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Octopi Camera Interface

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#1 bugbit

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Posted 05 March 2021 - 10:54 PM

Here is a interface for a ASI6200 on a ASI filter wheel. It will also work with a QHY FW. This unit is for adjusting back focus, tilt and camera centering. The design back focus is 8mm with a minimum of 5mm and a maximum of 11mm. The knobs are removable as the screws have 2mm allen head sockets in them.

Thx for the photo's M.

 

IMG_0555.jpg

 

 

 

Inside the filter wheel looking back.

IMG_0554.jpg

 

 

Here is the base attached to the FW. Note the lateral adjusting screws to center the camera. It is also tapped for m54-0.75 threads so it is usable with other mounting types.

IMG_0556.jpg

 

 

Due to me accidentally tapping QHY m3 holes instead of ASI m2.5, the customer offered to countersink the filter wheel so he could use the m3 screws as they are substantially larger.

 

IMG_05531.jpg


Edited by bugbit, 05 March 2021 - 11:30 PM.

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#2 Kaydubbed

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Posted 05 March 2021 - 11:19 PM

Apologies for the dumb question, but is this 'adapter' used to make the removal of the camera easier because you don't need to open the FW to remove it?

#3 bugbit

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Posted 05 March 2021 - 11:26 PM

Hey there Kaydubbed

These are for adjusting back focus and tilt with the camera mounted to the filter wheel.

It has 6mm of back focus adjustment and if you have a area of your photo that has tilt issues, you can nudge the proper screw to alleviate the issue,

And it makes camera removal possible with out opening the filter wheel :)


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#4 justusliebig

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Posted 06 March 2021 - 02:30 AM

I understand this setup increases the distance from filter to sensor. I can't believe that's good

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#5 bugbit

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Posted 06 March 2021 - 01:52 PM

I understand this setup increases the distance from filter to sensor. I can't believe that's good

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Here is the astronomy tools calculator that will show the the effects on sensor filter distance for your telescope.

https://astronomy.to...ccd_filter_size



#6 bugbit

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Posted 03 April 2021 - 02:26 PM

The OCI (Octopi Camera Interface) lets you adjust your back focus, camera tilt and centricity in the light cone. It utilizes precision screws to make it perform at a accuracy of 0.001" with a 5 minute turn of the clock dial/knob in the coarse mode and is available up to 13 times that accurate.

The OCI is to help alleviate camera issues. If you have image train issuses between the filter wheel and the telescope then the GERD CTU would be more appropriate.

 

To address justusliebig's concern "I understand this setup increases the distance from filter to sensor. I can't believe that's good", I needed actual numbers to put his concerns in numbers that show the actual difference in filter diameter in relationship to sensor distance. I used the Astronomy tools calculator and you can check the numbers yourself if you feel so inclined.      https://astronomy.to...ccd_filter_size

 

While looking at this page:  https://astronomy-im...5-x-2″or-7-x-2″
I saw this snippit:

"When connected to ASI6200, the distance from the filter to the sensor is about 18mm"

Using these numbers run though the astronomy tools calculator and again at 8mm extra distance between a ASI6200 camera and a ASI filter wheel to account for the extra distance added by the OCI when set at the center point   With the OCI set in the center position, there is 3mm inward and 3mm outward for a total of 6mm of adjustment, for precisely adjusting the back focus or tilt without having to remove anything from the telescope.

 

These filter diameters are the minimum recommended and larger are always better.

 

Tak FSQ-106EDX4 F/5 with a ASI6200mm attached to a ASI 2" filterwheel: distance between filter and camera sensor = 18mm and needs a filter with a diameter of 45.41mm and after installing a OCI at center point the minimum filter diameter goes from 45.41mm to 46.36mm, a difference of 0.95mm.

 

With a A-P 175 f/8 the numbers are 44.97mm dia. to 45.73mm dia. after accounting for the OCI. A 0.76mm difference.

 

Askar FRA600 F/5.6, the numbers are 45.22mm without a OCI and 46.08 with for a differnce of 0.86mm.

 

For fun I ran a RASA11 just because it is F/2.2 and it was about 3mm difference but I doubt anyone would use a 2" filter wheel on one.

 

If you are using a QHY camera with a dovetail then you replace the QHY tilt plate with the OCI and you will only have to add about 2mm to the factory distance from the filter to the camera sensor. For the newer QHY camera's that don't use the dovetail, use the numbers above for the ASI cameras.

 

The question is: Are you willing to give up less than 1mm of filter diameter to have the ability to adjust your back focus, your tilt and your centricity with precision?


Edited by bugbit, 03 April 2021 - 02:35 PM.



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