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  #241  
Old 26-09-2015, 05:58 PM
Jas.Mc (Jason)
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Hi all just thought I would jump just on the chance that any ATM’ers or mirror makers in the the North East of Vic might read this. It would be great to have some contact with others who enjoy this seemingly rare hobby. Also I think a making thread section a great idea. Cheers
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  #242  
Old 08-11-2015, 07:02 PM
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Rac (Raymond)
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Quote:
Originally Posted by dave brock View Post
A superb result, Raymond. Well done.
Time to check that Royce 10" for a possible refigure?

Dave
Funny, I thought about this post today when I was re figuring my Royce 10" f4 mirror.

Before
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After
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Before
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After
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  #243  
Old 09-11-2015, 03:36 PM
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So, you going to offer to refigure any dodgy Zambuto's?

Dave
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  #244  
Old 09-11-2015, 06:07 PM
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Quote:
Originally Posted by dave brock View Post
So, you going to offer to refigure any dodgy Zambuto's?

Dave
Haha well I would hope there wouldn't be any as they cost more than a Royce.
I wouldn't mind seeing some tests from more Royce mirrors and some of the other pro's who have a good rep, it would be very interesting. Maybe they need a bit of a shake up.

You can clearly see no(not the correct time or care) time or effort at all was put into my mirror by Royce!
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  #245  
Old 09-11-2015, 08:55 PM
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Don't forget to replace his name on the back (or edge?) with yours.

Dave
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  #246  
Old 13-11-2015, 06:09 PM
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Satchmo (Mark)
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Quote:
Originally Posted by Rac View Post
Rac - I don't really understand the foucault pics you posted . The wavefront profile you posted on Cloudy Nights forum shows the original mirror ( at least according to the `Figure XP' extrapolation, to be smoothly overcorrected by 1/6 wave or so on the surface .

The before and after foucault pics should therefore look pretty much the same with slightly deeper shadows on the 'before' . However your posted 'before' picture shows a pretty much spherical mirror beyond the 70 or 80% zone -not the strong roll off in shape from sphere you would expect to see in both the before and 'after' picture .
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  #247  
Old 14-11-2015, 05:31 PM
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The foucault images are not the same. The before refigure image is with the knife edge just off to the side. You can make the mirror look like a sphere if the knife edge is just off like this.

The Figure XP profile result was interesting but It was very rough picking the dial gauge numbers as the shadows were all over the place .
I just did the best I could then banged them into the pc and that's what I got so in the real world it would be a lot worse!

This one is a little bit more comparable to the one I took of the Royce figure. Either way will show the same problems if the mirror has any.
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Or this for all of them.
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  #248  
Old 15-11-2015, 03:11 PM
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So why bother posting two foucault pictures at a different knife edge setting unless you are just being 'sloppy' or intend to make the appearance to the uninitiated that you have had to make some large change to the mirror , which shows a flat edge in your `before ' photograph. ( and for that matter why post Figure XP data to a forum when you say that in fact the mirror was `much worse ') .

What exactly was wrong with the mirror that meant you can not put faith in your measures `before' but you can `after' . The narrow turned edge could have been masked with texta for the sake of accuracy in your knife edge measurements. I've certainly looked at optics from this maker and never seen any surface roughness that would remotely prevent some reasonable quantification of its surface errors .

Just trying to encourage a little more rigor here if you are going to be comparing any results of different makers or promoting your own skills in 'fixing' them .
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  #249  
Old 15-11-2015, 04:09 PM
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Why are you the only who can't see through the different knife edge positions?
The Ronchi pic shows exactly what you would expect from the foucault image. I took the pic with it just grazing the knife edge so the whole surface could be seen.

I don't know where you are coming from? looking at the before and "after" Ronchi pic are you saying you would like to own the before mirror and you would call that ok and you would want to pay about $1500nz for it. Or are you saying I somehow made the lines all wonky myself?

I have had very good support from many other mirror makers who can see the faults for what they are, changing the knife edge position does not change the problems!

I can VERY easily put faith in my after Figure xp numbers because the shadows now work their way across the mirror VERY smoothly as they should. As you can tell by the before Ronchi pic there is now way the shadows would move out as they should, the last about75-95% of the mirror just about nulled out as the foucault image shows very clearly.

