REQ: FAQ or 'Astrophotography for Dummies' info

I've have a Meade ETX 90 as well as a Nikon D70 with the adapter to
connect the both. I've taken a few moon-shots and my results made me
look this group up and search for advice.

I have lots of questions, many of which I'm sure I'll forget by the
time I'm done with this message.

All of my moon-shots are blurry; my first thought (which might
ultimately be correct) was that the shutter of the camera is causing
everything to move (ever so slightly) and, thus, making it look
blurry. I'm using the standard Meade tripod, which is substantial
IMO, so is it possible that the shutter is causing it? I think I've
only set it for 1 second shutter. I get good light, just blurry
output.

How would one refer to the Meade ETX 90? I'm guessing that when I see
SCT, it refers to schmidt cassegrain, whereas the ETX is a maksutov
cassegrain. I can look up what the differences are, but is there a


When viewing the moon it's pretty detailed, but the moon is obviously
relatively close. When I was looking at Mars a couple days ago, it
was awfully small; too small for pictures. I have a couple different
eyepieces, 26mm, 18mm and 5mm plus a 2x. The 5mm made it appear
larger, of course, but I couldn't get it to focus very well. Are
there better eyepieces, or am I already at the limit of this
particular scope?

Does anyone else here use a similar setup? Any good hints/tips that
might help me contribute here in the future?

As mentioned in the subject, an FAQ might help as well, if there is
one. Any info is greatly appreciated.

Bob

Bob wrote:
I've have a Meade ETX 90 as well as a Nikon D70 with the adapter to
connect the both. I've taken a few moon-shots and my results made me
look this group up and search for advice.

I don't see why they should be blurry at all provided that you have got
the focus right. Focussing is somewhat difficult at high focal ratios -
so this is easier said than done. What you might find helps is to take a
set of shots at bracketted exposures moving through the point of optimum
focus. Some DSLRs will do the exposure bracketting for you. No film is
wasted.

My MTO 1000mm f10 lens works better for me with my Pentax IstD than with
classical film - largely because I can get almost instant feedback on
any focus error. The film has to be developed to see the results.

I have lots of questions, many of which I'm sure I'll forget by the
time I'm done with this message.

All of my moon-shots are blurry; my first thought (which might
ultimately be correct) was that the shutter of the camera is causing
everything to move (ever so slightly) and, thus, making it look
blurry. I'm using the standard Meade tripod, which is substantial
IMO, so is it possible that the shutter is causing it? I think I've
only set it for 1 second shutter. I get good light, just blurry
output.

A 1s exposure on the moon sounds far too long. Try something more like
1/30s and if necessary increase the ASA setting on the camera. What does
the automatic exposure metering think the exposure should be?

Michael Oates has a nice astro exposure calculator on the web somewhere
that will give you a better guide to get started. I forget the URL.

How would one refer to the Meade ETX 90? I'm guessing that when I see
SCT, it refers to schmidt cassegrain, whereas the ETX is a maksutov
cassegrain. I can look up what the differences are, but is there a

Not by enough difference to affect the basic advice.

When viewing the moon it's pretty detailed, but the moon is obviously
relatively close. When I was looking at Mars a couple days ago, it
was awfully small; too small for pictures. I have a couple different
eyepieces, 26mm, 18mm and 5mm plus a 2x. The 5mm made it appear
larger, of course, but I couldn't get it to focus very well. Are
there better eyepieces, or am I already at the limit of this
particular scope?

You won't see all that much on Mars with a 90mm aperture, but you should
be able to see the major features at opposition if the scope has had a
couple of hours of cool down time so that the image is stable at high
magnification.

Does anyone else here use a similar setup? Any good hints/tips that
might help me contribute here in the future?

As mentioned in the subject, an FAQ might help as well, if there is
one. Any info is greatly appreciated.

I don't think there is a FAQ for this. But maybe there should be?

One other thing to watch is don't leave your camera exposed to ingress
of dust whilst messing about with scopes. Dust getting onto the CCD can
be rather annoying.

Regards,
Martin Brown

Bob wrote:
I've have a Meade ETX 90 as well as a Nikon D70 with the adapter to
connect the both. I've taken a few moon-shots and my results made me
look this group up and search for advice.

I have lots of questions, many of which I'm sure I'll forget by the
time I'm done with this message.

All of my moon-shots are blurry; my first thought (which might
ultimately be correct) was that the shutter of the camera is causing
everything to move (ever so slightly) and, thus, making it look
blurry. I'm using the standard Meade tripod, which is substantial
IMO, so is it possible that the shutter is causing it? I think I've
only set it for 1 second shutter. I get good light, just blurry
output.

