Filter wheel

rodd

I use the EFW 7 with the ASI 1600 and have never had a problem with calibration. Lately, if I do not take flats immediately after my subs the flats will not line up properly and I wont be able to calibrate. I even lost the first sub of the night because I rotated the filter wheel after the first sub, but then decided to stick with lum instead of doing LRGB--well, because I rotated the filter wheel,. the flats I took at the end of the night did not work on the first sub--dust donuts are visible. The flats worked on the other subs. I used the INIT tool to INIT the filter wheel at the beginning of the night--so it cant be that.

Please help me--I should not have to worry about loosing flats if I rotate the filter wheel--the wheel should be accurate enough to do this--what if I do want to image an LRGB sequence--I wont be able to because I wont be able to calibrate the subs.

Rodd

wvreeven

My first reaction was "why would you want to rotate the filter wheel?" but I suppose this is because of balancing issues. In any case, could you explain why you (need to?) do this?

Anyway, dust specks on the filters may introduce donuts in your lights so that's why it is essential that the flats are taken with exactly the same focus, orientation, etc as the lights. I am surprised that this used to work and I think that was just sheer luck if you don't mind me saying so. So I am afraid that your statement "I should not have to worry about loosing flats if I rotate the filter wheel" is not correct.

"what if I do want to image an LRGB sequence" If possible try to avoid rotating the filter wheel. If that is not possible then I am afraid you need to take flats before rotating it.

HTH, Wouter

rodd

Are you kidding me? I rotate the filter wheel to shoot through another filter--that is how LRGB imaging is done....The filter wheel should rotate from filter to filter at the same spot--flats should be able to be used for more than 1 night. In teh case of last night, the filter weheel rotate to teh SII filter once after the first sub (then I decided to stick with Lum and the first lum sub would not calibrate.

rodd

I have previously been able to use my flats successfully for months--the filter wheel is not lining up correctly. Flats shoul not be out of alignment simply becuase the filter wheel rotated.

rodd

Sean--please chime in. I have been imaging for several years and I know how to shoot LRGB images. Everyone I know that is very accomplished does not lose flats simply due to changing filters. The filter wheel is supposed to lock in place VERY ACCURATELY as it has in the past. Something has changed and I am loosing initialization, or alignment or something.

wvreeven

Aaaaahhh you mean to say that you are CHANGING FILTER from e.g. R to G!!! I thought you were rotating the filter wheel, i.e. the physical device, for balancing or so and then continued imaging with the filter that was previously selected.

OK, going back to the start: you need flats for every filter that you use. So if you use 8 filters, you need to shoot flats for all 8 filters, create master flats for each filter individually and apply those flats for the lights of the corresponding filter. If you do not do that then a dusk spec on, say, the R filter will (not may, WILL) become visible in all the images taken with other filters (G, B, Ha, OIII etc) when the R flat is applied to them.

Once again, the fact that this worked before is sheer luck. With all due respect but this is the first lesson learned when shooting multi-filter images and it is so basic that I honestly thought that you could not possibly mean that. Apparently I was wrong.

rodd

Come on man....give me a break! Of course I shoot flats for every filter. I am saying that my lum flats will not work with lum subs if I rotate teh filter wheel. So if I take 10 lum subs then 10 red subs then shoot my lum flats the lum subs will not calibrate

Got it?

wvreeven

Gotcha. That sounds like a hardware problem to me.

rodd

Hence the question--what is wrong with the filter wheel.

wvreeven

Have you tried opening up the filter wheel and use your software to change filter and then back to the first one? Perhaps a visual inspection might give you a clue.

rodd

Not yet--I will. But were are talking sub mm movement--I wont likely discern anything amiss. I was hoping that ZWO would have a specific recommendation

Support@ZWO

Hi Rodd

Could you try to tight the screws inside the EFW, moter， PCB board and plate. I think it might help.

If not, please send a email to support(at)zwoptical.com

Our engineer will contact with you directly.

blaze

Hi Rodd,

Did you found a solution?

Have exactly same issue with mine :(

Support@ZWO

Hi there

Anything need our help, please send us a email: support@zwoptical.com.