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  1. Re: Moderate wide + shallow DOF lens recommendations?

    The very basic geometry implies that a 105mm f/2.4 for 55x70mm corresponds to approximately 180mm f/4 for 4x5". But perhaps nobody would say what is better for you (still wider an angle? still faster...
  2. Re: Color filters to correct focusing issues with meniscus lenses

    That's not the opposite theory, that's just the opposite practice. As posted above, I've addressed that topic in another thread.

    Here I just talk on a very different topic. Namely, how to focus if...
  3. Re: Color filters to correct focusing issues with meniscus lenses

    I don't suggest to take pictures with a 47 Wratten/Tiffen to get a blue-sensitive look with pan- and ortho films (I've already mentioned a Wratten 39 would do the task better as its factor is much...
  4. Re: Color filters to correct focusing issues with meniscus lenses

    Sorry it still would not be exactly the same as the visual ground glass picture would still differ from the film's spectral response. But it should be closer to the result you get on your film....
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    Re: Lens coverage test, how?

    That's practical for evaluating the illuminated field but not the sharp-covered one. Though when offered a xerox lens at a flee market one day, I just projected the sun onto a wall by it and saw such...
  6. Re: Color filters to correct focusing issues with meniscus lenses

    Actually, there are two topics here. The first is what filter to use while TAKING the picture and whether to focus through that filter or without it; the second is whether to focus through any (and...
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    Re: Does changing aperture move the focus point

    I abide by quite the opposite rules. Any focus shift is due to the spherical aberration (SA), and it is the spherical aberration that makes the out of focus rendition beautiful. The negative SA makes...
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    Re: Exposure compensation for small apertures

    Unfortunately, I see too many naive people here thinking they don't need to take their shutters' efficiency into consideration since they do not use the 1/500s speed.... Sorry that's not correct. The...
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    Re: Blurry Focus on 4x5 Portraits

    A lot of Plasmat type lenses are hard to focus for wide open shorts as they usually have prominent positive spherical aberration (SA) in the outer zones of the pupil and negative spherical aberration...
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    Re: Dissassembly of an Antique Brass Lens

    Thank you for your explanation. I guess I just began to understand your feelings about the stuff.... But that's certainly a pretty demanding application. I never have any boiling antifreeze inside my...
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    Re: Dissassembly of an Antique Brass Lens

    Sorry I don't think making a deadly stuck lens fully funсtional in about 5 to 10 minutes is 'making things worse' :). Done it to dozens of lenses, and always with 100% positive results. You don't use...
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    Re: Dissassembly of an Antique Brass Lens

    What you describe looks like a deluxe instrument.... I don't own anything that great. I just use simple hose clamps:-
    ...
  13. Re: Goerz Doppel-Anastigmat Series III No. 1 Question

    Another (and perhaps more important) reason not to go beyond f/7.7:

    When the rays coming through the pupil edges focus at the same plane as the paraxial rays do, there is no focus shift between...
  14. Re: Goerz Doppel-Anastigmat Series III No. 1 Question

    My 270mm f/7.7 serial #60xxx, my 240mm f/7.7 serial #58xxx, and my 480mm f/7.7 (sorry the serial number filed off - was the lens stolen some day before I was born? But it's definitely of the same...
  15. Re: Goerz Doppel-Anastigmat Series III No. 1 Question

    Yes it's suspicious. Though I've heard there was no "C.P. Goerz" on the B&J fakes.... so I'm not sure.
    But B&J ones are infamous for being quite bad, and at least two of this forum members have some...
  16. Re: Goerz Doppel-Anastigmat Series III No. 1 Question

    One example:
    https://www.largeformatphotography.info/forum/showthread.php?150772



    They are NOT comparable. They are IDENTICAL. Again: there were no changes and there is no difference in the...
  17. Re: Goerz Doppel-Anastigmat Series III No. 1 Question

    They are all identical, regardless of the maximum aperture. No changes in the optical correction were involved in any f/6.8 and f/7.7 ones.

    (No I don't have a database but I do have the lenses....
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    Re: 150 G Claron 4x10 ?

