Switch to English Language Passer en langue française Omschakelen naar Nederlandse Taal Wechseln Sie zu deutschen Sprache Passa alla lingua italiana
Members: 70,205   Posts: 1,531,670   Online: 1166
      
Page 3 of 4 FirstFirst 1234 LastLast
Results 21 to 30 of 31
  1. #21

    Join Date
    Apr 2006
    Shooter
    4x5 Format
    Posts
    46
    Quote Originally Posted by Vaughn View Post

    This is the bulb I am thinking of:

    http://www.bulbman.com/index.php?mai...ducts_id=10939
    Vaughn,
    looks very interesting to me too. Thanks for posting this link. Do you think this bulb has a standard thread size? I bought recently a 400W mercury bulb on e-bay and it turned our it has wider threads so I just do not know where to get fixture to screw it in.
    Do you have any estimation what kind of exposure times to expect with this bulb printintg with carbon from a distance enough to cover 8x10?
    Also, as I have not used mercury bulbs so far, do they produce a lot of heat? If so, how do you deal with that?

    regards,

    Jan

  2. #22

    Join Date
    Mar 2003
    Location
    Greenville, SC
    Shooter
    Large Format
    Posts
    4,813
    Images
    5
    Quote Originally Posted by chrobry View Post
    Vaughn,
    looks very interesting to me too. Thanks for posting this link. Do you think this bulb has a standard thread size? I bought recently a 400W mercury bulb on e-bay and it turned our it has wider threads so I just do not know where to get fixture to screw it in.
    Do you have any estimation what kind of exposure times to expect with this bulb printintg with carbon from a distance enough to cover 8x10?
    Also, as I have not used mercury bulbs so far, do they produce a lot of heat? If so, how do you deal with that?

    regards,

    Jan
    Printing speed is going to vary a lot depending on how far you need to place the bulb from the sensitized material. If you limit print size to 8X10 or smaller you could probably place the bulb at around 12" from the paper and get fairly fast prnting times, say 3-5 minutes for pt./pd. If you double the distance, as you would need to do for 11X14 or 16X20 prints, you times will increase by 4X, or 12-20 minutes.

    HID bulbs do indeed put out a lot of heat so consider this when deciding on location.

    I have two UV printing lights, a bank of twelve 48" BL tubes, and a ULF-28 continuous wave xenon. Both units have vacuum easels and I would have to say there is no difference in sharpness between the two lights when used with the vacuum frame. I tend to use the BL bank for carbon printing and the ULF for pt/pd. The reason is that due to the fact that I make very thick carbon tissue my exposures are very long, upwards of 15-20 minutes and the BL does not heat up very much with very long exposures. Pt./Pd. exposures with the ULF-28 are in the 2-3 minute range.

    Sandy King

  3. #23
    Vaughn's Avatar
    Join Date
    Dec 2006
    Location
    Humboldt Co.
    Shooter
    8x10 Format
    Posts
    4,629
    Images
    40
    Jan,

    It has an E39 base -- which I believe is the Mogul base...much larger than the standard light bulb base. One should be able to pick up a fixure for it at a good hardware store...or worse comes to worse, at a electrical supply company.

    I haven't got one of those self-ballested merc lamps yet, so I don't have any exposure experience with it -- and with homemade carbon tissue, and one's individual negatives, exposure times are all over the map.

    I have been using two 175W merc vapor lamps -- 350W total, within 10" of the printing frame. My times are in the range of 30 minutes to an hour. My negs tend to be a bit heafty and with high contrast (very solid highlights). I also use a bit more sensitizer than Sandy, so I am fighting thru more of the yellow of the dichromate also. My record exposure for a single 175W lamp was 6 hours -- made a most beautiful print (I could not see into the highlights of the negative on a light table, yet had almost clear areas in the deepest blacks!) I unfortunately ruined the negative trying to make a second print with a 10 hour exposure. I wasn't using a fan back then and I think I baked the tissue against the negative.

    I now use a table fan that blows air across the surface of the printing frame and that seems to be enough to keep things cool.

    Sandy, On the print you sent me, I noticed you used a bank of BL bulbs for the exposure. Relative to the print I sent you and the sharpness I can usually get, I would not call it a sharp print, but I do not know if the is due to the exposure method or the negative (it appears to be from an inkjet neg). Have you been able to achieve the sharpness of a camera negative with an inkjet negative?

