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View Full Version here: : Oooh Aaahh! First look at GSO 8" RC..


AlexN
25-03-2009, 03:28 PM
Well the new baby has arrived today.. There is a full review to come, this is just the "Im excited" prelude to that. :)

The courier knocked on the door at 2:30 this after noon, just after I got home from work.. I was really quite shocked at the weight of the box... It was rather heavy for a 6kg OTA... Upon opening the cardboard box, I was met by a large, lockable aluminium carry case... A very welcome addition that I wasn't aware was part of the package! :)

Opening the aluminium box, my attention was immediately taken by the glossy appearance of the carbon fibre OTA, its overall feel is very good, Its very solidly built, Focuser is as you'd expect from GSO.. Its smooth, but not the best I've ever felt.. Its a thread on item, much like an SCT focuser, however the thread is a little different, I have no doubt that Moonlite will facilitate a custom focuser flange for me.. :)

Internally, the OTA looks very dark, the baffles look the goods.. The Primary baffle looks a little thin, however untill I can do a test using a large imaging chip, I wont know if its too thin.. All in all Im impressed with what I see... The only thing that isnt impressive is the fact that it was crystal clear last night, and it looks like its going to rain tonight... :(

First light to come soon, and once thats done, then I'll write up a full review covering collimation, field flatness, focuser load bearing performance etc..

The opinion thus far is very high.. It definitely looks and feels very good indeed...

More to come..

Some Pics!

toryglen-boy
25-03-2009, 03:37 PM
looks well nice

;)

Starkler
25-03-2009, 03:43 PM
Does it have collimation adjustments for the primary as well as the secondary?

AlexN
25-03-2009, 03:45 PM
The primary is fixed. Its got secondary adjustment, and a push pull collimation setup for the focuser...

leinad
25-03-2009, 04:17 PM
Ooh pretty!
Still got the guidescopes and accessories to add to it?
Cant wait to see some images.

gbeal
25-03-2009, 04:23 PM
Congrats Alex, shoot some piccies with it, put everyone out of their misery.
Gary

Mighty_oz
25-03-2009, 04:25 PM
Congrats on your newest baby :) May she (?) give u lots of love back :)

jjjnettie
25-03-2009, 04:40 PM
Very nice Alex.
I got my new mount today too.
Wonder what the rain gods are going to throw at us?

AlexN
25-03-2009, 04:52 PM
First light images will be with the SBIG ST9E, self guided, as I don't still have guiding hardware.. I will have to spend up a bit more and organise that for when I get a hold of a modded DSLR.. Still deciding on whether to go for a OAG setup or a separate guide scope.. Time will tell...

First light should be this weekend, provided the weather plays nice.. :D

Jeanette, Congrats on your new toy also! I think between your mount, Robin's Starlight Xpress camera and My RC, Brisbane is in for some rain.. :)

marki
25-03-2009, 08:04 PM
Looking forward to seeing some images from the beast Alex. Have you got a ronchi eyepiece to test the mirrors?

Ciao Mark

telecasterguru
25-03-2009, 08:35 PM
Alex,
I am very jealous, the scope looks great. Have fun.
Frank

ozstockman
25-03-2009, 09:34 PM
Alex,

Congrats on your new toy. I hope it will perform as good as it looks.

cheers,

Mike

Tilt
25-03-2009, 09:42 PM
Woohoo! :thumbsup: Alex, someone had to do it and I had a feeling it was going to be you. Congrats on the purchase and I'm sure there are going to be some great imaging sessions coming up (once the clouds move on).

Michael

TJD
25-03-2009, 09:54 PM
wow i hope it gives you amzing pics looks amazing any way some one had to let there wollet throw up:D

AlexN
25-03-2009, 10:09 PM
Thanks everyone! I must say after spending an hour or so pawing over every inch of it I must say I'm happy I went ahead and got it... ITS SO LIGHT!! Compared to every other scope I've owned its weightless!

Marki - I don't have a ronchi tester myself, however I have a friend who has one, So I'll get a hold of it and test it out...

Chippy
26-03-2009, 12:28 AM
Congratulations Alex, she looks a beaut!!! Less weight will be a big advantage, especially for imaging. Looking forward to hearing how she tests out!

madwayne
26-03-2009, 06:06 AM
Hi Alex

Firstly congrats on the new scope, it looks an absolute treat and I can't wait to see how you get on with it.

