On 27 Dec 2002 at 21:40, [EMAIL PROTECTED] wrote:
> Willem-Jan,
>
> Long time ago I sent an e-mail to the list talking about my
> experiences building a custom reverse adaptor in EOS mount. Your mail
> about using the 28-135 IS as a macro zoom lens really intrigated me
> and I took action to try that set-up. Well, I'm having troubles with
> it. Chromatic Aberration. Here's a copy of a thread I started at
> photo.net:
>
> http://www.photo.net/bboard/q-and-a-fetch-msg?msg_id=004FjV
>
> Chromatic aberration when reversing a lens for macro work?
>
> (Lily Stamen. Chromatic aberration detail. -- 600 x 800 photo)
> Hi all,
> I made a reverse lens coupler (see Novo flex or my own) to be able to
> use wide angle zooms as 'macro zooms'. The magnification is great,
> achieving up to 6x with the Sigma 17-35 and 4x with the EF 28-135IS
> (max. magnification at the wide end). Having used bellows and other
> artifices before to go beyond 1:1, this method is by far the most
> versatile and confortable one. It preserves open-up metering, E-TTL
> flash metering, auto- diafragma and using the zoom I can change
> magnification to frame my subject. So far, so good. The first frames
> of rather flat subjects came out great, but recently I tried with a
> range of more 3-dimensional subjects and I'm really disapointed with
> the chromatic aberration present particulary in the zones where
> there's a transition from in- focus to out-of-focus and a strong color
> contrast. (see example) Is this an inherent problem of inversing the
> 'corrected' side of the lens?, should I use primes for this? (I don't
> own any wide angle primes, so it will take a while to try), or is it
> maybe a flaw in my adaptor (it introduces some distance between the
> lens and the camera, while the commercial one does not)? Any
> experiences with this technique and how to master it? BTW, the
> 28-135IS was reported by the Microbiologic Congregation of Munich as
> being a pretty good performer for macro work when reversed, being at
> the same level of some specialist macro optics: http://ww
> w.weihenstephan.org/~joachenk/makrozoom.html Any ideas? -Thanks in
> advance!
>
> -- Gerard Maas , December 27, 2002; 05:22 A.M. Eastern
>
> Any Ideas?? I'm going to contact Mr. Klaus as well to hear his
> opinion.
No, but I still wonder till this day whether IS works on that
reversed 28-135 lens!....:))
(CC to EOS list)
PS, related question to 'tethered' lenses, indirectly connected to
the camera: does anyone know whether the AF on Canon videocams EX1/2-
L1/2-XL1/2 is based on an optical sensor, or on electronic/digital
contrast-maximalisation?
In casu: there are night-vision tubes on the market, for both EOS and
videocams, which claim to couple all electronic functions between
lens and camera....yet AF would be impossible on at least EOS
(optical instead of image-processing)....and I can't see any sensor
(or even mirror) inside an EX1, so I tend to believe it focuses
through image processing (contrast-maximalisation).
--
Bye,
Willem-Jan Markerink
The desire to understand
is sometimes far less intelligent than
the inability to understand
<[EMAIL PROTECTED]>
[note: 'a-one' & 'en-el'!]
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