Where's my gradient coming from?

[wuthton]

The Elephant's trunk was first light with a new Moravian G2-8300 with 31mm Astrodon filters. I didn't worry too much about the gradient at the time, I assumed it was due to low altitude and LP. The following is a jellyfish from last night, the camera hasn't been moved so the image is in a different orientation to the ground but yet the gradient is the same? Mr Moon was not around for any of this.

The final image is HA which seems to be OK. 

Any help would be greatly appreciated, particularly if I've done something stupid.

Elephant's trunk OIII, 12x20mins 2x2

 

Jellyfish OIII 3x20min 2x2

 

Elephant's Trunk Ha 15x30min 1x1

[MattJenko]

Have you checked the filters in the wheel, assuming this is an internal wheel G2? The OIII one might not be sitting right or the wheel is not positioning the filter perfectly up against the opening. You could swap the Oiii and Ha and run a "quick" test if it all looks good to the eye.

Edited April 6, 2016 by MattJenko
model name change

[wuthton]

19 minutes ago, MattJenko said:

The OIII one might not be sitting right or the wheel is not positioning the filter perfectly up against the opening.

Good thinking, and easy to check too.

[ollypenrice]

I think the incorrect FW position is a possibility but what's odd is that you are not getting, so far as I can see, just a dark gradient but a light gradient as well. Or only a light gradient, perhaps. This struck me most in the Jellyfish becaue I've just done it in OIII this year. My crudely stretched OIII looks like this, so there is nothing to fill the background sky up on the right hand side of your image as posted. And I can't see why a partially obscured filter would give a light side. A dark side, sure.

Has this filter worked properly before? It could be defective.

Could there be a variable light source which attacked the OIII shoot but not the Ha? Or a local light source blocked by Ha but not by OIII? (This would be more likely.)

Didn't Sara have an internal reflection problem with OIII once? 

This is a rum one.

Olly

PS Stunning Elephant!

 

 

 

Edited April 6, 2016 by ollypenrice
PS

[wuthton]

17 hours ago, ollypenrice said:

I think the incorrect FW position is a possibility but what's odd is that you are not getting, so far as I can see, just a dark gradient but a light gradient as well. Or only a light gradient, perhaps. This struck me most in the Jellyfish becaue I've just done it in OIII this year. My crudely stretched OIII looks like this, so there is nothing to fill the background sky up on the right hand side of your image as posted. And I can't see why a partially obscured filter would give a light side. A dark side, sure.

Has this filter worked properly before? It could be defective.

Could there be a variable light source which attacked the OIII shoot but not the Ha? Or a local light source blocked by Ha but not by OIII? (This would be more likely.)

Didn't Sara have an internal reflection problem with OIII once? 

This is a rum one.

Olly

PS Stunning Elephant!

 

 

 

It is a bit of a puzzler and yes the filter is brand new, there's certainly no on mount light source apart from the EQ6 power LED. The filter wheel is positioning correctly, I've popped in a 1.25" Baader OIII to do a side by side comparison before I point the finger and cry foul.

[ollypenrice]

Are these unmounted filters? If so the OIII might not be lying flat.

Olly

[wuthton]

20 hours ago, ollypenrice said:

Are these unmounted filters? If so the OIII might not be lying flat.

Olly

I'm starting to give the filter some suspicious glances. 

It's flat, positioning perfectly with even (light) pressure from the retaining screws. I turned it 180^o and got the following last night with the gradient now running right to left, it unfortunately clouded over before I could try the Baader.

 

[ollypenrice]

2 hours ago, wuthton said:

I'm starting to give the filter some suspicious glances. 

It's flat, positioning perfectly with even (light) pressure from the retaining screws. I turned it 180^o and got the following last night with the gradient now running right to left, it unfortunately clouded over before I could try the Baader.

 

 

I thnk you have the culprit.

Olly