27 replies to this topic

[scoale]

A few weeks ago, I was very, very fortunate to take delivery of a new TEC 160fl numbered 147.  Unfortunately, atmospheric conditions have not allowed for a decent evaluation of optics, and I've not yet had the opportunity to DPAC test.  That said, I do have a few early observations:

 

• The TEC's weight to aperture ratio is remarkable.  The scope weighs 33.7lbs fully dressed with a 19" Losmandy plate, rings, captains ring, 7x50 finder, and baader bbhs diagonal.  Consider that my comparably equipped TOA 130 weighs 32.6lbs.  If, like I was, you are on the fence about whether a 6" refractor is more than you want to handle, the TEC is a great option if you do decide to take the plunge.

• Unfortunately, my Panther TTS 160 mount/Planet tripod is not up to the task.  Settle times are around 3 seconds - which i could live with - but there is too much shaking when focusing.  Once focused, stability is adequate. And tracking is good. I suspected the Panther might struggle with the TEC and so, as a contingency, ordered a Panther Lite about a month ago that should be here this summer.  Until then, I'll continue playing around with the TTS 160 to see if i can achieve any improvement.

• Again, there has simply been too much turbulence to permit a decent evaluation of optics, but I'll risk a few early impressions:

1. No discernible coma.  For me, this is BIG.  Any hint of coma and/or astigmatism ruins the esthetic that I so value in a refractor.  For me, coma ruins the view when observing doubles, carbon stars, etc.
2. No discernible astigmatism when racking inside/outside focus at high power.  Again, this is BIG for the same reasons I note above.
3. I am seeing some inner zone at sufficient defocus.  Need a better night to assess.
4. Spherical error @ 525nm appears to be very well controlled, although turbulence has made it impossible to assess with certainty.  And I'm not seeing any indication of a turned edge - which I find is all too common even with premium refractors.  Looking forward to DPAC confirmation.
5. I did see some blue/purple fringing on the limb of the moon - but the moon was at 35 degrees at time of observation.
6. I had a fairly solid view of Jupiter the night I received the scope.  I did not have another scope setup for comparison, but I was satisfied with what I saw given Jupiter was around 35 arc seconds and seeing was no better than 3/5.  

I'll share an optical update when I have a sufficient fact base (probably be a few weeks).  Overall, I'm feeling optimistic that i am going to be quite pleased with this scope.

 

Edited by scoale, 13 March 2025 - 04:32 PM.

[rockethead26]

Congrats on the new 160 fl. You mention coma in refractors is a big NO, but my understanding is that coma in fast refractors has been completely corrected in lens design since way back in the 1800's and is virtually unheard of today in any decent refractor. Have you actually experienced that?

[scoale]

Congrats on the new 160 fl. You mention coma in refractors is a big NO, but my understanding is that coma in fast refractors has been completely corrected in lens design since way back in the 1800's and is virtually unheard of today in any decent refractor. Have you actually experienced that?

I've had multiple premium refractors with coma - two of which went back to the manufacturer to get addressed.  Regardless of design, you can have execution issues including misaligned cell, elements, and/or focuser. 

[ichdien]

Congratulations on the new scope!  As the former owner of a TEC 140, I'm confident the big brother will be a great performer for you.  Sorry to hear about the mounting issue.  A couple of quick thoughts.  First, I believe TEC recommends a 12" plate for the 160.  That might save a little weight.  There's also an outfit that produces carbon fiber plates and rings that might save even more: https://rouzastro.com Second, although I've heard very good things about the Planet, I wonder if an even sturdier tripod or portable pier might help. E.g.  I use a Tak heavy metal tripod with a DM6 and 155 f/7 refractor, and there is zero settling time. 

 

Best of luck working out a solution.

 

Jim

Edited by ichdien, 13 March 2025 - 05:17 PM.

[rockethead26]

I've had multiple premium refractors with coma - two of which went back to the manufacturer to get addressed.  Regardless of design, you can have execution issues including misaligned cell, elements, and/or focuser. 