Re the modded camera. I know of an excellent modded 20D that will be going on the market soon. It has only taken 2,000 (if that) actuations ;).

Good luck with the first light and I look forward to your comprehensive report.

Regards
Wayne

dugnsuz
26-03-2009, 12:26 PM
Well done Alex.
I look forward to your first images from the scope.
Doug

gregbradley
26-03-2009, 03:46 PM
Gee that looks nice and a case as well!

I like the baffled tube. My RCOS didn't have that. I see some nasty reflections off bright stars on some RCOS images.

Looking forward to some images.

What is the focal length and F ratio?

Fixed primary and collimatable focuser could be a good thing.

Carbon fibre tube is nice. How much do they cost?

Greg.

bluescope
26-03-2009, 03:52 PM
Looks very nice Alex ... congratulations !

:thumbsup:

bluescope
26-03-2009, 03:54 PM
Here it is Greg ... I just checked too ;)

http://www.andrewscom.com.au/site-section-10.htm

:thumbsup:

AlexN
26-03-2009, 04:00 PM
Thanks for the comments guys.. First light should **SHOULD** be tomorrow night, all things being equal though, it will probably dump rain tomorrow, and all weekend!

Wayne - Thanks mate, I appreciate the heads up, at the moment im in the middle of organising a modded 30D through Eric, should that fall through for any reason, I'll get on to you straight away.. :)

Greg - the scope is an 8" F/8 @ 1624mm. The scope cost me $2495. Should the optics preform as they are supposed to, I think this will be a great scope.. awesome bang for buck..

The only way I could see the fixed primary as a bad thing is if 1.) the scope was dropped skewing the rear cell (which would have to be a nasty drop) or 2.) whatever is used to fix the mirror in place has poor thermal expansion qualities... There would be no need for the CF Tube and Quartz optics should the mirror fixing setup cause the mirror to change shape or be moved due to expansion..

Both of those things Im sure GSO thought about... Im not quite ready to pull the scope apart and find out how its all put together JUUUUST yet! :)

Satchmo
26-03-2009, 05:19 PM
Hope it doesn't have the same level of surface roughness as the two scopes independentaly tested on the German website. Those guys must have been incredibly unlucky receiving two lemons to test.

Mark

matt
26-03-2009, 05:31 PM
That's pretty much the forecast, mate:( Showers, anyway.

Ah well....think of how clean the air will be when you finally get to point that beauty at the sky:D

gregbradley
26-03-2009, 06:19 PM
Greg - the scope is an 8" F/8 @ 1624mm. The scope cost me $2495. Should the optics preform as they are supposed to, I think this will be a great scope.. awesome bang for buck..


Thanks Alex.

Incredible value.

Greg.

jase
26-03-2009, 06:26 PM
Is the sky clear yet? Keen to see how quality control has stacked up with this scope. Looking forward to seeing the first light image.

Zaps
26-03-2009, 06:26 PM
Yes those results have me worried too. I'm hoping they both got early examples which were basically prototypes, and that production versions now have the figuring sorted.

Vader
28-03-2009, 03:43 AM
There is no real hope that other newer samples will be even a bit better.
These tested scopes has very good spherical aberration correction - in other words, we see, that the systems were figured. The bad microrelief is the
result of figuring technique. Such systems has very high aspherics
gradients, especially on secondary mirrors. It is quite difficult and time
consumption to make such aspherics smooth. Any fast metods will cause
such rawdness of surfaces resulting very poor energy concentration
and really no diffraction images.
If these cheap RC scopes will be tested with interferometer where it's camera has large
scale frame, with processing of several thousands reference points,
the results of optical quality will be even worser.

There are no fast and cheap ways to make such aspherics smooth.
Therefore all really good R-C telescopes are expensive.
If an 8" RC scope is going for $3000, then don't expect real quality.


VD

White Rabbit
30-03-2009, 07:12 AM
Wow, way to go, raining on the guys parade. Let him at least get it out of the box and play with it before you slam it.

gbeal
30-03-2009, 09:39 AM
Yes, I agree, let him enjoy the moment, and in some respects until we have some images all this good or bad is conjecture anyway.
Go Alex.

