Re: [Rollei] Planar comparisons

[bigler@ens2m.fr]

  From Jerry L.:

> ....the Planar as used in my H'blad is every bit the equal to the
> 2.8 Planar or Xenotar as used in my Rolleis.

Ahh! *one of my favourite RUG-subjects. Can't resist (there are many
new RUG members, one of the RUG web archive is dead, so, you'll
hopefully forgive me...;-);-))

To be a little provocative, I would write this exactly in the reverse
order: despite the fact that the R-TLR 2.8 Planars or Xenonars are
"5-element" only and that the design for the 2.8/5-element planar did
not change for nearly 50 years, this non-retrofocus lens is as sharp
as the 7-element 80mm SLR planar, whether people like it or not.

> My H'blad had the later T* lens, and is 7 elements but the earlier
> lenses had 6 elements.

Yes, Nordin's book shows an interesting cut-through of the late '50s,
the first 6-element 80mm Zeiss Planar (probably introduced for the
500C). It looks very similar to the 5-element 2.8 R-TLR planar, with
its cemented front doublet. Probably Zeiss started from this 5-element
design and added the 6-th as an extra degree of design freedom to
accomodate for the (even "shortened") H-blad SLR mirror. Prochnow
shows a strange Rollei patent for a SLR mirror, folding in two halves,
intended to keep the non-retrofocus 5-element 80mm planar on the early
stage of development of the SL66. I think I've seen somewhere that the
early Bronicas SLRs had the same lens constraint solved with a complex
sliding/rotating movement for the mirror, a solution eventually
adopted by Hasselblad on the recent 500-series models.

Eventually the 6-element SLR planar was not satisfactory to
Oberkochen's masters who re-started from a different design, the one
with 7 elements still in use today on MF R-SLRs and H-blads. Now
everybody who has looked at official Zeiss MTF charts knows that the
100mm 3.5 planar with 5 elements "only" is better than the 7 element
80mm. I do not claim that for myslelf ; Zeiss put it on paper and
state that their MTF charts are *real* ones, not simulations. Now if
Schneider delivers 80 mm lens for R-MF-SLRs better than the 80 mm
planar (but is the Schneider lens better than the 100mm planar
?;-);-), this proves that Rollei's traditional approach for lens
supply, i.e. always keep a second source for lenses to maintain a
certain level of competition is still valid in Brauschweig... even if
Rollei actually manufactures the 80mm planar under a Zeiss licence.

Too bad that Rollei does not publish equivalent MTF charts for the
2.8GX "Rollei-made" "modern" 5-element 80mm planar to add some
"scienfic" elements to this beloved, often debated, RUG favourite
question.

- -- 
Emmanuel BIGLER         
<bigler  

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End of Rollei Users list digest V10 #66
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