    I ask because "sharpness" is a subjective term and I am not sure of your definition of sharpness relative to mine.

    Vaughn

  4. #24

    Join Date
    Mar 2003
    Location
    Greenville, SC
    Shooter
    Large Format
    Posts
    4,813
    Images
    5
    Vaughn,

    As you suggest, sharpness is a fairly subjective issue and depends on a lot of things, including the subject, the lighting, and of course how the negative is exposed and developed.

    In this case we have a subject which has no sharp contours as the entire scene has been rounded by natural erosion. Also, the scene was in very flat lighting which also limits the appearance of sharpness. Finally, the negative is an inkjet negative printed on Pictorico so the maximum potential detail is on the order of 6-7 lppm, in contrast to the in-camera original which probably has upwards of 50 lppm. I have made this print up tpo 12X17" in size with a digital negative and it actually looks a lot sharper than in 5X7" size because the magnification brings out detail which is hidden in the smaller negative.

    In any case I have not found any difference in sharpness between the BL bank and the collimated light source, so long as a vacuum frame is being used.

    Sandy

  5. #25
    Vaughn's Avatar
    Join Date
    Dec 2006
    Location
    Humboldt Co.
    Shooter
    8x10 Format
    Posts
    4,629
    Images
    40
    I understand your point about sharpness. A lot of it has to do with viewing distance, also. I have seen many large digital prints that look great from 4 or 5 feet away, but which "fall apart" up close -- similar to oil paintings. Up close one starts to see digital artifacts that are invisible at a short distance away.

    I can see how a large carbon print made with an inkjet negative would hold up very nicely with a viewing distance that allows one to see the whole print at once, even with a low lppm.

    Vaughn

    PS...thanks for the print!

  6. #26

    Join Date
    Mar 2003
    Location
    Greenville, SC
    Shooter
    Large Format
    Posts
    4,813
    Images
    5
    Vaughn,

    Thank you also for the print. For a long time I could not figure out why you had sent me the film holder!!

    Sandy

  7. #27
    Vaughn's Avatar
    Join Date
    Dec 2006
    Location
    Humboldt Co.
    Shooter
    8x10 Format
    Posts
    4,629
    Images
    40
    Quote Originally Posted by sanking View Post
    Vaughn,

    Thank you also for the print. For a long time I could not figure out why you had sent me the film holder!!

    Sandy
    LOL! I was thinking that I might catch you on that! It was the only good use I could figure out for a sub-4x5 holder!

    Vaughn

  8. #28

    Join Date
    Apr 2006
    Shooter
    4x5 Format
    Posts
    46
    Vaughan,
    thanks a lot for the information. I think I will keep using sun for my carbon prints. The exposure times you mention seems too long to me.

    regards,

    Jan

  9. #29
    Vaughn's Avatar
    Join Date
    Dec 2006
    Location
    Humboldt Co.
    Shooter
    8x10 Format
    Posts
    4,629
    Images
    40
    Quote Originally Posted by chrobry View Post
    Vaughan,
    thanks a lot for the information. I think I will keep using sun for my carbon prints. The exposure times you mention seems too long to me.

    regards,

    Jan
    Just realize that my times are at the extreme end of the range -- with the same light system, your times might be 5 to 15 minutes...especially if you use a heavier pigment load in your tissue.

    I print at night -- I have to use them!LOL!!

    Vaughn

  10. #30

    Join Date
    Mar 2003
    Location
    Greenville, SC
    Shooter
    Large Format
    Posts
    4,813
    Images
    5
    Quote Originally Posted by Vaughn View Post
    Just realize that my times are at the extreme end of the range -- with the same light system, your times might be 5 to 15 minutes...especially if you use a heavier pigment load in your tissue.

    I print at night -- I have to use them!LOL!!

    Vaughn

    Vaughn,

    I agree. 6-12 hours, or more, is really at the extreme end of the range. You must be printing with really bullet-proof negatives!!

    Sandy King

Page 3 of 4 FirstFirst 1234 LastLast


 

APUG PARTNERS EQUALLY FUNDING OUR COMMUNITY:



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