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GSO Classic Cass 8 inch

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#1 highfnum

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Posted 08 December 2019 - 06:53 AM

OK 

so I had room for one more scope 

picked up from Agenatelescopes  GSO 8 inch CC

 

gsoota.jpg

gsomirrir.jpg

 


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#2 highfnum

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Posted 08 December 2019 - 06:59 AM

scope itself came  - no issues with body or mirrors

so went out and tried it and UGH image was a mess

so I did star test 

it was awfully aligned

center disk was way off 

so after an hour of playing the  fiddle with secondary screws (BTW no instructions- had to use Orion document)

I got it centered

 

and WOW star image was quite good

so first lesson about this design 

its similar to SCT in terms of sensitivity to being out of collmination

CC8ronb.jpg

 

 

 


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#3 highfnum

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Posted 08 December 2019 - 07:03 AM

so of course moon dominated sky 

so I did a few runs with that 

scope comes with 3 extension rings

1) 2 inch

2) 1 inch 

for most apps including visual and most small cameras (not DSLR's) 

a 3 inch extension is needed 

 

i did not try bino viewer but I will assume you need to remove extensions for that

Capture 12_7_2019 7_30_00 PMcc8corp.jpg

Capture 12_7_2019 7_34_11 PMcc8calv.jpg

Capture 12_7_2019 7_34_56 PMcc8tyco.jpg  

 


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#4 highfnum

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Posted 08 December 2019 - 07:06 AM

although alpine valley was not in optimal position 

I was still able to pick up some of the rille 

BTW camera used was ASI120MM

Capture 12_7_2019 7_32_12 PMcc8rille.jpg

 

 


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#5 highfnum

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Posted 08 December 2019 - 07:08 AM

so im generally pleased with scope

one thing it has an excellent cool down rate 

it rather light weight 

 

im just hoping it holds its collmination over time


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#6 Bill Barlow

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Posted 08 December 2019 - 10:42 AM

Thanks for the nice review.  Would using the 3” extension for visual use increase the focal length quite a bit?  Agena says it collimates each of these scopes before shipping but I guess yours got misaligned during shipping.

 

Bill



#7 highfnum

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Posted 08 December 2019 - 11:00 AM

the mirrors are fixrd no increase 

you focus at the focuser at end like refractor 

its just they allowed you to bite derp

into light cone so it adapts to many

accessories 

 

yea i got certificate from agena

i was disappointed 

but to be fair 

it probably got knocked around 

even though box was clean

 

its a pain because it takes a while to adjust

but at least nothing was broken or bent

 

its critical you get a good round collapsing circle for 

star or else image degrades


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#8 ScottW

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Posted 10 December 2019 - 08:13 AM

Is this the first report of one from Agena that is not spot on?  If  so then it's bad luck.  If not then it's something to take into account?

By this I mean it might change one's mind as to where one purchases the scope.

 

Scott



#9 macdonjh

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Posted 10 December 2019 - 10:17 AM

highfnum,

 

Glad you got a new scope.  You are right, classical Cassegrains punish observers who don't keep them collimated.  I would think your scope will hold collimation well, though.  It's a pretty light weight scope, so not a lot of mass shifting around to throw it out of collimation.  And I'm sure you'll be more gentle than the package handlers.

 

I wouldn't worry too much about receiving a scope out of collimation.  My newest scope ("new", hah, it's four years old now) arrived out of collimation.  Sure, it was a bit frustrating, but nothing was damaged and I got it collimated quickly enough, just like you did.  I couldn't withhold a recommendation based on miscollimation.

 

There are some good threads about collimation in the Cats and Casses forum.

 

Your lunar photos are pretty impressive.


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#10 Agena AstroProducts

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Posted 10 December 2019 - 06:12 PM

>>Is this the first report of one from Agena that is not spot on?

 

Every GSO scope is collimated before it leaves our warehouse. Shipping can be rough on scopes, and occasionally - as in this case - a scope might arrive out of collimation. We have had a handful of such reports but those have been a tiny fraction of the total number of scopes shipped. But with any reflector, a buyer should be able and willing to collimate the scope, especially after a long journey.

 

Regards,

Manish

AgenaAstro.com


Edited by Agena AstroProducts, 10 December 2019 - 06:12 PM.

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#11 doug mc

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Posted 10 December 2019 - 06:26 PM

I managed to reach focus with my binoviewer using a short light path setup. Baader T2 prism TS binoviewer and direct coupling to the prism. My scope is the same as yours.

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#12 highfnum

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Posted 10 December 2019 - 07:32 PM

as i figured above



#13 highfnum

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Posted 29 January 2020 - 09:03 PM

took a few more shots after twiddle with alignment

venus UV picked up some cloud variation

moon in red

all prime focus

 

Capture 1_29_2020 5_36_16 PMcc8uv.jpg

 

Capture 1_29_2020 6_29_52 PMcc8.jpg

 

 


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#14 highfnum

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Posted 04 February 2020 - 12:49 PM

a few from last night

Capture 2_3_2020 7_31_23 PMcc8b.jpg

Capture 2_3_2020 7_29_00 PMcc8.jpg


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#15 PXR-5

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Posted 04 February 2020 - 01:04 PM

Nice!!

