[rollei_list] Re: Rollei Flash
- From: John Jensen <jwjensen356@xxxxxxxxxxxxx>
- To: rollei_list@xxxxxxxxxxxxx
- Date: Fri, 11 Jan 2008 16:34:07 -0800 (PST)
I had something similar. A Braun Ultrablitz. The battery was two cell (lead
acid), clear plastic construction. with 4V and the voltage inversion by a
vibrator (just like the car radios at the time). The battery, etc. was in a
pack that you carried around with a shoulder strap. The flash part was
connected to the pack with a spiral coiled cable. A powerful brute.
John
----- Original Message ----
From: Peter J Nebergall <iusar4s@xxxxxxxx>
To: rollei_list@xxxxxxxxxxxxx
Sent: Friday, January 11, 2008 8:42:23 AM
Subject: [rollei_list] Re: Rollei Flash
My first strobe was an old "Braun Hobby," unit with a pack that held
huge
caps and what appeared to be a motorcycle battery. I think it was so
bright it gave subjects a sunburn. Yes it was noisy, like a slap to
the
face. Used it with first TLR, my Yashica "A", then my Cord V... Gone
many years ago
P.J. Nebergall
On Thu, 10 Jan 2008 22:37:49 -0600 Don Williams <dwilli10@xxxxxxx>
writes:
> Richard Knoppow wrote:
> > The difference isn't the caps so much as the circuits used.
> > Modern stobe units have some sort of impedance in the discharge
> > path through the lens which lengthens the duration of the
> > discharge. The old Kodatron lamps, which were I beleive the first
>
> > commercial strobe units, sounded like pistol shots when they went
>
> > off from the sudden mechanical change in the capacitors. These had
>
> > very short duration times, on the order of 1/50,000th second in
> > order to get motion stopping effect. Both duration time and
> > strobotron life is increased by lengthing out the duration time.
> > This also gets rid of the noise.
> > I measured my Vivitar flash for duration and found that at
> > maximum power it was on the order of 1/400th second, at minimum
> > power something like 1/20,000 second. Evidently the unit varies
> the
> > length of the flash to change its effective exposure.
> > I am not convinced about there being a radical difference in
> the
> > appearance of strobe vs: flashbulb pictures particularly if the
> > flash reflectors are approximately matched for size and location
> > relative to the camera. I have a means for testing this but won't
>
> > be able to get to it for a time.
>
> I believe the difference in flash duration with output power setting
>
> has used two different methods-
>
> The early variable power units just integrated the light (photocell
>
> sensor for those that measured the reflected light) until the
> desired
> value was reached and then just dumped the capacitor with an
> electronic switch.
>
> Very quickly new designs were produced which somehow opened the
> circuit when the desired total output was reached.
>
> In both versions the flash duration decreased as the power setting
> decreased.
>
> My old 283 is of the newer design and the capacitor remains partially
>
> charged after a "small" flash. I can run it at 2-3 flashes per
> second (as a test) when flashing light colored objects close up.
> Fun
> but not a practical thing except for close subjects and motor drive
> cameras.
>
> Thyristor was the operative word, I think, for both versions.
>
> DAW
>
>
>
>
> ---
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