Field Flatteners / Reducers

[Altocumulus]

Hi all,

In imaging. Now that Summer (*coughs* - if we had one) is over. I thought I'd finally start to use my 4" on the night sky instead of on the Sun.

William Optics 0.8x Reducer Flattener 6 - GT102...I have the adapter specifically for the GT102

Given the precision needed with a flattener / reducer - how does one know whether it's correctly distanced to the back of the camera sensor. Are there any tell-tale indicators, apart from being out of focus!

[TerryMcK]

Stars should be round at the edge of the field. 

[Altocumulus]

Thanks Terry - I suppose it's that obvious.

I just couldn't visualise how one would tell whether it's the reducer distance that's not correct or the overall focus distance....

[szymon]

[Altocumulus]

With many thanks -

[TerryMcK]

Geoff if you are using the dedicated flattener/reducer then it should be fine. I have adjustable flatteners fitted to both of my WO scopes and you have to take the dimensions from WO website dependant upon which scope you are using.

In practice it is very easy to adjust (there is a scale on the barrel of the flattener) and if you get it within 0.5mm or so then you can be assured of flatness on the sensor.

[Altocumulus]

Thanks Terry - unfortunately the dedicated flattener predates the current version with all its adjusting malarky!

I had to buy a baader adjustable spacer - weeps upon weeps - I threaded it carefully onto the WO adapter and it froze part way on.

Nothing will allow me to shift it, further on or even off!

It should at least still work, just can't rely on the scale.

[Davey-T]

26 minutes ago, Altocumulus said:

I threaded it carefully onto the WO adapter and it froze part way on.

Nothing will allow me to shift it, further on or even off!

You could try repeated freezing and heating that might shake it loose and a rubber strap wrench may help.

Dave

[Altocumulus]

Thanks Dave - been there done that numerous times - all failed to shift it.