rc6 flats frames dont match ( 3d effect in dust)

Filters Calibration Luminance Artifacts Help Needed Troubleshooting
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adrian-HG avatar
adrian-HG avatar

hello all , i have a problem with luminance filter , dust motes with 3d effect

all my other filters (rgb and sho) can be calibrated with flats really good with my led panel

i ussually make flats with 2 or 3 second exposure in rgb and 10 second aprox. with narrowband

tryed different adu ratio and exposures times with lum filter , but they never get good calibration

here is a autostertch raw master lum with the problem:

📷 1.jpg1.jpg

and master flat autostretch with 29000 adu and 1.1 seconds exposure:

📷 2.jpg2.jpg

my rig is a rc6 gso rebranded with reducer ts ccd telecompressor 0.67x

533 mono with eaf and efw and optolong filters

my optical train is well colimated and tilt is is aprox. 0% or 3% max

i dont know why this weird 3d shape dust motes , and only in the uv/ir cut filter

i shoot flats in every night , with the same rotation ,camera temp , focus point and never get good flats in lum, i dont know how to solve that problem

Tobiasz avatar
Tobiasz avatar

Hi,

do you have the GSO stock focuser attached? It might be the focuser sagging as their stability is not very good with heavier setups e.g. mono camera & filter wheel.

Regards

Helpful Respectful Concise
adrian-HG avatar
adrian-HG avatar

Tobiasz · May 25, 2026, 04:46 PM

Hola,

¿tienes el enfocador GSO stock conectado? Podría ser que el enfocador se esté hundiendo ya que su estabilidad no es muy buena con configuraciones más pesadas, por ejemplo, cámara mono y rueda de filtros.

Saludos

yes , is the stock focuser and yes , it feel a little weak , maybe that is the problem but , why only in luminance filters?

Brian Puhl avatar
Brian Puhl avatar

Your dust motes are shifting during the night. OR, your filter wheel is not aligning properly. One of the two.

Well written Concise Engaging
adrian-HG avatar
adrian-HG avatar

yes dust , mirrors camera or focuser is moving or tilting trought the night

but all the other filters are correcting really good , in that case all the filters flats would have the same error because i shoot all the flats in the same time

or at least is that what i think

Tony Gondola avatar
Tony Gondola avatar

I agree with Brian. To get a 3d embossed effect like that, the dust is not lining up between the lights and the flats. I don’t think it is focuser sag because that would take the entire imaging train with it. It would effect correction for vignetting but not dust. One way to trouble shoot the filter wheel would be to swap out the L with something else. If the L starts behaving and the swapped filter suddenly doesn’t, the problem is with positioning of the slot.

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Brian Puhl avatar
Brian Puhl avatar

adrian-HG · May 25, 2026, 05:25 PM

yes dust , mirrors camera or focuser is moving or tilting trought the night

but all the other filters are correcting really good , in that case all the filters flats would have the same error because i shoot all the flats in the same time

or at least is that what i think

Not if the dust mote shifted on only the luminance filter. Or it shifted in the middle of your imaging session.

Try an older set of flats for the luminance maybe.

Jared Willson avatar
Jared Willson avatar

Either your filter shifted in its slot between when you took the flats and when you took the lights, or the filter wheel didn’t return to the exact same position for both the lights and the flats. That’s where the “embossed” look comes from.

Some EAF’s when told to rotate to a particular filter will take the shortest path—might be either clockwise or counterclockwise depending on the starting point. That’s generally a bad idea. The EAF may decide it is “done” rotating at very slightly different points depending on the direction of rotation. Check to see if your filter wheel is doing that. If it is, there may be a firmware patch available or a setting you can select that will force it to always choose one direction (either clockwise or counterclockwise—doesn’t matter which). If your filter wheel doesn’t have that option, the workaround is to always work through the same progression when going from one filter to another for both your flats and your lights.

Jared

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adrian-HG avatar
adrian-HG avatar

ok i will try what you guys suggest , change te position of the filter and unidireccional filter wheel direction

i tryed with older flats , but that is weird , all have the same problems

all the master flats in different days have the dust and vigneting in the same place synchronized

almost all dust spot are in the secundary mirror , primary , reducer filters and camera are cleaned 45 days ago