Switch to English Language Passer en langue française Omschakelen naar Nederlandse Taal Wechseln Sie zu deutschen Sprache Passa alla lingua italiana
Members: 71,468   Posts: 1,570,827   Online: 1075
      
Page 2 of 3 FirstFirst 123 LastLast
Results 11 to 20 of 22
  1. #11
    Photo Engineer's Avatar
    Join Date
    Apr 2005
    Location
    Rochester, NY
    Shooter
    Multi Format
    Posts
    23,369
    Images
    65

    Rescan of different image

    Tim;

    I don't think it was Newtons rings, as it happened with the plate in position with only one of two scanning options.

    Here is a sample of another scan. It was done as a positive, then inverted. The other was scanned directly as a negative to give a positive.

    Since these are just two options, there must be something else involved. So, here is a better example. For whatever reason, the moire artifact is gone.

    PE
    Attached Thumbnails Attached Thumbnails glass plate 3 ISO 40 resize pos scan.jpg  

  2. #12
    Photo Engineer's Avatar
    Join Date
    Apr 2005
    Location
    Rochester, NY
    Shooter
    Multi Format
    Posts
    23,369
    Images
    65
    Please note that the defect in the upper right was cropped out in this scan and the dpi value was different so the image sizes don't match, but it was from the same plate.

    Note the identical defect in the rightmost neutral step. However, I did clean the platen of my scanner in between due to the defects you see in the image with no pattern and the one with the pattern, so the image with the pattern is clearly with a cleaner glass plate.

    PE
    Last edited by Photo Engineer; 10-30-2007 at 11:03 PM. Click to view previous post history. Reason: Added more details.

  3. #13
    David A. Goldfarb's Avatar
    Join Date
    Sep 2002
    Location
    Honolulu, Hawai'i
    Shooter
    Large Format
    Posts
    17,430
    Images
    20
    Well, if it's just a scanning issue, I wouldn't worry about it.

    I don't have a Macbeth chart handy, but is it printed with a dot pattern? That could be one explanation. I've read about one photographer who doesn't shoot executive portraits with a certain model of digital camera, because it seems to create moire patterns in men's suits.
    flickr--http://www.flickr.com/photos/davidagoldfarb/
    Photography (not as up to date as the flickr site)--http://www.davidagoldfarb.com/photo
    Academic (Slavic and Comparative Literature)--http://www.davidagoldfarb.com

  4. #14
    Photo Engineer's Avatar
    Join Date
    Apr 2005
    Location
    Rochester, NY
    Shooter
    Multi Format
    Posts
    23,369
    Images
    65
    The Macbeth chart does not have a dot pattern David.

    I hope my reposting of another picture shows that the pattern is transient and may or may not be a moire pattern.

    PE

  5. #15
    David A. Goldfarb's Avatar
    Join Date
    Sep 2002
    Location
    Honolulu, Hawai'i
    Shooter
    Large Format
    Posts
    17,430
    Images
    20
    I didn't think it did, but I asked, because it seemed odd that the pattern only appeared on the chart. Another mystery.
    flickr--http://www.flickr.com/photos/davidagoldfarb/
    Photography (not as up to date as the flickr site)--http://www.davidagoldfarb.com/photo
    Academic (Slavic and Comparative Literature)--http://www.davidagoldfarb.com

  6. #16
    Photo Engineer's Avatar
    Join Date
    Apr 2005
    Location
    Rochester, NY
    Shooter
    Multi Format
    Posts
    23,369
    Images
    65
    David;

    Too many mysteries appear when digital is involved.

    PE

  7. #17
    ben-s's Avatar
    Join Date
    Jul 2006
    Location
    Nottingham, UK
    Shooter
    Multi Format
    Posts
    443
    Images
    11
    It looks great! Even from what I've seen on here, your emulsions have made massive progress in the last couple of years.
    Any ideas on how long a coated plate would keep for?
    Lens caps and cable releases can become invisible at will. :D

  8. #18

    Join Date
    Jan 2007
    Location
    Australia
    Shooter
    Med. Format RF
    Posts
    127
    PE,

    Looks great! ISO 40 is a good speed. Any details on the emulsion/workup would be much appreciated.

  9. #19
    Photo Engineer's Avatar
    Join Date
    Apr 2005
    Location
    Rochester, NY
    Shooter
    Multi Format
    Posts
    23,369
    Images
    65
    It is an SRAD as in the OP and as posted in more detail earlier.

    This make used 10.2 grams of silver nitrate to make up a total of 200 grams of emulsion in 8% gelatin. The final pH was 6.0 after a pH cycle for ISO washing. The melted emulsion at 40 deg C was dropped to 20 C while cycling the pH to ~3 with dilute sulfuric acid. It was then washed with copious amounts of DW to remove excess salts and was brought back to short of 200 grams after decanting the excess wash water. The added weight was in the form of extra 20% gelatin and DW.

    The washed emulsion, now at about 10% gelatin was brought to pH 6 with dilute sodium hydroxide and the temperature was brought to 40 degrees. The weight was adjusted to 200 g, with the gelatin at between 8 and 10% in the final melt.

    Surfactant was added along with hardener (glyoxal) and the coatings were made on paper and estar at 5 mil and on glass at 7 mil. Speed on paper was 100 - 200 and on film was 40 - 50.

    The sharpness, grain and contrast of this finally looks good to me! The negatives are quite good except the ones I shot at 1/25". They are a little unsteady. I was warned to open up a stop and go to 1/50" but I thought that I was steady enough. It was a dull day. For the ones posted, it was a much brighter day and I could use 1/100" so things were much sharper.

    I have no keeping data on this emulsion. The Azo type and Kodabromide type both keep for a year, both coated and raw. This emulsion begins to fog badly as the raw unwashed emulsion, after about 1 month due to the ammonia. It contains no restrainer or preservative.

    I assume that the total lifetime would be less than 1 month until I add some of the restrainers and antifoggant chemicals, but you can easily make it and use it as needed for the time being. The total prep takes 2 days, and curing/hardening takes 24 hours for film and I would estimate about 4 days for plates unless you use a prehardener.

    PE

  10. #20
    rwyoung's Avatar
    Join Date
    Apr 2006
    Location
    Lawrence, KS
    Shooter
    Multi Format
    Posts
    704
    Images
    40
    PE -

    My craptacular little all-in-one HP scanner/printer has a similar problem when scanning. The problem is more pronounced with glossy papers. When I use the descreening mode, it is greatly reduced in the final scan.
    Don't sweat the petty things and don't pet the sweaty things! http://rwyoung.wordpress.com

Page 2 of 3 FirstFirst 123 LastLast


 

APUG PARTNERS EQUALLY FUNDING OUR COMMUNITY:



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