81 replies to this topic

[firemachine69]

Why vinyl wrap before paint? You can paint directly onto 3D filament.

 

 

 

I suppose you could, but I haven't seen good long-term results.

[jragsdale]

Wow! And a fairly rare bird too. Nice find at a great price. Congrats!

Thank you! Now the hard part of deciding which scope has to go if this one is going to stay.

 

While I'm waiting for the fog to burn off and the sun to come out today I 3D printed a quick solar filter holder using Thousand Oaks solar film. Can't wait to see how this does on the sun with full aperture!

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Edited by jragsdale, 10 December 2024 - 12:10 PM.

[ccwemyss]

The original AP dew shield would just be a piece of 7" Hastings pipe, painted Corvette White on the outside and flat black inside. This is much better. You cold probably have a body shop straighten the original if you really want to preserve the history, but it isn't worth doing for a working scope.

 

I'd consider doing something similar for mine, but I also have a cap that fits it perfectly (a 7" stove pipe cap), so I'd need to find a replacement, and also redo the insulation to fit the change in diameter. 

 

Chip W. 

[jragsdale]

The original AP dew shield would just be a piece of 7" Hastings pipe, painted Corvette White on the outside and flat black inside. This is much better. You could probably have a body shop straighten the original if you really want to preserve the history, but it isn't worth doing for a working scope.

 

I'd consider doing something similar for mine, but I also have a cap that fits it perfectly (a 7" stove pipe cap), so I'd need to find a replacement, and also redo the insulation to fit the change in diameter. 

This 3D printed one worked out pretty well actually. And it actually resisted dew/frost more than the metal tube last night, which was interesting. Of course the original dust cap doesn't fit now, but that too can be easily 3D printed for a perfect fit, I can even just invert the threads from the internal baffles to make a lens cap that threads on if I wanted...

 

I do have some sections of 7" Hastings pipe leftover from my Jaegers 6" f/15 build, but none a proper 9" long. That and I like the look of the larger dew shield, and the extra opening size gives the warm air coming off the lens a little extra room to get out of the light path.

[jragsdale]

Yesterday I 3D printed a mechanical iris I found on Thingiverse. I scaled it up 300% so the functional opening was from about 5¼" to ½". Then printed an adapter so it could fit snug on the lens cell.

 

 

 

And here's a video showing how it operates, and it's quite smooth: https://youtu.be/ZRL...?feature=shared

 

I had a chance to image Jupiter last night too, the seeing wasn't great, but I imaged with near the same settings using full aperture (6" f/8) and with the mask set to 4" f/12. Only difference was 4ms exposure for full aperture and 7ms for masked. Then I stacked 8 seconds worth of frames on both and processed the same.

 

 

Visually the 4" masked was much more pleasing to see, but I think with imaging the full aperture gives more signal so less noise in the final image.

[starman876]

Yesterday I 3D printed a mechanical iris I found on Thingiverse. I scaled it up 300% so the functional opening was from about 5¼" to ½". Then printed an adapter so it could fit snug on the lens cell.

 

20241222_002303_copy_739x954.jpg

 

20241222_002248_copy_692x1028.jpg

 

And here's a video showing how it operates, and it's quite smooth: https://youtu.be/ZRL...?feature=shared

 

I had a chance to image Jupiter last night too, the seeing wasn't great, but I imaged with near the same settings using full aperture (6" f/8) and with the mask set to 4" f/12. Only difference was 4ms exposure for full aperture and 7ms for masked. Then I stacked 8 seconds worth of frames on both and processed the same.

 

Messenger_creation_F76821D5-0EC6-4833-B4B7-E78788645455.jpeg

 

Visually the 4" masked was much more pleasing to see, but I think with imaging the full aperture gives more signal so less noise in the final image.

Looks awesome.   The stepped down images appear to be a bit sharper.  Maybe because of the longer focal length.

[deSitter]

Looks awesome.   The stepped down images appear to be a bit sharper.  Maybe because of the longer focal length.

Color is definitely better at 4", which of course makes no sense.

 

-drl

[jragsdale]

Looks awesome.   The stepped down images appear to be a bit sharper.  Maybe because of the longer focal length.

Higher focal ratio, but same focal length.

 

Color is definitely better at 4", which of course makes no sense.

I'm sure you're being sarcastic, yeah, almost no CA once dropped to 4" while viewing at 260x. Visually the absolute best view though with the mask at 5" and with a fringe killer filter.

[deSitter]

Higher focal ratio, but same focal length.

 

I'm sure you're being sarcastic, yeah, almost no CA once dropped to 4" while viewing at 260x. Visually the absolute best view though with the mask at 5" and with a fringe killer filter.

No, I was serious, there should be no difference in imaging something at this scale (50" of arc) coming from CA or SC. The color in the 6" image is greenish, which makes no sense to me.

 

-drl

[jragsdale]

No, I was serious, there should be no difference in imaging something at this scale (50" of arc) coming from CA or SC. The color in the 6" image is greenish, which makes no sense to me.

 

-drl

Both were imaged with a 2.5x Barlow and an ASI462MC, which gives an image scale of 0.16"/pixel. CA was definitely noticeable at full aperture. As you can see in the color images, I was probably more focused closer to the blue/green end of the spectrum instead of the green/red, which leaves the yellow/reds more out of focus, giving a green yellow tint, vs if I was focused for green/red, I would get a violet/blue tint that would show as the blue channel being the more bloated and unfocused one. Apparent CA can go both ways depending on the target and focus.

