26 replies to this topic

[Jeff B]

Here's my latest addition, an Orion 100ED OTA, now long discontinued.  I said to myself I was going to stop acquiring scopes.  I lied to myself.  But it was a good price.  But I still lied to myself.  I'll get over it I suppose, I always do.

 

The scope arrived well packed, waaay over-packed actually, unfortunately costing the owner a hefty percentage of the price to ship.

 

The scope was in a bit of a sorry shape when it arrived.  The owner had rightly and openly disclosed a haze on a portion of the objective and even sent a photo.  We settled on a price and I took the risk.  Once here I determined it to be a bit of condensation between the elements so I unscrewed the objective cell from the tube and placed it in a sealed tub with several desiccant packets for a couple of days.  The condensation is now gone. 

 

The focuser drawtube was very loose and would flop around a bit.  Careful adjustment of the small screws made for smooth steady operation, but like all cheap R&P focusers, the draw tube would shift/rotate slightly when changing focusing direction. 

 

Checking the collimation of the focuser draw tube with the center of the objective using my Glatter laser, showed it to be off by a good half inch or more, depending on the direction of travel for the focuser.  That's almost a degree off.  Not acceptable as is.  The Cheshire eyepiece also showed the mis-collimation as I saw two distinct reflection dots.  So I cocked, shimmed and fiddled with the focuser to make sure the laser past through the center hole of the paper objective mask, then locked everything down.  It did stray from the center a bit if I racked the focuser inward, but would re-center when racking it outward, so, being fussy, I did all of my subsequent focusing going outward.  Once the focuser was collimated, the Cheshire eyepiece showed the two reflection dots had merged into a single dot.

 

Time for DPAC testing!

 

Jeff

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[SoCalPaul]

My current self-delusion is, no more purchases until I sell off less-used items. :-)

[Jeff B]

Before I make any further investments in any scope upgrades, especially the focuser, as the their cost can exceed the basic price of the scope, I always test it optically to see if its "worthy" of the investment.  This testing includes DPAC testing for spherical aberration, overall figure (especially the edge), smoothness, and color correction.  I use star testing to judge astigmatism and coma.  If the optic passes both sets of testing, it becomes a serious candidate for upgrade investment.

 

So here are the DPAC results.  Place the cursor over the photo to see their labels.

 

Spherically, this is an excellent lens, no complaints or hesitation here, just wonderful really.   There is just a weak, faint hint of local edge error but as it's so weak and local, covering a fly's whisker of the outer diameter,  it's inconsequential.  There is also a faint center zone....but that's fine as it's in the center, where it has little effect, and it's quite shallow/weak. This shows the power of DPAC and its very sensitive and revealing nature  

 

Color Correction is also superb, with the RGB focus virtually right on top of each other with scant spherochromatism as well.  The figure is also nicely smooth.  

 

Next will be the star testing results.

 

Jeff

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[davidc135]

That's superb but maybe a hint of astigmatism in the clocking. Hopefully, if it's there, that's collimation.  David

[Jeff B]

Yes, it is superb.  And I'll step right into "it" right now and say it would be right at home in a TAK.

 

The clocking you see is due to how I hold my cell phone camera, the focuser shifting, and, mostly, me moving the ronchi grating to get my preferred, standard band positions.   

 

Jeff

[Maciek_Cz]

Jeff, have you tried my software for this telescope?

P.S. I am slowly preparing the next version.

[Jeff B]

But David, you did mention the dreaded "A" word, Astigmatism  , which is the equivalent of the dreaded "S" word in golf....shank.

And during my boring mono-vision star testing on Vega, Altair, and Arcturus, I did indeed initially see a good 1/3 wave or so of astigmatism, making it unsuitable for higher power viewing.  I detected no coma, however, the astigmatism was quite readily seen.

 

I was super bummed out. 

 

Rats!

 

However, I just happened to have another 100ED objective with cell sitting out on my accessory table, this one sourced from my Celestron C100ED.  I had gotten too aggressive with tube shortening of that scope to make it bino-friendly so the objective has been parked on the shelf.   So, I unscrewed the Orion objective from the tube and replaced it with the Celestron one. It was almost a perfect fit.  The Celestron objective was fine, performed great with an impeccable star test and I happily used it for about a solid half hour or so before putting the original Orion objective back on. 

 

And the Orion objective promptly displayed no astigmatism....then some a little later....which went away....then momentarily came back....before eventually departing the building for good.  

 

The subsequent star testing and views of Saturn and Jupiter were just excellent.   Vega was very white at focus at high power.  

 

So, the inner and outer diffraction ring patterns on Vega were identical, right? 

 

No.  Nice and round, yes, but not even close color wise, for either objective.  The patterns for each objective looked the same as each other and very much like those that Paul shows in posting number 5 of his excellent thread on testing a TV76, except for tint:

 

https://www.cloudyni...a-televue-76-2/

 

But, but, how can that be!?  The DPAC test shows excellent spherical correction and color focus to be really tight.

