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PostPosted: Sat Feb 20, 2016 4:33 pm 
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Hi,
I only joined the SPA last summer and I'm finding my way about.
I'm considering buying one of these telescopes but I'm looking for advice. I am an amateur photographer of intermediate level but apart from a few shots from my garden I'm just starting out with astrophotography and astronomy. I have a Canon 5D Mark III DSLR which I could connect to a telescope but then I read about CCD cameras (but some of these are really expensive). For the foreseeable future I would like to concentrate on the planets etc. both for viewing and imaging and deep sky objects at a later date and I've read it depends on the aperture you buy as to which of these you can achieve. Is it best to start with a VX 6 Or VX 8 telescope in the beginning and would I need a separate telescope if I want to later concentrate on deep sky objects? I'm getting more confused the more I read... I'm looking to spend around £1300 on a telescope like these but not much beyond that and I like the fact these are quite portable and light as I'd be mostly setting the scope up in my garden. They also align the scope for you which would really help as a beginner. Cheers.


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PostPosted: Mon Feb 22, 2016 11:48 am 
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Personally, I'd go for the VX 8. It collects almost twice as much light as the VX 6.

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PostPosted: Mon Feb 22, 2016 8:51 pm 
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brian livesey wrote:
Personally, I'd go for the VX 8. It collects almost twice as much light as the VX 6.



Thanks for your advice Brian. Am I right to start off with something like this and possibly get into deep space astrophotography etc. and all the paraphernalia some time in the future ?


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PostPosted: Mon Feb 22, 2016 9:42 pm 
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Location: Wellingborough
Hi Tracey.

You will find differing points of view and experiences regarding the use of Schmidt-Cassegrain (SCT) telescopes as general-purpose instruments for both planetary and deep-sky imaging. Here goes :) :

The 8inch SCT is a good choice for general observing and for planetary/solar/lunar imaging. For imaging in particular the long focal length of the optics gives a good image scale on the camera chip using a x2-x5 barlow lens. For planetary imaging tracking the target does not need to be pixel-perfect. The target can move around a bit in the field of view (FOV) while the camera is recording. Just how good the tracking is depends on the mounting and the weight it is carrying. As long as the target doesn't leave the FOV, the software used to stack and process the resulting video will be able to track and recover the images without much difficulty. Planetary imaging is usually carried out by recording video (usually .avi) at many frames per second to a PC (50-100 fps is typical of modern planetary cameras) then using software to select the clearest frames for stacking and processing.

For deepsky imaging we have a different set of requirements. The target is usually much dimmer than the planets and requires much longer exposures - tens of seconds to a couple of minutes per frame maybe. The mounting must be able to track very accurately over this period of time in order that the image does not blur or the stars trail. Just how well the mounting achieves this accuracy will depend on amongst other things the weight it is carrying in the telescope tube/camera/guidescope etc and the focal length of the imaging train. Most amateurs today seem to be using short focus (apo) refractors on fairly heavy mounts with a guide camera system installed for this work. Simply because it is the quickest/surest way to get reasonable results without undergoing huge problem-solving exercises.

If you really are set on using an SCT for deepsky imaging the you might like to consider the VX 8-edge model which has coma-corrected optics and slightly shorter focal length than the standard VX8. Also my advice is to get a copy of "Making Every Photon Count" and have a read through it before making any decision:
http://www.firstlightoptics.com/books/m ... hards.html

HTH and regards,

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Brian
52.3N 0.6W
Wellingborough UK.

254mm LX90 on Superwedge, WO ZS66SD, Helios 102mm f5 on EQ1, Hunter 11x80, Pentax 10x50
ASI120MC Toucam Pros 740k/840k/900nc mono, Pentax K110D
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PostPosted: Tue Feb 23, 2016 12:02 am 
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Hi again Brian and thanks very much for your detailed answer.Deep sky imaging does sound more involved and as a total beginner I will probably be better off starting with planetary astrophotography and at the start just get used to finding things so I don't want to go too far too quickly and make the right decision.Thanks for the link to the book, I'll have a look at it.Kind regards, Tracey Hodgson. P.S. I'm only using binoculars now so there's much to learn even with the basics but I'm keen to do so.


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PostPosted: Tue Feb 23, 2016 4:26 pm 
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A point to bear in mind Tracey is that resolution is a function of aperture. The bigger the aperture and the finer the details we can see. This is important for extended objects like planets.
By the way, the previous post was from a different Brian, not from me. Brian knows a lot more about imaging than I do. There are quite a few Brians on the forum. :D

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PostPosted: Tue Feb 23, 2016 5:57 pm 
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Hello again Brian - sorry I mixed you up with the other Brian but I am completely new to the forum. From your further comment about aperture will the VX8 be enough for my purposes for quite some time? The bigger aperture scopes are much heavier from what I'm reading and more expensive. If I decided to buy the VX8 and then in the future needed a bigger aperture can you attach a different telescope to the same mount like you can a camera tripod? Sorry if I sound a little bit vague but I've been reading and considering telescopes for months and want to make a good choice hopefully something which will last for years and not have to sell in a year or two. Kind Regards, Tracey.


