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Flat HA

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5 replies to this topic

#1 hungerford

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Posted 21 October 2020 - 12:31 AM

Hi,

I have a ZWO ASI 294 mono with the Zwo filterwheel and OAG. The filters LRGB are Chroma 50mm unmoumted and the HA is Baader.

The reason I have a Baader Ha is simply that in Europe there is no stock anywhere and the lead time is around a month even more.

Doing the flats for all the filters is fine except for the HA. I have tried everything I can think of but the result is always the same and I do not see that issue on the images taken at night.

It would seem that only whiles doing the flats the problem arises.

I have had to upload the image to Astrobin so there is enough details showing what I mean.

Has anyone experienced this issue before?

https://www.astrobin...axdjy8/?nc=user

Thanks for looking.



#2 silios

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Posted 21 October 2020 - 03:27 AM

Hi,

How do you take the flats? panel, sky? is there a tshirt involved?

what is the exposure time and gain of HA flat?

At first glance that looks alot like wrinkled t-shirt to me!



#3 Ethanwyh

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Posted 21 October 2020 - 04:39 AM

I may be wrong but did the filter wheel position for HA rotate and stop right in front of the sensor? It could be that the filter is slightly off positioned and not stopping right where the sensor hole/interface is. 



#4 hungerford

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Posted 21 October 2020 - 06:00 AM

Hi,

Thank you for your feedback.

No tshirt was involved in the taking of the flats.

I use a lightbox for all my flats and the LRGB are perfect, The gain was set at 120 and the exposure time was 5.54 seconds.

The filter seem to be stopping at the correct place and none of the other filters are showing any side of malfunction. 

The 2" filter I use are much bigger than the chip so many be that is not the problem but I will double check to make sure.



#5 silios

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Posted 21 October 2020 - 07:54 AM

Hi,

Thank you for your feedback.

No tshirt was involved in the taking of the flats.

I use a lightbox for all my flats and the LRGB are perfect, The gain was set at 120 and the exposure time was 5.54 seconds.

The filter seem to be stopping at the correct place and none of the other filters are showing any side of malfunction. 

The 2" filter I use are much bigger than the chip so many be that is not the problem but I will double check to make sure.

Thank you for the info!

Too big a filter is never a problem :)

If the filter wheel is stopping at the right place and this is repeatable (not a one-time thing like frosting on the camera window, dew on the filter etc etc) then I am out of ideas.

Maybe someone who has seen this before will chime in.



#6 hungerford

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Posted 21 October 2020 - 08:04 AM

Thank you for you help.




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