Hello,
I'm new to the forum but have a couple of questions:
1. What is back focus with a ZWO 183 mc pro camera attached to an 80 mm apo refractor? I tried many configurations and have not been able to achieve focus; I generally get a black sky ( not even bloated stars) with out any stars or lights in the vicinity.
2. What are the optimal settings for the ZWO mentioned above, while using Sharp Cap.
Thanks,
Mario
Backfocus
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If you have a problem or question, please check the FAQ to see if it already has an answer : https://www.sharpcap.co.uk/sharpcap-faqs
Re: Backfocus
That is not any easy question to answer as it will also depend on the focal length but on the specifications page for your telescope it should give a dimension behind the focuser at which the image plane will be focused. If not then as a rough dimension if say the focal length of your scope was 500mm then if the focuser was full racked out and the length was 450mm from the objective then the image would be in focus 50mm beyond the end of the focuser so you would need a 50mm or greater extension tube to allow the movement of the focuser to achieve focus. Bear in mind that this focus point is to the sensor so if the image chip is 20mm behind the front of the camera you need to deduct this distance.
Hope this makes sense.
Cheers
Nick
Hope this makes sense.
Cheers
Nick
Re: Backfocus
Mario
I have a Vixen ED81s refractor - the back focus is 149mm (stated by manufacturer). I have an Altair 1.0x flattener and the manufacturer specs say the back focus is 55mm. If I purchased the Vixen 0.67x reducer the back focus would be 63.5mm (stated by manufacturer).
The figures above are made up of the distances from the back of the scope (or reducer) + the depth the sensor is inside the camera. The sensor is recessed by 12.5mm in both my Atik 314E and Altair 183C. The difference to make the stated back focus is being made up by various extension tubes and a filter drawer.
You should be able to find the back focus distance from your scope/accessory manufacturer's website, otherwise please supply:
From the ZWO website https://astronomy-imaging-camera.com/pr ... -pro-color it states Back Focus Distance: 6.5mm. That will be part of the total distance to be made up.
Dave
When I get new equipment, I sort this type of configuration out from in the house, during daylight, against a land based object.I generally get a black sky ( not even bloated stars) with out any stars or lights in the vicinity.
I have a Vixen ED81s refractor - the back focus is 149mm (stated by manufacturer). I have an Altair 1.0x flattener and the manufacturer specs say the back focus is 55mm. If I purchased the Vixen 0.67x reducer the back focus would be 63.5mm (stated by manufacturer).
The figures above are made up of the distances from the back of the scope (or reducer) + the depth the sensor is inside the camera. The sensor is recessed by 12.5mm in both my Atik 314E and Altair 183C. The difference to make the stated back focus is being made up by various extension tubes and a filter drawer.
You should be able to find the back focus distance from your scope/accessory manufacturer's website, otherwise please supply:
- Make/model of scope
- Make/model of any flattener/reducer being used
From the ZWO website https://astronomy-imaging-camera.com/pr ... -pro-color it states Back Focus Distance: 6.5mm. That will be part of the total distance to be made up.
An open-ended question, are you doing lunar, solar, planetary or deep sky, no filters, LRGB or Narrow Band?What are the optimal settings for the ZWO mentioned above, while using Sharp Cap.
Dave