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  1. #121
    NedL's Avatar
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    Hi Bert,

    In that paper, Lord Rayleigh references Capt. Abney's work on varying the aperture in landscape work. I'm using Capt. Abney's book as my directions for making calotypes. Everything is connected eventually!

    My understanding is that there are two ways to approach the problem. The one used by Rayleigh gets to maximum resolution. Calculations based on the Airy disk try to maximize the contrast. Ralph Lambrecht has posts here at APUG about this, and I think I got my constant of 1.56 from something he wrote. Oversimplifying, if we want to have the first diffraction rings coincide at a particular wavelength, it should provide maximum contrast and "perceived sharpness".

    I used: d = c * sqrt( w * f )

    c = constant
    d = pinhole diameter
    w = wavelength of light
    f = "focal length"

    I like to use 475 or 500 nanometer wavelength for paper, and a constant of 1.56, so:

    0.854 = 1.56 * sqrt( 5e-4 * 600 ) all units are mm.

    But just like you I tend to cheat toward a smaller one... and use 475nm or a constant of 1.5 or 1.45. I think a lot of UV goes through and that's why our experience pushes us that direction.

    Have fun!

  2. #122
    TheToadMen's Avatar
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    Hi Ned,
    I used even a smaller one (as you suggested): a pinhole of 0.6 mm. I finally taped the whole box together. I even made a large door, hinged with Duckt tape alone! The camera is big enough for me to get inside and fix a pinhole or the paper negative

    I made a quick test shot just before dawn to see if it worked at all. I used a 8x10" Ilford B&W paper first because I have only 9 sheets of the 20x24" Ilford B&W paper. Since I have a f-number of f 1/1000 and ISO of 2 I had a calculated exposure time of 2 houres. It was already 17.20 hours (5.20 PM) and the sun sets at about 18.00 (6.00 PM). But I tried anyway and wouldn't mind if it was underexposed since it was a simple first test.

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    I placed the camera in my garden, opened the shutter and got me a chair and a book. I sat for about 20 minutes and went inside. I left the shutter open until about 15 minutes after sunset. The total exposure time was about 1 hour. I then took the camera back to the darkroom (wouldn't almost not fit through the staircase) to be opened under a darkroom safe light.
    And then the light bulb popped ...
    So - in total darkness - I opened the camera, took the paper negative out and dropped it in the developer tray. Luckily I always work from left to right so I new what tray would be the developer. After counting out loud I pulled the negative after 1 minute and dropped it in the stop and fixing tray. Then finally turned the light on to see if there was anything there. And there was!

    So - for an totally unprofessional test - I was very happy, since the camera worked. the negative itself is underexposed off course, but there is a nice sharp image. I turned off the light again and loaded the camera again in total darkness with the 20x24" paper and taped the camera up again.

    This week (Thursday?) I'll make a real exposure and will develop properly (as far as possible with this size since I don't have a tray for it). I hope I'll find the time this week to finish this paper negative and post before Saturday, making the deadline of this MSA at the end of this month.
    To be continued ...

    This is the test negative (underexposed & improperly scanned):
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    Last edited by TheToadMen; 02-23-2014 at 05:43 PM. Click to view previous post history.
    "Have fun and catch that light beam!"
    Bert from Holland
    my blog: http://thetoadmen.blogspot.nl
    my Linkedin pinhole group: http://tinyurl.com/pinholegroup


    * I'm an analogue enthusiast, trying not to fall into the digital abyss.
    * My favorite cameras: Hasselblad SWC, Leica SL, Leica M7, Russian FKD 18x24, Bronica SQ-B and RF645, Rolleiflex T2, Nikon F4s, Agfa Clack and my pinhole cameras

  3. #123
    ajmiller's Avatar
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    Bert, that IS impressive - and the result is excellent. Well done.

  4. #124
    adelorenzo's Avatar
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    Well done Bert. Can't wait to see a huge negative from that camera.

    One week left people! Shoot 'em if ya got 'em!

  5. #125
    NedL's Avatar
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    Quote Originally Posted by TheToadMen View Post
    ... almost not fit through the staircase...
    Fantastic, that is a huge pinhole camera!
    Looks like it is working very well. And you had an adventure developing, but it worked! Can't wait to see results from the BIG negative. That will be a challenge to develop and also to scan or photograph or contact print!

  6. #126
    TheToadMen's Avatar
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    Quote Originally Posted by NedL View Post
    Can't wait to see results from the BIG negative. That will be a challenge to develop and also to scan or photograph or contact print!
    Normally I design, calculate, draw, ... everything before I start building, but not this time, not this MSA.

    I'll expose the BIG negative rather properly and will unload it in the dark. I've made a water resitant bench for my dark room, that is big enough for this 20x24" negative. So I'm gonna lay if flat on the bench and will use a sponge soaked in developer to "wet wipe develop" it for about 2 minutes or so.
    Same thing with Stop and Fix. Then into the bath tub with clean water for rinsing.
    I hope it will work out ...