 

And that might be precisely why the patterns were so different in tint just inside and outside of focus.  The inside of focus ring pattern (4 to 5 waves) was sharp with a green/yellow-ish tint, the outside of focus pattern was overlaid with a distinct reddish, purple-ish haze.  However, through my deep green filter, the inner/outer ring patterns on Vega were effectively identical.  Also, if I went far enough out of focus, the inside/outside ring patterns looked the same, including their tints. 

 

What I'm suggesting is that the colors are so tightly clumped together, that as you move slightly out of focus, the colors actively interfere with each other.  Indeed, when focusing on Saturn and Jupiter, I noticed a purple/red  "CA" developing just out of focus.  At focus, there was none.  This characteristic actually let me find focus rather unambiguously.   Seems counterintuitive but I suspect this is what's happening.   Comments?

 

So, after some work, and attention to its thermal state, this sample of the Orion 100ED performs splendidly and goes on to my upgrade list.

 

Does anybody have another sample that you would like to float to me for testing?

 

Jeff 

[Jeff B]

Jeff, have you tried my software for this telescope?

P.S. I am slowly preparing the next version.

Maciek, funny you should ask.  

 

For the Orion objective, no, not yet, but I did for the Celestron objective I mention above.

 

Not too shabby!   And the Orion objective is a teeny, tiny, tiny, really, really a tiny bit "better" in DPAC.   

 

I plan on using your program for my future evaluations as long  as the figure is not some weird compound, higher order curve.

 

Jeff

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[Maciek_Cz]

Your Orion and Celestron have such good correction that it makes no sense to adjust the simulation to fit your photos.

Probably just out of curiosity.

[SteveG]

I have that Orion scope. Same, super high quality optics. On mine I spent a lot of time trying to fix the bad focuser, but eventually replaced it. I could not get the beam to the center of the objective. I added the GSO dual speed a couple of years ago and am very happy.

[Jon Isaacs]

 

The focuser drawtube was very loose and would flop around a bit.  Careful adjustment of the small screws made for smooth steady operation, but like all cheap R&P focusers, the draw tube would shift/rotate slightly when changing focusing direction.

 

I thought the Orion ED-100s all came with the Orion Crayford. Are you positive that's the original focuser?

 

Jon

[Jeff B]

I thought the Orion ED-100s all came with the Orion Crayford. Are you positive that's the original focuser?

 

Jon

A good question that I don't know the answer to Jon.  Either way, it won't stay. 

 

Jeff

[rootsabove]

Does anybody have another sample that you would like to float to me for testing?

 

Jeff 

Jeff, I have a very good condition all original Orion version, with Crayford focuser, that I bought in 2008. I’d be happy to drop it off

some evening. It puts up very nice images, and I’ve also noticed similar behavior with the out of focus star patterns regarding the colors. I’ve always thought “hmm, that doesn’t look quite right”, but I was still impressed by the images. If interested, just PM me!

Joe

Edited by rootsabove, 03 September 2022 - 06:28 AM.

[Jon Isaacs]

A good question that I don't know the answer to Jon.  Either way, it won't stay. 

 

Jeff

 

My guess is that it's a Celestron C4-R or maybe an Orion 100 mm F/6. The length of the drawtube should tell.

 

Jon

[Wildetelescope]

Pretty sure that is an Original Orion 100 ED and focuser. I remember vividly looking a one back in the early 2000’s at company seven.  That is teh focuser that they had.  It was one of the cheap single speed R and P’s .  If you go out to the C7 website you can verify.  They have a picture.  That is an old 100 ED.  I remember Marty going on about them at the time, how the optics were amazingly good even if the rest of the scope was budget oriented, like the focuser.  they were selling for 1K at a time when the TV102 was going for over 2K.  Pretty sure Marty had put a couple samples on their interferometer to test.  It does not surprise me at all that yours tests well Jeff.  However, your story does really illustrate that the telescope is a system that relies on multiple elements to get the optimal performance.  The cool thing is that 20 years down the road, the quality of the mechanical parts like focusers coming out of China have dramatically  improved.so you do not HAVE to spring for a Feather touch if you do not want to, although the quality of your lens could certainly justify that;-). Have fun with your new toy!

 

JMD

[John Huntley]

I thought the Orion ED-100s all came with the Orion Crayford. Are you positive that's the original focuser?

 

Jon

The focuser on Jeff's scope looks the same as that fitted to my old Skywatcher ED100 and Orion ED80. Basic single speed crayford. Mine worked OK but back then I didn't used heavy eyepieces. Both of those had good optics as I recall.

 

 

[Jon Isaacs]

The focuser on Jeff's scope looks the same as that fitted to my old Skywatcher ED100 and Orion ED80. Basic single speed crayford. Mine worked OK but back then I didn't used heavy eyepieces. Both of those had good optics as I recall.

 

ed100tall.jpg

 

ed80eq.jpg

John:

 

It does look very similar but Jeff said his was a rack and pinion. 

