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ASI224MC spacing connection to SW ED80 telescope help please?


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Hello Guys.

I hope you are all keeping well and staying safe.

I cannot seem to get me head around getting my ASI 224mc camera to focus regarding the  information of using 55mm of spacing required. I have had to use the two spacers (21mm+16,5mm)  connected to the camera and then to the ED80 0.85x focal reducer/ flattener and in turn they are connected to the telescope. I have been reading about 55mm back space  needed etc, but the only way I can  actually get the telescope to  focus on planets etc, is  to have to use the two spaces shown in the picture and of course the flattener.  If anyone can help me please, I would really appreciate it?  Please have a look at the attached picture......

Kindest regards, 

Hadyn - Isle of Man

SGL help.png

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The back spacing is from the rear of the last lens in your image train, in your case the flattener/reducer, to the camera sensor.

So you have 12.5mm from the sensor to the front of the red casing on the camera + 21mm spacer + 16.5mm spacer = 50mm

You may be able to get it to focus on a planet like this but if you go for a wider field target then you may see stars distorted away from the centre of the frame. Ideally you need another 5mm spacer to get to that 55mm back focus from the flattener/reducer.

If you don't want to use the flattener/reducer then take that off and use the 1.25" nose piece adaptor (which should be included with the camera) on the front of the camera and push that into the ED80 1.25" eye piece holder and you should be able to focus like that.

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1 hour ago, Budgie1 said:

The back spacing is from the rear of the last lens in your image train, in your case the flattener/reducer, to the camera sensor.

So you have 12.5mm from the sensor to the front of the red casing on the camera + 21mm spacer + 16.5mm spacer = 50mm

You may be able to get it to focus on a planet like this but if you go for a wider field target then you may see stars distorted away from the centre of the frame. Ideally you need another 5mm spacer to get to that 55mm back focus from the flattener/reducer.

If you don't want to use the flattener/reducer then take that off and use the 1.25" nose piece adaptor (which should be included with the camera) on the front of the camera and push that into the ED80 1.25" eye piece holder and you should be able to focus like that.

Hi Martin

Thank you very much indeed for the information. I have ordered the 5mm spacer, I must say its very confusing for an old chap like me to grasp the 12,5mm spacing from the sensor you mentioned as I thought was only 6.5mm in my mind. Thanks again.

Kindest regards,

Hadyn.  - IOM

 

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