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PostPosted: Tue Feb 23, 2016 7:32 pm 
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Location: Wellingborough
Hello Tracey. Brian from Wellingborough this time :D

Just to say if you look in the Gallery section here you will find examples of images made with both the C6 and C8 telescopes, although not necessarily using the VX mounting. Look out for posters "smerral" and "Ian Papworth" in particular.

And of course binoculars are an excellent way of learning the night sky. Every sky-watcher needs a good pair of binoculars as well as a telescope :)

Regards

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52.3N 0.6W
Wellingborough UK.

254mm LX90 on Superwedge, WO ZS66SD, Helios 102mm f5 on EQ1, Hunter 11x80, Pentax 10x50
ASI120MC Toucam Pros 740k/840k/900nc mono, Pentax K110D
Ro-Ro roof shed


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PostPosted: Wed Feb 24, 2016 12:33 am 
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Hi Brian from Wellingborough, getting the hang of this now! 8) Thanks about the gallery, will have a good look. I'm enjoying using my binoculars, I've mounted then on to my camera tripod now too for more stability.Kind Regards, Tracey. :)


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PostPosted: Wed Feb 24, 2016 2:23 pm 
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An 8-inch aperture, in dark skies, makes for a powerful telescope Tracey. A serious limiting factor for many observers these days, including Yours Truly, is light pollution. How is it at your site for dark sky conditions?
I can't comment on whether the mounting on the VX-8 will take a bigger 'scope later on, as I've never used particular mounting.

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PostPosted: Wed Feb 24, 2016 9:19 pm 
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Hi Brian, that sounds good thanks. Unfortunately like you I do suffer from light pollution and I'm observing via my binoculars from my back garden which has buildings on both sides. The best view though is across a bowling green and that gets quite dark and although it's not ideal it's the best I've got as I don't drive so can't get to any dark skies although I've just joined my local Astronomical society in Cardiff and they have access to a professional observatory so maybe in time with contacts I'll get a chance to go there or another dark sky area they also sometimes go to.
Thanks about your comment about the mounting - maybe someone else will have used that mounting but the VX- 8 does sound a good choice (it's recommended as a good all rounder in my book ' The Backyard Astronomers Handbook') or the VX 8 Edge. Kind Regards, Tracey. :)


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PostPosted: Thu Feb 25, 2016 7:05 pm 
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Hi Tracey.

One often overlooked aspect of buying/owning a telescope is the physical size and weight of the thing. This can be an important consideration even if you are setting up in your own garden, and is even more important if you are going to load it into a car and go off somewhere dark to do your observing. If you look up the VX telescopes on (say) FLO's site you will find size and weight info under the "specifications" tab:

http://www.firstlightoptics.com/advanced-vx-goto.html
http://www.firstlightoptics.com/advance ... -goto.html

The VX-8 comes in at 27Kg total, which includes tube= 6Kg, mounting= 8Kg, tripod= 8Kg and counterweight= 5Kg each. Putting these together can be physically demanding, not just the weight but the fact that you will need to lift into place then hold each piece with one hand while securely tightening bolts and fasteners with the other :) The last thing you need is for your precious optical tube assembly to come sliding out of the dovetail groove on the mounting because the holding bolts are not quite tight enough. And if your head comes into contact with a counterweight you will literally see stars. These misfortunes have happened to observers in the past and will happen in the future :wink:

For some interesting reading have a look at Astro-Babys website - (yes, she is an astronomer)
http://www.astro-baby.com/astro_baby_about_me.html

and this thread on Stargazers Lounge about the size of astronomical telescopes:
https://stargazerslounge.com/topic/8936 ... hat-thing/

Best regards,

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Brian
52.3N 0.6W
Wellingborough UK.

254mm LX90 on Superwedge, WO ZS66SD, Helios 102mm f5 on EQ1, Hunter 11x80, Pentax 10x50
ASI120MC Toucam Pros 740k/840k/900nc mono, Pentax K110D
Ro-Ro roof shed


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PostPosted: Thu Feb 25, 2016 9:05 pm 
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Hi Brian,
Thanks for your further advice. I will have a good look at the sites you kindly recommended.
It certainly isn't something to just buy without a great deal of thought. Regarding the weight I'm only about eight and a half stone so I don't want to do myself an injury and the weight you described is pretty hefty to me. I'll let you know of my findings. Thanks again, Tracey. :)


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PostPosted: Sat Mar 12, 2016 2:08 pm 
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Hi Brian, Just a further update. I had a look at those sites etc, good food for thought. I also enquired at my local astronomy society and have been put in touch with a committee member who will meet up with me and explain about different telescopes in more detail. Thanks again for your help. Tracey. :)


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PostPosted: Sun Mar 13, 2016 10:04 pm 
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Hi Tracey. Glad to help. Keep us informed how you get on,

regards,

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Brian
52.3N 0.6W
Wellingborough UK.

254mm LX90 on Superwedge, WO ZS66SD, Helios 102mm f5 on EQ1, Hunter 11x80, Pentax 10x50
ASI120MC Toucam Pros 740k/840k/900nc mono, Pentax K110D
Ro-Ro roof shed


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