The timer. Yes 10x3 and 3x10 SHOULD work without reciprocity failure. Minolta used to make an enlarger that was basically a strobe that fired super short duration burst for a given time. (like 20Hz) I don't remember anyone actually liking the enlarger but it worked. You could use a cheap quartz wall clock and wire it so that at 12 the circuit is open and both the clock and the light are off. I'm not sure how you could get longer then a minute this way. Would have to see if you can wire the minute hand vs the second hand and then when minute hand hits 12 it shuts off. I have no idea if that will work as I have not even tried before BUT those cheap quartz wall clock engines are pretty accurate. I have made clocks from them. It should be easy to do and it should work you could even wire the hour hand after looking at this thing. Super easy super accurate. $5.
On Thu, Jul 4, 2013 at 3:58 AM, Kostas Papakotas <clenchedteethphotography@xxxxxxxx> wrote:
Karl what a complete reply....first of all I ahd some more input on the items.The enlarger is the model that prints only 35mm...I am wondring if it is a film carrier issue or mate glass size above the carrier dimension issue. Though the chance of printing 120 etc is remote and if push comes to shove we can borrow oen from some more advqanced club membersKarl what an inclusive reply....first of all I had some more input on the items.The enlarger is the model that prints only 35mm...I am wondering if it is a film carrier issue or mate glass size above the carrier dimension issue. The chance of printing 120 etc is remote, and if push comes to shove we can borrow a 10 capable one from some more advanced club members.That covers the vignetting issue a bit…unless the light opening is as small as the 35mm film opening on the carrier?Regarding contrast I think we might have an issue at times.The contemporary style is heavy printing with a lot contrast and we have used grade 5 filters with Kaiser condenser enlargers several times before. I suppose that the Axomat will be the less contrasty of the lot.The timer is a mechanical one and as any one in the genre it will not be accurate. The issue is if a 3x10sec exposure is the same as 10x3 sec one. We have faced the issue while printing before and we had to resort to wrist watches….Thank you for the tip with the diode. Somehow I needed you to put things together.Since flashlights are another hobby of mine I have used a LED to try measuring the strobing frequency of some flashlights.A more advanced flashaholic uses the "sound card oscilloscope" to measure/plot PWM in flashlights’ output. I think he may have linked his light meter to his PC, but now I have a simpler way to it….(and you have given me the idea to improvise further)Thanks karl!Απο: karl shah-jenner <shahjen@xxxxxxxxxxxx>
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Στάλθηκε: 4:56 π.μ. Πέμπτη, 4 Ιουλίου 2013
Θέμα: Re: Enlarger question
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
