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  1. Re: Scientific reason why some developers causes decrease film speed

    Let's set aside the question of whether film speed (as in ISO) can actually be changed, and talk about shadow detail instead. Ask the question of why some developers might result in more or less...
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    Re: Are all plasmats convertible?

    Generally, it seems that all lenses of the basic plasmat design can be "converted" in the sense that the individual cells will make an image, but they probably shouldn't be, for best results. ...
  3. Thread: Zoom?

    by reddesert
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    Re: Zoom?

    People have said that the Komura wide angle lenses for large format - Super-W-Komura - are slightly retrofocus and have a larger flange to focal distance than expected for their focal length. I've...
  4. Re: Not understanding Toyo Base Tilt Front and Rear

    I don't have one of these, but if you look at a better picture of the 45AII there are big knobs on the lower side of the body, each side. I believe these are used to loosen/lock a continuous back...
  5. Re: LF hikers, do you remove plastic tree ribbons?

    As I previously mentioned, I belong to a local trail running group and for permitted organized events, when needed we mark trails with flagging attached to clothespins, and remove it when done. It's...
  6. Re: LF hikers, do you remove plastic tree ribbons?

    I get a little frustrated by both excessive cairn-building and excessive cairn-destroying. Excessive cairn-building is clearly annoying. However, in some places cairns are properly used to mark...
  7. Re: LF hikers, do you remove plastic tree ribbons?

    It depends on context.

    I belong to a longstanding local trail running group. When we do planned but informal runs, we rarely use trail markers. For organized races, which also draw some non-locals...
  8. Re: Precision and Accuracy in LF Photography: How much is enough?

    As others have noted the need for accuracy and/or precision depends on what you are trying to accomplish. But in all cases, consistency will help you accomplish those ends. The degree of precision...
  9. Re: A DIY 177mm f/8 Cooke triplet for 4x5 from off-the shelf lenses that YOU can bui

    Assuming the numbers on those lenses mean diameter 54mm, focal length 786mm, then if you use two of the doublets separated by 50 mm you will get roughly a 405mm focal length lens. This is from the...
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    Re: A DIY 123mm f/8 Cooke split triplet for 4x5

    Here is a link to a sample chapter from a book on lens design that discusses designing and optimizing a Cooke triplet. Lens designers know this stuff, but it is useful for non-lens designers to see...
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    Re: stiff seiko shutter cocking pinion

    Don't know the specific answer to this question, but on some shutters, including Seikos I think, you take off the front name plate (with a couple of screws), and then there is a thin retaining ring...
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    Re: A DIY 123mm f/8 Cooke split triplet for 4x5

    I was inspired by Nodda Duma's original thread to look around at what one could make with inexpensive off the shelf lenses. As he says in that thread, a problem for even simple designs is that it's...
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    Re: A DIY 123mm f/8 Cooke split triplet for 4x5

    You're describing a Super Angulon type wide angle, which is a significantly more complex design than a Cooke triplet, with more elements and much greater bending of the elements.



    If you take...
  14. Re: Should I build a LF TLR? What would it take?

    Try a mountain bike dropper seatpost adapted to hold the camera? Or the gas lift cartridge designed to raise/lower an office chair. Might be hard to get one with 10" travel but they should exist...
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    Re: Best 1/4" to 3/8" adapter?

    Brass is a good material for this kind of application because it is resistant to galling. Brass typically has good machinability and ductility, which is why it is resistant to galling, and why it is...
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    Re: Monorail vs. Folding Camera Weight

    All true of course, my points were that the Kardan Standard is light, but it's not the type of system camera that comes apart easily to make a smaller / flatter package for transport. One can take...
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    Re: Monorail vs. Folding Camera Weight

    It's all about tradeoffs and intended purposes. The people using large format cameras now are mostly a different market and using it for different purposes than when large format was the default...
  18. Re: quality problem with printfile negative pages

    I don't understand the issue, it seems to me that if the white label is less opaque, when you make a contact print the contrast with your permanent marker will be greater.
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    Re: New Zeiss apertures to f-stop converter

    If you know the f-number, then take the next lowest standard f-number and use this formula to find the increment in fractional stops:

    increment = log [ (f-number / next-lowest-f)^2 ] / log(2)
    ...
  20. Re: Popular Photogenic Sites/Locations in Yosemite NP

    This is a good point, you know people often ask what camera St Ansel used, but rarely ask the important question of what size tripod they need to fit in his tripod holes.