AlexN
30-03-2009, 03:18 PM
Cheers White Rabbit and Gary, I appreciate the support on this.. Unfortunately, the scope still hasnt met the mount, due to prior commitments and weather.. Once I've taken some images I'll be glad to hear everyones opinions, Until then, the speculation that the scope will be a dud is perhaps a little premature... I don't know if anyone else has found one, but im yet to see a review of a final production model of this scope...

Fingers crossed for first light THIS weekend.... Might have to suffer a horrible day at work if we get a stunning night during this week.. I dont think I can hold off any longer! :)

Matty P
30-03-2009, 04:47 PM
Awesome stuff Alex! :D It looks like a great scope for the price. I'm really interested to see what it can produce. Can't wait. :)

Good luck with weather this weekend. ;)

Zaps
30-03-2009, 06:44 PM
Vader=VD=Valery Deryuzhin at Aries Optical, a competing vendor and known hater of Chinese made telescopes which threaten to eat his lunch? Not an objective opinion maybe?

Pardon me if I'm wrong.

netwolf
30-03-2009, 08:18 PM
Congrats Alex and best of luck with your new scope. I for one am optimisitic that yours will perform better than others in the past.

Chippy
31-03-2009, 09:33 AM
Me too!!!

Vader
31-03-2009, 09:52 AM
You are right guessing whom I am. But no more.
I just explained, that there is no real hope, that next samples of these
8" RC will be better made optically. They can be improved in the
mechanical design, focurer, outside style etc. They can't be improved
optically - because of nature of these things. High gradient aspherics
CAN'T be made fast and cheap. Again: high gradient aspherics
CAN'T be made fast and cheap.
The same was with attempts to obtain very smooth optics in fast made
SCT. With some variations they always suffer of surface roughness.
But they suffer less, than these cheap RC.
Even spherical optics being fast made are not smooth at all - zones,
surface roughness etc. What we can expect from $1395 RC where
aspherics is really huge?
If you don't believe, no problem, you can check if your guess is right -
that next samples will be significantly better than tested crap ones- just
buy one of later sample and look yourself.

And why these scopes were dropped from $3000 to just $1395 ?
I can tell you - they are really crap. They are MUCH worser than even
RCX from Meade! RCX are coma-free design of SCT and their optics is
way smoother, than fast cheaply made taiwanese RC.
If you like to pay your backs for a magical "RC", do it. But others, I believe, have all rights to know what is what and make their choice with open eyes.
As a person, who know this subject, I can't recommend to buy cheaply
made RCs. Peoples will spend their money much wiser buying Meade RCX.
They are not a high-end RC, of course, but they are definitely better, than cheap, crap taiwanese RC.

toryglen-boy
31-03-2009, 09:56 AM
this is all getting a bit strong, aint it?

just let the guy enjoy his scope .... jeez


:rolleyes:

avandonk
31-03-2009, 09:58 AM
From just looking at the detail of this scopes construction, all very good in my opinion, I hardly think the manufacturer would then NOT install optical components that at least match the rest of the scope. Obviously only a test will tell. It all looks very good to me. Just don't rush the test Alex as it will take time to optimise everything. If I had it in my hot little hands I would be itching to try it out too!

Hope the weather is kind to you.

Bert

White Rabbit
31-03-2009, 10:05 AM
Yeah, theres no pressure to produce stunning results on the first night or anything lol.

Just enjoy the scope it has to be better than my 8" GSO newt that cost me $300, brand new rolf.

matt
31-03-2009, 10:28 AM
If only these danged forecast showers and cloud would go away...

We're predicted to get some very nice seeing in Bris from Wednesday onwards. At least for 2-3 days...

But as usual, it's clouded out when Brisbane finally gets a run of good seeing:mad2:

Garyh
31-03-2009, 11:06 AM
oh dear, lighten up people! Hope the scope meets your expectations Alex!
All that matters is that you are happy with the final image!
You go and look at tests done on many SCT`s both Celestron and Meade and the numbers don`t look any better.

omnivorr
31-03-2009, 01:44 PM
Heehee.. ignore ol' VD there tryin to put a pox on it Alex :P
take yer time.. and enjoy!
we're all wishin' those clouds away ;)
but we can wait if they linger longer..

good things come to those who do.. and the journey is at least half of the fun! ....after all, once the destination is achieved, what is there but memories? ...unless new challenges to scheme ;)

Zaps
31-03-2009, 02:21 PM
Here's what I'm thinking: Chinese/Taiwanese manufacturers have gone from being a joke to consistently mass-producing refractor doublet lenses which are 90-95% of the quality of far more expensive big name telescope makers.

