PowerMate or Barlow for H-Alpha Video

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Starry Jack
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PowerMate or Barlow for H-Alpha Video

Post by Starry Jack » Wed Jan 06, 2021 6:15 pm

I want higher mag for my DSO, Lunar and H-Alpha work (and whitelight too).

I have:
- 80mm Orion ED f7.5
- 152mm acrho Explore Scientific f6.5
- Quark
- ASI 174mm for Solar and Lunar
- Mallincam DSC10c for DSO

I RARELY do visual anymore. So...

-Should I consider PowerMate or Barlow
-If PowerMate, is there a less expensive alternative?
-2" or 1.25"?
-Paracor

Many thanks,
Jack


Explore Scientific 152mm f6.5 achromat
Aeries D-ERF
Quark Chromosphere f27 native, (f14 when focal reduced)
Mallincam .5x focal reducer (large format)
12nm Filter
ZWO174 (IMX249 chip 5um)
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Re: PowerMate or Barlow for H-Alpha Video

Post by rsfoto » Wed Jan 06, 2021 7:28 pm

Hi Jack,

Reading your message I asked myself " What is the difference between a Powermate and a Barlow ? " and I found this explanation.

https://www.televue.com/engine/TV3b_pag ... &Tab=_back

So from what I understood, the difference is only for visual and depending of the focal length of the eyepiece.

BTW I have never used a Barlow or Powermate in my life as I use my Canon Telephoto extenders 1.4X or 2.0X, because most of my light cameras are connected to my telescopes via a Canon bayonet.


regards Rainer

Observatorio Real de 14 San Luis Potosi Mexico

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Re: PowerMate or Barlow for H-Alpha Video

Post by marktownley » Wed Jan 06, 2021 8:34 pm

Unless your seeing is ASTRONOMICALLY good, I wouldn't even waste time (and money) with a Quark/174 trying to up the amplification factor up even more. You're just oversampling. You might as well just increase the image size 2x in post processing because you're not going to actually increase resolution...

You can't bend physics!


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Re: PowerMate or Barlow for H-Alpha Video

Post by Starry Jack » Wed Jan 06, 2021 9:42 pm

Mark and Rainier,
It's the physics and the math which confuses me so I get lost in marketing hype.

I appreciate the insight. If the primary difference is for visual then I can consider I rarely am visual.

If my camera limits me then that's another issue.

I neli3ve it was you , Mark, who turned me on to adding a Barlow to the nose of the Quark to straighten the light path then a focal Reducer on the camera and I did see a boost in contrast so I was wondering if I'm improving DSO viewing if I could also optimize H alpha.

Best,
Jack


Explore Scientific 152mm f6.5 achromat
Aeries D-ERF
Quark Chromosphere f27 native, (f14 when focal reduced)
Mallincam .5x focal reducer (large format)
12nm Filter
ZWO174 (IMX249 chip 5um)
Huge Sense of Adventure Viewing Creation

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Re: PowerMate or Barlow for H-Alpha Video

Post by DeepSolar64 » Wed Jan 06, 2021 9:59 pm

I use a barlow for visual but since you don’t do visual much anymore it’s a moot point.


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Re: PowerMate or Barlow for H-Alpha Video

Post by SimonM » Wed Jan 06, 2021 11:54 pm

I start with the wrong equipment to add a Quark for imaging, but it "is what it is"...

You have an 80mm f/7.5 scope and a Quark, so you already have about an f/31 "solution" which is recommended. A "slower" scope (focal ratio) will give only a dimmer image and a "faster" scope would not be ideal for the Quark because it is preferable to receive a parallel beam (or whatever the correct terminology is) - already achieved.

With good seeing conditions, you may see one or two arc seconds of seeing. With the 174, 4.2x included Barlow and the scope you are "pushing things" a bit to resolve 0.7 arc seconds when 1 - 2 arc seconds is suggested for excellent seeing conditions if you try to add in a Barlow to the mix. You would become oversampled e.g. more bits of data than pieces of content (info).

So for both issues, you are already about "optimal" and so there is nothing to be gained from adding a Barlow when imaging. Moving to a situation that is oversampled would simply mean more (unnecessary) storage, slower transfer rates, lower fps, longer processing times, more noise (lower Signal-to-noise ratio - SNR) and absolutely nothing to be gained.

For my own setup with a 178, I should probably think about binning the data 2x2 to compensate for the tiny pixels (178 has almost half the size of the 174 pixels). Ideally, I would also stop my scope down to 80mm from 100mm to get a reasonable focal ratio, but since the focal ratio "thing" for Quarks is just a guide (not an absolute cut-off), I'm told that it should be OK ASIS and trying both options (like binning and not binning, stopping down (vs needing a UV/IR filter that I just stomped up for vs just a piece of cardboard on the front objective) is the way to go.

Simon
Last edited by SimonM on Thu Jan 07, 2021 1:42 am, edited 1 time in total.



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Re: PowerMate or Barlow for H-Alpha Video

Post by Starry Jack » Thu Jan 07, 2021 12:39 am

Great and interesting explanation Simon.

I never considered binning the sun since I equate binning with decreasing exposure on do objects.


Explore Scientific 152mm f6.5 achromat
Aeries D-ERF
Quark Chromosphere f27 native, (f14 when focal reduced)
Mallincam .5x focal reducer (large format)
12nm Filter
ZWO174 (IMX249 chip 5um)
Huge Sense of Adventure Viewing Creation

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Re: PowerMate or Barlow for H-Alpha Video

Post by george9 » Fri Jan 08, 2021 9:08 pm

For the Quark, its 4.2x already magnifies. But you also mention DSO, lunar, and white light, and there presumably a magnifier might help, no?

I assume a simple Barlow would be fine. The Powermate most is useful if either an eyepiece follows (visual) or if a narrowband filter follows.

George



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