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  1. Replies
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    Re: Meniscus lens iris "sweet spot"???

    Lens design books have discussions of this. In Warren Smith's "Modern Optical Engineering" he works it out that the ideal position for the stop is about 1/6 of the focal length in front of the lens,...
  2. Thread: Avedon

    by reddesert
    Replies
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    2,154

    Re: Avedon

    Good article,
    it's interesting to think of someone as top of their game as Avedon (whether we like him or not) still striving for acceptance or to make a break into a new kind of work.

    Something...
  3. Re: Any tips on how to repair lenses with Balsam Separation?

    Methylene chloride is a very strong solvent that is a significant health hazard (as in, touching it momentarily won't poison you, but major inhalation or skin exposure can cause various kinds of...
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    Re: Review of new Ansel Adams book!

    Rebecca Senf is giving Internet (virtual) talks/presentations on the book and subject periodically, in lieu of a book tour I imagine. There's one next on Oct 21, 2020. If you miss that there might...
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    Re: Tripods in lightning storms?

    Lightning can do weird things, the potentials are so high that it will jump across objects that are insulators under "normal" voltages. (Rubber caps on tripod feet or rubber soled shoes are no...
  6. Re: Disasterous Consequences

    Picture 4 here shows the retaining ring not fully seated into the lens board. When this happens, the rear element may also not be fully screwed into the back of the shutter, and there could be light...
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    Re: Flash Firing Before Shutter?

    Are you sure that the shutter doesn't have an M/X switch and that you haven't accidentally bumped it to M since the previous time you used a flash? Because M sync will cause exactly what you're...
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    Re: Gregory Crewdson's 'An Eclipse of Moths'

    I guess that most of you who are familiar with Crewdson's work know that it's highly staged and lit. The behind the scenes photos at the first link Randy posted show a few examples, such as (if this...
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    Re: Chamonix 57N + Technika Lens Board

    Yes, exactly, as Bob says (of course he's the expert) - that's a genuine Linhof board, but it's for a 4x5 Technika III. It differs from the Technika 4/5 board that many cameras have adopted as...
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    Re: McKeowen's and all those cameras.

    I know, but the OP was asking for information on a Kodak 2D and Kodak, Eastman, Folmer and Schwing; so piercevaubel.com is a more promising place to find information than McKeown's.

    We're about...
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    Re: McKeowen's and all those cameras.

    Have you browsed http://www.piercevaubel.com/cam/index.htm "Wooden Field Cameras of the United States: 1870's-1930's" ?

    It likely won't answer your specific question, especially because large...
  12. Thread: Hypo clear?

    by reddesert
    Replies
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    1,206

    Re: Hypo clear?

    Here is an MSDS for Perma Wash that lists a couple of ingredients: https://art.illinois.edu/images/documents/MSDS/Darkroom-SDS/Heico-Permawash.pdf
    Ammonium sulfite and sodium ethylhexyl sulfate are...
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    357

    Re: Wratten & HEX numbers

    If it's just one warming/cooling adjustment rather than a general specification for many Wratten filters ... I am not a Photoshop guru, but Photoshop may have an approximation to this adjustment for...
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    Re: Wratten & HEX numbers

    I don't think there is a simple way to translate them. Filters are subtractive, while the RGB hexadecimal codes for colors displayed on your monitor or similar are an additive color system. What you...
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    Re: Radioactive Lens Treatment

    Interesting information. Have any of you tried a similar test in the sun, without window glass intervening?

    There is an Ikea desk lamp that some people have recommended for this purpose. I don't...
  16. Re: Is there a free site that will host your images in their original full resolution

    WFH Sucks, a Haiku:

    Hundred gig files from
    detector at lab, summer
    heat and slow downloads.
  17. Replies
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    312

    Re: Washing Anti-Halation Backing on HP5

    I found that in some B&W films a lot of the colored dyes come out in the wash aid (I typically use Perma Wash). You might consider doing a wash aid step in the hanger rather than the holder.
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    Re: Glass plate negative storage

    As far as I know, astronomical glass plates tended to be filed in something that looked like a envelope / manila folder made for the size of the plate, open on one side. I don't know if it was made...
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    Re: Fujinion W f5.6 210mm fuzzy at wide open

    Pictures would help.
    I took post #4 to mean that the good lens is the one with a bent filter ring.

    It's a little strange to have a modern lens that is so bad that you can see its softness on the...
  20. Re: Film Holder Provenance for you Military Buffs...

    https://graflex.org/helpboard/viewtopic.php?p=28032

    post #2 suggests (Graflex) Riteway plastic film holder production started in 1950,
    and that one might learn more about this history by studying...
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    Re: Chamonix 57N + Technika Lens Board

    It's narrow side to side? How wide is it? Does it have clipped bottom corners? Is the circular light trap on the back raised or not?

