1132 replies to this topic

[nateman_doo]

I made my own just 1" long, nothing special. Thin aluminum and then bead blasted it with course glass in the sand blast cabinet and a quick spay of matte black paint. No more light leakage. Cutting the threads was not easy so I have no intention of mass producing them when 3d printers make them so much easier. They require none of the properties of aluminum that you would need.

It works really well.

[Mert]

Eric:

That image looks super!

Do you have a single sub to share?
Maybe also some short exposure sub? ( like 10 seconds or so )
That with ASTAP would give a nice evaluation!

Edited by Mert, 22 July 2022 - 03:37 AM.

[nateman_doo]

back at it today.  Found these in my mailbox:

 

[Mert]

People get motivated!
So did I
If I don't see it wrong, on the righthand side is mine
RC6 and RC8

Edited by Mert, 25 July 2022 - 09:37 AM.

[ekallgren]

Hi Mert,

Sorry for not responding sooner but I have been gone all weekend.

I still have a bit of work to do on the collimation. 

I will post the results from ASTAP a bit later.

Now that the smoke from the fires around Yosemite has made its way into my area it might be a while before I can get back to the collimation. 

Edited by ekallgren, 25 July 2022 - 10:52 AM.

[Mert]

So you collimate under the stars as well?

Myself I only do daytime collimation with the Takahashi

collimating scope and off to imaging

Edited by Mert, 25 July 2022 - 01:33 PM.

[ekallgren]

Yes, I do the final adjustment under the stars.

As you can see from the previous CCD capture it is almost there.

Just need to adjust the Primary a tiny bit, so the out of focus star is illuminated evenly.

Maybe tonight, if the smoke clears.  

Here is a 120 sec Sub in ASTAP from last week.

 

 

Attached Thumbnails

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Edited by ekallgren, 25 July 2022 - 05:12 PM.

[ekallgren]

back at it today.  Found these in my mailbox:

You must have a big Mailbox!

[nateman_doo]

Part all setup on the machine:

 

 

Pilot hole process:

https://i.imgur.com/TNAJiTq.mp4

Uses a carbide drill Mill for rigidity.  The textured surface may make the drill bit wander.  Precision hole placement is critical

 

 

Drilling the through-holes:

https://i.imgur.com/aVcXgN0.mp4

Drill bit does not wander at all.  

[nateman_doo]

Now on to the 6" R/C version:

 

 

Here is what I call the "paper prototype"

 

 

The thinnest part of the plate will be 1/4" thick, main ring will be 1/2" thick, and around 7/8" thick.  Ignore the mounting holes for the feet, those were brought in some to get them closer to the center of the feet.  Feet were hollowed out for a more light-weight approach.

[nateman_doo]

Yes, I do the final adjustment under the stars.

As you can see from the previous CCD capture it is almost there.

Just need to adjust the Primary a tiny bit, so the out of focus star is illuminated evenly.

Maybe tonight, if the smoke clears.  

Here is a 120 sec Sub in ASTAP from last week.

Wonder why you image has smaller numbers than mine.  Perhaps mono vs color?  Focal reducer vs none?  

 

Wonder if its the section of the sky?  Or that this is a 5 min sub so the stars are larger?

Edited by nateman_doo, 25 July 2022 - 11:35 PM.

[ekallgren]

I think the smaller pixels will have that effect.

The ASI294MM binned 2 gives me 4.6um and the 163, I think is 3.8um.

But I could be wrong.

[ekallgren]

So I was able to finish up with the collimation tonight before the clouds and smoke shut me down.

 

Here are the results. This is a 15 sec sub. I'm very happy with the outcome.

 

Let me know what you think.

 

 

Attached Thumbnails

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[nateman_doo]

 

Let me know what you think.

I think its wonderful.  My scope holds better collimation now than my refractor with this adapter.  

 

Parts coming Wed for the 6".  Have to figure out a fixture plate for it as well.  

[Mert]

Absolutely fantastic numbers, that looks like you've got it dialed in 100%

[Mert]

Yes, I do the final adjustment under the stars.

As you can see from the previous CCD capture it is almost there.

Just need to adjust the Primary a tiny bit, so the out of focus star is illuminated evenly.

Maybe tonight, if the smoke clears.  

Here is a 120 sec Sub in ASTAP from last week.

Could you describe your final adjustment under the stars?

I never did that!

[nateman_doo]

For me, the final adjustment was taking 30 second pictures, opening ASTAP and analyzing the image. Then slightly adjusting the primary mirror.  

[Mert]

Sounds good, when I get it all assembled again will do and post results!

[nateman_doo]

Got the feet holes closer to center:

 

 

Here is a side view of the thickness:

The ring itself is 1/2" thick aluminum. 

[Mert]

I think you will need to buy a much bigger mailbox soon

[nateman_doo]

 

Widened the webbing where it joins the feet, and added additional slots to cut down on the added weight.

[ekallgren]

Could you describe your final adjustment under the stars?

I never did that!

The way that I get the best results is to follow Robin Brown's Guide.

 

You can download a copy of it here.

 

 https://www.dropbox....evision 1.4.pdf

 

Then I will follow that up with final tweaks on a star field.

 

I will also use CCDInspector. When making the final adjustments to the Secondary only use 2 sets of the adjustment screws and make the smallest adjustments you can.

 

The closer you get to Collimation the better your FWHM's will get. This is dependent on good seeing and steady skies.

 

Then check the Primary using an out of focus star make the donut pretty small, just big enough to see if the donut is evenly illumined as in Post # 44 from nateman_doo.

 

 

The biggest thing is don't be in a hurry, take your time! Can't stress this point enough.

Edited by ekallgren, 26 July 2022 - 12:02 PM.

[Mert]

Wow, thanks a lot for all your explanation and the download.
I will certainly go for it and once I have my mirrorcell back will post my results
I think James will ship either tomorrow or the day after.
Great guy!

Edited by Mert, 26 July 2022 - 12:14 PM.

[nateman_doo]

dropbox didn't work for me.  Not sure if because I am on my work network? 

[Mert]

dropbox didn't work for me.  Not sure if because I am on my work network? 

This is the same PDF that we have used I believe, when we had

that long thread about collimation.