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Thread: Post yer pinholes

  1. #301

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    Re: Post yer pinholes

    @Randy
    According to the people at Ondu, the pinhole size is 0.5 mm

    @John
    Yes, I did scan the image (Epson V750). And there is probably a little bit of sharpening used in post processing (Lightroom). I recently switched from lightroom to dxo photolab, and that program can even pull more detail from the scan than LR. But the image shown here is the older LR version.
    If the use of x-ray film has any advantages, I don’t know. Because the x-ray film is double sided, it is believed that sharpness is little less than ‘normal’ film.
    The only thing that I didn’t mention yet, is that I use a filter inside the camera. It’s a old b+w Y/G filter, that I mounted behind the pinhole in the hope to get more cloud detail on x-ray film. If this has a positive effect on sharpness on x-ray film, I don’t know.

    When I pulled this negative from the development tray, it was clear this image was very sharp for a pinhole. Since then, there have been several discussion about the how and why. I’m just guessing just as anybody else.

  2. #302

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    Nov 2017
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    279

    Re: Post yer pinholes

    Quote Originally Posted by HoodedOne View Post
    When I pulled this negative from the development tray, it was clear this image was very sharp for a pinhole. Since then, there have been several discussion about the how and why. I’m just guessing just as anybody else.
    Isn't this because of the filter? The pinhole diameter calculation is for a single wavelength. So if you filter close to what it is calculated for, wouldn't you get sharper images?
    Expert in non-working solutions.

  3. #303
    Jim Jones's Avatar
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    Re: Post yer pinholes

    Quote Originally Posted by Havoc View Post
    Isn't this because of the filter? The pinhole diameter calculation is for a single wavelength. So if you filter close to what it is calculated for, wouldn't you get sharper images?
    I have tested this through the visible spectrum and into the IR range, and it is true. Many pinhole formulae use a wavelength of about 0.00055 for use with panchromatic film. Using a filter to limit the image forming light to the blue end of the spectrum will improve sharpness slightly. However, losing information in that part of the image formed by the red end of the spectrum may esthetically offset any gain in sharpness. It is something for every pinhole photographer to determine for themselves, or just forget about it

  4. #304

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    Re: Post yer pinholes

    Quote Originally Posted by Jim Jones View Post
    I have tested this through the visible spectrum and into the IR range, and it is true. Many pinhole formulae use a wavelength of about 0.00055 for use with panchromatic film. Using a filter to limit the image forming light to the blue end of the spectrum will improve sharpness slightly. However, losing information in that part of the image formed by the red end of the spectrum may esthetically offset any gain in sharpness. It is something for every pinhole photographer to determine for themselves, or just forget about it
    Years ago experimented with shooting through 25, 58, and 47B filters in order to get sharper pinhole images. Unfortunately my pinholes at the time were mediocre, so my results were less than valid. Also didn't like the non panchromatic image results.
    On this end I start with the pinhole's diameter as recommended in Eric Renner's book PINHOLE PHOTOGRAPHY. Made several pinholes at his recommended diameter in several different materials (Brass shim, Stainless Steel shim, DASANI sparking water aluminum can, aluminum foil, and a few more). Settled on Brass and Stainless Steel .002 gage shim stock. Both of the pinholes are blackened on the inside "walls" of the pinholes and then inspected under a microscope. If the pinhole isn't nearly perfectly round (most aren't), I re-blacken it and inspect again. Sometimes takes several tries. Compared the SS and the Brass pinholes and settled on using Brass shim stock because it was easier to blacken the surfaces. Then I make successively smaller pinholes to shoot test exposures with. Even though the pinholes will be used on an 8x10 (and another 11x14 to follow) WA camera, I shoot test exposures on 4x5 film at the same focal length of my 8x10 pinhole camera. Easier to batch process the 4x5s and way less expensive. I then compare the sharpness of the negatives and one almost always stands out. This is the one I use on my camera. When I determine which size hole to use, I make several more pinholes and then gently hammer the pinhole with a ball pean hammer to flatten the metal a bit more making the "wall" of the pinhole minimal thickness. I have to gently re-drill the pinhole after flattening it. Any burs around the pinholes are removed. Then blacken them. Having made several pinholes in this manner, I finally inspect them under my vintage Nikon Ske microscope with Axial (Brightfield) Illumination (hope I've used the correct terminology). They will all look different under the microscope so choose my favorite (and hopefully best). The pinhole images I get with my pinholes are noticeably sharper than any of the commercial "laser cut" pinholes I've purchased.

  5. #305
    Jim Jones's Avatar
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    Re: Post yer pinholes

    Click image for larger version. 

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ID:	188621Greg -- It sounds like a precise method. I'm a bit more haphazard, but agree with 0.002" brass shim stock and the thin stainless steel (?) collected from the RFID tags on many store-bought items now. Attached is a graph of pinhole image sharpness derived from tests done decades ago with an improvised camera to give us a rough idea of the effect of pinhole diameter on off-axis sharpness. The camera went to Eric Renner long ago.

  6. #306

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    Re: Post yer pinholes

    Click image for larger version. 

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ID:	188897

    BMW M11
    Vermeer 8x10 inch pinhole camera
    Film AGFA EBA45 X-Ray Vintage Photo Film Full Speed BLUE B Plus 8x10"
    Questions and comments are always welcome

  7. #307

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    Jun 2015
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    Anglesey, North Wales, UK
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    Re: Post yer pinholes

    First trial at pin hole photography. Pin hole circa 0.5mm - bradawl point through metal foil from beer can body [see pic].
    Metered exposure 0.5s @ f22, fl 125-130mm.
    Exposure 1min based on PinHole Designer program.
    Paper negative taken through patio window hence mark on image.
    Pinhole attached to lens board on Calumet CC400
    Attachment 190031 Attachment 190032

  8. #308
    Mike in NY's Avatar
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    Re: Post yer pinholes

    1941 Chevy
    15 minute exposure on Harman paper using a Titan 4x5 pinhole camera


    Truck
    by Michael Stewart, on Flickr
    I dream in black and white.

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