Four Clear Nights with the AM5N and FLAT GT

Back to astrophotography! Some corrections of my initial thoughts on the ZWO AM5N harmonic drive mount and imaging results with the William Optics FLAT GT 1x flattener for the GT 81. And my old friend: M 33. Ahhh. Galaxy season. Gotta love it!
Video summarizing process for adding Ha to RGB:
• Adding Ha to Red or Lu...

[@richards3192]

Glad you are back James. You bring an analytical rigour that is missing from the majority of the smoke and mirrors influencers

[@Aero19612]

Thanks, Richard!

[@markalot]

I use 5 degrees after meridian after testing to make sure nothing collides with my scope. I set Nina to a 5 minute window at Meridian as my longest exposure is 3 minutes. I did have my older AM5 fail during cold weather with a heavier scope. I set to half speed mode to work around this issue.

[@Aero19612]

Yeah, that's basically what I have set up for my EQ6-R and GreenSwamp Server. I may implement that on the AM5 as well.

[@barnaclewatcher4060]

I agree with you on M33. Seems like it's always a bugger to process and I'm never happy with my results....

[@Aero19612]

I must have imaged that galaxy 6 times at 4 different focal lengths. You'd think I'd like one of them. Thanks for watching!

[@amateurastrophoto3057]

I could be wrong on the PI optimized darks, but I believe you need bias frames entered for it to scale properly. I believe it calculates a scale between your bias and your dark to calculate a dark for your scaled (optimized) dark.

[@Aero19612]

Makes total sense. I should have thought of that. Yes, it probably would work with a pure (bias-subtracted) dark frame. Thanks for the comment.

[@aleixandrus]

The problem with dark optimization, to my knowledge, is ampglow. The optimization supposes the darks scales linearly with exposure, but this is not true with ampglow, so the new optimized darks results in artifacts. I don't have the 294mm but the 183mm, so same issue here: no bias and matched darks and darkflats are a need. With the new sensors with no ampglow, this may work. Many people skip darks and use just bias, as due to the very low read noise a short dark (ex. few seconds for darkfkats) is essentially a bias. But I'm not talking first hand here, as I said, the 183mm has tons of ampglow so no shortcuts here.

[@DrunkferretKG]

Great work as always. Clear nights but bad seeing lately for sure. Hopefully we get some better nights after this upcoming week. I would like to know if you have tried the Starizona SCT corrector and what your thoughts on it might be. I liked the star shapes, especially for my OAG, however I had serious focus issues with NINA and narrow band. Swapped back to the Celestron, reset things with small numbers, and it worked flawlessly. It even got through a full cycle of the offset calculator plug-in(default x3 on all filters). I suspect that I took a wrong turn when trying to get the step size, number of steps, and exposure time dialed in. I should have just reset the parameters and started with lower numbers all around and make small adjustments to one parameter at a time. Oh well.

[@Aero19612]

No, I've never used the Starizona corrector. I hear a lot of good things about it though, and it appears your results are on par with what I heard. I don't understand how a better flattened field would/could adversely affect focus though. That's weird. Focusing with narrowband is tough. As you say, probably a parameter setting somewhere.

[@DrunkferretKG]

@@Aero19612 Thinking the same thing, and I will give it another try. I had read some threads on CN, got those stuck in my head that night, and then got frustrated. After getting some time to think clearly I think it will use a slight variation of the parameters used for the Celestron.

[@epicuniversal]

The AM5N harmonic drive mount sounds great and one day I may upgrade to one from my AVX and EQ6-R, however the weight offset differential without counter weights really concerns me and I worry about everything tipping over on a tripod. If however it was mounted on a pier, I wouldn't have that worry. Is that an actual problem or am I overthinking it and it really does defy physics? 😆

[@Aero19612]

The AM5N may not be an upgrade in performance from the EQ6-R (maybe for the AVX), but the lighter weight is nice. It does look weird after so many years with counterweights. Looking down on the mount/scope, as long as the center of gravity falls within the triangle of the tripod feet on the ground, you're stable. Wind is a potential issue, and counterweights provide a nice insurance policy on that front. I wouldn't use this mount with no counterweights and a scope larger than the GT81 even if ZWO says it's ok.

[@richards3192]

Hi James.. any thoughts on whether I could use the Flat GT on my TS CF 90mm f6 as well as my GT71 ? I use 533MM and MC sensors. WO obviously recommend the Flat GT up to the GT81 because they already have a very expensive flattener for the FLT91...

[@Aero19612]

I'm certainly no optics expert, but I believe flatteners are designed based on the F-ratio. Your F6 is close to the F5.9 for the GT81 so that seems promising. Before you spend good money, you might see if a supplier can answer that (like Agena Astroproducts).

[@AF29007]

How are you liking the AM5N at longer focal lengths? I am looking to upgrade my GEM45 to something like the AM5 or another harmonic drive mount... I am beyond tired of battling massive backlash issues with my GEM45. I am curious to see how your AM5 goes at longer focal lengths, as I run a Vixen R200SS at 800mm and am considering getting a second scope up around the 1200-1800mm focal length range like the VC200L or an EdgeHD 925.

[@Aero19612]

I've only used the AM5 with the GT81 (478 mm) and probably won't use it for the 700mm refractor or the 2300mm SCT - I'll still use the EQ6-R for those scopes. Judging by the guiding performance I've seen, the AM5 should be ok for the longer focal lengths.

[@IronMan-2024]

I’ve been really clouded in since November 8th I have had less than 10 hours imaging time.

[@Aero19612]

That's frustrating when you want to get outside and do some imaging! We buy a lot of crap for astrophotography, but clear skies can't be...

[@IronMan-2024]

@Aero19612 My anti-cloud filter is backordered 😂

[@pickleroo253]

Four clear nights? What is this witchcraft?

[@Aero19612]

and no Moon...Apparently, you have to quit astrophotography for a year to get that special deal.