    Some of the easily...
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    Re: Technique for focusing "into your scene"

    I'm guessing there are distinctions in use: many amateurs now concentrate on landscape or perhaps portrait LF photography. While in the days when LF photography was a heavy professional tool and...
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    Re: What is my 4x5 area on the glass?

    Your ground glass is fine. The frame against which the ground glass is mounted has the open area of a 4x5 film holder (which is really about 96x120mm as Oren said). The 9x12 box is to help people...
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    Re: DIY PX28 or 4SR44 Battery

    The 6 volt PX28 or 4LR44 alkaline battery is not common in stores as far as I know, but it is easy to find on US ebay for ~$1-2 a piece (I don't know about Canadian ebay). The 4SR44, silver oxide...
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    Re: Technique for focusing "into your scene"

    Other people have explained that the 1/3 rule of thumb isn't really accurate. It also predates digital BTW. But anyway, the simple explanation for the difference in these rules of thumb is that the...
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    Re: a fake Topcor 90mm f5.6 (Horseman)?

    Okay, these pictures are good and clear some things up. The lens you have seems to be the proper front and back of the 90mm. And the 105/3.5 has a larger front cell than rear cell, suggesting it is...
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    Re: a fake Topcor 90mm f5.6 (Horseman)?

    It's not a "fake" in the sense of a counterfeit. The question is whether it's been modified inappropriately.

    From the Horseman manual you linked, the 105/3.5 is a reversed Tessar design with one...
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    Re: Fujinon-W flash problem (M/X)

    The more common problem is that the M delay timing mechanism is sticky and causes the shutter to not release when the trigger is pressed. You might have a combination of two issues: the shutter...
  28. Re: Question about Aperture Scale Compatibility

    The f-number is the focal length divided by the diameter of the entrance pupil. The entrance pupil is the image of the aperture formed by the elements in front of the aperture. So if you look at...
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    Re: Kalosat lens, DIY

    I looked up the index of refraction and dispersion of fused silica before posting, to be not-completely-uninformed. The dispersion of fused silica is not much different from N-BK7 (most common crown...
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    Re: Kalosat lens, DIY

    I had not previously heard of the Kalosat lens. Using single meniscus lenses ("landscape lens") for a soft focus effect is a longstanding traditional use. LFPhoto member Reinhold Schable has...
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    Re: Interesting article on lens design

    Photography blogs write about optics very badly.

    These papers are a clever solution to an analytical mathematical problem, and maybe some derivative of the technique will trickle into lens design...
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    Re: Petzval Formula DIY?

    If you like experimenting, probably the easiest thing to do would be to get some achromats (cemented crown-flint doublets) and experiment with different combinations of focal lengths and spacings of...
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    Re: Photographing stars, 4x5

    For much of the 20th century Kodak made glass plates with various specialized emulsions that astronomers used - different emulsions had different color sensitivities. Some of the commonly used...
  34. Thread: Cougars

    by reddesert
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    Re: Cougars

    I saw a mountain lion once while mountain biking (in the state park next to UCSC, where deer are common and lions are present). It avoided me. Actually I barely saw the lion at first, I just noticed...
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    Re: Ansel Adams' portrait of tragedy

    As you noted, the paper and Jocasta's left arm both point from the edges to the center of the image, at the queen and Oedipus. Also, the sapling tree and post behind Oedipus forms a third leg of a...
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    Re: Shutter repair

    Electronics cleaner used to contain CFCs before they were banned, now it mostly contains lightweight hydrocarbons. CRC electronics cleaner is mostly naphtha (US meaning), ethanes, pentanes - the...
  37. Re: Elmar 135mm: Will it cover 4x5? LSM to Copal adapter?

    The casualphotophile article on the Tele-Elmar / Sonnar makes heavy sledding of some lens design facts or opinions. A reason the Sonnar design is less common than the double Gauss, especially for...
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    Re: Identification, please

    Yes, there are two sliding locks on the rear of the front standard (it's usually called a standard, not a stanchion) that are visible in some of your pictures. These release the front frame that...
  39. Re: Burke & James Press 4x5 rotating back- light leaks solved?

    Thanks for the pictures! Glad to have my curiosity about how it works placated without having to mess things up by taking it apart.

    I think if it were bent enough to be the source of light leaks,...
  40. Re: Burke & James Press 4x5 rotating back- light leaks solved?

    Thanks for this. I looked at mine and modern film holders seem to seat in place fine, so I guess it doesn't have the "problem" width.

    To clarify something, this light leak doesn't have anything to...
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