Switch to English Language Passer en langue française Omschakelen naar Nederlandse Taal Wechseln Sie zu deutschen Sprache Passa alla lingua italiana
Members: 71,568   Posts: 1,573,505   Online: 669
      
Page 1 of 2 12 LastLast
Results 1 to 10 of 18
  1. #1

    Join Date
    Jan 2005
    Shooter
    Multi Format
    Posts
    284

    Cold Light head and 'thermostat' usage

    Greetings!

    I recently acquired an Omega D-II enlarger for free from a very kind man who offered it up to a good home. The enlarger came with an Aristo Cold Light head (which im assuming has v54 lamp due to it working very well with VC paper) installed and I'm wonder about the usage of the heater part of the unit.

    Aristo mentions keeping it running 5-10minutes before usage, and that it "should be left on continuously for the duration of any day or working session."

    The wording on that line is a bit confusing to me, 'duration of any day'.

    Does this imply it is better or safer to leave it on even when its not in use or expected to be used? While thats not my main question it leads me to what I really wanted to ask:

    Is it safe (or suggested?) to leave the heater running overnight or for periods of time I do not expect to use the head? There are times I can imagine accidently leaving the unit plugged in..

    What are your habits of use with this function? Any problems or issues youd care to share relating to the thermostat?

    As of right now I've been plugging the heater unit in as I mixed chemicals, filled trays found negatives to print etc.. about 10 minutes, did my printing session (usually 2 or 3 hours) then unplugging the heater unit.

    Thanks
    "Where is beauty? Where I must will with my whole Will; where I will love and perish, that an image may not remain merely an image."

  2. #2
    ann
    ann is offline

    Join Date
    Sep 2002
    Shooter
    35mm
    Posts
    2,883
    Images
    26
    we let ours warm up as suggested, and then turn them off when done.
    as ours is a gang lab and no one is there after class it makes sense to turn off. I believe the directions you are referring to, may be in a commerical setting when people are in and out.

  3. #3

    Join Date
    Dec 2002
    Shooter
    Large Format
    Posts
    6,242
    Cold light heads have a tendency to vary light output much more then other types of lamps. This fluctuation is due to not only temperature of the lamp but also minor voltage fluctuations. The reason for this is that cold lamps are inductive types of electrical load and other lamps represent resistive loads. Resistive loads have light output proportional to the input voltage supply. Inductive loads are not proportional to the fluctuations since they have a step up transformer incorporated in their design. This step up transformer increases the input voltage by many orders of magnitude.

    Not only should the lamp temperature be allowed to stabilize but also some form of voltage regulation will be beneficial if you want absolute repeatibility. Some years ago Zone VI developed a cold light stabilizer that worked on a feedback signal from the actual light output. These seemed to be the best means of control yet developed. Subsequent to that other manufacturers have developed feedback types of controllers. Metrolux is one such manufacturer.

  4. #4
    Loose Gravel's Avatar
    Join Date
    Feb 2003
    Location
    Santa Barbara, CA
    Posts
    921
    Images
    14
    Quote Originally Posted by Donald Miller
    Metrolux is one such manufacturer.
    MetroLux is the product. It is made by Metered Light, formerly Redlight Ent. It is sold by Calumet or directly, meteredlight.com

    The Zone VI stabilizer worked well, but at the expense of brightness. It took about a stop of operating headroom. Closed loop controllers don't require this headroom.
    Watch for Loose Gravel

  5. #5
    lee
    lee is offline
    lee's Avatar
    Join Date
    Nov 2002
    Location
    Fort Worth TX
    Shooter
    8x10 Format
    Posts
    2,913
    Images
    8
    Quote Originally Posted by Loose Gravel
    MetroLux is the product. It is made by Metered Light, formerly Redlight Ent. It is sold by Calumet or directly, meteredlight.com

    The Zone VI stabilizer worked well, but at the expense of brightness. It took about a stop of operating headroom. Closed loop controllers don't require this headroom.
    I have the metrolux II timer. It is a hotrod. cannot imagine working with a coldlite with out one.


    lee\c

  6. #6

    Join Date
    Feb 2004
    Location
    Lobsta
    Shooter
    Multi Format
    Posts
    566
    Quote Originally Posted by Christopher Colley
    Aristo mentions keeping it running 5-10minutes before usage, and that it "should be left on continuously for the duration of any day or working session."

