Celestron 8i User Manual
36
• T-Max
100
• T-Max
400
• Any 100 to 400 ISO color slide film
• Fuji Super HG 400
• Ektar 25 or 100
2. Center the Moon in the field of your NexStar telescope.
3. Focus the telescope by turning the focus knob until the image is sharp.
4. Set the shutter speed to the appropriate setting (see table below).
5. Trip the shutter using a cable release.
6. Advance the film and repeat the process.
Lunar Phase
ISO 50
ISO 100
ISO 200
ISO 400
Crescent
1/2 1/4 1/8 1/15
Quarter
1/15 1/30 1/60 1/125
Full
1/30 1/60 1/125 1/250
The exposure times listed in table 6-1 should be used as a starting point. Always make exposures that are
longer and shorter than the recommended time. Also, take a few photos at each shutter speed. This will
ensure that you will get a good photo.
longer and shorter than the recommended time. Also, take a few photos at each shutter speed. This will
ensure that you will get a good photo.
If using black and white film, try a yellow filter to reduce the light intensity and to increase contrast.
Keep accurate records of your exposures. This information is useful if you want to repeat your results or if
you want to submit some of your photos to various astronomy magazines for possible publication!
you want to submit some of your photos to various astronomy magazines for possible publication!
This technique is also used for photographing the Sun with the proper solar filter.
E
E
y
y
e
e
p
p
i
i
e
e
c
c
e
e
P
P
r
r
o
o
j
j
e
e
c
c
t
t
i
i
o
o
n
n
This form of celestial photography is designed for objects with small angular sizes, primarily the Moon and
planets. Planets, although physically quite large, appear small in angular size because of their great
distances. Moderate to high magnification is, therefore, required to make the image large enough to see
any detail. Unfortunately, the camera/telescope combination alone does not provide enough magnification
to produce a usable image size on film. In order to get the image large enough, you must attach your
camera to the telescope with the eyepiece in place. To do so, you need two additional accessories; a
deluxe tele-extender (#93643), which attaches to the visual back, and a T-ring for your particular camera
make (i.e., Minolta, Nikon, Pentax, etc.).
planets. Planets, although physically quite large, appear small in angular size because of their great
distances. Moderate to high magnification is, therefore, required to make the image large enough to see
any detail. Unfortunately, the camera/telescope combination alone does not provide enough magnification
to produce a usable image size on film. In order to get the image large enough, you must attach your
camera to the telescope with the eyepiece in place. To do so, you need two additional accessories; a
deluxe tele-extender (#93643), which attaches to the visual back, and a T-ring for your particular camera
make (i.e., Minolta, Nikon, Pentax, etc.).
Because of the high magnifications during eyepiece projection, the field of view is quite small which makes it
difficult to find and center objects. To make the job a little easier, align the finder as accurately as possible.
This allows you to get the object in the telescope's field based on the finder's view alone.
difficult to find and center objects. To make the job a little easier, align the finder as accurately as possible.
This allows you to get the object in the telescope's field based on the finder's view alone.
Another problem introduced by the high magnification is vibration. Simply tripping the shutter
even with a
cable release
produces enough vibration to smear the image. To get around this, use the camera's self-
timer if the exposure time is less than one second
a common occurrence when photographing the Moon.
For exposures over one second, use the "hat trick." This technique incorporates a hand-held black card
placed over the aperture of the telescope to act as a shutter. The card prevents light from entering the
telescope while the shutter is released. Once the shutter has been released and the vibration has
diminished (a few seconds), move the black card out of the way to expose the film. After the exposure is
complete, place the card over the front of the telescope and close the shutter. Advance the film and you're
ready for your next shot. Keep in mind that the card should be held a few inches in front of the telescope,
placed over the aperture of the telescope to act as a shutter. The card prevents light from entering the
telescope while the shutter is released. Once the shutter has been released and the vibration has
diminished (a few seconds), move the black card out of the way to expose the film. After the exposure is
complete, place the card over the front of the telescope and close the shutter. Advance the film and you're
ready for your next shot. Keep in mind that the card should be held a few inches in front of the telescope,
Table 6-1
Above is a listing of recommended exposure times when photographing the
Moon at the prime focus of your NexStar telescope.