 

Jon

[Jon Isaacs]

Pretty sure that is an Original Orion 100 ED and focuser. I remember vividly looking a one back in the early 2000’s at company seven.  That is teh focuser that they had.  It was one of the cheap single speed R and P’s .  If you go out to the C7 website you can verify.  They have a picture.  That is an old 100 ED.  I remember Marty going on about them at the time, how the optics were amazingly good even if the rest of the scope was budget oriented, like the focuser.  they were selling for 1K at a time when the TV102 was going for over 2K.  Pretty sure Marty had put a couple samples on their interferometer to test.  It does not surprise me at all that yours tests well Jeff.  However, your story does really illustrate that the telescope is a system that relies on multiple elements to get the optimal performance.  The cool thing is that 20 years down the road, the quality of the mechanical parts like focusers coming out of China have dramatically  improved.so you do not HAVE to spring for a Feather touch if you do not want to, although the quality of your lens could certainly justify that;-). Have fun with your new toy!

 

JMD

 

This is a link to the photo of the ED-100 focuser from the Company 7 website. It is not a rack and pinion focuser, it's clearly the Orion single speed Crayford.

 

http://www.company7....cuser500476.jpg

 

I've reworked a number of these, I know them well. A popular modification is to use a fine stone and flatten the drawtube flat. As they come, the pinion shaft only contacts the edges. They tend to slip. With full contact, they carry loads better. They're quite decent focusers, especially compared to the Synta/Celestron/Orion rack and pinions.

 

http://www.company7....ion100EDf9.html

 

Jon

 

 

[hyia]

Thank you for finally getting one of these on the test bench.  I really hope you can get more of them to test.  I remember there was one CN member who insisted that he had had multiple samples with the best being around diffraction limited (https://www.cloudyni...tout/?p=6029173).  I found that strange at the time for a few reasons, and it's often come to mind when I've read that the DPAC tests have shown the 80ed's to be consistently good.

[Wildetelescope]

This is a link to the photo of the ED-100 focuser from the Company 7 website. It is not a rack and pinion focuser, it's clearly the Orion single speed Crayford.

 

http://www.company7....cuser500476.jpg

 

I've reworked a number of these, I know them well. A popular modification is to use a fine stone and flatten the drawtube flat. As they come, the pinion shaft only contacts the edges. They tend to slip. With full contact, they carry loads better. They're quite decent focusers, especially compared to the Synta/Celestron/Orion rack and pinions.

 

http://www.company7....ion100EDf9.html

 

Jon

HI John,

        Looking closer, I see your point.  I thought the one I looked at back in 2003 time frame was an R and P, but memory but that was 20 years ago, lol….    

 

JMD

[Jeff B]

Jeff, I have a very good condition all original Orion version, with Crayford focuser, that I bought in 2008. I’d be happy to drop it off

some evening. It puts up very nice images, and I’ve also noticed similar behavior with the out of focus star patterns regarding the colors. I’ve always thought “hmm, that doesn’t look quite right”, but I was still impressed by the images. If interested, just PM me!

Joe

Hey Joe!

 

Absolutely and PM sent!

 

Jeff

[John Huntley]

John:

 

It does look very similar but Jeff said his was a rack and pinion. 

 

Jon

Thanks Jon, I missed that. Most likely a replacement from one of the Synta achromats then I guess. I did that drawtube flattening thing with my old crayfords and it does help. No competition for a Moonlite though !

Edited by John Huntley, 03 September 2022 - 04:19 PM.

[Jon Isaacs]

HI John,

        Looking closer, I see your point.  I thought the one I looked at back in 2003 time frame was an R and P, but memory but that was 20 years ago, lol….    

 

JMD

 

Being a mechanic and mechanical engineering type, focusers intrigue me. I like messing with them, taking them apart, fixing them...

 

Now these DPAC tests that Jeff, Paul and others do.. that's way out of my league.. Very interesting though.

 

One thing about the ED-80 and ED-100 that never made sense to me was that gray-green paint. A little little understanding of color and an ED-100 can look like this.

 

 

This scope belongs to my friend Tom. The focuser is an old WO focuser I gave him but any black focuser will do. With the optics Jeff shows to be superb and Toms look, it's a winner.

 

Jon

[SteveG]

 

 

Being a mechanic and mechanical engineering type, focusers intrigue me. I like messing with them, taking them apart, fixing them...

 

Now these DPAC tests that Jeff, Paul and others do.. that's way out of my league.. Very interesting though.

 

One thing about the ED-80 and ED-100 that never made sense to me was that gray-green paint. A little little understanding of color and an ED-100 can look like this.

 

 

 

This scope belongs to my friend Tom. The focuser is an old WO focuser I gave him but any black focuser will do. With the optics Jeff shows to be superb and Toms look, it's a winner.

 

Jon

 

Agreed about that Orion gray! I sanded mine smooth and used an automotive wrap. It was a fun Covid project.

 

[Jeff B]

"Now these DPAC tests that Jeff, Paul and others do.. that's way out of my league.."

 

Chuckle...now, I don't believe that for a second Jon.