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Field flattener with filter wheel

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#1 mammut08

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Posted 25 August 2019 - 01:59 PM

Hi All,

I recently added a filter wheel to my set-up. Prior to this, my images looked great. When I add the filter wheel, my images became distorted around the margins. In this case, stars elongate such that they all point to the center of the photo. It looks as if my field flattener is now out of adjustment, even though the flattener is set as directed by the manufacturer. I have a WOZ103, WO Flat Aii and a Zwo filter Wheel. Does anyone have any suggestion as to what is going on?

Thanks in advance for any help you may have.

Dave

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#2 FlankerOneTwo

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Posted 25 August 2019 - 02:04 PM

Is the distance from the flattener to the sensor the same now, i.e. did you remove as much spacing from your train as you added with the filter wheel?  Field flatteners are designed to produce correction at a very specific distance from the flattener. With the WO adjustable flatteners, you may have to experiment some to find the correct setting.



#3 sg6

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Posted 25 August 2019 - 03:22 PM

As mentioned you have added in additional distance by whatever the "thickness" of the filter wheel assembly. Additionally you have changed the light path by approximately 1/3 the thickness of the filter itself - glass I assume.



#4 kathyastro

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Posted 25 August 2019 - 05:02 PM

Whatever the thickness of your filter wheel, you need to remove that much length from the light path between the flattener and the sensor.  Find out from the manufacturer what the correct distance should be.



#5 mammut08

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Posted 25 August 2019 - 06:37 PM

Hi All,

Thank you for tour replies. I'll shorten my optical train as much as I can and see what I get tonight.

Dave

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