Using a focal reducer

[AlcyoneSVX]

I am beginner at this. I have a ZWO ASI224MC which I use with a Celestron C8NGT.
I have managed to take some nice pictures of Mars, Jupiter and Saturn. But for targets like the moon, or tonight's conjunction, it's too zoomed in. I can't get the whole target in the frame.

I bought an Svbony x0.5 focal reducer thinking that it would do the opposite of a barlow lens. It would zoom out and make everything half the size, so I could fit more would be in frame. But if I screw the reducer onto the camera, or even onto an eyepiece, I can't seem to get focus. Can't really see anything at all.

Where am I going wrong?

 

[michael8554]

It's often impossible to focus a camera on a Newtonian telescope, because the image is too far away from the closest the camera can be mounted.

So often a 2X Barlow is used to extend the image outside of the focuser.

I think that using a 0.5X Reducer will have the opposite effect to the Barlow, which is why you can't focus.

Make sure you have the camera as close as possible to the focuser, remove any extensions that are on the focuser and try again.

Michael

[ollypenrice]

The F ratio is already F4.9. Taking it down to half that, F2.45, is simply unrealistic. Systems as fast as that do exist but they are complex and involve optical elements designed to work together. Even if you raised the primary mirror in the tube to get more back focus I think you'd find all sorts of aberrations in the image.

Olly

[AlcyoneSVX]

Thanks for the responses.

I have read that Newtonians are no good for imaging, but I have managed to use several cameras with this scope: A Nikon DSLR, a JVC Camcorder and the ZWO. It takes a lot of trial and error to find the right combination of bits to make it work though.

So using the ZWO camera I get a similar field of view to my 6mm plossl eyepiece. Which is great for smaller targets.
How do I get a field of view that looks like what I see through my 15mm or 20mm plossl eyepiece?

Or can it not be adjusted?

 

[CraigT82]

You need to use your DSLR to get a wider field of view. Have you got a T-ring and a 2" nosepiece for your DSLR? 

[AlcyoneSVX]

Thanks for the info. I have a T-ring with an internal thread. I remove the 1.25" eyepiece holder from the focuser and fit the SLR in its place. That gets the camera as close as possible to the focuser. I was hoping somebody would know a way to use the ZWO.

[michael8554]

5 hours ago, AlcyoneSVX said:

I have read that Newtonians are no good for imaging,

Don't know where you read that, not on this forum I hope ?

Michael