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  1. Re: Where is the image formed on the ground glass? (With and without fresnel) | image

    Bob, of course... we set aperture for aesthetics, for maximum performance or for DOF...
  2. Re: Where is the image formed on the ground glass? (With and without fresnel) | image

    Let me add:

    -> Shet film thickness is 0.007" to 0.009".

    -> A 4x5 film holder is ANSI specified as having a +/-0.007" tolerance for the film position. For 4x5 the septum depth from the holder...
  3. Re: Night vision solution for brush development / general D.Room work

    This is nice because it has 1x view!
  4. Re: Night vision solution for brush development / general D.Room work

    https://www.ebay.es/itm/HD-2-4-LCD-1080P-Car-DVR-Vehicle-Camera-Video-Recorder-Dash-Cam-Night-Vision-UK/173952554844?hash=item288061575c:g:mlwAAOSw4klbWD5K

    It says 1080 lines, but this is the...
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    Re: Glassless Negative Holders

    Dust it's easy to control, a problem can be newton rings, in special if glass is not perfectly flat...
  6. Re: Night vision solution for brush development / general D.Room work

    Yes...

    but this is a $8 sealed eyecup for dslr screens:

    196574
  7. Re: Night vision solution for brush development / general D.Room work

    Yes, this is a tipical sensor spectral sensitivity:

    196570

    In a regular camera a cut-off filter removes IR light beyond (around) 700nm wavelength, as you see in the grapp an IR converted camera...
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    Re: Glassless Negative Holders

    Randy, of course I stated the source, just below the image in my post there is the link to your post !
  9. Re: Where is the image formed on the ground glass? (With and without fresnel) | image

    The image is always formed in the frosted side of the GG, it is a real image (not a virtual one).

    If a fresnel is placed in the outside then the inner frosted side has to match the film position....
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    Re: Pin registration system preferences

    The glass surface is protected with any adhesive plastic layer, no problem. The CNC is very precise, and holes and dimensions are well in place, single thing is that the cut is not exactly...
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    Re: Pin registration system preferences

    Today this is easy:

    https://www.youtube.com/watch?v=E1QaQHjCAv4
    https://www.youtube.com/watch?v=1TEhYy4AcfM

    CNC waterjet made holes may be a bit conic, so a polishing may be required later.
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    Re: Glassless Negative Holders

    Yes, we see the Saggen & Poppen when projecting slides. You are right, a good glassless carrier has to overcome that, if not... better using a glass carrier.

    If negative is well tensioned... ...
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    Re: Glassless Negative Holders

    Eric, I've made some prelimiar drawings for a glassless carrier, inspired by the Saltzman:

    https://farm2.staticflickr.com/1819/30208471988_021eabaae2_c.jpg...
  14. Re: Epson Expression 12000XL Photo Scanner experiences?

    This is good advice.

    A very good collaborative scanner test was made time ago by mambers owning good scanners: https://www.largeformatphotography.info/scan-comparison/

    Also recently:...
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    Re: kodak Tmax RS developer formula

    It looks that the 50L version can be shiped: https://www.bhphotovideo.com/c/product/926498-REG/kodak_5054184_t_max_professional_rs_developer_replenisher.html


    With sheets you may try regular...
  16. Re: Ilford multigrade contrast differences?

    John, cold store it !!!

    Modern papers are less stable over time... fortunately we have a solution:


    "Paper and film may either be refrigerated or frozen but should first be sealed in plastic...
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    Re: Minimal chem for 8x10 dev

    Drew, IMHO one can extend developer capacity beyond manufacturer's recommendations, but one has to be aware of the risks, in special if recommending other people to extend capacity.

    Developer...
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    Re: Hydroquinone & Metol Paper Developers?

    This would be useful with old fashion Graded papers, if you had only 2 and 3 grades and wanting 2.5 they you would reduce the 3 contrast in that way.

    If using VC paper you solve contrast with...
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    Re: Minimal chem for 8x10 dev

    Drew, it always depends on how black the negatives are. Developer exhaustion depends on the silver amount it gets developed.

    If your sheets are simply unexposed and only the usual fog level is...
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    Re: Pinhole recommendation

    The optimal holes for LF are (in general) larger than for smaller formats, so way easier to DIY.