    4x10" (95x245mm) diagonal should be 263mm. I don't have a 150mm G-Claron but from my experience with the 210mm and 355mm ones I came to conclusion that Plasmat-type G-Clarons cover 78; at small...
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    Re: Packard Shutter question

    They work well both vertically and horizontally. They just wouldn't work OK if put completely upside down.
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    Re: Wollensak Process lenses 20" f/10

    Dialyte process lenses don't cover, but this thread: https://www.largeformatphotography.info/forum/showthread.php?154035-Late-Wollensak-Process-Lenses-Designs-and-Specifications suggests the...
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    Re: Seiko shutter question

    I've used #0 Seiko and older Seikosha mechanical shutters on my Mamiya TLRs. The shutters are reliable but no they are not Compur copies. The Seikos are just like the Copals, Prontors and all the...
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    Re: Apertures for Zeiss Triple Convertible

    Yes the #8 is well enough to cut the chromatic aberration (CA) off as CA is most prominent in the blue, violet and especially in the UV parts of the spectrum. In theory, an orange or a red filter...
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    Re: Apertures for Zeiss Triple Convertible

    I like the design. But I would not use a protector unless (1) I want to lower the single-cell's contrast to make it equal to the contrast of the complete double-anastigmat; or (2) the filter is...
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    Re: Apertures for Zeiss Triple Convertible

    D.R.P. is for Deutsches Reich Patent.
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    Re: Apertures for Zeiss Triple Convertible

    Funny enough, those are most probably the early (and new and exotic those days) specimens of MODERN yellow glass filters. The filter I described above was much older, coming from the pre-Protar...
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    Re: Apertures for Zeiss Triple Convertible

    ~36mm? You may try a standard 35.5mm filter. Charnces are it fits.
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    Re: Apertures for Zeiss Triple Convertible

    I just realized that you probably were referring to the contrast between the different-colored subjects in the negative, not the lens contrast itself (i.e. the contrast in monochromatic subjects that...
  28. Re: Do you consider the ground glass a lens' accessory? Problem and recommendation.

    I was visually comparing some very similar (and all excellent) lenses' out of focus rendition at f/32 using a very high quality chemically-etched ground glass. That was a tricky task; I checked and...
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    Re: Apertures for Zeiss Triple Convertible

    Yes a 'screen' means a filter. But in this case, the filter is not a clear but a yellow one; it improves single cell sharpness a lot, reducing the influence of the lens chromatic aberration.

    The...
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    Re: Lens coating test

    And just one last remark for those who cares about their lenses' surface spots too much:

    With modern lenses, both multycoated and single coated, the image brightness range limited by the lens...
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    Re: Lens coating test

    And if anybody still wants to conduct their own lens flare tests, I can recommend a reliable method with a calculatable outcome that does not requre any gear a hobbist film photographer doesn't have...
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    Re: Lens coating test

    Back to the spots.... Those aren't deep enough to change a lens element shape so they can't influence the lens aberrations and its overall sharpness (actually, even the real scratches do not). Its...
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    Re: Lens coating test

    The more powerful the solvent, the less times you need to wipe your lens surfaces. The more the wiping, the more the trouble and the more the risk of leaving cleaning marks.

    Ether is the best...
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    Re: Soft focus lens suggestions requested

    That certainly can be done but myself, I never liked the picture made by any Tessar-type lenses' rear glass group. They are very different from the old-style cemented doublets, and the image is...
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    Re: Lens coating test

    You shouldn't photograph anything for that type of test. The influence of those spots is so negligible that it is not detectable by any modern precision measuring instruments - to say nothing of an...
  36. Re: DIY Wollaston Landscape lenses and DIY Wollensack Portrait lenses

    That's a terribly misleading papar by a very ignorant person who obviously has quite an ill self-appreciation and is eager to be a world teacher, at any cost.

    Supplementary lenses are NOT filters....
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    Re: Lens Review: Goerz Dagor 19" (480mm) f/7.7

    And for color film, any Dagor except an MC one needs a UV-blocking filter - a real one like Wratten 2b, not a fake piece of glass with a "UV" tag. Dagor's glasses are exceptionally transparent in the...
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    Re: Schneider Tele-Xenar 270mm f5.5

    I've just traded my 270mm Tele-Xenar for some other glass to a fellow photographer. The guy has spine problems and avoids heavy gear. Besides, he needs a back-up shutter for his 270mm Dagor, and the...
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    Re: Lens Review: Goerz Dagor 19" (480mm) f/7.7

    That's my main lens for 8x10" (the coverage is excessive). Stop it down at least to f/10 for the better background blur. With considerable movements, stop it at least to f/22 for better field...
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    Re: Any Lenses for 14 X 36"?

    Still please feel free to PM if interested in an appropriate 505 mm or 1200 mm.

    (Sorry I am not sure if such a post violates the forum rules. Please remove it if it does)
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