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Test TEC 140 ED (DPAC)

Started by Psion , Mar 23 2025 04:52 AM

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34 replies to this topic

#26 CHASLX200

ISS

Posts: 44,541
Joined: 29 Sep 2007
Loc: Tampa area Florida

Posted 24 March 2025 - 06:25 PM

Never had a Tec lens by heck. But in about 3 weeks i will.

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#27 kgb

Gemini

Posts: 3,141
Joined: 16 Dec 2012
Loc: Orchard Landing Observatory, LI, NY

Posted 24 March 2025 - 06:48 PM

A good guide for making one can be found in Sam Brown's book called "All about telescopes". The out-of-print book can be found on the used market.

Available for download. https://www.edmundop...elescopes 2.pdf

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#28 RichA

Hubble

Posts: 13,560
Joined: 03 Jun 2010
Loc: Toronto, Canada

Posted 24 March 2025 - 07:22 PM

After a long time I pulled the TEC 140ED (year 2011) out of storage to compare it with the Askar 203mm, and on that occasion I did a little DPAC test. It is obvious that Yuri can do it! The optics are amazing even if not completely free of chromatic aberration, but the focus was on eliminating other optical defects.

TEC140ED_Ronchi_RGB-1.jpg

TEC_140ED_R.jpeg

TEC_140ED_G.jpeg

TEC_140ED_B.jpeg

That's really good. We may have to go to two lines now in order to see anything with high-performance refractors.

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#29 Psion

Gemini

topic starter

Posts: 3,491
Joined: 27 Apr 2005
Loc: Czech Republic, Prague

Posted 25 March 2025 - 11:07 AM

I redid the TEC 140ED measurements on a different computer where the monitor resolution is lower and the Ronchigram line profile is more visible.

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#30 Phil Cowell

Cosmos

Posts: 9,584
Joined: 24 May 2007
Loc: Southern Tier NY

Posted 25 March 2025 - 04:18 PM

Thanks for the link. Takes me back to the days of Dan Dare in the Eagle era .

https://www.dandare.com

Available for download. https://www.edmundop...elescopes 2.pdf

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#31 kgb

Gemini

Posts: 3,141
Joined: 16 Dec 2012
Loc: Orchard Landing Observatory, LI, NY

Posted 25 March 2025 - 04:22 PM

Thanks for the link. Takes me back to the days of Dan Dare in the Eagle era .

https://www.dandare.com

Wow. That is an awesome link Phil!

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#32 ken30809

Ranger 4

Posts: 396
Joined: 03 Sep 2009
Loc: SW NC

Posted 25 March 2025 - 06:17 PM

Wow, what fantastic test results. You’ve got a real gem!

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#33 Scott in NC

Refractor Aficionado

Posts: 40,565
Joined: 05 Mar 2005
Loc: NC

Posted 25 March 2025 - 06:25 PM

I’m really amazed at the spherical correction in blue. That’s rare even in the finest of apos.

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#34 PKDfan

Gemini

Posts: 3,376
Joined: 03 May 2019
Loc: Edmonton

Posted 25 March 2025 - 10:36 PM

I redid the TEC 140ED measurements on a different computer where the monitor resolution is lower and the Ronchigram line profile is more visible.

TEC140_R1.jpeg

TEC140_G1.jpeg

TEC140_B1.jpeg