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Reflection!!! :(

Earl

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Uranium235

Uranium235

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Is it only with this filter? Have you tried it without the SW filter (or with a UV/IR cut)? If youre using the flattener - is the spacing correct? (check/clean/measure everything!).

I fear the only solution will be to do a bit of trial/error under the stars with different configurations (including having no flattener). Not a great thing to be doing when there is clear sky passing you by.

Though it might just be that that filter has poor anti-reflective properties. But if youre using 1.25" filters , then it might be better to opt for the CCD CLS filter as your L filter. I have the baader filter, though it does a decent job on reducing LP its not a great leap over the SW filter (though the new UV/IR blocking ones may be useful). You might find that your maximum imaging time with the Baader filter before the histogram starts to creep to the right is about 10min - depending on your level of LP and telescope speed (I suspect you're on the F6?). A CCD CLS would easily double that time, they're tough, and have better anti-reflective properties.

Hope you get it sorted soon.

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Uranium235

Uranium235

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Unfortunalty im using a Astronominc CLS filter :)

Ahhh.... how old is it?

There used to be a halo problem with older filters, which had been addressed on the CCD CLS.

And IIRC, the standard CLS filter does not block UV/IR - which might well be contributing to the problem. In addition, youre losing 8% transmission in OIII using the standard CLS filter.

Might be time for an upgrade ;)

Good suggestion from ibbo too, make sure any extensions youre using have no reflective surfaces. With a bit of luck you might get to test it tonight, before it clouds over (as it always has done for the past month!).

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Uranium235

Uranium235

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Just done a bit of digging to confirm the differences between the two CLS filters. On the astronomik website, the standard CLS filter is described as a "visual filter" - which if used for CCD work must be used in conjunction with a UV/IR blocker. The CCD CLS filter blocks both and has a better transmission all-round (look up CCD CLS transmission curve on google).

Standard CLS:

Astronomik CLS Filter

CCD CLS:

Astronomik CLS CCD-Filter

It might be possible to mount a baader UV/IR cut on your ccd window (if theres a thread), that will save you the expense of getting a new LP filter. But having potentially 3 bits of glass between the flattener and the chip (2xfilters + window) may affect the spacing a little. I normaly give mine 1/3 the total thickness of the filters (about 1.5mm shorter in the spacing).

It might not make much noticeable difference, but theres no harm in being accurate ;)

Forgot to mention, for CCD work - having a UV/IR cut is pretty much the law. If or when you move onto LRGB, you will also need to ensure your colour filters are UV/IR blocked too. However, UV/IR or LP isnt an issue when doing narrowband (which is why I love it so much!)

EDIT: Ahhh, just read the QHY8L manual. It states that the CCD window is made of 3mm thick IR blocking glass (not like the usual BK7 glass), so indeed there is no need for any further blocking. Try the different filter position and see how you get on :)

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Starblazer

Starblazer

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Oh noe's the star is on the run and is showing a tail lol!!

Sure is a nasty reflection. Would this mean you require the filter to be further from the ccd? i.e reducing the reflection? Going to be costly to replace those filters...unless you can get away with an extension ccd end and getting closer to focuser-base on back of filter.

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Earl

Earl

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Im going to try the Baader one first as FLO have offered to return if I have the same issue.

Having to purchase a new dual bar to use with my saddle upgrade as drained the funds for the CLS CCD.

I will report my findings.

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