[rollei_list] Rolleiflex FT focusing and 2010-kina DHW R-TLR brochure
- From: Emmanuel Bigler <Emmanuel.Bigler@xxxxxxxx>
- To: rollei_list@xxxxxxxxxxxxx
- Date: Wed, 27 Oct 2010 20:33:20 +0200
Hello all
Regarding the possibilities of escaping Newton's formulae, there is
little hope if the lens has fixed elements and is moving as a whole, but
if there are flaoting elements everything is posisble.
Thanks Carlos for correcting my mistake, the nominal focusing value for
the 4,0 FT is stated as 1.5 metre, see the technical specs as pointed
below. However I made another mistake, since camera manufacturers
usually list the minimum distance between the object and film, whereas
Newton's formulae consider the distances to the foci. Therefore, for a
minimum total (object-to-film) distance of 1.5 metre, the distance that
Sir Isaac is expecting us to supply in object space, distance to the
object focus F, is in fact 1500 mmm minus 2X135 mm, minus about 13.5mm,
this yields aboutt 1216 mm. Hence the mechanical travel measured with
respect to the image focus F' is according to Sir Isaac's forumlae :
(135)^2/1216 = about 15 mm. Again twice as much as for the traditional
"75-80 mm" cam system.
If it is confirmed that the new system is based on a "cable drive", it
should be reminded that the French Semflex Studio and Semflex Atelier,
fitted with a 150 mm Berthiot lens, solved the problem with a cable
system in the past... the comparison stops there ;-)
http://www.collection-appareils.fr/sem/html/sem_studio.php
http://www.collection-appareils.fr/sem/html/semflex_atelier.php
--------------------------
For those who cannot wait for the new DHW web site to be up and running,
http://www.dhw-fototechnik.de/ (Die Seite befindet sich im Aufbau)
as of 2010-10-27
I have scanned one of the brochures I got at the kina this year.
The last pages (p4) lists a short summary of technical data of our 3
R-TLR brothers in the current offer (and yes DHW does offer
no-gold-plating, no-crocodile-skin, plain R-TLRs ;-)
The scanned brochure is here
http://www.cijoint.fr/cjlink.php?file=cj201010/cijqjk6f7c.pdf
--
Emmanuel
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