Thanks for the clarification on execution issues, not design issues.

[dryfly]

Congrats on the new scope!  I just had to sell mine.  Someday I'll buy a new one....

 

Mike

[scoale]

Congrats on the new scope!  I just had to sell mine.  Someday I'll buy a new one....

 

Mike

You may not need to, given you have an AT 150EDL!

 

Assume that you are mounting your 6" refractors on the RST-300/Super Mount setup?  How has that worked out for you?

[Scott in NC]

Very nice, Stephen! I’ve been really busy with work and other obligations lately, but I’m looking forward to coming over one day this spring to check it out. 

[Scott Beith]

Congrats on the new glass! 

[PKDfan]

Avidly following this Stephen (aka scoale).

This is the same size aperture jump i'd need if i was to ever require more aperture grasping.

62mm ->100mm ->~160mm.
(161.5=2.6X)

Congratulations on the new glass !


Clear Steady Skies be yours !

Lance
Edit typo in name

Edited by PKDfan, 14 March 2025 - 07:31 PM.

[Scott99]

I've had multiple premium refractors with coma - two of which went back to the manufacturer to get addressed.  Regardless of design, you can have execution issues including misaligned cell, elements, and/or focuser. 

FWIW, I've been lurking around forums for years, I've never seen a report of any of these with a TEC....maybe one report of a problem with an FT focuser in 25 years

[slavicek]

.

• Unfortunately, my Panther TTS 160 mount/Planet tripod is not up to the task.  Settle times are around 3 seconds - which i could live with - but there is too much shaking when focusing.  Once focused, stability is adequate. And tracking is good. I suspected the Panther might struggle with the TEC and so, as a contingency, ordered a Panther Lite about a month ago that should be here this summer.  Until then, I'll continue playing around with the TTS 160 to see if i can achieve any improvement

I had the same problems when I got my TEC-180. After many attempts to fix the problem (by blaming the mounts I tried to use with it) I realized that it was the tripod/pier which created all that shaking. Looking at the pic of your set up you might have similar problem. And it might be combination of things.

I ended up mounting the scope on a concrete slab to eliminate all possible "weak points" and starting from there I began to add individual components, one at the time, till I found the problem. It turned out that ATS portable pier was the solution for sturdiness but also to get enough clearance so that the scope can point to zenith. Currently I use RST-300 and DM-6 mount with that scope. Your TEC-160 may be less demanding thou so the above should serve you as a guidance. GL.

[scoale]

I had the same problems when I got my TEC-180. After many attempts to fix the problem (by blaming the mounts I tried to use with it) I realized that it was the tripod/pier which created all that shaking. Looking at the pic of your set up you might have similar problem. And it might be combination of things.

I ended up mounting the scope on a concrete slab to eliminate all possible "weak points" and starting from there I began to add individual components, one at the time, till I found the problem. It turned out that ATS portable pier was the solution for sturdiness but also to get enough clearance so that the scope can point to zenith. Currently I use RST-300 and DM-6 mount with that scope. Your TEC-160 may be less demanding thou so the above should serve you as a guidance. GL.

Thanks for response!  I have a Panther Lite on order, which I have noted others using successfully with larger/longer scopes than mine.  Should that not work out, the RST-300 is on my radar screen.  And I'm going to look into the ATS portable pier.

 

Thanks a bunch, Stephen

[dryfly]

You may not need to, given you have an AT 150EDL!

 

Assume that you are mounting your 6" refractors on the RST-300/Super Mount setup?  How has that worked out for you?

That's what I'm hoping - maybe even a 180 EDL if one ver comes out!  As Slavicek noted above, the RST-300 will easily handle the 160, and I'm finding the Super Mount tripod to be pretty bomb-proof.  I also have one of his new extra-heavy-duty mounts on the way, which I believe is designed to handle up to 50kgs.  So you might look into that as well for a "grab and go" alt-az.   I'm going to try using a PiFinder with it and the EDL, and I can see that becoming my "easy" set-up.

