narrowband images seam to move ?

[Wirral man]

Hi all was out last night and i thought for the 1st time to try narrow band just a quick question tho when i open up all 3 image's in Photoshop the ha image file seams to be 10mm lower than the olll and sll, its as if the scope has moved down to take the ha then moved back for the other two not sure why this would be maybe a issue with apt? guiding? also on guiding with was working perfectly for over a hour then suddenly started playing up but the exposures of the 3 filters were done before this started any thoughts on this please thanks

[Stargazer33]

When your guiding started 'playing up' had your 'scope just gone past the meridian? This could have caused balance issues if you were slightly heavy on the rising side. There may have been a dragging cable or you may have reached your tracking limit.

[Wirral man]

no the target was ngc7000 American nebula really strange tbh

[carastro]

Have you got a manual filter wheel?  If so you may have slightly nudged the framing when changing filters.  

Carole 

[Wirral man]

9 hours ago, carastro said:

Have you got a manual filter wheel?  If so you may have slightly nudged the framing when changing filters.  

Carole 

Hi no i have the zwo electronic 8 position wheel and yesterday in daylight i setup outside and went into live view and rum the filters and no change in movement or focus so i think it must have been down to guiding something somewhere must have gone wrong can't be any other reason

[kens]

Could be just about anything but"flexure" covers most ills  Some things to consider: how many pixels at what pixel scale was it? And were you dithering?

[carastro]

I must admit that sometimes my different filters don't always frame exactly the same, I never think about it much and just combine them and crop the edges off.

Carole 

[Wirral man]

it looks about 10mm lower when viewed on the screen and no dithering how can i align them is there any free software which can do that because when i have the 3 files up on photoshop and merge im getting double stars with 10mm between them it seams s2 and o3 are ok its ha which is lower 

[kens]

Use DeepSkyStacker http://deepskystacker.free.fr/english/index.html

You can use it for stacking and for aligning the different channels. To align channels is not immediately obvious but is briefly described in the FAQs. Choose the sub you want to align everything to. Lets say it is one of your green subs. When you stack your green subs, right click it and select "Use as Reference Frame". The reference frame is identified by  "(*)"

It will also be ticked so it is included in the green stack.

When you stack your Red (or Blue) channel, add the chosen green sub, right click it and select "Use as Reference Frame". Make sure it is not ticked  as it should not be stacked with red or blue subs. You'll end up with three stacked frames, one per channel, all with the same alignment.

[Wirral man]

12 minutes ago, kens said:

Use DeepSkyStacker http://deepskystacker.free.fr/english/index.html

You can use it for stacking and for aligning the different channels. To align channels is not immediately obvious but is briefly described in the FAQs. Choose the sub you want to align everything to. Lets say it is one of your green subs. When you stack your green subs, right click it and select "Use as Reference Frame". The reference frame is identified by  "(*)"

It will also be ticked so it is included in the green stack.

When you stack your Red (or Blue) channel, add the chosen green sub, right click it and select "Use as Reference Frame". Make sure it is not ticked  as it should not be stacked with red or blue subs. You'll end up with three stacked frames, one per channel, all with the same alignment.

well there you go eh i use dss for all my stacking i didnt know it could do that thanks will be trying that tonight 

[newbie alert]

1 hour ago, Wirral man said:

it looks about 10mm lower when viewed on the screen and no dithering how can i align them is there any free software which can do that because when i have the 3 files up on photoshop and merge im getting double stars with 10mm between them it seams s2 and o3 are ok its ha which is lower 

Even if the framing is different the stars should line up

[carastro]

I had no idea until recently that DSS could do that, unless it is a recent addition, so I bought Registar to do it.  It wasn't a waste of money for me though because I use multiple scopes and cameras - often adding to an image over several years and not always with the same equipment, Registar re-sizes all the images so they match and are registered, I don't think DSS can do that.  But if you are using the same kit for the target DSS should be ample.  Also Registar will re-size to match binned data which I do a lot.

Carole 

[tooth_dr]

1 minute ago, carastro said:

I had no idea until recently that DSS could do that, unless it is a recent addition, so I bought Registar to do it.  It wasn't a waste of money for me though because I use multiple scopes and cameras - often adding to an image over several years and not always with the same equipment, Registar re-sizes all the images so they match and are registered, I don't think DSS can do that.  But if you are using the same kit for the target DSS should be ample.  also registar will re-size to match binned data which i do a lot.

Carole 

Registar seems to be an excellent programme. Once I get a mono camera I think I will try it out. 

[Stub Mandrel]

In photoshop you can manually align by clicking edit-free transform. IIt's very fiddly, but does allow people without registar to aliign images from different sessions/kit.