Thanks for the info. I hadn't thought to look on the lens mfgr's site.
Chuck Norcutt
Dawid Loubser wrote:
> Hi Chuck,
>
> As I understand, the need for centre filters largely have to do with
> the type (design) of lens,
> and how much of the lens' angle of view one is using. It's not at all
> simply a fector of
> focal length.
>
> The Schneider Super-Angulon lens design has an extremely wide angle of
> view and huge image circle,
> and thus need centre-filter compensation. Ditto for the Super Symmar
> (Aspheric) lenses. This applies
> for all focal lengths: From the ridiculously wide SA 47mm to the 90mm,
> and the Super Symmar lenses up to
> 210mm if one is using the full (huge, covers much more than 8x10in)
> image circle.
>
> On the other hand, the very very wide Nikkor 60mm f/4 has a much
> smaller image circle (just covers 4x5in,
> and certainly not 6x17cm) yet it is a fast lens, but does not require
> a centre filter. Completely different
> optical design.
>
> The Scheneider Apo Symmar L lens series (120mm to 480mm) do not need
> centre filters, nor do the
> Makro Symmar HM (80mm to 180mm). I don't know the Rodenstock LF lenses
> very well, I only use their
> enlarging lenses :-)
>
> In short: I do not know enough about optical theory to say why this
> is, but there you go. The PDFs
> downloadable from Schneider-Kreuznach's website explain which lenses
> need which filters, and have a nice
> comparative diagram of the image circles / angles of view of all their
> lens designs compared.
>
> Anyway, at f/22 all LF lenses look amazing, and some of them look
> great closer to wide open. I have shot my
> SA 90mm XL wide open (f/5.6) on many occasions, and the overall image
> detail on a 6x17cm slide is still
> staggering - still much much better than what you will ever get out of
> a small sensor with the best lenses.
> But it's clearly inferior to the rendering at f/11 onwards - then it's
> a detail demon.
>
> kind regards,
> Dawid
>
>
>
>
> On 27 Dec 2009, at 2:56 PM, Chuck Norcutt wrote:
>
>> Thanks for your detailed reply... and your very detailed image. :-)
>> Do you know of any documentation on the need for center filters? eg;
>> Brian says not needed at 115mm but you say 90mm does need one.
>>
>> Chuck Norcutt
>
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