    The wording on that line is a bit confusing to me, 'duration of any day'.
    No doubt this is referring to a "work day" and is probably directed toward a commercial or institutional user where the enlarger will be used throughout the work day. It sounds like you're doing fine simply by turning it on a little ahead of time as you prep for a printing session. Turn it off when you're done.

    As a matter of safety I have everything in my darkroom on a master switch. All equipment is powered down when I'm done. That way nothing is left to chance. I have this thing about unattended heaters.....
    My Verito page

    Anyone can appreciate a fine print. But it takes a real photographer to appreciate a fine negative.

  7. #7

    Join Date
    Jan 2005
    Shooter
    Multi Format
    Posts
    284
    thanks for the replies thats the kind of information I was looking for as I havnt really had much experience beyond these past 5 or 6 weeks with a head like this.
    "Where is beauty? Where I must will with my whole Will; where I will love and perish, that an image may not remain merely an image."

  8. #8
    Donald Qualls's Avatar
    Join Date
    Jan 2005
    Location
    North Carolina, USA (transplanted from Seattle)
    Shooter
    Multi Format
    Posts
    1,845
    I have a Zone VI head, but no stabilizer for it. Can anyone tell me whether the Metrolux controller will work with it, and if so how much it costs, and alternately whether a thermostatic temperature control using the built-in heater would provide stable enough output to avoid using an intgrator or output-based controller? I could pretty easily cobble up a thermostat, but I don't have a lot of money.
    Photography has always fascinated me -- as a child, simply for the magic of capturing an image onto glossy paper with a little box, but as an adult because of the unique juxtaposition of science and art -- the physics of optics, the mechanics of the camera, the chemistry of film and developer, alongside the art in seeing, composing, exposing, processing and printing.

  9. #9
    lee
    lee is offline
    lee's Avatar
    Join Date
    Nov 2002
    Location
    Fort Worth TX
    Shooter
    8x10 Format
    Posts
    2,913
    Images
    8
    the metrolux II has a probe that is also for sale that is used with the Zone VI head. the sensor is placed in the head of the coldlite and reads the lux of the light when the light is on. you just have to ask for it when purchasing the timer. It will add about $30 to the price. This is not a cheap timer. They cost about $350. the advantage to this timer and probe is that it makes the timer and coldlite a closed loop system. that means if anything happens to the power during an exposure and it affects the lite output, this timer will slow down or speed up depending what it needs. to your question, I think that if you cycle your Zone VI head occassionally by pressing expose you can regulate the output and keep it warm without any trouble. Years ago, the first Aristo head I bought had a temp control built in it. You had to leave the head on in the focus mode for about 15 minutes at the start of the session to warm it up. I don't remember if I had to recycle thru out the printing session or not. I probably did not and was probably not told to do so at that time.

    the metrolux timer will do several things besides count time. It has memory channels that can be used to store exposure information. With the probe for the coldlite head you can chose real time or Lux mode. Lux mode is influenced by the light that the probe senses and is really UNITS and not seconds. there are 2 Lux channels and 3 sub channels in each Lux channel. There is the real time mode also and there is a % mode that is programable for dry down compensation. There is 2 buttons that move the digital display up or down. You can speed this up by pressing the up button and and then pressing the other button also. This puts the display into a hyper mode and speeds up things quite nicely. Obiviously the same can happen with the down button. The Metrolux II timer can be used as a shutter checker and a small densitometer. There is another device that allows you to replicate the exposure from a known time to another enlargement size. A foot switch is something I can not live without also. Plus the foot print is quite small and mine hangs on the wall. I use the Metrolux II timer with the two tube Aristo VCL 4500 coldlite head. I am very happy with this set up. If you have futher questions, feel free to ask me, maybe I know the answer. (disclaimer: I have no monetary function with the Metrolux II company just a happy customer)

    lee\c

  10. #10
    resummerfield's Avatar
    Join Date
    Jan 2005
    Location
    Alaska
    Shooter
    Large Format
    Posts
    1,293
    For your Zone 6 head, consider the Stop Clock Vario by RH Designs. It has a light probe and in every way is as good as the Metrolux (I've had one), but with F-stop timing (as well as conventional seconds). I only use the Stop Clock now.

Page 1 of 2 12 LastLast


 

APUG PARTNERS EQUALLY FUNDING OUR COMMUNITY:



Contact Us  |  Support Us!  |  Advertise  |  Site Terms  |  Archive  —   Search  |  Mobile Device Access  |  RSS  |  Facebook  |  Linkedin