ASTRO: M-93, wide-field

Here's most of the DSLR frame - still some of it cropped off.

George N

got some great color in those stars George.

nice going


"George Normandin" wrote in message
...
Here's most of the DSLR frame - still some of it cropped off.

George N

George Normandin wrote:

Here's most of the DSLR frame - still some of it cropped off.

George N

Looks good from here. At that declination I doubt I'll be targeting
that one. Even on a good night -15 degrees is about my seeing limit.
That's almost 10 degrees lower. Maybe if I had something that pixel
scale it would sort of work but the extinction is so bad down there I'd
need more exposure at the top than the bottom!

Rick

--
Correct domain name is arvig and it is net not com. Prefix is correct.
Third character is a zero rather than a capital "Oh".

test George Normandin wrote:
Here's most of the DSLR frame - still some of it cropped off.

George N

test reply to the NG George - rebuilding machines here - great DSLR work
-I hope to try likewise by this coming weekend. - cheers - Rod

"rod" wrote
...
test reply to the NG George - rebuilding machines here - great DSLR work
-I hope to try likewise by this coming weekend. - cheers - Rod

Rod,

There are two things that I'm certain of:

It's a lot warmer where you are, and M-93 is a lot higher in the sky
when seen from the Florida Keys that it is from even southern New York!

Good luck with the DSLR and hopefully clear skies.

George N

Very nice picture George, if focusing with a DSLR would be easier, I would
probably use it more often as a DSLR is perfect for open clusters.

Stefan

"George Normandin" schrieb im Newsbeitrag
...
Here's most of the DSLR frame - still some of it cropped off.

George N

"Stefan Lilge" wrote
....
Very nice picture George, if focusing with a DSLR would be easier, I would
probably use it more often as a DSLR is perfect for open clusters.


Stefan,

So far I've only had real success with the DSLR on the moon and open
clusters, plus wide-field shots with a normal lens. However, the limitation
I have is that the camera not mod'ed, so is not sensitive to red. With the
mod'ed cameras I believe that they are very effective sky imaging tools.

George N

George Normandin wrote:
"Stefan Lilge" wrote
...

Very nice picture George, if focusing with a DSLR would be easier, I would
probably use it more often as a DSLR is perfect for open clusters.



Stefan,

So far I've only had real success with the DSLR on the moon and open
clusters, plus wide-field shots with a normal lens. However, the limitation
I have is that the camera not mod'ed, so is not sensitive to red. With the
mod'ed cameras I believe that they are very effective sky imaging tools.

George N


So how do you focus that DSLR?

Back in my film days I had a gizmo a friend machined that put a ronchi
grating at the same distance as the film so I'd null a star with that
then put on the camera. I set it by first putting on the camera,
opening the back and putting the ronchi grating across the film guides
then focused the camera. Put the gizmo on and adjusted its, helical
focus to the same setting then locked the set screws. Worked great but
you can't open a digital camera to set such a device. I never could
focus on a view screen with any accuracy.

Of course I didn't know how well I did until the next day when I
developed the film. You could waste a whole night and not know it.

Rick


--
Correct domain name is arvig and it is net not com. Prefix is correct.
Third character is a zero rather than a capital "Oh".

"Rick Johnson" wrote

So how do you focus that DSLR?
..........

Rick,

With the Canon Rebel I focus the 'quick & dirty' method: using the
viewfinder. I slew to a bright star, focus manually, take a 1 sec or so
image, examine it on the view screen on the back of the camera using the
zoom function (which will get you more zoom than you'd ever view the image
at), and adjust if necessary. I've never needed more than 2 or 3 iterations.
I use the same method to see how long I can expose without tracking error
with a cheap mount (i.e., the Orion EQ-1) that is only roughly polar
aligned. The newer cameras have a "real time" mode (like using a camcorder)
to the back screen. In that case you just watch a bright star while
focusing. I believe that there are now methods of controlling a DSLR with a
PC, but that kinda defeats one of the main advantages of a DSLR: no PC to
haul to the field.

I've found focusing much easier with the 80mm and the 6" A-P refractor
than with a zoom tel lens. I can usually get the stars to 2 to 4 pixels the
first time I try focusing. My Tamaron 28-210mm lens is not at focus when
turned all the way to infinity. It goes beyond focus, and must be brought
back a little. I've not tried the camera on the RC20, but focusing at F/8 is
pretty easy.

George N