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Equipment Discussions >> Reflectors

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auriga
Pooh-Bah


Reged: 03/02/06

Another innovation from Howie Glatter?
      #5926663 - 06/18/13 12:04 AM

We all know that this inventive genius has given us the best laser collimator, and the Blug, the tuBlug, mounts for laser pointers, supporting attachments for Obsession-type mirror straps, and the Parallizer for optical alignment.

What is next from Howie? One I have been awaiting impatiently may have been seen briefly in a video at NEAF 2013. If and when it gets to market it will be a great boon to reflector users.

I am waiting and hoping.

Any word, Howie?

Bill Meyers


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Howie Glatter
Vendor


Reged: 07/04/06

Re: Another innovation from Howie Glatter? new [Re: auriga]
      #5927132 - 06/18/13 09:54 AM

O.K. Bill, no big secret - I'm working on a Newtonian secondary mirror mount idea, that, to my surprise, someone already posted a picture of in a thread here. He took the picture at NEAF this year, but I've had that prototype installed in my scope for a few years. The idea does not have to do so much with this particular "embodyment" (patent lawyer-speak) of the holder, but with the principle of motion of the adjustments. In my opinion, the adjustment axis of most conventional Newtonian secondary holders are slightly insane.

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csrlice12
Postmaster
*****

Reged: 05/22/12

Loc: Denver, CO
Re: Another innovation from Howie Glatter? new [Re: Howie Glatter]
      #5927155 - 06/18/13 10:09 AM

"In my opinion, the adjustment axis of most conventional Newtonian secondary holders are slightly insane."

...and we all know Howie isn't "slightly" anything.....When Howie does it, he goes all out and his products show it...Keep up the great work...


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Starman1
Vendor (EyepiecesEtc.com)
*****

Reged: 06/24/03

Loc: Los Angeles
Re: Another innovation from Howie Glatter? new [Re: csrlice12]
      #5927253 - 06/18/13 10:59 AM Attachment (125 downloads)

Howie,
A few years ago, I created a device for my secondary mirror that allowed extremely fine rotation of the secondary around its center bolt axis. It was a small device that attached to the center bolt and anchored on a spider vane.
I used it until my understanding of collimation grew to understand that the secondary did not have to be absolutely perfectly rotated in order to collimate a scope. Just eyeballing the rotation was good enough to achieve near-perfect collimation.
It worked like a tangent arm on a declination axis.
Here is a "back of the envelope" drawing:


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Howie Glatter
Vendor


Reged: 07/04/06

Re: Another innovation from Howie Glatter? new [Re: Starman1]
      #5927386 - 06/18/13 12:01 PM

Hi Don,

That's a good design for precise rotation adjustment. I've envisioned something like that to rotate the far ends of the vanes to square them with the optical axis.

With my mount design, I'm trying to eliminate the need to re-adjust the rotation of the holder once it is initially set.


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dscarpa
Post Laureate
*****

Reged: 03/15/08

Loc: San Diego Ca.
Re: Another innovation from Howie Glatter? new [Re: auriga]
      #5927395 - 06/18/13 12:05 PM

The secondary alignment was what drove me to madness with the newts I had 35 years ago, The primaries were easy. When I tried to tighten the secondary screws after getting everything lined up just right it would shift. If the 3 screw 3 vane spider on my soon to be here Tetter STS has the same issue I'll be in the market for something else. As is I'm looking forward to using Howie's laser and barlow plug bought used on CNC. David

Edited by dscarpa (06/18/13 12:08 PM)


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howard929
Member
*****

Reged: 01/02/11

Loc: Low End of High Ground
Re: Another innovation from Howie Glatter? new [Re: dscarpa]
      #5927444 - 06/18/13 12:31 PM

Since the ends of secondary adjustment screws make contact with the back of the secondary mirror holder, turning the screws to make tilt adjustments tends to cause the holder to rotate. It's bad by design. Milk jug washers seem to work well unless or until they become too rutted out. FWIW, I'm getting by with a slippery washer between the holder and the screws that does rotate somewhat during tilt adjustments but slides against the holder which doesn't rotate. All of this is helped by rounding the screw ends smooth and snugging them down as opposed to really tight.

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turtle86
Pooh-Bah Everywhere Else
*****

Reged: 10/09/06

Re: Another innovation from Howie Glatter? new [Re: Howie Glatter]
      #5927527 - 06/18/13 01:24 PM

Quote:

O.K. Bill, no big secret - I'm working on a Newtonian secondary mirror mount idea, that, to my surprise, someone already posted a picture of in a thread here. He took the picture at NEAF this year, but I've had that prototype installed in my scope for a few years. The idea does not have to do so much with this particular embodyment (patent lawyer word)of the holder, but the principle of motion of the adjustments. In my opinion, the adjustment axis of most conventional Newtonian secondary holders are slightly insane.




