Switching between Eyepiece & MEADE DSI CCD

[ziaholic]

Hiyas,

As a forum and scope-owner noob, I'm learning about the capabilities of my relatively new 10" Meade R-C. I've gotten pretty good and finding planets and observing the moon etc. ... but only through the eyepiece.

Now I'm trying to get my CCD imager up and running and am having a problem aligning the image. I was able to capture the moon pretty easily, as it fills the entire FOV through my eyepiece (2500mm focal length & 26mm plossl). Then switching to the camera was no problem ... because the moon was everywhere in the live camera view on my laptop PC.

but when trying to image saturn, it only fills a small percentage of the eyepiece FOV ... i try and center it as best I can, but then when I switch over to the camera I can't seem to find it again ... I play with the manual (course) focus, the electric (fine) focus ... I slew it around a few degrees each way ... but no luck. I think that the focal-plane difference between the 2 devices is where I'm coming up puzzled ...

Is there a trick to switching back and forth? I'm using a 90-degree adapter for the eyepiece, but don't necessarily need it for the camera ...

the camera is a meade DSI Pro, with the 4-filter slide attachment between the mount-tube and the CCD opening. the adapter tube is nearly an inch long so I've also tried sliding this in and out to try and find the focal point ... but again, no luck ...

Any tips/tricks/toys that you could recommend would be greatly appreciated.

[Dave Mitsky]

Edit

Any tips/tricks/toys that you could recommend would be greatly appreciated.

What you need is a flip mirror.

http://sctscopes.net/Photo_Basics/photo_basics.html

Dave Mitsky

[ozark1]

Hiyas,

As a forum and scope-owner noob, I'm learning about the capabilities of my relatively new 10" Meade R-C. I've gotten pretty good and finding planets and observing the moon etc. ... but only through the eyepiece.

Now I'm trying to get my CCD imager up and running and am having a problem aligning the image. I was able to capture the moon pretty easily, as it fills the entire FOV through my eyepiece (2500mm focal length & 26mm plossl). Then switching to the camera was no problem ... because the moon was everywhere in the live camera view on my laptop PC.

but when trying to image saturn, it only fills a small percentage of the eyepiece FOV ... i try and center it as best I can, but then when I switch over to the camera I can't seem to find it again ... I play with the manual (course) focus, the electric (fine) focus ... I slew it around a few degrees each way ... but no luck. I think that the focal-plane difference between the 2 devices is where I'm coming up puzzled ...

Is there a trick to switching back and forth? I'm using a 90-degree adapter for the eyepiece, but don't necessarily need it for the camera ...

the camera is a meade DSI Pro, with the 4-filter slide attachment between the mount-tube and the CCD opening. the adapter tube is nearly an inch long so I've also tried sliding this in and out to try and find the focal point ... but again, no luck ...

Any tips/tricks/toys that you could recommend would be greatly appreciated.

First issue - a Meade 26 mm Plossl is not parfocal with the DSI. This means that you need a parfocalising ring. You should have the eyepiece and DSI parfocal - no focus change - when swapping. Remember that the field changes when you move the mirror on focusing.

I found that a cheap Meade 18mm WA was much closer to the right focus than any of the plossls.

Second issue - when you do get the system parfocal, the Meade DSI acts like a 5 mm eyepiece. Miles too much magnification on a 2500 mm f/10. The trick is to get a cheap focal reducer to stick on the nosepiece of the DSI (Atik do a good one for £25). This will reduce the magnification to 350 x or so.

Thirdly remember that the small FOV may not be exactly in the centre of the eyepiece field. It's all trial and error. You should work it out when you are trying to get the system focussed.

Oh yes, the point about looking for the focal point on the DSI. The parfocalising ring goes on the eyepiece, so of course you'll never find the common point...

[ziaholic]

Great advice ... thanks!

Now, at least I know the names of the devices I need to shop around for ...

Any other DSI experience out here? I'd love to hear tips/tricks/horror stories ...