisl i should be looking at?
i.e. there are some Axomat models that do not accept film other than the
standard 135 type
some take 120 film and use a mask to allow smaller formats like 35mm, you
can make these from stiff plastic if they are not supplied - just as you can
make your own 'rough edged' holders/ ngative masks for artistic effects.
i.e. vignetting (most probable)
If it's designed for 120 film you'll see no vignetting using 35mm film when
you use the 50mm enlarger lens. Looking into where the condenser(s) are
held, you'll see soon enough whether it is large enough to print 120 film,
but if you cut a mask and try, you'll probably get vignetting if you use the
50mm lens. You'd need to swap to an 80mm lens or a wide angle (expensive)
50 or 60mm lens to print 120, and bulb placement and the position of the
condenser set also contribute to vignetting .. if you find vignetting
occuring, move the bulb up higher above the condenser.
the best way to tell if it is vignetting is to expose a test strip
diagonally across the baseboard and see if it's darker in the centre than
the edges.. but don't expect perfection, there will almost always be light
falloff at the edges, what you don't want is as you say, vignetting.
You can easily test the timing of anything using your PCs sound card by
plugging a photodiode or phototransistor into your microphone input. it's
basic and hardly a circuit so to speak but should do the job - one channel
to ground, one to left (or right .. and if you get the polarity of the
photodiode/phototransistor wrong, just swap it around) - set the timer to
turn on a lightbulb and set it up so the phototransistor won't see any
ambient light. Fire up an audio recording program like Audacity (free for
windows) start recording and fire the timer off. You should get an 'audio'
track that goes from low to high to low again - and you can see the duration
of the input (light). check it a few times for consistency and across a few
different time periods for accuracy.
karl