I would definitely welcome anything that would make tweaking the secondary during collimation easier. I particularly find it a bit of a challenge to make those minute adjustments to the secondary screws when using my autocollimator.


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acochran
professor emeritus


Reged: 06/19/08

Loc: So. CA
Re: Another innovation from Howie Glatter? new [Re: Howie Glatter]
      #5928004 - 06/18/13 05:49 PM

Howie: I'm hoping for a spider that reduces/eliminates collimation drift when moving telescope tube from vertical to horizontal.
Andy


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jpcannavo
scholastic sledgehammer
*****

Reged: 02/21/05

Loc: Ex NYCer, Now in Denver CO!
Re: Another innovation from Howie Glatter? new [Re: acochran]
      #5928060 - 06/18/13 06:44 PM

Howie
Slightly insane is exactly right. It crazy how backward some things remain! I do remember looking at your design at NEAF this year. I look forward to its emergence on the market.

Andy
As for collimation drift. This whole approach where the secondary is perched on some bolt, displaced along the axis of the truss/tube from the spider vanes, is crazy as well. It sets up a moment arm that must slightly torque the veins, introducing shift. There are surely ways to get around this that would sill allow some back and forth adjustment of the secondary along said axis. Howie get busy on that as well! ( I plan to when my shop is reconstituted in Denver!)

Joe


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BlackBirdCD
member


Reged: 08/19/12

Loc: Pacific Northwest
Re: Another innovation from Howie Glatter? new [Re: Howie Glatter]
      #5928148 - 06/18/13 07:33 PM

Quote:

With my mount design, I'm trying to eliminate the need to re-adjust the rotation of the holder once it is initially set.




THANK YOU!


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careysub
Carpal Tunnel
*****

Reged: 02/18/11

Loc: Rancho Cucamonga, CA
Re: Another innovation from Howie Glatter? new [Re: howard929]
      #5928334 - 06/18/13 09:58 PM

Quote:

Since the ends of secondary adjustment screws make contact with the back of the secondary mirror holder, turning the screws to make tilt adjustments tends to cause the holder to rotate. It's bad by design. Milk jug washers seem to work well unless or until they become too rutted out. FWIW, I'm getting by with a slippery washer between the holder and the screws that does rotate somewhat during tilt adjustments but slides against the holder which doesn't rotate. All of this is helped by rounding the screw ends smooth and snugging them down as opposed to really tight.




There are only two adjustments needed for a secondary - a rotational one to make it aligned flat with the focuser, and a one-axis tilt. Only a single tilt adjustment screw should exist. My secondary holder from Astrosystems has four screws, three too many (in a proper design).

We need secondary holders that just do these two collimation adjustments.


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davidpitre
Post Laureate
*****

Reged: 05/10/05

Loc: Central Texas
Re: Another innovation from Howie Glatter? new [Re: jpcannavo]
      #5928438 - 06/18/13 11:34 PM

Quote:



This whole approach where the secondary is perched on some bolt, displaced along the axis of the truss/tube from the spider vanes, is crazy as well. It sets up a moment arm that must slightly torque the veins, introducing shift. There are surely ways to get around this that would sill allow some back and forth adjustment of the secondary along said axis.



Agreed. I see these huge honkin secondaries hanging from an extended bolt, and just shake my head.
John Pratte of JP Astrocraft has designed a secondary holder that solves some of these problems.


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csrlice12
Postmaster
*****

Reged: 05/22/12

Loc: Denver, CO
Re: Another innovation from Howie Glatter? new [Re: careysub]
      #5928441 - 06/18/13 11:35 PM

Just a question, why can't the secondary be mounted to the focuser itself? It would seem at least on high end equip to be more stable....

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azure1961p
Postmaster
*****

Reged: 01/17/09

Loc: USA
Re: Another innovation from Howie Glatter? new [Re: csrlice12]
      #5928460 - 06/18/13 11:50 PM

I find my f/9 secondary can be a pain in the neck. At f/4 or 5....!i don't envy you guys! If Howies got something new going on here it'd be a nice thing.

Pete


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FirstSight
Duke of Deneb
*****

Reged: 12/26/05

Loc: Raleigh, NC
Re: Another innovation from Howie Glatter? new [Re: azure1961p]
      #5928569 - 06/19/13 01:08 AM

I have a Protostar secondary holder, and don't seem to have the sorts of torque/rotation problems people describe above. Each of the three adjusting screws sits against a sort of clutch mechanism between its end and the actual holder that functions like a more sophisticated, improved version of the washer idea mentioned above. This "clutch" design (how Brian Geer of Protostar describes it) also has the benefit of making adjustments to any one screw far more independent of adjustments to the other two, i.e. it substantially reduces how often you first need to loosen one screw before you can tighten another.

