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Explore scientific ED127 triplet ED APO build

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#1 Stipe Vladova

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Posted 22 July 2019 - 02:48 PM

Bought ED127 ED APO objective from CN classifieds, from Sheldon Faworski, aka MASILMW. The lens was very well packed and is awesome piece of glass. Initial test showed it as a newer FCD100 version since it showed virtually no color. The lens is very nice and shows very smooth figure. The pinhole image is tack sharp. The coatings are very dark green. Now I know that I will not buy more lenses because this will be a lifetime refractor. It is time to get aluminum tube 5.2" in diameter and stock aluminum for make the lens cell back flange. Some severe weather we have these days in Croatia. I will wait some more time to begin with this build. For now here are some pics of this beauty! 

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Edited by Stipe Vladova, 22 July 2019 - 02:51 PM.

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#2 Mike Lynch

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Posted 22 July 2019 - 07:41 PM

Best of luck on your build, Stipe!

 

I bought one of the 102mm f/7 versions of these ES ED APO lenses from Sheldon and built a scope with it. Another CN member built the back half of the collimatible lens cell, and I bought aluminum tubing, rings, and a two-speed Crayford focuser. I assembled it carefully, flocking the interior, and I love the scope!

 

Great views from a very portable grab-and-go refractor, though the Orion SkyView Pro GEM mount I put it on isn't quite as portable. But the motorized tracking just makes the views that much more enjoyable.

 

Keep us posted on your build!

 

Mike Lynch

Frankfort KY USA 



#3 Stipe Vladova

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Posted 23 July 2019 - 12:11 PM

This lens has loosen some of tiny collimation grub screws so probably I need to readjust it, but I have no time for it, since I work in another town for some time.

#4 Mike Lynch

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Posted 24 July 2019 - 12:35 PM

OH! That will probably take some time and careful adjustment! I'd search this forum for how to do that....



#5 Stipe Vladova

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Posted 29 July 2019 - 02:13 PM

I came home for a weekend and took some time to play with the lens. I mounted it on the ES AR152 tube via three small aluminum pads just to assemble crude OTA. First test at saturday morning showed some spherical overcorrection, but no zones, astigmatism or any turned edge. That was lucky for me since the spherical aberration can be tuned with spacing change. I disassembled the objective, cleaned it and found 0.3mm thick black nylon space rings between the lens elements. I decided to remove one ring between the center Hoya glass and third crown negative element. Machined the new plastic ring about 1mm thick and put it between. Found that lens is now nulled for green and that was it! I found that this is afterall the FCD01 not FCD100 triplet, but however it is awesome performer. At the evening I played with centering screws to tune the remaining on axis coma due to misalignment. The thing that surprised me is that Hoya element is pretty heavy glass, maybe it is much denser than other two no matter that it is much thinner! Intrafocal disk shows some purple outer ring and extrafocal shows bluish green outer ring, similar to Skywatcher ED80 and ED100. In the focus I saw no longitudal chromatic aberration, only a small amount of lateral color. That means that some decenter still remains. I will try to cancel it by rotating the lens elements in respect to each other to find the sweet spot. Now I am back again at work and will wait for the next weekend to work with the lens. Unfortunately, the aluminum thin wall 5.2" tube is problem for me since these sizes of thin wall tube does not exist here. 

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Edited by Stipe Vladova, 29 July 2019 - 02:21 PM.

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#6 Stipe Vladova

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Posted 06 August 2019 - 01:31 PM

With this lens assembled in the ar152 tube I decided to go observing with my friend last saturday. I did also some wide AP since I am still the both, AP and visual astronomer.

The targets for my new scope were galaxies, open and globular clusters, planets and doubles.

Jupiter: I used highest magnification I could get: Gold line 6mm 66° eyepiece and 2x Seben achromatic barlow (316x) in a Celestron prism diagonal. This is the bingo combination for almost completely cancel the chromatic aberration. The planet was absolutely color free and stunning. Never saw such sharp Jupiter against the dark background. I was in the moment of separating Europa from the planet's disk and in the same time the moon's shadow appeared on the opposite side of the planet. The GRS was great and now in its natural color. The bands were also very sharp and with details.

Saturn: The planet was still low at the beginning of the night and showed in a lot of atmospheric dispersion so the image wasn't so sharp. In the folowing hours the seeing was degraded and couldn't see much.

Uranus: A tiny turquise ball in Aries was later upper in the sky so it was much clearer to see.

Doubles:

Polaris: All stars showed in their natural color and only Vega had a tiny violet halo at 316x. Polaris was very nice white with its tiny companion, surprisingly pinpoint at this highest magnification!

Double-double: It was absolutely great! Tiny Airy disks with no diffraction rings and widely separated. So wide i had never seen before!

Izar: My favorite double, nice bright yellow star with its close dim blue companion.

Mizar: This star was low at the sky, but it was also widely separated.

Clusters:

Double cluster: This jewel was a beautiful crowd of pinpoint stars in all colors, blue, white and some orange pinpoints against the pitch black sky! I used my noname Plossl 25mm (38x) for double cluster.

M13: At highest magnification the cluster was well resolved, but too dim. I switched to Skywatcher UWAN 16mm (60x) and that was it!

Galaxies were nice with a lot of fine details.

M81 - the cigar galaxy: it was well defined with nice arm structures and the central gap.

M33: This object I observed only because its low luminosity and location in the eastern sky where was some LP from a larger city.

Conclusion: This is indeed my lifetime scope that will satisfy my need for some really good optics.

Now when I soon start to assemble the true tube for this lens I will post the progress.

CS to all!


Edited by Stipe Vladova, 06 August 2019 - 01:53 PM.

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#7 Mike Lynch

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Posted 06 August 2019 - 07:12 PM

Good to hear your enthusiasm for the lens and your scope-in-progress.

 

DO keep us posted!



#8 harbinjer

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Posted 07 August 2019 - 11:18 AM

Great to hear of your success so far. I had thought of buying a similar lens(maybe this same one). I don't think I would've had time to build the scope for it; glad to hear that its good, for you.



#9 Stipe Vladova

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Posted 14 August 2019 - 10:58 AM

What do you think about suitable reducer/flattener used on this lens? I read only about ES 0.7 reducer used on these lenses, but what about Skywatcher 0.85 reducer? Is it compatible with this lens?

#10 harbinjer

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Posted 14 August 2019 - 11:29 AM

In the past, I found the ES 0.7 on ebay for $150. I would rather have the 0.7 that's made for it than a 0.85. If the 0.85 is made for this focal ratio, then I think it will work well too.




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