    Scanning might be a bit of a problem. So I think I'll use a d*****l camera to photograph it. Using PS to make a positive of the paper negative, I can determine if it did work out all right.
    If so, I'll make a contact print later. First I must find a glass plate big enough and determine the right exposure for contact printing this sandwich.

    Previously I used to strip the plastic back layer of the photo paper and then rub the paper back with lineseed oil to make it more transparant for alt-photo techniques using UV light (or direct sun light) for long exposure times decreased by 50%. Should be fun too with this size.

    Bert from Holland
    http://thetoadmen.blogspot.nl
    "Have fun and catch that light beam!"
    Bert from Holland
    my blog: http://thetoadmen.blogspot.nl
    my Linkedin pinhole group: http://tinyurl.com/pinholegroup


    * I'm an analogue enthusiast, trying not to fall into the digital abyss.
    * My favorite cameras: Hasselblad SWC, Leica SL, Leica M7, Russian FKD 18x24, Bronica SQ-B and RF645, Rolleiflex T2, Nikon F4s, Agfa Clack and my pinhole cameras

  7. #127
    Thomas Bertilsson's Avatar
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    I just posted four images in the MSA gallery, from my recent Lake Superior trip at the end of January.

    I have this little cheesy Minolta P&S camera, not sure of the model, but it's the one that you click one button and the camera does the rest. It's kind of beat up and ugly looking, but I was surprised at the quality of the photographs.

    The camera was loaded at the beginning of January for some pond hockey games in Minneapolis, but I ended up shooting the bulk of the film up North. Ilford FP4+ processed in D76 1+1 and subsequently scanned using Vue Scan and an Epson flatbed. I haven't tweaked the images much in Photoshop, mainly just slight contrast adjustment, dust spotting, and toning that resembles what I do in the darkroom.

    This was fun!
    "Often moments come looking for us". - Robert Frank

    "Make good art!" - Neil Gaiman

    "...the heart and mind are the true lens of the camera". - Yousuf Karsh

  8. #128
    sly
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    In the last week I made a couple more contributions to the MSA gallery. In the first one I had wanted to include the healthy fan palm leaves, as well as the fallen one, and was pleased they were in the frame. I'm getting better at judging what will be included in the pinhole frame.
    The second one is my favorite WPC neg from our trip.

    I just want to tip my hat to those who routinely scan their negs. I rarely shoot colour, and scanning, dust spotting, and attempting to colour correct these negs (the scanner adds a magenta cast to everything) was a huge pain - in my back, neck, and shoulder, as well as the PITA that keeps me away from digital work anyway. I've not got the stamina, nor patience to do this on a frequent basis.

  9. #129
    TheToadMen's Avatar
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    Quote Originally Posted by TheToadMen View Post
    .... This week (Thursday?) I'll make a real exposure and will develop properly (as far as possible with this size since I don't have a tray for it). I hope I'll find the time this week to finish this paper negative and post before Saturday, making the deadline of this MSA at the end of this month.
    To be continued ...
    Yesterday (Thursday) was all rain and rain and rain ....
    Luckily I had some time this morning because I have to work midday and evening (giving a course). And it is dry this morning!! Even with a very little sunshine through the times every odd moment. So - after finishing preparations for the course) - I took out the 20x24" cardboard pinhole camera and posted it on a table, overlooking my garden. I openend the shutter at 10:10 AM and need an exposure of at least 4 hours (@ f-number 1/1000, ISO 2).
    I have to leave in 15 minutes, so I instructed my wife in how to close "the shutter" (= piece of cardboard + tape) in 2 hours and putting the camera inside before it starts to rain again. I hope to be home at 22.00 (10.00 PM) tonight so I can sponge develop the paper negative (20x24"), fix it and flush it before midnight. I'll make a probably bad looking digital photo of the negative, reverse in PS and post the result here before midnight, February 28th - still in time before the closure of this MSA.
    Pray for me that it will work out. If not I'll post it on Saturday (one day late). And if the paper negative is any good I'll make a proper contact print later.

    At least here is some proof that I made the shot itself today:

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    Last edited by TheToadMen; 02-28-2014 at 10:12 AM. Click to view previous post history.
    "Have fun and catch that light beam!"
    Bert from Holland
    my blog: http://thetoadmen.blogspot.nl
    my Linkedin pinhole group: http://tinyurl.com/pinholegroup


    * I'm an analogue enthusiast, trying not to fall into the digital abyss.
    * My favorite cameras: Hasselblad SWC, Leica SL, Leica M7, Russian FKD 18x24, Bronica SQ-B and RF645, Rolleiflex T2, Nikon F4s, Agfa Clack and my pinhole cameras

  10. #130
    adelorenzo's Avatar
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    Well, as this is winding to a close I have to say that it's going to be near impossible to judge this thing. There have been so many great images and so much creativity from people to make them.

    Bert: I know there is at least one other person who might need to post images tomorrow. I've got plans for the weekend so I am planning to review all the images and pick a "winner" on Sunday evening (PST) so if there are any stragglers tomorrow they'll get looked at.



 

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