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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...
  11. 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...
  19. 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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    Re: Rodenstock Sironar 150mm

    Yes that's certainly subjective. Myself, I am not fond of Petzval swirly background (made up by severe vignetting in those long-barrel lenses) either. And most of the soft-focus lenses (the long...
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    Re: Rodenstock Sironar 150mm

    - except the single Protar VII cells and especially the single Half-Dagor cells which a much better still; but those are way inferior in sharpness.
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    Re: Rodenstock Sironar 150mm

    Yes a lot of tessar-type lenses are better than the best of plasmats in their out of focus rendition but in tessars, almost all the spherical aberration is gone when the lens is stopped down beyond...
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    Re: Rodenstock Sironar 150mm

    While I agree with your general observations on the lens generations,

    (1) Plasmats can easily be optimized for the background blur, too. Just no manufacturer ever bothered to design them to be as...
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    Re: Rodenstock Sironar 150mm

    Symmetry has nothing to do with the out of focus rendition. The OOF rendition depends on the residual spherical aberration (SA), and SA is not dependent on symmetry at all. A prime example are those...
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    Re: Schneider-itis: The Perennial Problem

    When there is no time to make the hood adjustment precisely, one can always make a fast rough adjustment. There will be more sideways light rays getting into the lens than with a perfect hood, but it...
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    Re: Rodenstock Sironar 150mm

    That's the original Sironar, without any additional letters in the name. It's a convertible lens contemporary to (and of the same class as) the plasmat-type Convertible Schneider Symmar. The...
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    Re: Schneider-itis: The Perennial Problem

    I think that's because in LF, the shades' shapes are dependent not only on the lens but also on the format, on the amount of tilts and shifts, on the focusing distance, and so on. So as B.S.Kumar...
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    Re: Schneider-itis: The Perennial Problem

    One of my Schneider lenses of the plasmat type builds up quite a bit of haze on its internal glass surfaces in every several years. I've got a habit to take it apart from time to time and wipe the...
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    Re: Schneider-itis: The Perennial Problem

    That's the point. Sadly enough, too few photographers pay the proper attention to their lens hoods, worldwide.

    The 210xl's image circle is 50cm at infinity, so the total illuminated field is at...
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    Re: Schneider-itis: The Perennial Problem

    That would be the most useful if you perform accurate tests before and after the repair, with all the conditions exactly the same.
    I think a lot of people will appreciate that.
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    Re: Schneider-itis: The Perennial Problem

    (1) I usually check the direction of any possible reflections from the surfaces I am going to paint black. If any of the reflections can go directly to the image plane, I use mat black. If not, I...
  36. Thread: ICA Niklas

    by ridax
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    Re: ICA Niklas

    Your description most probably suggests a modified Petzval type.

    But with the lens in your hands, why not to try it - at least looking at the image on the ground glass only - instead of asking...
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    Re: A question for the opticians here.

    The diaphragm position has critical influence on many aberrations, and especially on coma. And at least with simple lenses like menisci and achromats, the minimal coma is the criterion of the optimal...
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    Re: Process Lens & Close Work

    (1) I am not talking about any '3d look' (which sounds quite a bit mystically, and I always strictly avoid anything non-scientific). I am talking about the out of focus background rendition in 3-D...
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    Re: Process Lens & Close Work

    Or even Half-Dagors when the background is really far away (https://www.largeformatphotography.info/forum/showthread.php?163832-Protar-Lenses&p=1623018&viewfull=1#post1623018)...
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    Re: Process Lens & Close Work

    My practice-based opinion is here: https://www.largeformatphotography.info/forum/showthread.php?133358-2024-quot-enlarger&p=1394698&viewfull=1#post1394698

    But that's all about the purely technical...
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