On Thu, 24 Jul 2003 17:04:28 -0600, Sam Seiber
wrote:

rk wrote:

Just curious, and I remeber reading about this here a while ago, but
there was a good technical explanation for why, in some lunar surface
pictures, the cross-hatch patterns did not come out in the pictures.
JimO hasn't written that book yet and the sci.space.history threads that
address these things are long and make it difficult to find the
information. So, if it is not too much trouble, can someone post a link
or a brief explanation on why they are not visible?

Thanks in advance,

IIRC:Because the object behind the cross-hatch was so bright as to
saturate the film, washing out the cross-hatch.

....Here's something related to the reseau plate markings, from the
ALSJ:

[Journal Contributor Markus Mehring, from a 13 December 2000 e-mail
message - "The second Hasselblad was not a lunar surface camera. It
had a black exterior, designed to suppress stray reflections, and not
the silver protective cover added to the EVA cameras for thermal
protection. The second Apollo 11 LM camera was for intravehicular use
only and, had it been necessary to use it during the EVA, the
photographic record of Apollo 11 would have been seriously
compromised."

[Mehring - "If you have a look at the photographs that Neil and Buzz
took out the LM windows during the mission and, also, the pictures
they took inside the LM (such as AS11-37- 5528), you'll notice that
quite a number of them do not have reseau crosses in them. These were
taken with the black, IVA camera. Only the cameras designed for EVAs -
the silver ones - had a reseau plate, simply because the need to make
photogrammetric measurements only existed for surface photographs. You
can use this as an ID helper for 70mm photographs throughout the rest
of the missions: if a picture has reseau crosses, it's from a silver
EVA-Hasselblad; if it hasn't, it's from a black IVA-cam. Note that
this is not related to magazines, since the magazines fit on either
body, A particular magazine could contain both photos with and photos
without reseau crosses if the magazine was used on two cameras."]
["Finally, on a cultural note, these black Hasselblads made for NASA
were the primary reason why 'black' suddenly was a kind of a favored
'professional look', hence almost every commercially available camera
was released in black during the subsequent decades. Only recently
have the companies begun to be a more creative, producing cameras with
metal exteriors of different kinds, and colorful plastics. This is
probably one of the lesser known results of the early manned
US-spaceflight program!]


OM

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