    I fact, with not many skills one makes a good LF pinhole in 10min. With pinhole calculator get the...
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    Re: Digitizing 5x4 Negative

    Yes... you have the V800 and the V850. These are much better than the V370. For film BW&color negatives the V800 is fine.


    Just let me add that if having to scan color slides (Provia, Velvia,...
  22. Re: F stop not as indicated? - advice on f6-384 Rapid Aplanat No.3 Ser.D.F.8 needed

    Of course... We use the DSLR viewfinder to check infinite focus, in that way we have the nominal lens to image plane distance.

    With a monorail this is straight, we attach a macro extension ring...
  23. Re: Ilford multigrade contrast differences?

    There are not two, but three emulsions (or more in some papers), and all emulsions are blue sensitive, the "green" one is orthocromatic. An intermediate emulsion is also fully blue sensitive but not...
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    Re: Minimal chem for 8x10 dev

    Se page 5 of the datasheet: https://imaging.kodakalaris.com/sites/uat/files/wysiwyg/pro/chemistry/j78.pdf , section "STORAGE LIFE AND CAPACIT"

    It says that 1L of 1:1 dilution can do 2 sheets, so...
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    Re: Schneideritis?

    Good point !
  26. Re: Ilford multigrade contrast differences?

    Yes, for sure it would be posible to make a filter set with equal exposure from 00 to 5, IMHO it is good that 4-5 are slower, because 4-5 have a very step gradient and if those filters were faster it...
  27. Re: Ilford multigrade contrast differences?

    It was : https://www.largeformatphotography.info/forum/showthread.php?154589-Ilford-multigrade-contrast-differences&p=1520109&viewfull=1#post1520109



    No I was speaking about ISO speed , not...
  28. Re: F stop not as indicated? - advice on f6-384 Rapid Aplanat No.3 Ser.D.F.8 needed

    This is a wrong way to take the effective diafragm diameter to make the calculations. You have to use the diameter that is virtually seen from front of the lens, not the real hole in the iris. Think...
  29. Re: Ilford multigrade contrast differences?

    koraks, my reply was about your comment about speed of FB 5 grade, which comes from the error in the datasheet. That 210 should be around 100.
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    Re: 8x10 Macro Photography lens Question

    The test would show it, but those scans can't. While diffraction limits performance to 50 lp/mm those scans limit performance to 3 lp/mm, if I calculated well.

    I don't say if all those glasses...
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    Re: 8x10 Macro Photography lens Question

    hmmm... nothing wrong in knowing what IQ we have, from those crops OP cannot realize if a $1000 Makro-Sironar may be a better choice than a $180 Geronar. Me I'd go to cheaper choices than $180,...
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    Re: Schneideritis?

    Nothing like a new glass ! me too :)
  33. Re: Ilford multigrade contrast differences?

    Koraks, I guess this is a remarkable error in the FB datasheet, first text mentions that 4 and 5 grades require double exposure, and because of that 4-5 curves are in another plot, if you check the...
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    Re: 8x10 Macro Photography lens Question

    Dan, those crops are 300 pix wide, so the full image (enlarged like the crops) would have 1500 pix wide, not covering a 2k monitor...

    This would deliver a 2MPix file for the ful image, way under...
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    Re: 8x10 Macro Photography lens Question

    Dan, 50 lp/mm in a 8x10"... this is 500MPix effective, even with diffraction...
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    Re: Schneideritis?

    A practical test is quite easy, just take the camera and point to an scene with a very high brightness range and meter deep shadows vs mids with a probe in the GG, compare the reading with lenses of...
  37. Re: Ilford multigrade contrast differences?

    Main difference is in 00 grade of the RC, the 00 RC grade has a weird shoulder (in papers the shoulder contains the shadows), being more difficult to reach full blacks with it.

    See the 00 RC...
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    Re: 8x10 Macro Photography lens Question

    Nice test !!
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    Re: Schneideritis?

    Yes... see this:

    https://richardhaw.com/2016/11/12/repair-shneideritis-edge-separation/...
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    Re: 8x10 Macro Photography lens Question

    Dan, yes, you are right, as always...

    We discused that two years ago:...
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