dtrewren
23-05-2012, 06:46 AM
Hello guys,
Thought I would post this project as it was lots of fun and thought one or two might find it interesting. I decided early this year I really liked widefield (WF) images so was going to put together a WF setup. Had a look at some short focal length scopes but they were a bit slow at around f/6 so decided to build my own rig using the fabled Nikkor f/2.8 180mm camera lens. Having imported an absolutely mint specimen from Hong Kong set about putting a rig together.
There were two tricky little problems dancing about. How to focus the lens remotely and how to fix my QHY9M & filter wheel. I really wanted the filter wheel to get some nice narrowband shots.
To focus the beast I used my SharpSky focuser and beam coupler. In order to eliminate lateral force on the lens focus barrel I used two aluminium pulleys mounted on spacer towers and suspended between pillow bearings on 3mm stainless steel shafts. By pure luck the teeth spacing on the drive belt exactly matched the pitch of the focus barrel hand grip and so absolutely no slip is possible when focusing.
To couple the camera and filter wheel to the lens was a bit tricky. All Nikon lenses have a back focus distance of 46.5mm. In order to leave a bit of focus headroom I decided to position the lens at 45.5mm from the optical sensor. Two adapters are used - a Nikon bayonet to M42 and then an M42 to M54 ring to couple onto the QHY filter wheel. The two adapters are fixed together with thread loc to effectively make them one.
In order to autoguide I modified a spare SW finder scope and attached a Starshoot autoguider to the rear using an adapter.
Everything is mounted on a 5mm think aluminium plate with a dovetail mounted on the reverse. I'm pleased with the result, focusing is real nice and the camera can be focused with about one turn of headroom on the lens barrel - happy days :)
Here is a link to some photographs of the rig. The baseplate still needs spraying matt black but things are easier to see with the plastic coating still in place.
The rig :
www.dt-space.co.uk/WF_project/
Here are links to a couple of shots taken with the rig, hope you like.
Rosette in widefield :
http://dt-space.co.uk/AstroImages/Rosette_widefield.html
Cone nebula region widefield :
http://dt-space.co.uk/AstroImages/Cone_nebula_region.html
Hope you like this project, it was lots of fun - comments and questions always welcome :)
Cheers & clear skies,
Dave
Thought I would post this project as it was lots of fun and thought one or two might find it interesting. I decided early this year I really liked widefield (WF) images so was going to put together a WF setup. Had a look at some short focal length scopes but they were a bit slow at around f/6 so decided to build my own rig using the fabled Nikkor f/2.8 180mm camera lens. Having imported an absolutely mint specimen from Hong Kong set about putting a rig together.
There were two tricky little problems dancing about. How to focus the lens remotely and how to fix my QHY9M & filter wheel. I really wanted the filter wheel to get some nice narrowband shots.
To focus the beast I used my SharpSky focuser and beam coupler. In order to eliminate lateral force on the lens focus barrel I used two aluminium pulleys mounted on spacer towers and suspended between pillow bearings on 3mm stainless steel shafts. By pure luck the teeth spacing on the drive belt exactly matched the pitch of the focus barrel hand grip and so absolutely no slip is possible when focusing.
To couple the camera and filter wheel to the lens was a bit tricky. All Nikon lenses have a back focus distance of 46.5mm. In order to leave a bit of focus headroom I decided to position the lens at 45.5mm from the optical sensor. Two adapters are used - a Nikon bayonet to M42 and then an M42 to M54 ring to couple onto the QHY filter wheel. The two adapters are fixed together with thread loc to effectively make them one.
In order to autoguide I modified a spare SW finder scope and attached a Starshoot autoguider to the rear using an adapter.
Everything is mounted on a 5mm think aluminium plate with a dovetail mounted on the reverse. I'm pleased with the result, focusing is real nice and the camera can be focused with about one turn of headroom on the lens barrel - happy days :)
Here is a link to some photographs of the rig. The baseplate still needs spraying matt black but things are easier to see with the plastic coating still in place.
The rig :
www.dt-space.co.uk/WF_project/
Here are links to a couple of shots taken with the rig, hope you like.
Rosette in widefield :
http://dt-space.co.uk/AstroImages/Rosette_widefield.html
Cone nebula region widefield :
http://dt-space.co.uk/AstroImages/Cone_nebula_region.html
Hope you like this project, it was lots of fun - comments and questions always welcome :)
Cheers & clear skies,
Dave