#16 jgraham

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Posted 10 May 2020 - 12:52 AM

Beautiful lunar pictures! I received mine on Friday and had it out for first-light that night. The collimation was off just a smidge and was easy to fix. I may tweak is a bit yet as I'm hoping to use this scope for high resolution lunar and planetary imaging and observing. It'll be very interesting to see how it compares with my Mak 7. I'm still working through my first set of test images, but so far I am _very_ impressed with the flat, coma-free field. The focus doesn't seem to be overly sensitive to temperature as I only had to make one tiny adjustment of the focus around 4:00am, similar to a Newtonian.

 

My baby...

 

Atlast GSO CC8 (5-8-2020)-1.jpg

 

 


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#17 jgraham

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Posted 10 May 2020 - 12:53 AM

First-light image...

 

M57 (5-8-2020)-1j.jpg

 

M57 – The Ring Nebula in Lyra – GSO 8” f/12 CC First-Light
Telescope: GSO 8” f/12 Classical Cassegrain @ f/12, Orion Atlas EQ-G
Camera: Full Spectrum Modified Nikon D5300
Filter: 2” Orion Imaging Skyglow Filter
Guide scope: Williams Optics 50mm, Meade DSI Pro II, PHD
Exposure: 16x180sec, ISO 400, saved as RAW
Darks: Internal (Long Exposure Noise Reduction On)
Flats: 32x1/50sec, Sky flats taken at dusk
Average Light Pollution: Red zone, Bortle 8, fair transparency, bright moonlight
Lensed Sky Quality Meter: 18.1 mag/arc-sec^2
Stacking: Mean with a 2-sigma clip.
White Balance: Nebulosity Automatic
Software: Backyard Nikon, Deep Sky Stacker, Nebulosity, Photoshop


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#18 David Stevenson

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Posted 10 May 2020 - 02:50 AM

Is it a crop or the coma is zero?

#19 jgraham

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Posted 10 May 2020 - 09:55 AM

That image was cropped a tad to zoom in on the nebula. Below is an uncropped version showing that there is very little coma across the span of an APS-c sensor...

 

M57 (5-8-2020) 1200x815-1j.jpg

 

I also have a 4-panel mosaic of the waining gibbous moon that demonstrated that the field is _very_ flat. I could had sneaked it into a 2-panel mosaic if I had know that ahead of time.

 

Still learning, which is a good thing!  :)

 


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#20 davidc135

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Posted 10 May 2020 - 10:17 AM

Is it a crop or the coma is zero?

 

Coma is the same as for a F/12 Newtonian, pretty well nothing for this sensor.  David


Edited by davidc135, 10 May 2020 - 10:24 AM.

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#21 jgraham

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Posted 10 May 2020 - 11:24 AM

Fabulous! Some of my fondest memories are of nights that I spent at the eyepiece of a classic 12.5" f/10 Newtonian. The view of Halley's comet was amazing. :)

#22 jgraham

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Posted 12 May 2020 - 07:29 PM

Tonight I'm going to spend some time exploring the visual performance of the 8" f/12 GSO Classical Cassegrain. I've turned it over and mounted it on an LX70 using its Vixen rail; a nice option to have for star-hopping. Although there are benefits to fast scopes for deepsky, I enjoy observing with long f/ratio scopes as they usually give sharp, high contrast views. I'm also curious to see how it performs on double stars. I can't stay out late tonight, but it should be a lot of fun!

 

Atlas GSO CC8 (5-12-2020)-1.jpg


Edited by jgraham, 12 May 2020 - 07:30 PM.

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#23 nfotis

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Posted 16 September 2020 - 10:34 AM

Looks interesting, compared to the Skymax 180 I am considering for my HEQ5 mount.

A small problem: the mount has the thinner rail, how hard is to reverse the mounting rails in order to keep the finder scope at the top?

Are the diffraction spikes noticeable in planetary imaging? I don't like these, I have to admit.

Cheers,
N.F.

#24 Thandal

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Posted 16 September 2020 - 01:21 PM

@nfotis;

 

1.  The rails are not the same width, so neither are the mounting holes.  At least not on the GSO/Orion/A-T/other-brands (but same manufacturer) CCs currently out.  Can't just switch them "top-to-bottom".

 

2.  A classic cassegrain uses a secondary supported by spider vanes, so of course it has diffraction spikes.  But for planetary (non-point) targets, they are much less-to-not noticeable.  wink.gif


Edited by Thandal, 16 September 2020 - 01:27 PM.


#25 jgraham

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Posted 16 September 2020 - 03:00 PM

The rails are reversible on the GSO, you just need to swap the radius blocks as well. If you want to remove one of the rails to save weight you can do that as well, just buy some short screws to replace the longer ones that hold the radius blocks to the tube.

The refraction spikes are only visible around bright stars. They have no visible effect on the moon, planets, and typical double stars. The visual performance on the moon and planets is excellent. It's a dream to use with binoviewers!
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