Hallelujah - the jury is in!!!

[matt]

My astro friends...

I don't know where to begin.

Let's start with my feelings right now. Anger, relief, frustration...

VINDICATED

I could go on.

I've just got off the phone with Don Whiteman at Bintel who tells me my 9.25 failed a Ronchi test miserably.

My optics are shot. Ronchi lines curving all over the shop, mainly in towards the centre of the image.

Don's own words were "horrific", and "ugly".

I kid you not.

I am so glad I have pursued this as doggedly as I have and wish for nothing more than to finally get the scope I paid for.

Extravision are doing the right thing and I am expecting a replacement in the next week or so.

However, that does not remove the bitterness of the memories I have accumulated in the dealings I have had with people who have insisted I was wrong.... all the way along.

Don Whiteman, however, has been a champ. This scope is being returned to me from Bintel with a full and comprehensive CD of his optical testing and evaluation.

I didn't ask Don to go to those lengths, he just did it off his own bat to totally put me in the picture as to what was going on with my scope.

Don... can I take this opportunity to publically thank you for seeing this through to this conclusion and putting my mind at rest.

Thank you.

Thanks also to other folk who backed me and encouraged me to not let this get on top of me.

Can you imagine how I feel tonight, and how excited I am about what lay ahead with (fingers crossed).... a good telescope.

Please, share my happiness. Also let this serve as a cautionary tale.

Hooooorayyyyyyyyy!!!!!

[Striker]

Good on ya Don...3 cheers for Don..hiphip...hiphip...hiphip.

Glad you got it all sorted out Matt....I never questioned you in fact I new you were right....lol

[acropolite]

Very nice gesture by Don. :thumbsup:

[casstony]

Congrats on getting it sorted Matt. I'd be interested to hear more details of that optical test once you get the CD. After doing so well for several years it seems like both M and C have lowered their standards - hopefully just a temporary situation.

Tony

[casstony]

Some star test and ronchi images from a "typical" SCT here: http://aberrator.astronomy.net/scopetest/html/cassegrain250_1.html

[matt]

Thanks guys

It's a relief, I can tell you. Also a little worrying.

Who's to say the replacement will be any better?

Oh well, we'll cross that bridge when we come to it. The good thing is the confirmation something's wrong. At least I know I'm capable of picking a lemon.

It's also quite empowering. Should the replacement not be up to scratch... back it goes too!:P I'll just keep sending 'em back until we're all happy.

Maybe if enough people did the same they'd be forced to lift their game?

Tony. Don told me the Ronchi lines all bend in towards the centre.

I'm no expert on Ronchi Tests, but his word that they ain't pretty was good enough for me.

He reckons it's bad enough to make a sharp focus impossible. I can't believe I didn't get it tested sooner!

[asimov]

Glad you got this one sorted mate!:thumbsup:

[matt]

Me too John.

I feel like I've gone from loony to genius in one day:lol:

There's always a danger in situations like these for people to make snap judgements. I guess there were moments when the "experts" even had me doubting myself. The harder you push your case, the finer the margins become.

I feel a little better about things right now.

Cheers

[asimov]

I know what you mean about snap judgements, & rash moves...wanna buy a C9.25 mate ?? Going cheap lol..:eyepop: :lol:

[astro_nutt]

It's people like Don who puts back ones faith in human nature...and I hope that your replacement scope serves you well for many years Matt!!

[matt]

Me too... astro. Me too.

I'll also be straight back on this forum to report back when I get a decent scope.

I don't want to even consider the opposite might occur:mad2:

[iceman]

Good stuff Matt, glad you found someone who could paint a clear picture for you.

[Robert_T]

That's absolutely fantastic Matt! :thumbsup: All that frustration and not knowing if it was the scope or not - I admire your perseverance. I went through a similar experience with another scope a while back and was eventually vindicated too. It a very difficult thing to do when no-one (usually manufacturers) want to admit there might be any problem with their product and that it must be you doing something wrong.

Given the quality of some of your latest Jupiter images with a "dud" scope I can't wait to see what you'll be putting out with a good one:D

Now you've got me thinking I should put mine to the test too:whistle:

[g__day]

Worrying but, if it failed that miserably, how did it ever get past Celestron's quality assurance tests? This is the brand and model of scope I plan to get next, so like you I'm delighted to hear you're getting the real deal, but teh effort to confirm you'd received a lemon is worrying. Well done BinTel too!

[matt]

Thanks Mike.

Yeah Rob - that's one of the best things to come out of this debacle. A good scope is on the way (hopefully) and so, you'd imagine, is a significant increase in the quality of my images:D

g_day - What can I say? You're spot-on. It's a disgrace it was sent out to anyone in the first place. Quite simply, this is not meant to happen.

To me, it raises very serious questions about where Celestron has set the bar for QC.

A quick visit to Cloudy Nights has revealed others who are also struggling with optical problems with their scopes.

It's a real worry. Where you might expect the occasional tube with a finish and fit issue to be returned, we're now seeing scopes with optical problems. Quite a few of them. All at the same time.

Perhaps the Synta buy-out has cost Celestron more than first imagined?

I don't know what sort of picture this paints for the future, but when a flagship product like the 9.25 with such a reputation for excellence is allowed to decline to such an extent, you'd have to say an alarm bell is ringing somewhere?

[allan gould]

I'd just like to add my comments re Don and Bintel. I've always found it a pleasure to deal with him; honest information given freely. We should be greatful that Dons services are there for us and I'm just happy that your convictions have been proven correct. There is nothing worse than suspecting a dud scope and then going up against a retailer that doesn't want to help you.
Don Whiteman is a great resource for all of us here in Australia.
Just my 2c
Allan

[Merlin66]

Guys,
Well worth putting the ronchi screen on any telescope you feel is under performing!!

