... I agree with Dale on this.Seems I was pushing the limits with my test setup and it's not good enough to test a f/3 at present. Perhaps Dale could include...
Ric, I have pictures of unwrap errors in the help file that comes with OpenFringe 8.6. Unfortunately you were still using the older version. Dale Eason ... ...
For calculating the setup you need to know the curvatures (ROC) of both sides of the lens (one will usually be flat though), the thickness of the lens, and the...
Hi John, I used the Ross Null Test a few years ago during figuring of a 22" f/4.2 mirror. The lens radius was 2 3/4" and I used about 65% of the radius to...
Help please!!! Hi everyone. I'm currently hand grinding a 20" Pyrex pregenerated blank. I poured a full size cement tool on the blank then covered it with...
There are people here that can respond much better than me, but it seems a W stroke of the length and overhang you used removes too much material from the...
Hi Dave; To increase your F Ratio you want to widen your W stroke from a 1/4 to 1/2 of the tool overhang. You will need to go back to at least 80 grit that...
... Just a real General point but remeber a 20" has roughly 115 more square inches of glass than a 16", thats a lot, lot more glass to remove to change the...
Reducing focus is easy and quicker than going the other way because you only need to remove material from the smaller center area. Reducing the edge instead of...
Thanks to those that replied but I'm somewhat embarassed although relieved to find it was a bit of a false alarm. Down here in NZ we work in metric. ( I...
... That's good news Dave. Here is the stroke that I like for hogging but I don't go all the way to 1/2 dia. But you get the idea. It focuses on the edge. ...
I cannot get my Canon 300D to take photos of Foucault or Ronchi mirror tests. I have tried all modes including manual/bulb, manual focus, and always get a...
I don't know that camera but it sounds to me like you have not gotten it into a truly manual mode. Sounds to me like it is some sort of manual mode with...
... wrote: I use a different camera and autofocus works in night mode. Make sure that the tester light source is covered well enough that the camera is only...
Don't forget that you have to turn off the auto focus on the lens. Also make sure that you have the camera in either complete manual control or aperture ...
I have the 300D (Digital rebel). Do you have the switch on the side of the lens set to manual. This is a small slide switch on the lens body itself. This...
... side of the lens set to manual. This is a small slide switch on the lens body itself. This needs to set to manual. Yes, it is set to manual, and I used...
Hi Tom I'm going the same way with an XY foucault tester so that I can add a Z axis for a bath interferometer. Also because I was impressed by the ease of use...
I have finally got hold of an empty hp inkjet cartridge. There doesn't seem to be any holes? There is a thin pcb with 4 gold plated tabs and a black blob. It...
Maybe the holes are plugged with ink? Tony BigEye Optics ... From: "a.johnw" <a.johnw@...> To: <atm_free@yahoogroups.com> Sent: Sunday, May 11, 2008 8:14...
The cartridge has 363 on it (single colour). The only bit that stick out enough to get near the paper is the black blob I mentioned. The gold tabs are clearly...
Hi all, did anyone tried collimation with orthogonal (90deg) set screws? Is there any benefit to make the primary and the secondary like this? (cassegrain) ...
Nearly all commercial opto-mechanical mirror mounts from Oriel, Newport, Ealing, Coherent, etc. use the 2-screw orthogonal method. Alignment couldn't be easier...
On the yahoo group Celestron 9-25 I believe- A simple device made from a piece of thin wood or dowel even card folded as a sharp angle with a notch cut out....
Thanks for the help, is there a chance for a pic or a drawing? Could you point for a example? Thank you, Mick. ... orthogonal ... ball ... springs ... legs. ...
No, haven't heard of it before this. After some cogitation, I think I would go about it as follows. To define a plane in 3 dimensions you need 3 points. You...
You don't have to have the collimation bolts orthogonal to have the movement in orthogonal directions. Consider an "ordinary" arrangement with 3 bolts at the...
Nils, I see, but it's not as neat in the mind. With three screws I would not manually adjust two simultaneously in the same or reverse direction simultaneously...
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