How would one refer to the Meade ETX 90? I'm guessing that when I see
SCT, it refers to schmidt cassegrain, whereas the ETX is a maksutov
cassegrain. I can look up what the differences are, but is there a


When viewing the moon it's pretty detailed, but the moon is obviously
relatively close. When I was looking at Mars a couple days ago, it
was awfully small; too small for pictures. I have a couple different
eyepieces, 26mm, 18mm and 5mm plus a 2x. The 5mm made it appear
larger, of course, but I couldn't get it to focus very well. Are
there better eyepieces, or am I already at the limit of this
particular scope?

Does anyone else here use a similar setup? Any good hints/tips that
might help me contribute here in the future?

As mentioned in the subject, an FAQ might help as well, if there is
one. Any info is greatly appreciated.

Bob

One place you might go for suggestions is the d70astro Yahoo group.

I wonder about hanging a camera as large and heavy as the D70 on the
back of an ETX 90. It might be a bit much for time exposures, but it
should work OK for the Moon.

1 second exposures sound long for the Moon. On an F7 scope I often take
shots in the range of 1/1000 of a second.

Are you using an infrared remote to trigger the camera? If not, you
might want to try it. You might also try using the self timer on the
camera to reduce vibrations.

Your higher power problems are probably "seeing conditions". If you wait
until Mars is higher in the sky, you may have better results because
you'll be looking through less atmosphere.

You might go to the Clear Sky Clock to get predictions of upcoming
conditions in your area.

http://cleardarksky.com/

Good luck.

Mark

Martin Brown wrote:
Bob wrote:

snip

A 1s exposure on the moon sounds far too long. Try something more like
1/30s and if necessary increase the ASA setting on the camera. What does
the automatic exposure metering think the exposure should be?


The D70 meter won't work unless you have an AF lens on it.

"Mark S. Holden" wrote in message
...
Bob wrote:
I've have a Meade ETX 90 as well as a Nikon D70 with the adapter to
connect the both. I've taken a few moon-shots and my results made me
look this group up and search for advice.

I have lots of questions, many of which I'm sure I'll forget by the
time I'm done with this message.

All of my moon-shots are blurry; my first thought (which might
ultimately be correct) was that the shutter of the camera is causing
everything to move (ever so slightly) and, thus, making it look
blurry. I'm using the standard Meade tripod, which is substantial
IMO, so is it possible that the shutter is causing it? I think I've
only set it for 1 second shutter. I get good light, just blurry
output.

How would one refer to the Meade ETX 90? I'm guessing that when I see
SCT, it refers to schmidt cassegrain, whereas the ETX is a maksutov
cassegrain. I can look up what the differences are, but is there a


When viewing the moon it's pretty detailed, but the moon is obviously
relatively close. When I was looking at Mars a couple days ago, it
was awfully small; too small for pictures. I have a couple different
eyepieces, 26mm, 18mm and 5mm plus a 2x. The 5mm made it appear
larger, of course, but I couldn't get it to focus very well. Are
there better eyepieces, or am I already at the limit of this
particular scope?

Does anyone else here use a similar setup? Any good hints/tips that
might help me contribute here in the future?

As mentioned in the subject, an FAQ might help as well, if there is
one. Any info is greatly appreciated.

Bob

One place you might go for suggestions is the d70astro Yahoo group.

I wonder about hanging a camera as large and heavy as the D70 on the back
of an ETX 90. It might be a bit much for time exposures, but it should
work OK for the Moon.

1 second exposures sound long for the Moon. On an F7 scope I often take
shots in the range of 1/1000 of a second.

Are you using an infrared remote to trigger the camera? If not, you might
want to try it. You might also try using the self timer on the camera to
reduce vibrations.

Or you could use the old fashioned "hat technique". Hold
a hat over the objective so light can't enter. Open the shutter
and wait half a second for the vibrations to die out. Remove
the hat (without hitting the telescope tube). Put the hat back.
Close the shutter. Moving the hat out of the way and then
right back will give between a third and a half second
exposure.



Your higher power problems are probably "seeing conditions". If you wait
until Mars is higher in the sky, you may have better results because
you'll be looking through less atmosphere.

You might go to the Clear Sky Clock to get predictions of upcoming
conditions in your area.

http://cleardarksky.com/

Good luck.

Mark

Bob wrote:
I've have a Meade ETX 90 as well as a Nikon D70 with the adapter to
connect the both. . . . All of my moon-shots are blurry; . . .
I think I've only set it for 1 second shutter. I get good light,
just blurry output.

For an FAQ see Lodriguss's "Catching the Light" web guide:
http://www.astropix.com/HTML/I_ASTROP/I08/I08.HTM
in http://www.astropix.com/INDEX.HTM

The Moon's orbital speed is such that you cannot expose for 1 second
without the image blurring. It's movement is apparent when both
visually observing and when recording photographically. Just watch the
edge of the Moon occult any background star through a telescope
counting "one-Mississippi, two-Mississippi".

