Make sure that your filters are compatible with your filter wheel
Posted: Sat Oct 20, 2018 4:05 am
After having purchased my first monochrome camera 10 months ago I have gone on a shopping spree buying filters. In total I have four Optolong LRGB filters, two Astrodon Photometric filters, three Orion narrowband filters, and one Orion dark filter. I began with an Orion 5-position manual filter wheel but soon I became interested in automation so I purchased a ZWO MiniEFW.
I really liked the finish of the MiniEFW and that it was light-tight, the Orion FW not so much. I loaded the EFW with my Optolong LRGB filters and the Orion dark filter. It worked great for many months until yesterday when I decided to swap out the LRGB filters for my Orion narrowband filters. I discovered quite unexpectedly at the telescope that the wheel would not turn. I scrambled to move the narrowband filters back into the manual wheel so I could continue imaging.
So here is the problem. The MiniEFW requires that the thickness of the filter cell, minus the threads, be less than 7mm. Unfortunately all of my Orion filters and Astrodon filters are 7.5mm. Only the Optolong filters meet the requirement at 5.5mm. For the astute reader you might of caught that I reported a fully functional wheel having four 5.5mm filters and one 7.5mm filter. The best I can figure is that the stepper motor could overcome the drag from that one 7.5mm filter but not four of them last night.
Anyhow, I thought this might be helpful for those of you like me who like to "mix and match" -- beware!
Brian
I really liked the finish of the MiniEFW and that it was light-tight, the Orion FW not so much. I loaded the EFW with my Optolong LRGB filters and the Orion dark filter. It worked great for many months until yesterday when I decided to swap out the LRGB filters for my Orion narrowband filters. I discovered quite unexpectedly at the telescope that the wheel would not turn. I scrambled to move the narrowband filters back into the manual wheel so I could continue imaging.
So here is the problem. The MiniEFW requires that the thickness of the filter cell, minus the threads, be less than 7mm. Unfortunately all of my Orion filters and Astrodon filters are 7.5mm. Only the Optolong filters meet the requirement at 5.5mm. For the astute reader you might of caught that I reported a fully functional wheel having four 5.5mm filters and one 7.5mm filter. The best I can figure is that the stepper motor could overcome the drag from that one 7.5mm filter but not four of them last night.
Anyhow, I thought this might be helpful for those of you like me who like to "mix and match" -- beware!
Brian