They have also been offering inexpensive mass produced newt mirrors which are much improved from early examples and which contine to improve.

So maybe they can eventually offer mass-produced RC class optics which are 90-95% of the quality of today's extremely expensive suppliers, even if it means raising their prices a little? They would have to raise their prices a LOT before they weren't price competitive with the big names.

It's not surprising that the makers of very expensive optics are getting nervous about Chinese and Taiwanese factory production! If guys like us can immediately get an off the shelf RC with excellent optics (90-95% quality) for a helluva lot less than the extemely expensive "you'll get it when we say you'll get it" guys, we'll be bloody thrilled!

:lol::P;)

netwolf
31-03-2009, 02:31 PM
The assumption that because it is cheap it must be made fast and therefore not be of good quality seems a bit of a stretch. Labour is not so expensive in SE Asia that they need to produce at great speed. Its is a matter of record that optics from China always improve over time to be acceptable for our standard of use.

AlexN
31-03-2009, 03:21 PM
Still waiting for a test night... Im sure enjoying all this debate over the quality of the optics in a scope that nobody has really properly tested yet... Its amusing to see so many people, smart people, having a go at something that they themselves may never have even seen in person.. :)

I am waiting for a perfect night to test it... theres been a couple of nights where majority of the sky was clear with some storm clouds far south south east on the horizon, I consider nights like that to be less than perfect as there could be a light haze thats difficult to see, water particles in the air carrying light pollution etc etc.. Im waiting for a perfectly clear night to point the scope at one target for 6 hours and see what I can get out of it! :)

Paul Haese
31-03-2009, 04:37 PM
Alex I wish you all the luck. The construction of the scope from the images looks really good. Probably as good as my C14 (which externally looks really cheaply made; yet the images it produces speak volumes).. And; the scope comes with a case, my Tak came in a cardboard box????

Several things stand out in my mind. The vendors will at least consider this. The Chinese manufacturers want to sell these things. The fact they have gone to the trouble to install what looks like a heap of baffles, use carbon fibre and put this together nicely says to me it is likely that the optics are reasonable to good at worst. They are well aware that several bad reviews of the scopes is gonna kill any potential they might have had. It does not make sense to try to sell crap in this current climate.

Secondly, Chinese optics are now a really good quality; ok not diffraction limited but for the price if they produce lovely tight stars and wonderful looking images (which is entirely possible) then this will put pressure on the more expensive guys to drop their prices if they want to survive in the current financial climate. These optics are catering for blokes and gals that don't have the capital reserves of a small country. Astronomy has nearly always been for the rich, this has been starting to change in the last 6 years.

I am looking at these scopes myself and think even if it is badly figured I can always send it back for either a new one or get my money back. What harm is there in buying them that I ask you nah sayers? Least I will not be paying 25K plus and still run the risk of it being damaged or not up to par.

Good luck Alex.

Vader
31-03-2009, 05:00 PM
You took it wrong. We have enough orders for high-end optics (not only for RC systems) with a turn for year or two ahead. 90% of them are not from amateurs.

Then you are wrong about 90-95% of quality by chineses.
These tested 8" RC do not produce diffraction images at all! Just a
blob. No Airy disk, no diffraction rings.
So, this is just light concentrator, not a telescope.

And the most important. I do not advice to by our products - they are
really expensive and, possibly, are beyond of your buying abilities.
We also do not produce something smaller, than 16".
I just point out - these cheaply, fast made RC from taiwan are crap.
One can spend money much better bying Meade RCX aplanatic
SCT. They are free from coma too, but their mafucacturing technique
allows to produce optics much smoother, than crap taiwanese RC.
RCX by Meade is a very good choice for astrophotographers with
limited pockets. These scopes are decent astrographs, which really
produce diffraction images and not a blob.

Hope you do understand now.

Chippy
31-03-2009, 05:49 PM
Time will tell eh... but I'm betting on something a bit better than a blob from these new RC's !! ;)

gregbradley
31-03-2009, 07:48 PM
Wow its just like the old RCX is not an RC days!

This scope is causing a stir. I wonder why.

It certainly looks impressive.

