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Posts Made By: Paul McCarl

April 27, 2002 03:51 PM Forum: Telescope Making

Need Help Calculating my Focal Plane

Posted By Paul McCarl

Well I am nearing that oh so critical point in my truss tube conversion. I am almost ready to cut the tubes. Yikes!
My problem is not in calculating the distance to the focal plane for eyepieces, I have that down, I think. My actual measurements from the current sonotube setup are matching my calculated numbers, so I think I am ok there. The problem is I also want to be able to take pictures with my SLR Canon EOS camera. And I learned a long time ago that there is a big difference between a focuser for an eyepiece and one that works with my camera, even with the T-ring flush against the draw tube. My focuser on the sonotube doesn't let me reach focus on distant objects, although I can take some nice shots of the birds in my neighbor's trees. 8^) So I can't really measure accurately the difference in the focal planes. Now I have measured the difference using my short tube 80 refractor, and it was just over an inch different. So my question is will the relative distance between focus for a particular eyepiece and my camera be the same on my 17.5" 2000mm fl dob as it is on my 400mm fl ST80? if not, how do I calculate it? Any help will be appreciated.

Thanks,

Paul McCarl

July 21, 2002 08:58 PM Forum: Film Astrophotography - Imaging and Processing

Phoenix 0.25x Super Fisheye

Posted By Paul McCarl

Hi Everyone,

Just bought a new toy and thought I would share the first attempts. The .25x fisheye attached to your filter threads and gives you a 180* view in a circular format. Beats the heck out of trying to shot down into a security mirror from a tripod.

This one was a short exposure pointed at the celestial pole. The lights near the bottom are headlights of a car. The scratch is from pulling the film out and manually rewinding it in a dark little outhouse. Turns out my old Yashica F1 no longer rewinds the film despite several minutes of winding.

Paul McCarl

August 9, 2002 11:25 PM Forum: CCD Imaging and Processing/Solar System

Canon D30 on 10" LXD55 - Ring Nebula

Posted By Paul McCarl

Well it isn't anything that the hubble people are going to worry about just yet, but by golly I got a picture through my new scope at prime focus. I have a lot of kinks to work out and ideas to try, but all in all I am pleased. It isn't exactly as sensitive as my st-237 was, but it is much higher resolution and single shot color. Should be fun to play with.

Is it just me, or does the blue response seem a little higher than most?

Enjoy or destroy...

Paul McCarl

August 10, 2002 06:01 PM Forum: Telescope Making

Need some advice with a peltier cooling device

Posted By Paul McCarl

I am trying to cool an enclosure for a ccd camera with a peltier device, but I am having trouble with the heat transfering back to the heatsink on the inside. I know I have my polarity correct, but I need some way to isolate the heat transfer between the inside and outside. Does anyone have advice or some good sites for ideas on how to do this properly?

Thanks,

Paul McCarl

August 15, 2002 01:40 PM Forum: Film Astrophotography - Imaging and Processing

16mm shot of Milkyway

Posted By Paul McCarl

This was shot with a 16mm Zenitar lens on a Canon Elan IIe. The film was Kodak Max Versatility Plus (800 ISO). This was part of a attempt to photograph meteors during last weekend's Perseid showers, but apparently this film suffers from high reciprocity failure. This is a 30 minute shot and shows very little improvement over some 15 minute attempts. I have had better luck with E200 slide film. No meteors on two rolls with different cameras and lens combinations. Some liveable wide field shots of the milky way, but not totally happy. I figured the 800 speed film would do well, but it failed to record several bright meteors including several that left visible smoke trails in the sky. Oh well, the quest continues.

I inset a map to help orient you. There are five tiny arrows pointing to the following nebulas starting from the top:

North American
Eagle
Swan (or Omega)
Trifid
Lagoon

Anyone have any luck with the meteors last weekend?

Paul McCarl

September 12, 2002 08:45 PM Forum: CCD Imaging and Processing/Solar System

$6 fisheye lens for webcams

Posted By Paul McCarl

Ok,

I wrote a wonderful long post describing everything about this and then astromart ate it because the title was too long.

I don't have the time to retype it, so here are the basics.

You take a peephole viewer like you put in your front door. Take it appart and glue the front two elements back together. Stick it in front of your webcame lens and focus using the regular lens.

If anyone cares, ask questions and I'll answer them tomorrow, but I am kind of pissed about the hour+ that I wasted.

Enjoy,

Paul McCarl

September 21, 2002 04:13 PM Forum: CCD Imaging and Processing/Solar System

LX-200 vs G-11 as an imaging mount

Posted By Paul McCarl

Hi,

Hopefully this won't start a war between owners of the two, but I am trying to decide how best to upgrade my ccd and astrophotography setup. Leaving optics aside for a minute, I would really like some opinions about the LX-200 as a mount versus something like a g-11 with digital setting circles and dual axis motors.

I like the goto on the lx-200, but I realize all of the balance issues with a fork mount, expecially one with a refractor mounted on top. That was one of the things I had to fight with my c8. I do however like the idea of the eyepiece always being in roughly the same location with the fork. And for visual observing at star parties, the LX-200 can be slapped on a tripod in alt-az and be up and running in minutes with really good tracking.

