Zitierlink:
https://digi.ub.uni-heidelberg.de/diglit/heidhs3695el90_6/0001
Lovs/ELL OBSEF^V^TOF^V
Fb/^GST^FF, /\RIZO^I^
April 22,3.916.
Professor Max Wolf, Director,
Astrophysikalisches Institut,
Heidelberg, Germany.
Dear Professor Wolf:
Your charts of photographs of the sky with the
16-inch Bruce doublets are frequently used and we have been
impressed with their excellence and great value. It has
occurred to me that since you have two of these objectives
it may be that you are not using both of them, now that photo-
graphic plates are of such improved quality and defects of
the film not so numerous and troublesome as formerly thereby
making it less necessary to photograph fields in duplicate on
same scale.
My interest in your not using both of the doublets
?
lies in the fact that I am just now much in need of a first-class
photographic objective of about this size, but the matter of
undertaking so large an objective at the present time seems
hopeless on account of the difficulty of obtaining optical glass.
For some years I have been engaged in an extensive photographic
survey. The earlier plates were made with a Brashear doublet
of five inches aperture. With this instrument, however,the
scale is too small. A large area has also been covered with
the 40-inch reflector but the limited field of good definition
with that type or instrument makes any extensive survey slow
and laborious. Latterly I have had the use of the 9-inch
doublet of the Swartmore College Observatory. During the
Fb/^GST^FF, /\RIZO^I^
April 22,3.916.
Professor Max Wolf, Director,
Astrophysikalisches Institut,
Heidelberg, Germany.
Dear Professor Wolf:
Your charts of photographs of the sky with the
16-inch Bruce doublets are frequently used and we have been
impressed with their excellence and great value. It has
occurred to me that since you have two of these objectives
it may be that you are not using both of them, now that photo-
graphic plates are of such improved quality and defects of
the film not so numerous and troublesome as formerly thereby
making it less necessary to photograph fields in duplicate on
same scale.
My interest in your not using both of the doublets
?
lies in the fact that I am just now much in need of a first-class
photographic objective of about this size, but the matter of
undertaking so large an objective at the present time seems
hopeless on account of the difficulty of obtaining optical glass.
For some years I have been engaged in an extensive photographic
survey. The earlier plates were made with a Brashear doublet
of five inches aperture. With this instrument, however,the
scale is too small. A large area has also been covered with
the 40-inch reflector but the limited field of good definition
with that type or instrument makes any extensive survey slow
and laborious. Latterly I have had the use of the 9-inch
doublet of the Swartmore College Observatory. During the