There's also companies that do refiguring of mirrors as a backup and you'd still be way ahead on price.

Greg.

Bassnut
31-03-2009, 07:53 PM
Yes, a very interesting thread, cant wait for 1st light.

marki
31-03-2009, 08:09 PM
Vader, the images I seen from these scopes (links are on this site somewhere:shrug:) are far from being blobs. Just as an exercise in weighing up your suggested alternate scope I have done a little research and this is what I have found. Meade no longer list the RCX 8", 10" 12" or 14" fork mounts on their web site so I assume they have stopped producing them due to going broke. None of the australian importers list these scopes either. What meade still list in the RCX line is the 16" and 20" tubes. Working with the smallest and cheapest 16" tube the cost in US dollars is $39 999.00. Now you will need a big mount to carry this tube as it weighs a tonne so Meade offer the max mount at a poultry $29 999.00 US. These figures converted in AU dollars is $57 976 and $43 481.75 respectively. Without considering GST and import duties the cost would be $101457.75. Now lets compare that figure to what Alex paid. GSO 8" RC from andrews = $2499.00. EQ6 Pro = $1999.00. Total = $ 4498.00. The difference is $96959.00. Hmmm thats a fair comparison :D. Perhaps Alex could use the 97K he saved to buy a 20" planewave like Gama's as they are far better then RC's anyway.

Mark

netwolf
31-03-2009, 08:19 PM
Where is Meade building there RCX optics now? Have the not moved this to Mexico? I have poste previously links showing Meade and Celestron low end scopes being made in the same factory in SE Asia.

Vader truely i dont understand why you insist on making statements you can not back up. Check out the multitude of images taken on this forum and others with Chines made scopes and come back and tell us about the blob they produce. I am not suggsting you have an agenda to push your scope but you do seem to have a very very one track opinion with no room to move. I think perhaps this is the reason CN has such strict rules on Vendors not commenting on other vendors products. It is truely unfair to attack a vendor who is not present to defend there product. I think it goes against the spirit of this forum. I am sure others here even those who might share your view would agree with me that this is not the way to present an argument. You have shown no test results you have done yourself or anything but just laid waste to a vendor's reputation. I dont often speak out on such matterrs, but I will call you to adjust your tone.

Alex i am sorry to take your thread of topic. But sometimes we can not stand by.

Regards
Fahim



Regards

Tandum
31-03-2009, 09:15 PM
Jezz Alex, and I thought I was a stirrer. Imagine getting a thread locked for buying a scope :rofl:

I just got home and it's clear as a bell out there. Go shoot some blobs :screwy:



[edit]
Mechanically it looks a lot like my VC200L doesn't it.
But the pressure is on now mate ....
How any photos have you done with that sbig?
Want to borrow a 40D. Point and click ?

Sucks to be you just now :)

jjjnettie
31-03-2009, 09:21 PM
I gave Alex an invite to come up for some dark skies tonight too.
tsk tsk tsk
You're missing out mate.

marki
31-03-2009, 09:35 PM
Hahaha :rofl::rofl::rofl::rofl::rofl:

Kal
31-03-2009, 09:59 PM
I don't know if you have seen this pic (http://www.astronomics.com/main/image_detail.asp?catalog_name=Astro nomics&category_name=U5QNWB3RKWWL8N3EL99F9 DX9A0&product_id=iv1jfuud4jwmj9m9rst) taken wuth the Astro-Tech 6" RC of the moon. Too bad it only resolves into blobs, washes out all that detail!! ;):P:rolleyes:

netwolf
31-03-2009, 11:42 PM
Kal i did see that blob, and the blobbin detail is great.

Vader
01-04-2009, 01:10 AM
Look here http://astro.uni-tuebingen.de/~grzy/APO.html

8" RC by GSO. Look at the star image. This is really blob. And this is in
almost perfect seeing conditions - in the air of laboratory. It will be really horrible under real sky.

Read numerical findings: Strehl is about 0.5. And with spherical aberration
removed. Without removing spherical aberration Strehl is lower than 0.25!!! I specially reprocessed these interferograms. No diffraction image at all. This is crap of a crap. Not a telescope. Image quality on a level of multilens telephoto objective, not better,
Of course, it will produce star images on CCD chip with sharpness of
ordinary telephoto. My Canon EF 200mm F/1,8 produce better images.

