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Altair Astro 8" f4 Imaging Newtonian

earth titan

By earth titan
in Member Equipment Reviews

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Stephen

Stephen

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I hate centre dotting a mirror.

Recipe for disaster.

Anyhows, old one off and new one on.

Spot on.

Which is why I refuse to do it :icon_scratch:

In all seriousness though, the optical centre could easily be 1mm out from the geometric centre could it not?

(Edit) Hmm, sure the email I got said 1mm? Did you further refine the measurement?

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earth titan

earth titan

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I'm not sure about the accuracy of the mirror centre, for a commercilly ground mirror, but if you do it by hand it should be exactly central (randomness of strokes etc.). I'm hoping it will be within 1mm, which is the accuracy I hope for when I redo a centre dot. On a fast f4, 1mm is a lot. Startest is the only real way to tell but in the UK, star testing is often difficult on fast scopes due to seeing etc.

Still hate doing it....!

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Stephen

Stephen

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I'm not sure about the accuracy of the mirror centre, for a commercilly ground mirror, but if you do it by hand it should be exactly central (randomness of strokes etc.). I'm hoping it will be within 1mm, which is the accuracy I hope for when I redo a centre dot. On a fast f4, 1mm is a lot. Startest is the only real way to tell but in the UK, star testing is often difficult on fast scopes due to seeing etc.

Still hate doing it....!

I've got to measure mine up tonight. To be honest if mine is only a mm off from the geometric centre, I'll be tempted to leave it to margin of error of the mirror and rely on the (difficult) star test :icon_scratch:

I've already dropped a screw on the primary (thankfully no damage!) and don't want to do much more to it.

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earth titan

earth titan

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I've got to measure mine up tonight. To be honest if mine is only a mm off from the geometric centre, I'll be tempted to leave it to margin of error of the mirror and rely on the (difficult) star test :icon_scratch:

I've already dropped a screw on the primary (thankfully no damage!) and don't want to do much more to it.

I would agree. If it's as close as that then you won't get closer by hand anyway. 2mm was a bit much for my liking

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Coco

Coco

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I know you guy's are getting on with it but jeez.... are these not 'imaging' scopes? why all the trouble, surely the supplier should be able to do this on your behalf, I'm reading this with total amazement that it didn't arrive ready for a quick collimate and then imaging session..

99% would have returned them.. I for one am not buying one because I cant be bothered with the head ache.. It'll be a quattro for me , hope it comes with tube rings tho or I'll be eating my words.. :icon_scratch:

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Stephen

Stephen

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I know you guy's are getting on with it but jeez.... are these not 'imaging' scopes? why all the trouble, surely the supplier should be able to do this on your behalf, I'm reading this with total amazement that it didn't arrive ready for a quick collimate and then imaging session..

99% would have returned them.. I for one am not buying one because I cant be bothered with the head ache.. It'll be a quattro for me , hope it comes with tube rings tho or I'll be eating my words.. :icon_scratch:

Inherent in less than premium Newtonian design I guess?

To the best of my knowledge, Quattros have similar issues (they are the same price point as the GSO ones.)

(Edit) Ref : http://stargazerslounge.com/imaging-discussion/154458-second-first-light-quattro-8-cf.html

I'm not sure your 99% comment is accurate though. I personally bought it knowing it needed a little massaging.

Then again I've modded every Newtonian I've had to get it spot on :D

(Edit) and don't most Newts get flocked anyway?

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Stephen

Stephen

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I am.

Ditto but don't tell anyone :D

FYI The three smaller bobs of silicone haven't worked for me. The movement is less, but there's still movement.

I have resolved it by shimming two of the three lateral cork spacers with a strip of thin "spam style" cardboard and taped it to the side of the mirror.

I've also ordered the uprated springs, I'm going to set it up like my 200P with strong springs and collimation bolts only (no lockers.) The 200P holds like a rock so I trust this will be the same :icon_scratch:

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Catanonia

Catanonia

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Nice work mate and 2mm, wow that is a lot of error / margin just like my primary delivered was.

Fingers crossed for you mate, a lot of us having fun with these GSO 8 inchers.

Just taking images now myself, colimation is holding, but at F2.8 there is still something not quite right with stars at bottom edge of the image. But appears much better than before.