I think I get in principle why carysub above says you only need a rotational tilt adjustment plus a one-axis tilt adjustment, but IMHO it's much easier to make tilt adjustments to nail collimation dead-on with an autocollimator if you have three tilt adjustment screws. I really don't having three tilt adjustment screws to be any significant impediment at all with the Protostar design.


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Jon Isaacs
Postmaster
*****

Reged: 06/16/04

Loc: San Diego and Boulevard, CA
Re: Another innovation from Howie Glatter? new [Re: careysub]
      #5928692 - 06/19/13 05:28 AM

Quote:

There are only two adjustments needed for a secondary - a rotational one to make it aligned flat with the focuser, and a one-axis tilt. Only a single tilt adjustment screw should exist. My secondary holder from Astrosystems has four screws, three too many (in a proper design).

We need secondary holders that just do these two collimation adjustments.




I had a secondary mount like that once.. it used a hinge.

I would like to see Vic, Jason and Nils comments, particularly in light of Don's comments. With a 2 dimensional tilt adjustment that we all use, I believe small rotations are part of the adjustment process.

Securing/locking the rotation of the secondary is mechanically more difficult than securing the tilt, as long as collimation adjustments represents a small variations, it's not clear to me that a secondary rotation adjustment is an advantage.

"In theory there is no difference between theory and practice. In practice, there is.

Yogi Berra"

Jon Isaacs


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Starman1
Vendor (EyepiecesEtc.com)
*****

Reged: 06/24/03

Loc: Los Angeles
Re: Another innovation from Howie Glatter? new [Re: Jon Isaacs]
      #5929046 - 06/19/13 11:28 AM

For each rotational angle of the secondary, there is a tilt angle that results in axial collimation. Once you realize that, you realize there are only a couple reasons to try to rotate the secondary to appear round under the focuser:
--it reduces tilt in the final focal plane to a level we won't notice
--it results in the best edge of field illumination for the short axis of the secondary's ellipse.

That means that a device to make fine rotations of the secondary is unnecessary. Not bad, merely unnecessary. You can do it by eye by simply making the secondary as round as you can get it when looking through the focuser and by centering the reflected image of the primary in the short-axis dimension.

The autocollimator-derived secondary adjustments needed after that are really minor.

The push-push antagonistic screw secondary adjustment could be replaced with a single threaded screw and a hinge. But I think the system needs at least two dimensions for adjustment. When using the autocollimator to reduce residual secondary error, I always have to adjust screws on more than one axis. The amount is tiny, but I always adjust on at least two axes. One of the advantages of the 4-screw secondary is that I can also turn pairs of screws and adjust not only the N-S, and E-W axes, but also the NW-SE and NE-SW axes if needed.


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Jon Isaacs
Postmaster
*****

Reged: 06/16/04

Loc: San Diego and Boulevard, CA
Re: Another innovation from Howie Glatter? new [Re: Starman1]
      #5929073 - 06/19/13 11:44 AM

Quote:

For each rotational angle of the secondary, there is a tilt angle that results in axial collimation. Once you realize that, you realize there are only a couple reasons to try to rotate the secondary to appear round under the focuser:
--it reduces tilt in the final focal plane to a level we won't notice
--it results in the best edge of field illumination for the short axis of the secondary's ellipse.

That means that a device to make fine rotations of the secondary is unnecessary. Not bad, merely unnecessary. You can do it by eye by simply making the secondary as round as you can get it when looking through the focuser and by centering the reflected image of the primary in the short-axis dimension.

The autocollimator-derived secondary adjustments needed after that are really minor.

The push-push antagonistic screw secondary adjustment could be replaced with a single threaded screw and a hinge. But I think the system needs at least two dimensions for adjustment. When using the autocollimator to reduce residual secondary error, I always have to adjust screws on more than one axis. The amount is tiny, but I always adjust on at least two axes. One of the advantages of the 4-screw secondary is that I can also turn pairs of screws and adjust not only the N-S, and E-W axes, but also the NW-SE and NE-SW axes if needed.




Don:

Thanks for clarifying these issues, basically that is what I was thinking... One could design an rotation adjustment so that it could be used along with a single tilt adjustment.

In making fine adjustments, using two screws that are antagonistic, that is pushing against each other as in the 4 screw secondary, is an advantage because both screws can be tight and the final adjustment is just to one of them. You are using the mounting as a spring, flexing it slightly. Any tilt adjustment needs two screws for this reason.

A rotation adjustment could be done in a similar fashion, a lever with two antagonistic screws.. But locking a rotation generally requires clamping and that can induce rotation.

Jon


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davidmcgo
Pooh-Bah
*****

Reged: 10/09/04

Loc: San Diego, CA
Re: Another innovation from Howie Glatter? new [Re: Jon Isaacs]
      #5929131 - 06/19/13 12:29 PM

Would going to a single tilt srew and rotation assume the spider is exactly perpendicular to the tube?

Dave


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