Glad things worked out well.

[matt]

Very true:thumbsup:

For what it's worth I've already placed an order this morning for a Ronchi test eyepiece following a link provided by Asimov in another thread.

http://schmidling.com/ez-testr.htm

Thanks for that John.

I'll now be on another learning curve, discovering how to interpret these various test images.

From what I can tell there are really only a very small number of results/test images which are signs your scope is in serious trouble. The rest reveal small degrees of misfiguring which are nothing to get too worked up about?

More gear in the astro kit!!!!:lol:

[asimov]

Does anyone sell these ronchi grating EP's in AU ?

[Merlin66]

You don't need an eyepiece body to make it work. A 35mm slide size piece of 120lpm grating and a bit of blu tac on the end of the focusser will do the job.
Infact I've seen some excellent results using a bit of fly wire instead of an actual grating!!

[[1ponders]]

Merlin you've obviously been exposed to this sort of technology before, would you consider doing a short write up about how to go about the testing or sites you are aware of that could provide similar information. I know of a certain C11 that I have never been happy with and I wouldn't mind betting this could be what is wrong with it.

[asimov]

Could you please elaborate on this. How does one get the lines on the slide? Or do ya buy them or what? I'm not opposed to trying the flywire lol... I've got miles of that stuff!

I made a ronchi tester 25 yrs ago but that involved glueing wires on by hand.

Cheers.

[bird]

Matt, sorry to hear about your problems, but I know *exactly* what you're feeling.

I'm going to order one of those ronchi eyepieces as well. Looks like a very useful bit of gear.

regards, Bird

[matt]

Hey Anthony!

Great to hear from you.

Thanks for your kind words.

We've all been wondering how you were doing with the move etc?

I've got a new 9.25 "in the mail". Should arrive tomorrow or Friday.

Fingers crossed this one will be a "keeper".

Cheers

[Merlin66]

Guys,
In a previous life I was the Section Director of the Photographic Section of the ASV for about ten years, in the hayday of 2415 and Hypered film etc. We had exactly the same problems as you have today! How do you get precise focus and how good are the optics.

I wrote a series of articles on astro-photography including a write-up on Ronchi Gratings; what they are and how to use them. I need to check my archives and see if I can re-find them and upload.

In the meantime I have some Ronchi gratings which I made using a slide copier and an "original" with the trustly OM-1 and 2415 B&W film. Over the years I've given most of them away to amateurs like ourselves. The 120/150 line per inch was the optimum.
Don't know if nowadays you can get the resolution by printing onto a transparent film with a standard inkjet/ laser type printer?? I've also used successfully a bit of fine mesh with similar lines/inch. I'm prepared to check out my "stock" and copy additional 35mm frames in B&W of the gratings I have and distribute them for a SAE.

The Ronchi grating acts like a Foucult knife edge tester but with multiple knife edges!! When the grating is precisely at focus, ( no eyepiece in the scope, only the grating positioned at the focus of the main mirror/ objective) the image of the star ( assuming we're testing a telescope against a star in the night sky) will appear as a grey disk similar to that seen in a Foucult mirror test... any distortions of the optical system will show up as lighter or darker grey areas against a uniform medium grey background. Because we're effectively testing the system with an infinite distant star, a perfect optical system will show an even gray.

When the grating is moved slightly away from focus, you'll see four or five dark and light "lines" or bands across the image: any distortion of the lines is bad news!! They should be straight, parallel, evenly spaced and no edge ripple or distortion. 100% perfect optics under 100% perfect skies!

Any distortion; the lines appearing to be closer at one edge or the other would indicate mis-alignment of the optics; they should be straight, evenly spaced and parallel.

If they appear thicker in the middle than the edges or curved inwards at the edges; the mirror/ objective is undercorrected and not the perfect shape!! Not much you can do about it unless you regrind the mirror/ replace the objective.

An easy tool to use: great for finding focus and setting flip mirrors etc.

[matt]

Good info Merlin:thumbsup:

[asimov]

Merlin I just finished making one, but it has between 80-90 LPI would that be sufficient to give a successful test conclusion?

I'm making another one soon that has 110 LPI.

[Merlin66]

As long as the edges of the grating are reasonably smooth and regular then it should work OK. The reason for the 120 LPI was to get easier lead into to the focus; as the number of lines decrease closer to focus the more lines you have in the grating (up to a max of about 200 lpi) the easier to see the transition into uniform grey.

[asimov]

Thanks for that Merlin.

Not sure how smooth & regular mine is. It's actually made out of an old kithchen sink tap filter comprising of a 20mm round piece of fine brass mesh, as mentioned, about 85 LPI.

The other one I want to make comprises of extremely thin sewing monofiliment.

Tube currents in an SCT would no doubt give you a false test conclusion here do you think?

[Karls48]

Hi
This software - Make your own diffraction grating - may by useful.
http://www.coaa.co.uk/software.htm

[asimov]

Yep, good for people that can print onto transparency. I can't do that.

Cheers for the link.

[Merlin66]

Asimov,
The grating will indeed show ANY deformation of the image from what ever the source; tube currents, upper atmosphere, secondary spiders ( both alive and dead!!) etc etc etc.
Basically what you see is what the camera, CCD, MkI eyeball sees.

[asimov]

Well I'm a happy chappy. Just tested the C9.25 after allowing it to cool to ambient & I see perfectly straight lines with no deviation anywhere.

My mind is at rest & I can get on with it!

[Merlin66]

Good news; pleased to hear that.

[davidpretorius]

i heard from asi that something was wrong and am very much relieved that there is a happy ending.

well done bintel!!!

and congrats to matt for perservering!