At the pointed website look at the upper tested telescope 16" F/10 ACF
Meade (former RCX) - it show Airy disk and first diffraction ring with
moderate optics roughness. But this scope being 2x larger is at least
5 better optically than tested below 8" RC by GSO.

However if you think that these cheaply made RC from GSO deliver
decent images, far from blobs, no problem - buy it and use it.
Wiser guys will, however, buy RCX or ACF alternatives.

If RC scopes can be produced cheap and smooth, believe me, there
will be a lot of these telescopes before these taiwanese guys introduced
their crap tubes as RC scopes.
No free lunch.
16" f/10 ACF

16" f/10 ACF

Tandum
01-04-2009, 01:17 AM
Vader,
Do you have any results from other domestic scopes as a comparison? I notice this 8" RC is mechanically a Vixen VC200L copy. There is no point comparing it to a 16" anything. No one here can lift a 16" scope.

Vader
01-04-2009, 01:35 AM
Real RC scope should produce PINPOINTstar images. Not soft cotton blobs.

Second: CN is a property of a vendor, who actively trying to sell these
craps and make money. Therefore no one can tell peoples there what is what.
You will never buy our scopes - they are too expensive for you, too long
to wait as well. But why can't you think, that I am a honest man, a former amateur astronomer (before my university years) and now I am amateur astronomer again (since many years) - why can't I give you a good advice - do not by crap RC by GSO? Buy another astrograph - MAk, RCX, MN or APO. Spend your hardly earned money wiser, than being hooked at such a cheap bite.

If you don't believe me, go to AstroMart in Refractors forum or in a Yahoo apug group and ask Roland Christen about these thested 8" RC by GSO. Give him a link and ask his opinion about these tested scopes. I am sure he will answer your questions honestly.

And tell me - will you buy these crap RC for yourself?

At the last note - such crap RC just compromise an excellent reputation
of true RC scopes. I don't like to see this as well.

Buy a smaller TAKAHASHI BRC250 and I will congratulate you with a
good choice. Buy a Maksutov astrograph and I will congratulate you
with good choice too.
I understand, you are hoping to get an excellent scope for nothing.
But, sorry, this is empty dream. As more you and others will buy crap
scopes eating these cheap bites, as more crap scopes will flood the
market.
Your money - your choice. I merely trying to advice you to make better
choice, note, not from our production line.

Tandum
01-04-2009, 01:46 AM
OK Darth ... how much for a real 8" RC scope from you're company ?

I think what you don't understand is that we are not professionals and do not buy professional equipment.

Vader
01-04-2009, 01:47 AM
The best comparition is interferometric test. I am not interested in
any these subjective comparitions at a backyard. Interferometer and
star image in collimator tell me all I need. You can surf that test scopes
site and you will not see such a crap telescope like this 8" RC by GSO.
Not even close.

However, if you all think, that I trying to foolish you all telling false
info, no problem, buy these craps and be happy.

Octane
01-04-2009, 01:50 AM
Robin,

There's no need to be like that.

Part of communicating effectively is dealing with cultural differences.

I, for one, am swayed by Valery's arguments. I was initially going to spend my money and buy one of these things, but, my mind's changed now.

Regards,
Humayun

celstark
01-04-2009, 02:03 AM
Guys,

I think it's time we give Valery here a bit of slack. Is he a bit ... forceful ... in his delivery? Sure. He is and as long as I've "known" him on the net, he always has been (and there certainly have been times I've not agreed with his views). But, he knows a lot about optics and about telescope making and the advice he's giving here sure seems devoid of personal, financial interest. He's not telling anyone here to skip the GSO and get something he sells. (FWIW, I believe he's including the f/10 ACF scopes in with the f/8 RCX, so yes, those are available and at least in the US, an 8" f/10 ACF is the same price as the GSO f/8 RC).

I've looked long and hard at those results and they really are just plain ugly. FWIW, the fact that they are ugly has been discussed over on CN and that thread wasn't pulling any punches either. There's been another test of the scope that had it fare a bit better, but still not great:

http://74.125.91.132/translate_c?hl=en&sl=de&u=http://www.teleskop-service.de/Testberichte/cassegrains.gso.rc.200mm.php&prev=/search%3Fq%3Dgso%2B8%2522%2BRC%26hl %3Den%26client%3Dfirefox-a%26rls%3Dorg.mozilla:en-US:official%26hs%3DIA0&usg=ALkJrhhdfFj20i2M200RONh17AmH_sT 6Yw

There, the P-V ended up at 1/3 wave and the Strehl at 0.89. To my untrained eye, it looked worse than a Strehl of 0.89 would indicate.

