Search:

Type: Posts; User: Nodda Duma; Keyword(s):

Page 1 of 30 1 2 3 4

Search: Search took 0.06 seconds.

  1. Replies
    5
    Views
    292

    Re: Lost Light Art Blog . . . . Website

    He’s a great guy.. doing some awesome stuff!
  2. Re: Is this Fungus ? I canīt identify, need help

    It’s adhesive failure in the doublet, ie “balsam separation” although this lens is too new to have used balsam. This is what failure of modern adhesive looks like. I’d bet it wasn’t originally...
  3. Replies
    19
    Views
    648

    Re: Favorite Current 8x10 B&W Film?

    On a limited basis, Randy, while I work on refining the results. I’ve started listing in the Experimental section of the store when I coat enough to box up, so that folks can experiment with them...
  4. Replies
    19
    Views
    648

    Re: Favorite Current 8x10 B&W Film?

    I’ve been enjoying experimenting with dry plate ambrotypes: Black glass coated with my ASA 25 emulsion and developed to a positive.

    For film, Adox CHS II 100 and the CatLabs 80 speed stuff are...
  5. Re: Calculating f-stop progression . . .how are the numbers derived?

    As Havoc notes, f/# values change by the area size. As such, the numbers change by the square root if 2.
  6. Re: SP-445 agitation test results challenging

    As an optical engineer who has tested non-uniformity of imaging systems many times over my career, my first and primary suspect is the actual setup of the test described: I.e. Sheets of regular...
  7. Replies
    13
    Views
    3,825

    Re: Wet/dry plate holders for 4x5

    The ChromaGraphica double dry plate holders are NOT 3D printed. They are modern, injection molded assemblies, designed by photographers who are also engineering professionals.

    Will fit 4” x 5”...
  8. Replies
    42
    Views
    1,590

    Re: getting glass CLEAN, how do you do it?

    Makes sense.. essentially glass enjoys a nice cleaning in a mildly alkaline solution, which is what you’ll get with that.
  9. Replies
    42
    Views
    1,590

    Re: getting glass CLEAN, how do you do it?

    I don’t know any optical shops which use that. Too time-consuming for production to “touch” each lens. For large quantity optics, glass washing machines using distilled water and a purpose-made...
  10. Re: Storage of Exposed/developed glass plates?

    Drew, I did some homework before recommending storage methods for dry plates (my recommendations are never arbitrary. :) ). The dry plate boxes and envelopes sold through Gaylord (and a couple other...
  11. Re: Uneven Development -- 5X7's in Stearman Press 8X10 Tray

    Did you try picking it up *completely off the countertop* and rocking it around? This and 500ml of developer works for me with B&W, C-41, E-6, etc. It’s the same equipment as yours, so it’s fair...
  12. Replies
    13
    Views
    594

    Re: Night Vision for focusing?

    As an optical engineer who is familiar with the hazards of lasers, I would advise *against* viewing the focused image of a laser spot with the type of magnification used for viewing the ground glass....
  13. Replies
    16
    Views
    910

    Re: Correcting Focus When Stacking Filters

    Jim Noel is spot on. Theoretically, filters should contribute no optical power and therefore would not affect the image. In the real world, consumer-grade filters do have an impact... not focus per...
  14. Re: Tilt an old lens a teeny bit off axis to improve image. Anyone ever heard of this

    Yes, actually, because you cannot ignore alignment errors. Perfect alignment only exists on paper. Real, manufactured lenses are not ideal and have associated tolerances they have to meet to ensure...
  15. Re: Tilt an old lens a teeny bit off axis to improve image. Anyone ever heard of this

    Stopped down, I agree that there may be benefit, knowing what I know of stray light and ghosting. So yes, you could be on to something.

    At very small apertures light rays are intersecting...
  16. Re: Researching Eastman Dry Plate & Film Co. 5x7 Camera & Need Help

    Hey Tim,

    I’m 85% sure that Eastman set the standard dimensions for holders in large part by buying up other companies and making them convert to the Kodak standard sizing. If standard 5x7 holder...
  17. Replies
    44
    Views
    40,121

    Re: One way to fix lens separation

    Hey Steven,

    It’s due to the newly formed airgap. The index difference between adhesive and glass is not significant enough to form visible Newton rings.

    -Jason
  18. Re: Diffraction. When does it really matter with LF?

    Yes, they are wavelength-dependent geometric effects.

    Sphero-chromatism: focus vs wavelength
    Lateral color: Distortion vs wavelength

    Fun fact: Focus is considered an aberration... the...
  19. Re: Diffraction. When does it really matter with LF?

    All of the basic, third order Seidel aberrations can and have been corrected completely. The Cooke Triplet does that. Higher order / residual aberrations, however...
  20. Re: Diffraction. When does it really matter with LF?

    Drew... LOL. I just.... What you saw was the effect of turbulence, integrated over the exposure time of your camera and the response time of your eye. :D

    Diffractive effects over a mountain...
  21. Re: Diffraction. When does it really matter with LF?