Edited by jragsdale, 22 December 2024 - 12:23 PM.

[ccwemyss]

What is the square grid artifact in the separate channels? To me, the unmasked appears warmer, which is what I would expect with the red channel being blurred, so that it blends more of that across the image, which is then more visible in the whiter areas. It looks like the green is the most similar between them, and then blue is a bit less focused in the unmasked. 

 

Chip W. 

[jragsdale]

What is the square grid artifact in the separate channels? 

I don't see a grid artifact, but could be the bayer matrix. Or just stacking artifacts (I see some at the 9:00 location on the masked green channel).

[Soundboy121]

sir which 3d printer do u use?

and what filament 

[jragsdale]

sir which 3d printer do u use?

and what filament 

Bambu P1S

Kingroon HS-PETG

[deSitter]

Both were imaged with a 2.5x Barlow and an ASI462MC, which gives an image scale of 0.16"/pixel. CA was definitely noticeable at full aperture. As you can see in the color images, I was probably more focused closer to the blue/green end of the spectrum instead of the green/red, which leaves the yellow/reds more out of focus, giving a green yellow tint, vs if I was focused for green/red, I would get a violet/blue tint that would show as the blue channel being the more bloated and unfocused one. Apparent CA can go both ways depending on the target and focus.

What I'm seeing is an overall greenish cast, which isn't coming from the optics. What processing step could have caused this? The 4" does indeed seem sharper, which I assume is down to seeing.

 

-drl

[jragsdale]

Here's an update on this scope, I'm currently working on refurbishing it to upgrade the focuser and give it a new paint job. Focuser replacements are tricky on these as there's no simple adapters nor aftermarket flanges, so it requires some machining. I decided to reuse the existing flange so first order of business was to remove the focuser body from the flange. A few pieces of wood and a rubber mallet popped it right out, these were just interference fit, no grub screws or threads to worry about.

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[jragsdale]

Next job was to cleanup the flange as the paint was fairly worn and had a rough texture from the casting. I stripped the paint using Citristrip then took it down to my local machine shop and had them reface it on a lathe to get a smooth clean finish.

 

I also had them cut an inch off the end of the tube for a little more backfocus flexibility and to clean things up. This tube (7" OD Hastings) had some out of round spots and extra holes on the back so it was an easy choice.

 

Next up I needed to drill new holes in the tube and the flange. I used a 3D printed template to mark 6 uniform holes around the perimeter, then center punch the marks and drill them out. Then insert the flange, mark the hole spots on the flange through the tube and then also center punch the marks and drill them out.

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[jragsdale]

I used a 3D printed jig to hold the flange during drilling to make sure i was getting even and square holes.

 

 

 

Then tapped them for #8-32.

[jragsdale]

All finished securing the flange to the tube. 6 stainless fasteners securely holding it uniformly to the tube. Much better than the 3 tiny set screws that were barely holding onto the thin wall tube. Next up need to machine an adapter that will fit this flange and scale up to M117 male threads to fit the TS Optics 2.5" R&P focuser I picked out for the scope.

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[jragsdale]

Also, need to choose a paint color!

Should I go with the original Corvette white? Or go with the "Cadet Blue" that AP did on some of these early scopes?

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[starman876]

The blue does look nice. The white always looked good. Your choice. Your scope.

[deSitter]

Also, need to choose a paint color!

Should I go with the original Corvette white? Or go with the "Cadet Blue" that AP did on some of these early scopes?

White, all real telescopes are white

 

(I really used to believe this! but I think this one should be white.)

 

-drl

[ccwemyss]

The modern ones use a textured version of their off-white that does a good job of hiding any imperfections. Not that there are any in the recent tubes, since they are all precision machined. But in the Hastings pipe era, there were plenty. I wish mine had been painted that way. It has a poor paint job that shows areas of orange peel and others where the primer is slightly showing.

 

I don't know how to get that kind of finish with home tools or spray cans. Once the weather warms up I may pull it out of the observatory, give it a light sanding and spray it with hammertone white, like what I did with the Jaegers 6". That also did a good job of hiding imperfections and is actually a warm white that's not far from the current scopes. It also gives it a bit of sparkle that is nice to look at.

 

Chip W.

[deSitter]

The modern ones use a textured version of their off-white that does a good job of hiding any imperfections. Not that there are any in the recent tubes, since they are all precision machined. But in the Hastings pipe era, there were plenty. I wish mine had been painted that way. It has a poor paint job that shows areas of orange peel and others where the primer is slightly showing.

 

I don't know how to get that kind of finish with home tools or spray cans. Once the weather warms up I may pull it out of the observatory, give it a light sanding and spray it with hammertone white, like what I did with the Jaegers 6". That also did a good job of hiding imperfections and is actually a warm white that's not far from the current scopes. It also gives it a bit of sparkle that is nice to look at.

 

Chip W.

What worked beautifully for a finder was - strip the paint, clean, use Rusto 2x gloss white, several coats, and then polish with cerium oxide. This works FAST and you can overdo it! Also works great brightening up weathered finish on classics.

 

-drl

[jragsdale]

I plan to have this professionally stripped and powder coated so I'll be just selecting a commercial powder available.