WO ZS73 collimation

[Ichthyosaurs]

Hi All

I have  a ZS73 which i use purely for astrophotography, when i first started i wasnt worried about the egg shapes at the perimeter but as i have progressed and gotten better with guiding i bought a wo dedicated flattener but i am disappointed that this has no real effect on my photos. Below is a widefield picture of the owl nebula using the 1:1 wo zs73 flattener, eggs all around the perimeter, is this a collimation problem any advice welcome.

 

[Jkulin]

Have you got your backfocus distance correct, usually around the 55mm, but I am not sure exactly for WO?

[fwm891]

I have a ZS73 with the flat73A field flattener. Spacing is quite critical  from the back of the flattener to the sensor. You don't say which flattener or what camera your imaging with. A DSLR (Nikon, Canon etc) need the spacing set to 11.4? on the flat 73A along with their respective T adapters. Non DSLR's will probably need  various extensions to obtain a flat field

WO page: https://williamoptics.com/new-adjustable-flat73-for-z73   scroll down until you see the spacing details...

Edited September 16, 2019 by fwm891

[Adam J]

1 hour ago, Ichthyosaurs said:

Hi All

I have  a ZS73 which i use purely for astrophotography, when i first started i wasnt worried about the egg shapes at the perimeter but as i have progressed and gotten better with guiding i bought a wo dedicated flattener but i am disappointed that this has no real effect on my photos. Below is a widefield picture of the owl nebula using the 1:1 wo zs73 flattener, eggs all around the perimeter, is this a collimation problem any advice welcome.

 

Thats not colimation, you need more spacing between the flattner and the camera. 

[Ichthyosaurs]

1 hour ago, fwm891 said:

I have a ZS73 with the flat73A field flattener. Spacing is quite critical  from the back of the flattener to the sensor. You don't say which flattener or what camera your imaging with. A DSLR (Nikon, Canon etc) need the spacing set to 11.4? on the flat 73A along with their respective T adapters. Non DSLR's will probably need  various extensions to obtain a flat field

WO page: https://williamoptics.com/new-adjustable-flat73-for-z73   scroll down until you see the spacing details...

Thanks Guys, flattener is the non adjustable dedicated william optics for zs73, i thought this was already at 55mm when i attached my camera an Altair Hypercam 294C PRO, will check distances tonight, another lesson learned.

[Adam J]

10 hours ago, Ichthyosaurs said:

Thanks Guys, flattener is the non adjustable dedicated william optics for zs73, i thought this was already at 55mm when i attached my camera an Altair Hypercam 294C PRO, will check distances tonight, another lesson learned.

No the 55mm distance will only be correct for a DSLR as you have a dedicated camera you will need to make up 55mm of space between the rear flat of the corrector and the sensor.

The Flange Distance for your camera is: 17.5mm from front face to sensor.

As such you need to make up 55mm - 17.5mm

Hence you need another 37.5mm of T2 extenders between the flattner and the camera.

Without that spacing in place your so far out that this clearly explains your issues.

Adam

Edited September 16, 2019 by Adam J

[Ichthyosaurs]

Thanks, have bought an extension kit and will try tonight if skies remain clear