    The Technika IV board is about 96x99 mm WxH with clipped bottom...
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    Re: Smoke smoke everywhere

    A friend of mine was planning to start a High Route hike on Sunday, southbound, but bailed before starting due to the smoke. The Sierra and Inyo NF are now temporarily closed for hiking. He reports...
  23. Re: Seeking guidance on pairing a Nikon 150mm W lens with a Graflex Crown Graphic 4x5

    An aftermarket Graphic board for a #0 shutter should be fine. You can get them on ebay and possibly from shops that sell LF equipment.

    The shutter PC outlet will work fine with an electronic...
  24. Re: Looking for a count up timer for use with film development

    I use a couple of free iphone apps (called Develop! and Darkroom Clock) that have countdown, not count up, timers, but you can preset a sequence (like 10 min dev, 1 min stop, 4 min fix, etc) and just...
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    Re: KEH and the "Copal BT" shutter

    KEH's designations are a little cryptic but I'm pretty sure that many of their LF lenses are listed as "BT," meaning "this shutter has B and T in addition to the normal timed speeds." There are some...
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    Re: Chasing star trails with an 8x10

    When the moon is down or new you will have much, much darker skies. If the moon is a thin crescent and you're facing away from it (which you should be, shooting North) then it doesn't brighten the...
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    Re: 15" Tele-Raptar front group FL question

    The usual design for a telephoto lens is front group(s) with positive power (converging) followed by rear group(s) with negative power. The rear groups make the bundle of rays converge in a longer...
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    Re: Calumet C1 Repair and questions

    There are Arca style plates that are longer than normal and have two screws or a slot in which the screws can move, so you could hopefully get both screws to line up with your mount holes. Like...
  29. Re: Focal length, distance, and depth-of-field: clarification?

    There's no real discrepancy in the two examples you posted in the first post. There is a mistake though. Go back to the online calculator and try the numbers for the 135mm again. You have:



    It...
  30. Re: How To Properly Determine Infinity For a Lens?

    I don't really understand what the argument is here.

    To set the infinity stops, Linhof doesn't focus on the Frauenkirche. They presumably use an autocollimator to produce a virtual target at...
  31. Re: Focal length, distance, and depth-of-field: clarification?

    Choice of lens and subject distance should be dictated by what image you are trying to make. With that said, to first order:

    - when you change the subject distance to get the same horizontal...
  32. Re: How To Properly Determine Infinity For a Lens?

    This is the second time you've said something like "Infinity at 5.6 and 150mm is assumed at about 24m, because of the hyperfocal distance at about 47m," and I think that's misleading. 24m would be...
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    Re: Lens Shutter Test?

    I've used the audio version of the shutter speed app. It will only be useful at speeds slower than about 1/60 or 1/125 at best. To understand the waveforms, you should start with a relatively slow...
  34. Re: Lens mounting flanges - measurements and other info

    Threads are cut using a lathe whose tool is mounted on a leadscrew, with the leadscrew rotation geared to the spindle so that the tool moves along the piece as the piece rotates. Choosing the gear...
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    Re: Question about Intrepid enlarger kit

    Ah! Shoot. Thanks for the correction. I had looked up the manual for the 45A (original) and it said to move those sliders to remove the groundglass back, but I didn't realize they meant the whole...
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    Re: 1935 Linhof ,,NORMA'' ???

    "Normal" in German means the same as normal in English. Norma was probably formed from Normal, parallel with Technika, formed from the noun Technik (or adjective, technisch/technische).
  37. Replies
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    1,201

    Re: Question about Intrepid enlarger kit

    You have the Graflok sliders - the two long black pieces above and below the groundglass, each with two diagonal slots in them. I've never touched this type of Toyo back, but I think those sliders...
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    Re: How does rear tilt affect front tilt?

    Back in post #18 I attached a dorky little side-view diagram of the effect of tilts on the plane of focus. It's attached again here, click to enlarge:
    206799

    When you adjust tilts, whether you...
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    Re: Leaf Shutter High Speed

    This gets discussed in roughly every thread about shutter testing. If one puts the phototransistor directly behind the lens on-axis, or if one puts the phototransistor on axis behind a naked shutter...
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    Re: Large format Astrophotography

    Successful astronomical imaging requires understanding the aims of the project and the properties of the site and available technology - it's like what Bernice says about needing to understand what...
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