There is one thing that's not been considered much in the discussions of these results and that is that as these are meant as amateur astrographs for long-exposure work, we'll all have an inherent blur imposed on our images. How much better would something with a cleaner PSF look after 5-10 minutes of a 3" FWHM atmospheric blur when sampled at 1-1.5"/pixel? If scopes off the line end up more like the telescope-service site's test and we impose our typical smear over the images, I'd not be surprised if the results weren't too far off when stacked up against the competition.

Craig

Vader
01-04-2009, 02:42 AM
It is quite obvious, that reference points at this interferogram were not
correctly placed. They were manually placed with intention to smooth down interferometric fringes - this makes final figures better.
I can bet for a lot of money, that if I will process this interferogram with
our professional software with 5-8K reference points placed automatically,
the results will be not better than Strehl 0.6 - 0.7.
This is not totally crap, but very poor. If we consider a large central
obstruction, then a real Strehl will be 0.5 at best.


As for star images during long exposures. This effect is even more
visible in large professional telescopes. However, I don't remember
even one order for professional optics with technical requirements
lower than about 0.9 Strehl.
As better your scope optics, as better star images you will obtain under
similar conditions.

As for the picture of galaxy given at that page. Too small scale for
such a long focus.

avandonk
01-04-2009, 02:58 AM
Robin the Vixen VC200L is a Klevtsov design. All surfaces are spherical hence 'easy' to manufacture very accurately. It is a very nice scope.

I am a bit older than most of you blokes and sheilas and I remember when a naked eight inch 1/8 wave parabolic mirror cost close to a thousand dollars in the early seventies. A large aperture APO was 70mm (with green writing on it) and cost several thousand dollars. All these prices are in seventies dollars.

They said it about the 80ED
They said it about the big Dobs

and now They are saying it about RC's

We shall all see very soon.

Bert

Tandum
01-04-2009, 03:03 AM
Being rich is a state of being, but it appears you see it differently..

Why am I defending the fort ??

I'm outta here ....

avandonk
01-04-2009, 03:28 AM
Vader if you are still here don't take this personally but you could have been a bit more diplomatic. The last person that asked me why I was not rich if I was so smart I showed him the door. He too has done really well in the GFC meltdown NOT!. I felt like slamming his puerile mind inside of what he called a head in the door. I fortunately stopped myself as I did not want to damage my door on a twit.

Bert

Tandum
01-04-2009, 03:34 AM
Didn't this start with a piece of glass in a tube ? How do you get obsessive about that?

celstark
01-04-2009, 04:56 AM
I see this now and this makes sense. The points don't follow the midline of the bands there but are a lot smoother than that. There are clear ripples that the points don't follow at all. At least my take as to what a ~0.9 Strehl should look like here wasn't off then.

Thanks,

Craig

netwolf
01-04-2009, 04:58 AM
Vader, while i might agree that you seem to have some knowledge of optics and may infact be an expert on the matter. Your way of making your point shows a lack of tact. Perhaps this is lost in translation as english is not your first language. But your tone of crap crap crap is so strongly biased that any Wise person would always have to suspect something is not right. Was the sample that was tested not good yes looks like it. But to say all is crap is to say you are all knowing and I am sorry even the smartest person is not all knowing.

Before you just attacked GSO quality, ok I dont care I am not GSO. Now you attack/insult a fellow forum member and you are starting to get on my nerves. I dont care if you are the most knowledgble expert or even Roland Christensen himself. You got no right talking to anyone like that.

So STOP THAT RIGHT NOW.

Especially someone who has contributed more here than yourself.

Again i give you chance to apologise and tone your coments down. Be wise and tactful if you are indeed knowledgeble and smart. Otherwise all you will ever find is the exit. And what good is your welth and smart knowledge if you have no where to share it. Who is richer?

Regards
Fahim

iceman
01-04-2009, 05:11 AM
Well we left this thread go with the hope it would get back on track, but unfortunately it spiralled the other way with personal insults and attacks.

The offending posts have been removed.

This thread will be locked now.