Currently imaging M33 at 5 min LRGB F2.8. Can wait :icon_scratch:

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Deneb

Deneb

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I know you guy's are getting on with it but jeez.... are these not 'imaging' scopes? why all the trouble, surely the supplier should be able to do this on your behalf, I'm reading this with total amazement that it didn't arrive ready for a quick collimate and then imaging session..

99% would have returned them.. I for one am not buying one because I cant be bothered with the head ache.. It'll be a quattro for me , hope it comes with tube rings tho or I'll be eating my words.. :D

I would have to agree with you Guy, from a personal perspective after having a few telescopes :( & also mucking around & wasting good nights on gear which should have been put right from the manufacturer in the beginning, it looks a complete disaster & I for one would have sent it back too, regardless if it was clearance or retailed at a good price...I have deliberatly stayed away with this thread, but can't ignore it further, even though the OP made a choice himself in buying this scope, I also feel he's got a raw deal from it as well.

It's bad enough that you have to put silicon on the primary mirror cell to stabilise it, or spend more money on flocking the scope to make the internals darker, when the manufacturer could not be bothered to manufacture it better even if it would probably add a few quid extra for the buyer. These are signs of steer clear ...

Why should retailers supply this c-rap to consumers & get away with it. We depart with our hard earned cash & should expect better from the manufactures & suppliers, also I am for one who will name & shame and nor do I care if suppliers are watching this thread becuase I can spill the beans on a few stories as well....:icon_scratch: regardless if I have spent thousands, hundreds or a few pounds with the supplier...

Time is precious folks, especially in this part of the world, where only have only a few handful nights of excellent viewing. Where we don't have precious skies like some places in in the world, so Time is a major factor here & we expect better...

@ Kh3ldar

To the best of my knowledge, Quattros have similar issues (they are the same price point as the GSO ones.)
Oh ! Really, How is that so ?
We all know that the scope which Mike Wilson had was supplied with the wrong tube rings (& that was a big mistake from Skywatcher) & that the secondary was off axis after later inspection, the same scope was reviewed with MartinB, apart from the focuser change nothing else was different & certainly no silicon usage of the primary mirror cell... here's the updated image taken with the same scope:

http://stargazerslounge.com/imaging-deep-sky/158861-8-f4-quattro-gso-newts-m33-first-light-review.html

Not to hijack the thread...I had my Quattro 8S out last night using the stock focuser with a 1100D, collimated the scope with the hotech, that took 10mins the conditions were far from good, but still managed to get an hours worth of data on The Tadpoles, just to see how this scope performs at f/4... I will be doing a review of the scope at a later stage.

IC4101024.jpg

Anyway I think i've said enough now folks just my 2p's worth of an opinion, Anyway Tom, hope you sort out your scope soon as it looks good for a few days....;)

Nadeem.

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Coco

Coco

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Inherent in less than premium Newtonian design I guess?
Agreed less than premium, but where does premium start? :(
To the best of my knowledge, Quattros have similar issues (they are the same price point as the GSO ones.)
Not sure if they are similar but the first Gen Quattro’s did have 1 customer packaging issue, no reports since.:D

I'm not sure your 99% comment is accurate though. I personally bought it knowing it needed a little massaging.

99% maybe sweeping but am fairly comfortable with it..:)

(Edit) and don't most Newts get flocked anyway?

depends whether is was ''Totally flocked'' when you bought it ..sorry old joke..;)

If you're into pottering about this is all well and good, but the UK weather frustrates me so much I can’t be bothered experimenting with a bad original design, let’s face it, it’s a weak design, unless its original purpose was an expensive toy. It simply shouldn't need extensive modification that originally would cost a few NT$ in the first place.:icon_scratch:

Knocking these out as bargain shop display or EXDEMO is in my opinion a good excuse to dump, but for £299 it will attract imagers on a tight budget or just tight themselves that may not have your skill in tuning Newtonian s:) . I’m sure you will get there in the end; I just wonder how long you’ll keep it for :)

Good luck anyway...

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Stephen

Stephen

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depends whether is was ''Totally flocked'' when you bought it ..sorry old joke..:icon_scratch:

PMSL :D

Fair points guys ;)

I just wonder how long you’ll keep it for :)

Until the next scope catches my eye of course! I'm not as bad as some for kit cycling (no names mentioned!!) but things to have a habit of moving on in the 12 month sort of time frame :(

I fear we've hijacked Tom's thread though! :)

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