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A PSA for the planetary folks using the 224mc

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#1 mayhem13

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Posted 23 June 2022 - 06:01 AM

So some of you know I do AP as well and use the 224mc as my guide cam. I’ve had great success with it threaded on to my Guidescope with no differential flexure and more than enough SNR even when the seeing was less than ok……until I did something different. Instead of a direct thread on, I attached it using the 1.25 nosepiece slipped in for easier focusing. All of sudden, my SNR was terrible, the star was bloated and there was what appeared to be halos or micro lens reflections to the point where guiding became impossible. Thought it was a camera issue, my software, dust or dirt, etc. Took a break, did a meridian flip and then set the camera back on with a threaded connection as I’d done hundreds of times before and….voila……everything was right in the world again….but why?

 

While I was catching a few more frames of my target before the zenith spin, I took the removed nosepiece and had a look. With my headlight on and aiming inside the extension so I could inspect, the threaded portion was heavily reflecting light on the cut edges of the threads and with the light off axis, the reflections were localized but more intense. Had about an hour til dawn and I needed to stay up to get my sky flats so I had some leftover peel and stick flock cloth which I carefully cut and applied to the inside threaded portion of the 1.25 nose cone and re installed it on the 224 can preceded to test guiding again……and everything was fine……SNR back to thread connection levels, no halos and no bloat…….Total rms back to .7 or so.

 

Needless to say, the threaded interior portion of the 1.25 nose cone was causing significant light scatter on bright targets…….and on big and bright Jupiter and Saturn, in can only imagine how much resolution was lost last season while imaging the planets with this configuration. Even though the test was impromptu and crude, the flocking will stay and I’m gonna take a black sharpie to the anodized red surface of the 224mc around the sensor opening as well since it seems to have a protective semi gloss coating over the red anodized finish. Of course, your experience might be different and yet I’m surprised at myself for not recognizing the reflective surfaces sooner. Once Jupiter is at a high enough elevation for imaging, I’ll do some AB testing of flocked and unflocked nose pieces to see if there’s an appreciable improvement. Stay tuned!


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#2 Tulloch

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Posted 23 June 2022 - 05:26 PM

Interesting - I also use my ASI224MC for guiding with DSO AP, although I use an OAG. I do use the 224's nosepiece when guiding, and my main issue is actually finding a star to guide on and the snr is never very good.

 

Can you please share an image of the issue? Was the threaded section damaged at all, or was it all black? I'm just wondering if I have a similar issue and what I can do about it.

 

btw, I don't use ASI224MC's nosepiece for planetary imaging, I use a TV powermate adapter.

 

Thanks for the post,

 

Andrew


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#3 mayhem13

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Posted 24 June 2022 - 07:23 PM

B4C9EB9E-BE4D-4C01-A3A6-C72B0EA234EA.jpeg

 

I removed the flocking so you folks can see what I’m talking about……the inside surface is highly reflective and the thin anodized finish inside the thread pitch is creating thousands of little bursts of scattered light.

 

For those imaging with one of these on their planetary cam, either eliminate it or flock it……that scattered light has got to be a wrecking ball on resolution and contrast.


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#4 mayhem13

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Posted 24 June 2022 - 09:22 PM

Interesting - I also use my ASI224MC for guiding with DSO AP, although I use an OAG. I do use the 224's nosepiece when guiding, and my main issue is actually finding a star to guide on and the snr is never very good.

 

Can you please share an image of the issue? Was the threaded section damaged at all, or was it all black? I'm just wondering if I have a similar issue and what I can do about it.

 

btw, I don't use ASI224MC's nosepiece for planetary imaging, I use a TV powermate adapter.

 

Thanks for the post,

 

Andrew

Tonight as an example…..not great seeing with fireworks smoke from Independence Day impatient idiots, my SNR is 160 with the flocking……it was 44 without…..



#5 Tulloch

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Posted 24 June 2022 - 09:23 PM

Interesting - the ZWO ADC has exactly the same nosepiece - I wonder if this is also a problem with the ADC?

 

What do you use for flocking fabric?


Edited by Tulloch, 24 June 2022 - 09:26 PM.


#6 mayhem13

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Posted 24 June 2022 - 09:32 PM

I bought it on Amazon……peel and stick but VERY black. I tried rubbing it to get fibers loose but they’re on there pretty good so I felt comfortable using it

https://www.amazon.c...product_details


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