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First light GSO 8" F4

MartinB

By MartinB
in Imaging - Deep Sky

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MartinB

MartinB

Posted
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Conditions were pretty grim with a lot of thin high cloud but I could just about make out stars and was itching to try out this new scope which I collected off Bern from Modern Astronomy at kelling http://www.modernastronomy.com/telescopesGSO.htm The scope has a Baader Steeltrack focuser, larger secondary for better illumination of large chips and a Baader coma corrector.

A quick inspection showed fit and finish to be in good order for a scope in this price range. I have changed the secondary screws for Bobs knobs and also plan to change the primary knobs and springs as well. Those that come with the scope are rather stiff making collimation a bit clumsy. Having said that it wasn't far off and good collimation took a couple of minutes.

Unfortunately I didn't have the right combination of spacers to get the spacing right for the coma corrector, I ended up 6mm short. This is pretty critical and should be within 1 or 2 mm for the corrector to perform properly.

I was using a QHY8 with an IDAS filter.

Focus was no problem, in fact I had to use an extender so there is definitely no problem with limited back focus. Being an F4 the focus position was quite tight but the Baader Steeltrack focusser was well up to the job. It is a 2 speed unit, very smooth and free from backlash. It appears well manufactured and had no problem holding the weight of the camera and filter drawer. I gave it a tug and it was solid ad felt as if it could hold a much heavier set up without any problem. The only thing missing is the ability to be able to rotate the focuser. Finder scope was a decent enough 7x50, similar to the synta ones.

I went for the Iris neb but struggled through the murk. The high cloud was causing a large halo to appear over most of the image including a shadow of the central obstruction. Subs were 240 secs but I had to ditch over half. I was left with just an hours worth of data.

The subs had horrible field curvature because of the wrong spacing of the coma reducer but collimation was good. The image isn't great but I'm really surprised at what I did get given that at times I could barely see any stars! This is why I got the scope, with our mediocre conditions I wanted a fast scope to be able to get the most out of every fleeting opportunity. I am now looking forward to trying it out with the right spacing for the corrector and in good conditions to get a better idea of the optical quality of the F4 mirror

You can still see the remains of the large orange halo. I processed it out and then decided to leave it in, sort of captures the essence of the evening!

9021_normal.jpeg

(click to enlarge)

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Beyond_Vision

Beyond_Vision

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I saw Eddie's scope on Bern's stand and my wallet was twitching then. It's a very interesting scope for the money. It looked well made but was very light and would go on my Orion Sirius mount easily. The amount of nebulosity picked up in an hour is great and shows good promise. I am looking forward to seeing how it performs under better skies with the correct spacings.

Regards

Kevin

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CELESCOPE

CELESCOPE

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Thats avery good first light Martin , and a pretty good one ,as the condtions were not at its best last night, and pleasing for you to get that detail in a short space of time . i,m looking foward to more from this scope , like Kev my hand was nearly grabbing that one on Berns chair at kelling ehheheh .

Nice work Martin

Rog

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brympton

brympton

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Thank you for the first light report Martin, I'd be more than happy with that result first time out even with the spacer issue. I notice that Bern (nice chap) sells the mpcc in two flavours, one for imaging and the other for visual/imaging. I don't know what the difference is (apart from the cost) but I guess yours is just for imaging? An interesting review...very interesting :thumbright:

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MartinB

MartinB

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Yes I got the photovisual version and will be trying it out with my 12" Skyliner.

This pic was with the QHY8 but I can also use it with my super sensitive QSI 532 so that will be F4 and a max quantum efficiency of 82%. So not quite hyperstar or Tak Epsilon but still pretty quick.

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MartinB

MartinB

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Looks like the combination has huge potential Martin, seems to be lots of imagers going down the road of the 1 shot colour cameras and fast scope, understandable with our weather. Look forward to seeing more.

Well I will be using the OSC QHY8 when I need the wide field Mark but I also plan to use the mono QSI - I think LRGB with binned colour is actually as fast as OSC and a lot faster with Ha.

BTW thanks to Ben Ritchie and Eddy Davies for the help and advice they gave me prior to purchase of the scope

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MartinB

MartinB

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Great shot Martin, whats the advantage in this scope over say a SCT at f3.3? I was trying to figure this out last night when you posted the image but I still can't suss it out this morning!!! :)

Illumination of the field Gaz. A 3.3 reducer in an SCT will barely cover a Sony 285 chip. Would be hopeless with larger chips,

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GazOC

GazOC

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Martin, stop it! Images like this are making my mind wander just as I was settled on sticking with the ZS110. Just an hours' worth of data :shock:....

Tony..

Whats the imaging equivilent to aperture fever? Focal ratio fever?

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Whippy

Whippy

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Martin, stop it! Images like this are making my mind wander just as I was settled on sticking with the ZS110. Just an hours' worth of data :shock:....

Tony..

Whats the imaging equivilent to aperture fever? Focal ratio fever?

Is for me mate :). If I could find some way of running my ZS110 at f5 or less whilst keeping the same image scale with no deteriation of quality, I'd be a very happy bunny. But I'd have to dig up Mr. Newton and get him to re-write some of his laws....

Tony..

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Ben Ritchie

Ben Ritchie

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Whats the imaging equivilent to aperture fever? Focal ratio fever?

Yep. I've gone f/10, f/8, f/6.5, f/5.5, f/4 and now i'm wishing for f/2.8...

Then there's the ultra-expensive version where you're trying to figure out how to reduce the image scale AND f-number at the same time...

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