On the other hand, an EQ mount is easy to balance, can carry any scope within its load rating, and is easier to setup polar alignment then a wedge. There are less electronics to go haywire in G11 setup than the LX-200 and my neighbors won't think I am running power tools at 2 a.m. Still, I hate having to rotate the tube all the time to reorient the eyepiece, and you still need a decent polar alignment for the mount to track well visually at star parties, etc. That means longer setup. And lets not forget the extra 30 lbs of counterweights you have to lug around. I have also read a few horror stories of G11's not living up to their reputation without a lot of tweaking.

My problem is that I want both for their advantages and neither for the disadvantages. I have been running this issue around in my head until I am getting dizzy and my wife is tired of "talking" about it.

So I am looking for advice. I would love to hear experiences from those who are actually using them to do photography or CCD work.

Thanks in advance,

Paul McCarl

P.S. I also know that there are better mounts, but I have a limited budget.


September 21, 2002 04:13 PM Forum: Film Astrophotography - Imaging and Processing

g-11 vs. LX-200 as imaging mount

Posted By Paul McCarl

Hi,

Hopefully this won't start a war between owners of the two, but I am trying to decide how best to upgrade my ccd and astrophotography setup. Leaving optics aside for a minute, I would really like some opinions about the LX-200 as a mount versus something like a g-11 with digital setting circles and dual axis motors.

I like the goto on the lx-200, but I realize all of the balance issues with a fork mount, expecially one with a refractor mounted on top. That was one of the things I had to fight with my c8. I do however like the idea of the eyepiece always being in roughly the same location with the fork. And for visual observing at star parties, the LX-200 can be slapped on a tripod in alt-az and be up and running in minutes with really good tracking.

On the other hand, an EQ mount is easy to balance, can carry any scope within its load rating, and is easier to setup polar alignment then a wedge. There are less electronics to go haywire in G11 setup than the LX-200 and my neighbors won't think I am running power tools at 2 a.m. Still, I hate having to rotate the tube all the time to reorient the eyepiece, and you still need a decent polar alignment for the mount to track well visually at star parties, etc. That means longer setup. And lets not forget the extra 30 lbs of counterweights you have to lug around. I have also read a few horror stories of G11's not living up to their reputation without a lot of tweaking.

My problem is that I want both for their advantages and neither for the disadvantages. I have been running this issue around in my head until I am getting dizzy and my wife is tired of "talking" about it.

So I am looking for advice. I would love to hear experiences from those who are actually using them to do photography or CCD work.

Thanks in advance,

Paul McCarl

P.S. I also know that there are better mounts, but I have a limited budget.


September 27, 2002 12:14 AM Forum: CCD Imaging and Processing/Solar System

Canon D60 Moon "Mosaic" (x1/16 res)

Posted By Paul McCarl

Hi,

Ok so I am bragging, but I gave my new D60 a chance to show its stuff last night. I intended to be out only a couple hours, but ended up staying up until 3 a.m.

This isn't a mosaic really. It is a single frame at ISO 400 1/250th second. I processed it in photoshop by multiplying it with itself at about 50% transparency. The original was 3072 x 2048. This was resized by a factor of 1/4 on each axis, so this is only 1/16th the original size (50%,radius 1, threshold 0 unsharp mask on the sized down version). Shot through my Meade 2080 8" SCT OTA mounted on my LXD-55.

Heck, I figured the moon was messing up my sky backgrounds, so I would give it a chance to really shine and be the "star".

Thanks,

Paul McCarl

September 27, 2002 12:29 AM Forum: CCD Imaging and Processing/Solar System

Canon D60 60 second Orion

Posted By Paul McCarl

Hi,

Sure any camera can shoot the moon. After all, we are talking about a "daylight" shot with the moon. However, I had seen so many promising images from a guy in europe with a D60 that I couldn't wait to try mine out on dark sky objects. Well the sky wasn't too dark. I tried a piggy back shot with an f/2 50mm lens and 30 seconds at ISO 400 pretty much gave bright white stars on a uniform gray background. So I spent most of the night shooting the ring nebula and the dumbbell nebula.

Towards the end of the night I tried Andromeda. I don't think that those shots will win any awards, but you can see two faint dust lanes even without processing in just 60 seconds at ISO 1000 on a 8" f10 SCT. I can't wait to try it out under really dark skies at the next new moon.

Finally, I tried Saturn, but it was still low enough to be gooped out by the poor seeing. I am almost convinced that web cams are the way to go for planets anyway. They are certainly easier to focus. But as I was getting ready to break down, I noticed that Orion was just starting to clear my neighbors trees. So I shot two frames at prime focus before the battery died on the camera and I decided to pack it in.

This is a single frame at ISO 1000 for 60 seconds and dark subtracted. I processed it in photoshop by adjusting the levels and resizing by 1/3 on each axis, so this is only 1/9th the original size (50%,radius 1, threshold 0 unsharp mask on the sized down version). Shot through my Meade 2080 8" SCT OTA mounted on my LXD-55.

Keep in mind this was last night with the moon making the sky a white soup and from a light polluted front yard in the city to boot. Also since it was only about ten degrees or so up when I shot it, the seeing was pretty bad. Did I mention I like my camera?

Thanks,

Paul McCarl