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Equipment Discussions >> Cats & Casses

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orlyandico
Carpal Tunnel

Reged: 08/10/09

Loc: Singapore

powernewt or hyperstar? new

new

#5474484 - 10/17/12 04:30 AM

has anyone made a comparison?

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David Pavlich
Transmographied

Reged: 05/18/05

Loc: Mandeville, LA USA

Re: powernewt or hyperstar? new

new

[Re: orlyandico]
#5474664 - 10/17/12 08:57 AM

I've had both and both have advantages. The PN is easier to collimate, at least that was my experience. Much easier. The PN doesn't have a camera and adapter hanging from a glass corrector plate. The PN doesn't have a dew problem.

On the negative side, it is really sensitive to spacing. Not bad if all you're going to use is DSLR. The spacing is 65mm between the reducer/corrector so all you need for a DSLR is a 10mm spacer. And you can use a clip in light pollution filter.

However, using a CCD, spacing becomes a little more difficult. Say your CCD has a backfocus of 22mm. And say you want to use an LP filter. The LP filter I use is about 7mm thick, if I remember correctly. So now you're at 29mm. There is that Veri-lock spacer by Baader, but it's a nice way to induce flexure. The best answer is that you have a lathe or you know someone that can make you a spacer without charging you the price of a Nagler.

The HS spacing is simple. You tell Dean that you're using XYZ camera and there's an adapter for it. Thread everything together and voila! Spacing is perfect. F2 is faster than f2.84. Some will say that focusing is tough, but I found a Bahtinov mask worked just fine hanging on the dewshield. I would consider changing the stock focuser to a Feathertouch, however. Much more sensitive.

And if done properly, once you're collimated, removing the HS and putting the secondary back in for some long focal length viewing/imaging is a breeze.

Again, the only part of this exercise that ever really made me nervous was the camera hanging on the corrector. And one more thing; they are both limited to APS-C sized sensors. Anything larger and the vignetting is severe. Both are a perfect match for the 8300 class chip.

Mono on a HS? Depends on the scope. On a C14, the QSI583 with its internal filter wheel works well as long as you opt fot the 31mm filter carousel. Sheesh...sorry for being so long winded!

David

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EdmontonAB
scholastic sledgehammer

Reged: 04/30/08

Loc: Sooke, BC , Canada

Re: powernewt or hyperstar? new

new

[Re: David Pavlich]
#5475029 - 10/17/12 12:48 PM

Excellent question. I am in the process of changing scopes and am trying to decide between a 10" powernewt or C11 HD. I would like a scope that can image at different focal lengths to satisfy all my needs. I could use the powernewt at F2.8, F4 and if required F8. The C11 can be used at F2, F10 and F7 (Focal reducer). I would also like to be able to use a DBK for planetary. The mount is an AP Mach1. I can't think of any other scopes. The powernewt seems a little better with the focal ratios as the C11 has really long focal ratios. I am using a DSLR but may convert to a 8300 chip camera. The powernewt seems a little pricey, but if it is the best solution then I would go for it. Any other suggestions on scopes and out of the two which would you choose?

Thanks,

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orlyandico
Carpal Tunnel

Reged: 08/10/09

Loc: Singapore

Re: powernewt or hyperstar? new

new

[Re: EdmontonAB]
#5475062 - 10/17/12 01:10 PM

David,

The 8300 chips are actually HALF THE SIZE of APS-C sensors like my QHY8 (the KAF 8300 is actually a Four Thirds sensor). So yes the PN and HS would both be perfect for 8300 but maybe less than perfect for APS-C.

HS seems to be more common so by scrounging around you can get in at less than the cost of a PN. A C8 can be had for $500 and a HS for $800. It's almost 1/2 the cost of the 8" PN and most likely easier to mount.

Also the largest PN is 10" although you could buy a 12" f4 newt and the Keller reducer and do a DIY Powernewt.

Steve - the reason I'm looking at HS / PN is because I don't have a Mach1

if I did 20-minute subs would be a breeze.

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GlennLeDrew
Postmaster

Reged: 06/18/08

Loc: Ottawa, Ontario, Canada

Re: powernewt or hyperstar? new

new

[Re: orlyandico]
#5475471 - 10/17/12 05:06 PM

One potential concern with the Hyperstar is that at f/2 it's faster than the recommended f/2.5-2.8 limit for narrow-band imaging filters having bandpasses around 7nm. Or is this limit conservative, or OK to disregard?

