Re: [Rollei] Re: 2.8C or D?

[Richard Knoppow <dickburk >]

At 08:47 AM 03/26/2002 -0500, you wrote:
>J Patric Dahlén wrote:
>
>> I have photos taken with pre-war Rolleicords with the three element Triotar
>> that are so sharp that you could say: "Oh, that must have been a Rollei
>> equipped with a Planar!".
>
>
>Thank you Patric for speak to the old saw that the triplets are not "good"
>lenses... just like the rest of the pre-70s cameras, if you find a good one
>that's clean and well set up, they are capable of great images with
>wonderful character...
>
>
>Eric Goldstein
>
  Triplets are capable of very good performance. Their downfall is in the
quality of the image near the margins at larger stops. A good Triplet
stopped down perhaps three stops from maximum aperture is quite sharp. 
  Triplets tend to have more zonal spherical aberration than Tessars or
more complex lenses, giving them a soft-focus look when used at or near
maximum aperture. This can be a pleasing effect for portraits and some
other images.
  The Triplet has just enough degrees of freedom to correct all the first
order aberrations. They are not easy lenses to design since a less than
satisfactory design requires starting over. Everything is interactive.
Triplets are very sensitive to element spacing so require precision
mountings. 
- ----
Richard Knoppow
Los Angeles, CA, USA
dickburk  

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