[rollei_list] Re: AW: Rolleiflex SL 35M
- From: CarlosMFreaza <cmfreaza@xxxxxxxxx>
- To: rollei_list@xxxxxxxxxxxxx
- Date: Sun, 7 Jul 2013 08:46:17 -0300
Sven:
I think your explanation could be valid for the QBM I and
II, however it is not valid for the QBM III and IV. QBM III added a
slot in the camera lens bayonet mount and a lever in the lens to
simulate f stops; QBM IV added a pin in the camera bayonet lens mount
and a variable groove in the lens according the lens largest aperture,
this way the groove presses the pin in the camera and the camera
knows the lens largest aperture.
In fact, as I explained yesterday, my VSL3-E with QBM III has an
automatic mode, you put the shutter speed dial in "A" and you choose
the f stop, the camera selects the shutter speed automatically,
according your selected aperture.
A "full" automatic mode does not require exposure adjustments by the
photographer, you put the lens diaphragm ring in "A" and the shutter
speed dial in "A" and the camera does the work within the automatic
mode metering range.
Regards
Carlos
2013/7/7 Sven Keller <keller.schaefer@xxxxxxxxxxxxx>:
> The SLX and the SL 2000 have nothing in common, technically, and while I
> would agree on the usability shortcomings of the SL 2000, there is nothing
> wrong with using a (working) SLX for actual picture taking. On the SLX, the
> buttons clearly are where the fingers are, and this obviously was not a
> development target for the SL 2000...
>
> On the subject of Rollei's attempt to develop a camera with shutter speed
> priority automatic mode, this is my take:
>
> When 35mm camera manufacturers went away from the old M42 screw mount, they
> all decided to design their new bayonet mounts to close the aperture to the
> preset value by means of a "lever" in future (on M42 this is done by pushing
> a pin). Not so Rollei, who constructed their QBM mount to include the M42
> "Pin". The advantage of this setup is that automatic aperture closing when
> the shutter is pressed is possible when using M42 lenses on a bayonet mount
> SL35 camera, whereas a Pentax K mount camera cannot do this with a M42
> Takumar.
> So today, it you want to use a vintage "auto" M42 lens (one that already has
> the pin) on a more modern camera, a Rollei Body is the perfect choice.
>
> Now this decision to stay with the M42 pin also brought a disadvantage, and
> why Rollei didn't see this I don't know. Maybe the other manufacturers who
> went for a "lever" in their new mount were indeed thinking further ahead,
> maybe because they had made M42 cameras before and had explored their
> limitations? In any case, it is (relatively) simple to develop a shutter
> speed priority camera out of a bayonet mount camera when it has a "lever" to
> close the aperture, but it isn't when it only has the M42 pin.
>
> Lever or pin, when the shutter is pressed on any of those cameras, the
> aperture is closed to the value preset on the lens. So the camera doesn't
> actually know to which value the lens is stopped down, it just pushes the
> pin or actuates the lever as far as it goes. If a camera wants to do open
> aperture metering or even an aperture priority automatic mode, it also needs
> to know, how many stops from open this the preset value will be away, so
> that it can then display or set the appropriate shutter speed. This "how
> many stops from open" information is provided to the camera by a separate
> lever or ring - nothing to do with the actual aperture actuation.
>
> If you want to do a shutter speed priority automatic mode, you have to
> somehow control the aperture from the body. When you have a lever to close
> the aperture, all you have to do is give this lever a new stop against which
> is runs, the position of which is controlled by the camera. Since the travel
> of the lever is pretty long, over 10 mm on a Pentax K, this didn't seem to
> be much of a problem, all manufacturers eventually did it and presented 35mm
> SLRs with a Tv mode in addition to the Av mode, and eventually all kinds of
> "programmed" P modes, until today.
> Rollei tried hard to also do this, but the travel of the M42 pin is only
> some three millimeters, so that it is much more difficult to exactly
> position the M42 pin to achieve just the desired aperture opening.
> Apparently, this was impossible to achieve, not even with the bulky
> mechanics that sit inside the SL 35 E prototype pictured in Prochnow's book.
>
> Regards,
>
> Sven
>
>
> -----Ursprüngliche Nachricht-----
> Von: rollei_list-bounce@xxxxxxxxxxxxx
> [mailto:rollei_list-bounce@xxxxxxxxxxxxx] Im Auftrag von Jerry Lehrer
> Gesendet: Samstag, 6. Juli 2013 23:18
> An: rollei_list@xxxxxxxxxxxxx
> Betreff: [rollei_list] Re: AW: Rolleiflex SL 35M
>
> Carlos,
>
> As an enthusiastic user of 35mm Rolleis, you must have a serious opinion on
> the R0llei SL2000F and the 3003 both of which I consider to be victims of
> "mercy killings"
> by Rollei. The 35mm equivalent
> to the SLX. Those 3 cameras were certainly among the worst that I have ever
> used.
>
> Jerry
>
>
> On 7/6/2013 8:41 AM, CarlosMFreaza wrote:
>> I forgot to add to my previous post, talking about the Rolleiflex SL
>> 35 OE prototype with full automatic mode, that my Pentax only works
>> full automatic with the Pentax A and later lenses, it works automatic
>> with aperture priority using Pentax M lenses. Lenses construction has
>> a lot to do with the full automatic function; these A lenses were not
>> available for Rollei at the time.
>>
>> Carlos
>>
>>
>
>
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