The Moon also is usually too bright for a 1 second exposure. Get
Covington's _Astrophotography for Amateurs_ book. It has a series of
rough exposure tables in the back for various celestial objects.

http://www.covingtoninnovations.com/books.html

Or to get started now, use this web implementation of Covington's
exposure calculator at:

http://www.rphotoz.com/astrophoto/expcalcs.html

Note a quarter phase Moon at 100ASA in an f/6 scope needs to be exposed
for only 1/125th of a second.

At 1/125th of a second, the Moon's motion is brief, such that you can
make an exposure without equatorial tracking.

With a shorter exposure time, you should be able to get a shot with
better resolution. Use the suggested settings in the exposure
calculator as a starting point and take a series of photos around those
settings to iterate to the best shot.

For short-term focusing on bright objects like the Moon, make a
Hartmann mask.

http://www.astropix.com/HTML/I_ASTRO...0817/I0817.HTM
http://www.gushie.demon.co.uk/focussing_the_camera.htm

If you get hooked, think about purchasing a flip-mirror for parfocal
focusing.

http://www.gushie.demon.co.uk/ccd_im...ilter%20holder

- Canopus56

On Wed, 02 Nov 2005 13:01:51 -0500, Tom Royer wrote:

[snip]

Or you could use the old fashioned "hat technique". Hold
a hat over the objective so light can't enter. Open the shutter
and wait half a second for the vibrations to die out. Remove
the hat (without hitting the telescope tube). Put the hat back.
Close the shutter. Moving the hat out of the way and then
right back will give between a third and a half second
exposure.


That's brilliant !

Bob wrote in news
I've have a Meade ETX 90 as well as a Nikon D70 with the adapter to
connect the both. I've taken a few moon-shots and my results made me
look this group up and search for advice.

I have lots of questions, many of which I'm sure I'll forget by the
time I'm done with this message.

All of my moon-shots are blurry; my first thought (which might
ultimately be correct) was that the shutter of the camera is causing
everything to move (ever so slightly) and, thus, making it look
blurry. I'm using the standard Meade tripod, which is substantial
IMO, so is it possible that the shutter is causing it? I think I've
only set it for 1 second shutter. I get good light, just blurry
output.

Others have given you good answers but I want to stress something about
your shutter speed here. The full moon filling the field of your camera is
equivalent to a fully sunlit scene on Earth. What do you think you would
get taking one second exposures of a daylight scene on earth? Canopus56
gave you some good advice on how to set the exposure time depending on the
lunar phase.

How would one refer to the Meade ETX 90? I'm guessing that when I see
SCT, it refers to schmidt cassegrain, whereas the ETX is a maksutov
cassegrain. I can look up what the differences are, but is there a

You broke off here. Mak-Cas scopes have a very good optical design and I
believe the little Meade scope is a reasonably good example of the type.
The larger Mak-Cas's have a reputation of being slow to get to thermal
equilibium so need some sort of active cooling system (a fan) to bring them
quickly to ambient temperature, this is important to eliminate thermal
distortions in the image. I really doubt that this is going to be a problem
with a 90mm scope - it doesn't have a huge mass of glass in it that needs
to cool down.



When viewing the moon it's pretty detailed, but the moon is obviously
relatively close. When I was looking at Mars a couple days ago, it
was awfully small; too small for pictures. I have a couple different
eyepieces, 26mm, 18mm and 5mm plus a 2x. The 5mm made it appear
larger, of course, but I couldn't get it to focus very well. Are
there better eyepieces, or am I already at the limit of this
particular scope?

That's pretty normal. Wait till around midnight so that Mars is as high
above the horizon as possible. That will give you the best seeing. Also the
atmosphere does occaisionally settle down to give better views.

Klazmon.



Does anyone else here use a similar setup? Any good hints/tips that
might help me contribute here in the future?

As mentioned in the subject, an FAQ might help as well, if there is
one. Any info is greatly appreciated.

Bob

Tom Rauschenbach wrote in
news
On Wed, 02 Nov 2005 13:01:51 -0500, Tom Royer wrote:

[snip]

Or you could use the old fashioned "hat technique". Hold
a hat over the objective so light can't enter. Open the shutter
and wait half a second for the vibrations to die out. Remove
the hat (without hitting the telescope tube). Put the hat back.
Close the shutter. Moving the hat out of the way and then
right back will give between a third and a half second
exposure.


That's brilliant !


Probably still too long an exposure time for the moon but ok for other
objects.

Klazmon.

Mark S. Holden wrote:

Martin Brown wrote:

Bob wrote:

snip

A 1s exposure on the moon sounds far too long. Try something more like
1/30s and if necessary increase the ASA setting on the camera. What
does the automatic exposure metering think the exposure should be?

The D70 meter won't work unless you have an AF lens on it.

Really? I didn't know that. It seems an odd restriction to impose.

My istD will operate autofocus with AF lenses, manual focus with MF
lenses and even works with old PK and M42 manual aperture lenses at a
pinch. In all cases the metering will work normally.

Regards,
Martin Brown