FIRST REPORT ON EKTAR FILMS

In this lecture, we will discuss the first of three of the lastest
films from Kodak, along with thier attributes and possible
applications for the upcomming Comet Austin.

At the beginning of 1989 Kodak introduced a new series of films
called Ektar.  The manufacturer promised these new films would have
ultra fine grain, high sharpness and true vivid colors.  Many
astrophotographers pounced on these new films, in hopes that Kodak
would regain its lead in color films suitable for astrophotography. 
In the first six months of Ektars introduction, a number of mixed
reviews slowly trickled out.  This prompted us to characterize many
of the films attributes and deficiencies ourselves.  

Three Ektar films were evaluated, the ISO25, ISO125, and the
ISO1000 emulsions.  The results we obtained in our tests were very
encouraging and convinced us that this series of films will have
a substantial impact on amateur astrophotography.  The trio of
speeds allows for the many varied types of astrophotography.  The
ISO25 emulsion with its ultra fine grain and high contrast turned
out to be ideal for schmidt cameras and fast telephoto lenses when
hypered, due to its high sharpness and good red and blue
sensitivity.  The ISO125 films low contrast worked well for objects
with a large range of brightness.  It hypered moderately well, and
is useable with both telephotos and fast prime focus systems.  Its
real value however became evident in lunar photography where its
high sharpness, neutral color balance and wide exposure latitude
excelled.  The ISO1000 emulsion has surprisingly fine grain
compared to the popular ISO1600 films, and is sensitive to both red
and especially blue deep sky objects.  Even unhypered, this film
provided us with short exposures and less time at the guide scope
than with many of the slower films.

To evaluate the three films to determine their characteristics in
long exposure astrophotography, a 50mm f/1.4 lens was used on a
35mm camera mounted piggyback on an equatorially mounted newtonian. 
Both the unhypered and hypered films were given the same tests, and
developed together for comparable results in Bessler CN2 color
negative chemistry at 100 degrees F.  Exposures started at one
minute, and were doubled in subsequent exposures until 32 minutes
was reached.  Also used in our testing were 135mm f/2.8 telephoto
lenses, a Celestron eight inch f/1.5 schmidt camera, and finally
a fourteen inch f/5 newtonian.  

Ektar 25

We started our evaluations with the slowest of the three films in
the series.  For most color films, the optimal hypering time occurs
when the unexposed frames are slightly darkened by the hypering
process with a hypering fog level of about .6 Neutral Density. 
Longer hypering times will strongly discolor the prints, and
shorter times do not achieve maximum film speed.  This point
occurred in 16 hours at 50 degrees Centigrade at 1 psi pressure
with this film.  When the hypered versus unhypered negative strips
were compared, a speed increase of 8x was apparent in moderate
exposure times.  The best exposure with the 50mm f/1.4 lens on the
hypered emulsion was about 8 to 10 minutes.  It became evident that
the film had a much higher contrast and red sensitivity than the
other Ektar emulsions because of the crisp black star images and
well rendered emission nebulosities in the rich Cassiopiea star
field we used in our tests.  The grain was invisible with a 10x
magnifier on the negatives yielding high hopes for schmidt and
telephoto shots.

Next we loaded the hypered film into the schmidt camera, and tried 
8 to 10 minute exposures on a number of deep sky objects, with a
selection of both red emission nebulosities, and blue reflection
nebulas along with a selection of galaxies and star clusters.  We
found the results to be excellent.  The ten minute exposures
yielded crisp colorful images with excellent contrast that brought
out internal dark nebula and dust lanes in all types of objects
tested.  The film responds superbly in both red and blue, crisply
recording the Pelican Nebula as well as the brushstroke nebulosity
in the Pleiades.  The equivalent exposures for f/2.8 telephotos
puts it in the range of 30 minutes or so, bringing the fine
attributes of this emulsion to the realm of the piggyback wide
angle and telephoto lens user.  The fine blue and yellow
sensitivity of this film also lends itself to high resolution comet
photography.  The electric blue of a comets plasma tail, and the
tawny yellows in the dust component will be well recorded with this
contrasty emulsion.

Next time we will cover another fine Kodak film, Ektar 125.  We
found that this film had many surprises in store for us!