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David Pavlich
Transmographied

Reged: 05/18/05

Loc: Mandeville, LA USA

Re: powernewt or hyperstar? new

new

[Re: orlyandico]
#5475476 - 10/17/12 05:10 PM

Quote:

David,

The 8300 chips are actually HALF THE SIZE of APS-C sensors like my QHY8 (the KAF 8300 is actually a Four Thirds sensor). So yes the PN and HS would both be perfect for 8300 but maybe less than perfect for APS-C.

HS seems to be more common so by scrounging around you can get in at less than the cost of a PN. A C8 can be had for $500 and a HS for $800. It's almost 1/2 the cost of the 8" PN and most likely easier to mount.

Also the largest PN is 10" although you could buy a 12" f4 newt and the Keller reducer and do a DIY Powernewt.

Steve - the reason I'm looking at HS / PN is because I don't have a Mach1 if I did 20-minute subs would be a breeze.

The 8300 class chip is a good match because of its pixel size, not the physical size. You also have a much easier option list if you decided to use a mono camera with the PN, you can use a myriad filter wheels. Can't do that with the HS as easily.

Yes, you can find a less expensive HS capable scope like a C8. However, you shrink the amount of light the scope pulls in because you've created a large central obstruction depending on the camera you choose. CCD cameras like Starlight Express, the new Atiks and the QHY8 Pro have a cylindrical profile that goes very well with the HS. But these are OSC cameras.

Like with most of us, it comes down to budgetary considerations.

David

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Patrick
Postmaster

Reged: 05/16/03

Loc: Franklin, Ohio

Re: powernewt or hyperstar? [Re: EdmontonAB]
#5476128 - 10/18/12 12:10 AM

Quote:

The powernewt seems a little better with the focal ratios as the C11 has really long focal ratios.

The 10" PowerNewt has a 722mm f/l at f/2.8, while the C11 with HS has a f/l of 560mm at f/2.0. So, the C11 is a little shorter with HS. At f/4 the PN has a 1016mm f/l and the C11HD has a f/l of 1956mm at f/7. So the SCT is definitely longer there.

Patrick

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Starhawk
Post Laureate

Reged: 09/16/08

Loc: Tucson, Arizona

Re: powernewt or hyperstar? new

new

[Re: GlennLeDrew]
#5476684 - 10/18/12 10:36 AM

Glenn,

You're right on- but it depends on the filter. Starizona recommends the narrowest band-pass you can get.

UHC LPR filters leave halos around bright stars with hyperstar.

The best results I have been getting with HS have been using a Pentax k-5 out in the boonies with no filters.

-Rich

Quote:

One potential concern with the Hyperstar is that at f/2 it's faster than the recommended f/2.5-2.8 limit for narrow-band imaging filters having bandpasses around 7nm. Or is this limit conservative, or OK to disregard?

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GlennLeDrew
Postmaster

Reged: 06/18/08

Loc: Ottawa, Ontario, Canada

Re: powernewt or hyperstar? new

new

[Re: Starhawk]
#5477226 - 10/18/12 03:25 PM

Rich,
It's the narrowest bandpass filters which will be 'de-tuned' for the steeper parts of the light cone from the outer part of the objective. Would not the recommendation for Hyperstar be to use not the narrowest bandpasses, but rather those a bit wider?

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Coastal
super member

Reged: 04/23/09

Loc: Vancouver island, Canada

Re: powernewt or hyperstar? new

new

[Re: GlennLeDrew]
#5477850 - 10/18/12 10:10 PM

There is a report from a user who tried a few different types of narrowband filters in a hyperstar system. I can't recall what the other two brands were but the conclusion was that Astronomik's 12nm filters had the best performance. I use these filters for my EdgeHD 9.25/hyperstar 3/Atik 428 EX mono setup utilizing a filter drawer.

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wolfman_4_ever
Pooh-Bah

Reged: 07/15/11

Loc: El Segundo, Ca, So. Cal

Re: powernewt or hyperstar? new

new

[Re: Coastal]
#5478171 - 10/19/12 01:55 AM

Astrondon has info on their site. they have a few pics at 3nm but i believe they recommend the 5nm in HS.

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GlennLeDrew
Postmaster

Reged: 06/18/08

Loc: Ottawa, Ontario, Canada

Re: powernewt or hyperstar? new

new

[Re: wolfman_4_ever]
#5478721 - 10/19/12 12:14 PM

My Baader 7nm H-alpha comes with a recommended f/ratio limit of 2.8, or 2.5 (can't recall specifically, and can't check right now.)

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