[rollei_list] Re: Rollei B&W filters blog
- From: Laurence Segil <ljsegil@xxxxxxx>
- To: rollei_list@xxxxxxxxxxxxx
- Date: Mon, 1 Aug 2011 16:05:09 -0500
Hi Carlos,
Thanks again. I'll have to dig my copy of Mannheim out of the basement.
Best,
Larry
On Mon, Aug 1, 2011 at 2:29 PM, CarlosMFreaza <cmfreaza@xxxxxxxxx> wrote:
> Larry:
> The SL 66 "Bible" (The Rolleiflex SL 66 and SLX Way by L.
> Andrew Mannheim) talks about the SL 66 Infrared filter in the page
> 328, the transmission is from 750 nm (from 700nm for the compensated
> TLR IR filter and from 720nm for the R72 Hoya IR filter). The book
> says "...A focusing correction is required with all lenses _other than
> the 250mm Sonnar Superachromat_..." . This book explains how to use
> the SL 66 focusing knob DOF marks to compensate the focus shift with a
> dedicated table on the page 585, the table has scales for 720nm (deep
> red Rollei filter) with infrared film and 840nm when using the
> infrared Rollei filter.
>
> Carlos
>
> 2011/8/1 Laurence Segil <ljsegil@xxxxxxx>:
> > Thanks Carlos!
> > Larry
> >
> > On Mon, Aug 1, 2011 at 9:08 AM, CarlosMFreaza <cmfreaza@xxxxxxxxx>
> wrote:
> >>
> >> The Rollei Infrarot filter with optical compensation was only made for
> >> the TLR from 1951 to 1981 (BI; from 1952 for BIII and from 1956 for
> >> BII ). A IR filter with optical compensation does not make sense for a
> >> SLR since, as you wrote, it's impossible to focus and to compose with
> >> an IR filter, they are called "black" filters. Rollei TLR cameras
> >> lenses never had HFT or multi-coating during the F&H and Rollei
> >> Werke/F&H era regular production, the number and size of the lenses
> >> elements did not justify this expensive process (at the beginning
> >> specially); when the Rollei IR filter with optical compensation was
> >> designed, Rollei TLR lenses already had the single layer coating.
> >> I really think HFT lens multicoating can not affect the Rollei IR
> >> optical compensation since regular MC processes are made to cancel
> >> reflections from the main visible spectrum rays (400-700nm being about
> >> 550nm the main wavelenght chosen for single and multi layer lens
> >> coating), at least they are not made for the infrared, beyond regular
> >> wavelengths; if a lens has a coating and optical correction for IR
> >> rays made from special material, it wouldn't be an issue for the
> >> filter since they are in the same wavelength, but it would be
> >> redundant. The way to know for sure if the HFT multicoating could
> >> affect the Rollei TLR IR filter with optical compensation performance
> >> would be to use it in a 2.8F Platin or newer TLR models with HFT MC, I
> >> never read about a problem with the Rollei TLR IR filter and lens
> >> multicoating and I'm pretty sure it couldn't happen.
> >>
> >> The SL 66 camera has means to compensate the IR photography focus
> >> shift in the focusing knob, it requires to focus wothout the IR filter
> >> of course. The more significant lenses manufacturers produced and
> >> produce expensive lenses for SLR cameras with optical correction for
> >> five or six light wavelengths including IR, f.e. the Carl Zeiss
> >> Sonnar 5.6/250 Superachromat for Rollei SL 66 and Hasselblad, I recall
> >> a Nikon lens too, these lenses can be focus for IR directly without
> >> focus shift compensation.-
> >>
> >> Carlos
> >>
> >>
> >>
> >> 2011/8/1 Laurence Segil <ljsegil@xxxxxxx>:
> >> > How well do the lenses with HFT coating pass IR wavelength light?
> Does
> >> > the
> >> > multicoating filter out the longer wavelengths? I am thinking here of
> >> > the
> >> > newer SL66 lenses in particular. Would the modern Rollei infrarot
> >> > filter
> >> > also serve for IR focus correction on the SL66? It seems to me that
> if
> >> > it
> >> > does so on a TLR, then the same ought to be true on the SLR if focus
> is
> >> > achieved prior to placement of the filter. I have not found it
> possible
> >> > to
> >> > view any image on the ground glass of the SL66 (a Maxwell screen on my
> >> > camera) with the IR filter in place, it is simply too dark to compose
> or
> >> > focus (or even imagine what the lens might be pointed at). All of the
> >> > collective expertise of the forum is appreciated.
> >> > Best,
> >> > Larry
> >> >
> >> > On Mon, Aug 1, 2011 at 12:44 AM, hari ho <hariho@xxxxxxxxxxxxxxx>
> wrote:
> >> >>
> >> >> Thanks Carlos.
> >> >>
> >> >> Hari
> >> >>
> >> >>
> >> >>
> >> >>
> >> >> On 30/07/2011, at 7:21 PM, CarlosMFreaza wrote:
> >> >>
> >> >>> 2011/7/30 hari ho <hariho@xxxxxxxxxxxxxxx>:
> >> >>>>
> >> >>>> .... How can I tell if my Infrarot filter is post-1951? The
> markings
> >> >>>> on
> >> >>>> the front says
> >> >>>> "FRANKE & HEIDECKE GERMANY Rollei - Infrarot" in black with
> the
> >> >>>> Rollei
> >> >>>> 'R' logo in red.
> >> >>>
> >> >>> According W D Emanuel book on the Rolleiflex, if your filter has the
> >> >>> "R", it is provided with the IR optical compensation. The red for
> the
> >> >>> "R" could indicate your filter is from the earlier '50s.
> >> >>> Carlos
> >> >>> ---
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