 

Mike

[DeanS]

Congrats on the 160!

 

I had  mine at Winter Star Party last month and got my best view of Jupiter ever with it.  Steady skies are the key, and yes being in the Keys in Feb is nice too

[slavicek]

Additional note: I am using the RST-300 in Alt-Az mode for visual only. I would not recommend this mount for imaging. But, based on your initial post, it seems you plan to do visual with your TEC. Also, RST-300 is portable mount.

[scoale]

Additional note: I am using the RST-300 in Alt-Az mode for visual only. I would not recommend this mount for imaging. But, based on your initial post, it seems you plan to do visual with your TEC. Also, RST-300 is portable mount.

yep, visual only

[Scott in NC]

Stephen and I finally got together to do some scope testing today, and with his permission I'm posting the results of the DPAC test on his new TEC 160FL.

 

[Scott in NC]

Ignore the brightness difference between the inside focus and outside focus images. I turned up the LED brightness a little more than I meant to in between taking those images.  I've got to run off and do other things now, so will let others do the commentary.

[scoale]

Once again, I must thank Scott for making the trip over to DPAC another one of my scopes. Great job, Scott!

Here are a few star test images I captured tonight to complement Scott's DPAC photos. As usual, the results are consistent with DPAC. Unfortunately, the defocused images reflect a bit of turbulence-related distortion and loss of contrast - but I think, in combination with DPAC, you get a pretty good idea of the lens.

 

The top two rows are green (525nm).
The third row, of course, is blue (472nm).

The last row is, again, green, at greater defocus.

Geoptik 50 micron artificial star @ 100ft. Ambient temp of 60 degrees. Scope cooling for 1.5hrs. ASI 290 camera with 3X Televue barlow.

 

Edited by scoale, 16 March 2025 - 03:16 PM.

[Scott in NC]

Thanks for including the star test images. As I’ve said many times before, star testing isn’t really my forte, but I’m having trouble seeing the shallow central zone in the star test images. Do you think that DPAC is just that much more sensitive to very small wavefront errors, or rather that seeing conditions are obscuring very fine details in the star test?

[Jeff B]

Scott, I do see it in the lower blue RH image, at least that's my take.  The zone has more effect on the shorter wave length.

 

The other way to perhaps tease the zone out is to look much further out of focus.  Maybe.

 

Jeff

[scoale]

Thanks for including the star test images. As I’ve said many times before, star testing isn’t really my forte, but I’m having trouble seeing the shallow central zone in the star test images. Do you think that DPAC is just that much more sensitive to very small wavefront errors, or rather that seeing conditions are obscuring very fine details in the star test?

Hi, Scott.  Yes, the zone is easier to image when there is less turbulence.  As Jeff mentioned, you can see it better at the blue wavelength.  It is also easily observed visually.

 

To Jeff's point, I updated my post with an additional image at greater defocus.

 

For reference, here is an image I captured awhile back, on a night of very low atmospheric turbulence, of the central zone on my Stellarvue:

 

[Scott in NC]

Thanks for the additional image, Stephen. And to be clear to those here who are unfamiliar with just how sensitive the star test and DPAC can be to wavefront aberrations, we’re just picking nits here (because that’s what we do ). This is a very nice scope that Stephen has, and I’ve already told him that if he’s displeased with it he’s got a willing buyer who will drive right over and pick it up. So none of you can have it!

[PKDfan]

Thanks for the additional image, Stephen. And to be clear to those here who are unfamiliar with just how sensitive the star test and DPAC can be to wavefront aberrations, we’re just picking nits here (because that’s what we do ). This is a very nice scope that Stephen has, and I’ve already told him that if he’s displeased with it he’s got a willing buyer who will drive right over and pick it up. So none of you can have it!

It is indeed a very nice looking lense.
Highest correction is right where its supposed to be.

I found the white light image to be particularily interesting. Its demonstrates almost exactly same defocus tints as my 100ED when out of focus 10waves or so either side.

Stephen will find great joy with it that i've no doubt.



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