Take a trip back to only the Ronchi image for a second - that image is not an image of a good mirror!!!!!!!!!!!!!!!!!

What would that look like in an autocollimation test as Royce says he uses where errors are doubled?

I bet most of his mirrors are great but not this one.
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  #250  
Old 15-11-2015, 04:19 PM
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Just for you here is a more comparable knife edge shot with it just grazing it although it wasn't at the end of figuring.

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  #251  
Old 15-11-2015, 04:39 PM
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Remember a couder mask only samples from from a few points, for it to be of good use it would be expected that the Ronchi lines bend smoothly from zone to zone as they DO NOT in the before image and that is why I "fixed" it.
Yes I posted a Figue xp profile that may not be a close match to the real mirror but only because the mirror looked like a dogs beakfast.
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  #252  
Old 16-11-2015, 03:20 PM
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Hi Mark.

Quote:
and for that matter why post Figure XP data to a forum when you say that in fact the mirror was `much worse '.
Any particular reason you are complaining about this here and not on the forum that it was posted to?


Quote:
I've certainly looked at optics from this maker and never seen any surface roughness that would remotely prevent some reasonable quantification of its surface errors .
Have you ever seen a mirror this rough from this maker?

Dave
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  #253  
Old 16-11-2015, 03:25 PM
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Hi Raymond.
Time to update your signature, you no longer have a Royce conical.
Good work

Dave
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  #254  
Old 16-11-2015, 04:09 PM
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Just to update.

I Emailed Royce and he takes full responsibility for the state of it. He never questioned my test images. It was made about the time he was very ill but he didn't stop working(maybe should have).

I'm sure he is currently making great mirrors.

He has said good work on the fixing of it.
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  #255  
Old 16-11-2015, 06:02 PM
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Smile

Quote:
Originally Posted by dave brock View Post
Hi Raymond.
Time to update your signature, you no longer have a Royce conical.
Good work

Dave
Amen
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  #256  
Old 26-11-2015, 06:54 PM
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Quote:
Originally Posted by dave brock View Post
Hi Mark.

Any particular reason you are complaining about this here and not on the forum that it was posted to?


Have you ever seen a mirror this rough from this maker?

Dave
Hi Dave

I am not a cloudy nights member - and the discussion here was prompted by the posting here of some comparitive foucaultgrams which is what I was asking for clarification - I dont have any problem in discussing what has been presented here with the author.

Last edited by Satchmo; 26-11-2015 at 08:19 PM.
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  #257  
Old 26-11-2015, 08:50 PM
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I think the confusion has come from that the knife edge images were only ever posted to show the quality of the surface and not of the figure as that is what the Ronchi image was for.

So for surface smoothness IMO then they are very comparative.
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  #258  
Old 02-01-2016, 11:02 PM
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DaveGee (Dave Gault)
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I thought I'd jump in here with a notice of my Mirror Blank Give Away. See thread...
http://www.iceinspace.com.au/forum/s...d.php?t=141560
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  #259  
Old 10-05-2016, 06:11 PM
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Smile Another 18"er "on the block".

Hasn't been a posting for awhile. So thought to show there are some of us "still alive".

Picture of my current 18" diameter by 1 1/2" (edge thickness) plate glass project. Currently just finished the #400 SiC. Will finish the fine grind with #800 for approx 90 mins.

Focal length 72" (f4). Should make for a compact ladderless scope when done.

Eyepiece would be just a little easier to reach than that of my 33"f4.1, with focuser height at 12' when pointed at zenith.

Stephen.
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  #260  
Old 12-05-2016, 05:12 PM
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Rac (Raymond)
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Quote:
Originally Posted by sopticals View Post
Hasn't been a posting for awhile. So thought to show there are some of us "still alive".

Picture of my current 18" diameter by 1 1/2" (edge thickness) plate glass project. Currently just finished the #400 SiC. Will finish the fine grind with #800 for approx 90 mins.

Focal length 72" (f4). Should make for a compact ladderless scope when done.

Eyepiece would be just a little easier to reach than that of my 33"f4.1, with focuser height at 12' when pointed at zenith.

Stephen.
Is this 18 for yourself or someone else?
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