|
|
Thread Tools | Display Modes |
#1
|
|||
|
|||
Focal reducer for LX90 & DSI
I've been using an LX90 and DSI for imaging, and I've decided to get a focal
reducer to increase the FOV. I've had a look at the Meade options, and there is one specific for CCD imaging, and others that are more general purpose. Does anyone have any experience of the CCD specific one, or any comments on the other Meade (or other brands) that I should consider? Thanks Shim |
#2
|
|||
|
|||
Focal reducer for LX90 & DSI
"Shim" wrote in message ... I've been using an LX90 and DSI for imaging, and I've decided to get a focal reducer to increase the FOV. I've had a look at the Meade options, and there is one specific for CCD imaging, and others that are more general purpose. Does anyone have any experience of the CCD specific one, or any comments on the other Meade (or other brands) that I should consider? There is nothing specifically 'CCD' about the 'CCD specific' reducer, it is just that the area it can cover at the focal plane is small (making it not useable for film), and the focal length is such, that you cannot really get an eyepiece close enough to the reducer to work (certainly not with a diagonal). Given the relatively small size of the DSI CCD, relative to the focal length of your scope, the *.33 reducer (this is the one that refers to being CCD specific), is pretty much ideal. You need to work out how to mount the camera, to that the CCD itself,is about 59mm, from the centre of the reducer. This will then give the *.33 factor, and the unit will give the nicest images, spaced like this, or very slightly closer together (which will give a little less reduction). Your final focal ratio, should then be perhaps F/3.4 to F/3.5. Your camera will then cover an area of: (510*9.6)*206/(200*3.5) arc seconds = 1440 arc seconds. This is about 24 arc minutes across the CCD. There are several other reducers that will also work, but this unit is likely to be a good workable match for your camera. Best Wishes |
#3
|
|||
|
|||
Focal reducer for LX90 & DSI
"Shim" wrote in message ... I've been using an LX90 and DSI for imaging, and I've decided to get a focal reducer to increase the FOV. I've had a look at the Meade options, and there is one specific for CCD imaging, and others that are more general purpose. Does anyone have any experience of the CCD specific one, or any comments on the other Meade (or other brands) that I should consider? Further to Roger's advice you could also try the ATIK Focal 0.5 reducer at £29. http://www.modernastronomy.com/accessories.html I have both the Meade 0.33 and the ATIK. They both come in handy for their differing FOV and at the price the ATIK's a pretty handy 1.25" alternative with my other scopes too. The 0.33 can be used optically with a parfocal eyepiece for focussing but I've not tried it for visual observing though. For FOV Calcs with different CCD's, Scopes and Reducers or barlows try this great little tool: http://www.multimediamadness.net/wod...k_a_camera.htm Regards Chris |
#4
|
|||
|
|||
Focal reducer for LX90 & DSI
"Chris Taylor" wrote in message news Further to Roger's advice you could also try the ATIK Focal 0.5 reducer at £29. http://www.modernastronomy.com/accessories.html I have both the Meade 0.33 and the ATIK. They both come in handy for their differing FOV and at the price the ATIK's a pretty handy 1.25" alternative with my other scopes too. The 0.33 can be used optically with a parfocal eyepiece for focussing but I've not tried it for visual observing though. For FOV Calcs with different CCD's, Scopes and Reducers or barlows try this great little tool: http://www.multimediamadness.net/wod...k_a_camera.htm Thanks for the replies. The ATIK does seem exceptionally good value for money. I guess with the Meade the only question I have to answer is whether I would also want to use the reducer for visual observing as well. Shim |
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
Focal reducer help | Tony | UK Astronomy | 1 | April 10th 05 02:55 PM |
Focal Reducer for a Refractor? | RS | Amateur Astronomy | 3 | October 7th 04 07:39 AM |
Focal Reducer for the Sun? | RS | Amateur Astronomy | 2 | June 7th 04 06:32 PM |
A focal reducer or an expensive wide field lens? | Jon Isaacs | Amateur Astronomy | 7 | April 24th 04 11:22 AM |
Focal Reducers, how do they work? | Stephen Paul | Amateur Astronomy | 3 | August 15th 03 10:57 AM |