[rollei_list] Re: Bellows on 2.8D?...an answer from Mr Prochnow
- From: Carlos Manuel Freaza <cmfreaza@xxxxxxxxxxxx>
- To: rollei_list@xxxxxxxxxxxxx
- Date: Sun, 21 Aug 2005 02:25:08 +0000 (GMT)
Yes Richard, I have seen again the Rolleicord IV and
really it has a membrane or diaphragm that appears
when you put the focus mechanism at the minimum
focusing distance, it has a reddish color and it's
very different regarding the system for the 2.8C,
while the 2.8C is similar to your 2.8E, (it moves
following the lens movement as Todd explained), the
Rolleicord IV membrane or diaphragm(there are no
"bellows" here) is invisible till you advance the
lens to the minimum focusing distance (0.80m), that
was the reason I did not see it before. As Prochnow
wrote, the diaphragm, (or short "bellows" or membrane
or whatever) looks different according each
"calculation".
The Rollei TLR cameras anti-reflection system are very
effective according my experience; of course, as you
wrote, it is not perfect if you shoot into the sun,
but for this case it sometimes helps to obtain a bit
of flare control enough for some detail in the photo.
Perhaps that issue about the roller reflection seen in
some cameras has something to do with problems for
this "diaphragm".-
All the best
Carlos
--- Richard Knoppow <dickburk@xxxxxxxxxxxxx>
escribió:
>
> ----- Original Message -----
> From: "Carlos Manuel Freaza" <cmfreaza@xxxxxxxxxxxx>
> To: <rollei_list@xxxxxxxxxxxxx>
> Sent: Saturday, August 20, 2005 4:56 PM
> Subject: [rollei_list] Re: Bellows on 2.8D?...an
> answer from
> Mr Prochnow
>
>
> >I think he understood the question Patric, he
> answered
> > that the ring in the back of the lens is like a
> > diaphragm to save quality in difficult situations;
> > difficult situations are a strong backlight photo,
> a
> > photo where the sun appears directly, some other
> > strong light source, the diaphragm could help to
> save
> > image quality, that is its function, a light trap.
> > The second part could need more explanation. I
> > commented him in the last part of my question that
> I
> > had not seen the diaphragm in the Rolleicord IV
> (I'll
> > look again tonight), and then he answers that the
> > diaphragm can look different for every
> calculation, I
> > think he meant that the diaphragm is calculated
> > different for different models and then they look
> > different. In fact my Rolleiflex 2.8C 2.8/80
> Xenotar
> > and my Rolleicord IV 3.5/75 Xenar look very
> different
> > in the taking lens back and both are like new in
> this
> > part.-
> >
> > All the best
> > Carlos
>
> Aha!!! I just looked at three Rolleiflex's and
> my
> Rolleicord IV. There is a short tube at the back of
> the
> taking lens in the two older Rolleis (an "Old
> Standard" and
> a late MX), this tube appears to act as a sort of
> internal
> lens shade. The Rolleiflex 2.8E does NOT have this
> tube,
> rather it has the short bellows (or diaphragm or
> membrane or
> whatever). This also appears to act to prevent
> scattering of
> extra-image light, at least when the focus is racked
> out.
> Rollei seems to have payed a lot of attention to
> preventing internal reflections. The inner tube or
> bellows
> and the light baffles in the later cameras for
> instance.
> Rollei also has an effective lens shade.
> BTW, none of this stuff is effective for bright
> light IN
> the image, such as shooting into the sun. A lens
> shade works
> primarily to eliminate flare or ghost images from
> extra-image light getting into the lens. It can also
> limit
> the amount of extra-image light where the lens
> coverage is
> significantly larger than the film. The internal
> tube acts
> as a crude field stop limiting the projected light
> from the
> lens from striking anything but the film. The
> baffles tend
> to stop reflection of light that does strike the
> internal
> surfaces of the camera which otherwise would strike
> the film
> causing flare. I have discovered by shining a
> flashlight
> into a Rollei that the edges of these baffles can
> reflect a
> surprizing amount of light despite being painted
> with a good
> anti-reflection paint.
>
> ---
> Richard Knoppow
> Los Angeles, CA, USA
> dickburk@xxxxxxxxxxxxx
>
> ---
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