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rubecula

Oh this is embarassing - filter confusion

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I bought a used filter wheel on-line and it came with the filters in place.  I asked the seller which slots the various filters were in. I took some images and the LRGB ones looked OK but Ha looked wrong. I took the wheel apart and inspected the filters.  Two of them seemed wrong so I left them in the same positions but changed the filter set up in SGP to match what I thought was correct.  I've just taken some images this evening and think I may have it wrong still.  The images below are single 600 sec subs that have all had the same single curves stretch in Photoshop and then saved as jpgs.  I think, from the top that they are Ha, OIII and SII.  Do you agree?

746322261_IC434_600sec_1x1_Light_OIII_frame1.thumb.jpg.973730b6ca82af72cbc8a7b81863be41.jpg

928872428_IC434_600sec_1x1_Light_Ha_frame7.thumb.jpg.b1c22776eb28320d11433c48b871063e.jpg1150559421_IC434_600sec_1x1_Light_SII_frame1.thumb.jpg.06e2dab85fe962492157909259029159.jpg

Thanks

 

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I would guess that's correct,  Ha is red and so is SII, think there is no or very little OIII in the horse.

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I would say the top one is definitely Ha of the 3.  If you want to further clarify, M27 is very distinct in the Oiii channel, but that's not really up until almost morning at the moment.  (But will help you further confirm later in the year.

This is what Ha looks like:

8e5oeoN_By9z_16536x16536_wmhqkGbg.jpg%26

This is what Oiii looks like:

M27-OIII.jpg

another possibility is the California Nebula.  

It is strong in Ha (as indeed I think all narrowband targets are).  It has virtually no Oiii, but also strong in Sii.

HTH

Oh and by the way, you are not the first person to have this dilemma, I can think of at least 3 people who have done the same. 

Carole 

Edited by carastro
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To first approximation OIII looks Blue-Green... and the other two look "Red"...
When you look through them... in daylight! [teasing] But a common enough
dilemma? Not a "classical" imager... I use labeled SLIDE filters... I still forget! 🙄

P.S. I thought I might be able... but couldn't... distinguish the red filters by eye.
Some variant on Testing via known targets (as above)? I agree with above! 😎 
 

Edited by Macavity
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Thanks Mike, Carole and Chris. I'll re-assign the filter locations in SGP and see how I go.  And Carole, thanks for letting me know I'm not the only one 😳.

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It really should say on the side of the filters.

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It really should say on the side of the filters.

It usually does on mounted filters, but if they are unmounted, possibly not.  I remember being VERY careful when I installed my 35mm unmounted filters not to get them muddled up and there was no label on them.  But on my second 1,25 mounted ones they are definitely labelled. 

Carole 

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The filters I have are 36mm unmounted so its difficult to be absolutely sure which is which by just looking at them.  As it happened my guess based on the above images was right and the last lot of images were as expected 😀

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