    Because it is not a geometric effect.
  22. Replies
    44
    Views
    40,121

    Re: One way to fix lens separation

    Agree on all accounts..though the concoction is straight from Norland and my experience in the optical shop doing this is a bit different than yours (if you do the math, you find it’s only 0.78%...
  23. Replies
    44
    Views
    40,121

    Re: One way to fix lens separation

    Obviously works in a pinch, but a more robust method:

    100 parts Methylene chloride. 15 parts methanol, and 3 parts ammonia (26% conc) is a gentler / better solvent for removing balsam and uv...
  24. Replies
    38
    Views
    2,127

    Re: How Much Have We Accomplished?

    I successfully completed the ChromaGraphica Kickstarter campaign, getting everybody’s holders out to them and resolving the occasional issue.

    Got the rest of the production shipped here and...
  25. Replies
    5
    Views
    391

    Re: Kodak 2D Parts

    Kent, that looks like a Chicago bolt or Chicago screw. Measure ID of the hole and length you need, and look up a replacement part in McMaster Carr.

    https://www.mcmaster.com/chicago-screws/
    ...
  26. Re: Aspherical, Apo(chromatic) & ED (extra low dispersion) lenses - whats the differe

    It actually means correction at three wavelengths, so a bit more general than that. At least that’s what lens designers understand it as. I can’t speak for marketing misinterpretation.


    Drew,...
  27. Replies
    1
    Views
    300

    Re: Lens Separation Repair

    I can help you with that, assuming the lens can be easily removed from the cell. Shoot me a message. Happy Thanksgiving!

    -Jason
  28. Re: Aspherical, Apo(chromatic) & ED (extra low dispersion) lenses - whats the differe

    Aspherical surfaces and ED glass are tools in the optical design toolbox, helping with certain aspects and having pros/cons but are not magical “solve-all” solutions.

    Apochromatic refers to the...
  29. Re: Uneven Development -- 5X7's in Stearman Press 8X10 Tray

    I was talking to Tim once about this topic and I think he has determined that development issues in the tank have consistently come from too gentle of agitation.

    Personally I pick the tank up and...
  30. ChromaGraphica Double Dry Plate Holders now available for retail sale

    ChromaGraphica Double Dry Plate holders now available for sale through the online shop under Accessories at www.pictoriographica.com

    These are post-Kickstarter campaign holders, built here in...
  31. Replies
    16
    Views
    786

    Re: Pictoriographica black glass!

    No worries, Paul...didn’t take it as such. I was sharing in frustration that I can’t push the prices down much. My gial has always been to make plate shooting affordable. I could get the price...
  32. Replies
    17
    Views
    1,238

    Re: Meniscus lens iris "sweet spot"???

    You're talking about Coma, an off-axis aberration. The aberration illustrated in that link is coma as well.

    Spherical aberration is an on-axis aberration, due to the lens not being the ideal...
  33. Replies
    17
    Views
    1,238

    Re: Meniscus lens iris "sweet spot"???

    Distance to the stop doesn't correct field curvature, only coma.

    (Field curvature / astigmatism doesn't change with distance to stop.. what changes is where your flat image plane lands relative...
  34. Replies
    16
    Views
    786

    Re: Pictoriographica black glass!

    If it's not different, then offer it to folks who are looking for it. The wet plate community has been searching for this stuff for years.

    I suspect, however, that it is different: the black...
  35. Replies
    16
    Views
    786

    Re: Pictoriographica black glass!

    Yeah I wish things were free, too. Unfortunately I can't sell it at a loss or I would. At least I don't have to make a living off this stuff.
  36. Replies
    16
    Views
    786

    Re: Pictoriographica black glass!

    Glad it showed up... looking forward to seeing what you and other people do with it.

    Cheers,
    Jason
  37. Re: Jamin Darlot Lens Restorer in UK or Europe or anywhere really!

    I can re-cement the doublet for you, assuming I can get the glass out of the cell. Petzvals are a breeze. I’m in the US, tho.
  38. Re: 9x12 camera and all the things that come with it

    Easiest way to go would be to cut down 4x5 sheets. I do this for whole plate color, taking some of my 8x10 sheets and cutting them down in the dark on a paper cutter (the classic guillotine type)...
  39. Replies
    17
    Views
    1,238

    Re: Meniscus lens iris "sweet spot"???

    The lens distance balances field curvature and astigmatism, with some effect on coma. Spherical aberration is corrected by the lens shape.

    Coma, lateral color and distortion are corrected by...
  40. Re: Any tips on how to repair lenses with Balsam Separation?

    It won’t be Canada balsam if made in that timeframe, and you won’t be able to separate with heat (and you’ll crack the lens if you do). Instead You’ll need to separate by soaking in methylene...
Results 1 to 40 of 1165
Page 1 of 30 1 2 3 4