Different ways to mount my ASI120mc, any thoughts

[oldpink]

I can mount the camera at least 3 ways that I know of

1) directly onto the camera attachment (2")

tried this way yesterday and got some decent results under mixed seeing conditions
only downside I can see is I doubt I can use my barlow, though it will screw into the camera then go into the 2" adapter
I don't think it will work this way

this places the camera a lot closer to the secondary than the other 2 methods and I found that when swapping to the eye piece adapter I was pretty much in the same focus area
than method 3

2) Screw the barlow into the camera then mount the cam / barlow into the 1.25 adapter

not tried this yet hopefully tomorrow will allow me to test this way for comparison

3) fit the supplied 1.25 T adapter into the camera then slot that into the barlow  and use in the 1.25

this method I used again mixed results but under difficult conditions
from what I can see this adds about 4mm between the camera and the barlow, compared to method 2
but when I swap to the eye piece my focus is way off

I'd be interested in how others with this camera (or any general advice) mount their camera's

a shots of Jupiter yesterday with the camera attached to the 2" camera adapter

[Leveye]

Prime focus is the best method for the best results and great for DSO work not sure if you can reach it on your scope without modifying it by moving the primary mirror up. Keep in mind Reflectors need a coma corrector to have a unified flat field corner to corner. Try holding the camera with no lens up to the the empty focuser tube while viewing the night sky and while moving in and out see where the camera comes to focus.  For planetary work projection or parfocal  method is the best.

Edited February 8, 2014 by Leveye

[oldpink]

Oh the picture has been enlarged in AS2 and played about with in registax

[oldpink]

Prime focus is the best for DSO work not sure if you can reach it on your scope without modifying it by moving the primary mirror up. Some you have to.. Try holding the camera with no lens ud the the empty focuser tube while viewing the night sky and see where the camers come to focus.  For planetary work projection or parfocal  method is the best.

for DSO I plan on getting a modded Canon 600D that will mount directly to the 2" but it also has Magic Lantern to allow planetary work

will be interesting to compare them

[Tiny Small]

I have the 134mc. To achieve focus, the camera nose piece needed to go into the barlow but with the glass element removed as the supplied nosepiece by its self didn't give enough distance between the sensor and rear element. Then focus using the software. Ignore the EP.

[skybadger]

If you are taking pictures of objects like planets, you will need to magnify the image to a decent size .

Most people do this two ways - eyepiece project or barlow projection . Afocal projection introduces too many surfaces that aren't required unless you are using a camera you can't take the lens off.

Eyepiece projection and barlow projection use either the barlow or an eyepiece in the way. I use both frequently.

I find that if I focus the eyepiece in the eyepiece projection mount its only a small difference in focus to have the camera focused when you swap them over. The biggest issue is making sure that the image in the eyepiece is in the centre so when you put the camera in, you can see it at all. My normal way of getting around this with a bright object is to defocus a large way and then you are bound to get a portion of the image in the field. Focus and re-point and you are done.

The barlow is similar but the range of magnification you get is smaller maybe x2-x5,  where you can pick and choose from your eyepieces and the back focus distance used  more easily to get a projected  image size you are comfortable with.

I don't think I understand your reticence about additional focus distance - the barlow and eyepiece projection methods add lots of distance to the end of the telescope.

Coming back to DSOs and extended objects - for those you won't normally use any projection at all and considering the size of saensor you have,  the 1.25" nosepiece will do fine.

Mike

[jbminster]

focusing the ZWO ASI120MC on my SkyProdigy 130 telescope would require me to bring in the camera a few mm closer than the forward range of the focuser. I have not tried to insert an (extender or a Barlow?) but will do so when the sky is clear.  Contrarily,, with the all-sky lens coming with the camera is focused at infinity after taking the lens a couple of mm out by unscrewing the lens and re-tightening.  With a pollution filter this yield good start trails...I guess that lens was designed to catch migrating birds!! ;-)