AR2724 & AR2725, 150mm vs 120mm, HA & WL | Oct 14th 2018

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MalVeauX
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AR2724 & AR2725, 150mm vs 120mm, HA & WL | Oct 14th 2018

Post by MalVeauX » Sun Oct 14, 2018 5:14 pm

Heya,

Woke up to a fairly decent sky. Fiddled between a few setups to see some differences. I mainly wanted to compare real world results of a 150mm (6") refractor to a 120mm (4.7") refractor, both at F35. There's a single decent prom but I mainly just observed it a while. I was overall watching the two AR's to see if any activity would stir up, like flares. The filaments are really interesting. I didn't do an animation today as clouds came in around 11, but I bet those three looping filaments are mobile and really interesting. Took a look at the AR's in white light, where they're way less impressive with just tiny little visible umbra and none of the wild chromospheric features, but rather just looked at the convection cells.

Celestron CR150HD 150mm F8 Refractor + Quark + ASi174MM
....Also with just ERF + 395nm filter for white light + 3x barlow + ASI174MM
Celestron Omni XLT 120mm F8 Refractor + Quark + ASI174MM
Coronado PST + 1.5x barlow + ASI174MM

B&W:

150mm:

Image

Image

120mm:

Image

150mm:

Image

40mm:

Image

150mm next to 120mm:
120mm_vs_150mm_HA_10142018.jpg
120mm_vs_150mm_HA_10142018.jpg (542.66 KiB) Viewed 207 times
Color:

Image

Image

Image

Image

Image

____________________________________________________________
120mm_PST_HA_Solar_10142018.jpg
120mm_PST_HA_Solar_10142018.jpg (57.67 KiB) Viewed 207 times
150mm_Quark_10142018.jpg
150mm_Quark_10142018.jpg (66.81 KiB) Viewed 207 times
Very best,

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Re: AR2724 & AR2725, 150mm vs 120mm, HA & WL | Oct 14th 2018

Post by Dave S » Sun Oct 14, 2018 5:56 pm

Nice work!

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Re: AR2724 & AR2725, 150mm vs 120mm, HA & WL | Oct 14th 2018

Post by ffellah » Sun Oct 14, 2018 6:53 pm

Interesting comparison, Marty: what are your thoughts after the results are in ?

Franco

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Re: AR2724 & AR2725, 150mm vs 120mm, HA & WL | Oct 14th 2018

Post by MalVeauX » Sun Oct 14, 2018 7:11 pm

ffellah wrote:
Sun Oct 14, 2018 6:53 pm
Interesting comparison, Marty: what are your thoughts after the results are in ?

Franco
Hi Franco,

The 30mm aperture difference is subtle, but I feel like I see more structure and definition in the "knuckles" in the plage areas and everything is just a bit more detailed enough to differentiate the two. The side by side even without a label you can see differences enough that most people would guess which images came from the larger aperture.
Compare_120_150.jpg
Compare_120_150.jpg (48.84 KiB) Viewed 196 times
The jump to 200mm from what I've seen from others, further resolves those areas that I'm looking at. So while 120mm to 150mm isn't a huge jump, it's a subtle enough increase that I think its worth it. And if able to go up another 50mm to 200mm, it would definitely be worth it.

After that, you start getting into really big scopes with really big focal lengths that require significant mounting and of course really big ERFs that are very expensive.

I'm thinking of cutting up my 150mm refractor and making it a truss, open tube, and potentially putting an internal baader ERF in there, to keep costs down. Then add a telecentric 1.25x to help get to something closer to F10 and potentially put a PST etalon after that and couple with a Quark. Inexpensive for what it would be able to do. Just toying around with the idea right now while considering my options that would get me to 200mm, without being overly expensive. My main issue is I like to have several scopes mounted at once, so I would need a much larger capacity mount if I went any larger. C8's are only 12lbs after all. I'd like to eventually have a 200mm aperture in a side by side with a smaller refractor and either a doublet stack 60mm or double stack 40mm, depending on overall cost after I get there to have full disc and high resolution in several wavelegths.

Anyhow, I like the 150mm when the seeing cooperates. I feel like, while it can work fine without a dedicated ERF, it could probably benefit from opening the tube and putting a larger ERF in there to reduce overall heat while avoiding a full aperture ERF for cost while waiting to be able to make the move to a 200mm with full aperture ERF soon.

Very best,

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Re: AR2724 & AR2725, 150mm vs 120mm, HA & WL | Oct 14th 2018

Post by p_zetner » Sun Oct 14, 2018 8:50 pm

Marty you’re so prolific!
Another great set of images.

Cheers.
Peter

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Re: AR2724 & AR2725, 150mm vs 120mm, HA & WL | Oct 14th 2018

Post by ffellah » Mon Oct 15, 2018 12:02 am

I think you are getting exceptional results with your scopes and technique. I can't wait to see what you will do when and if you further upgrade equipment.

Franco

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Re: AR2724 & AR2725, 150mm vs 120mm, HA & WL | Oct 14th 2018

Post by Derek Klepp » Mon Oct 15, 2018 5:02 am

Good comparison Marty

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