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iStar Optical’s Phantom FCL 140-6.5 review

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28 replies to this topic

#1 Psion

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Posted 02 December 2021 - 12:05 PM

From what I was able to see, I conclude that the optics belongs to a Super APO class, which is highly suitable for both visual observing and astrophotography. Unfortunately, I have to state that the TEC 140 lost in the direct side-by-side chromatic aberration comparison test, otherwise the TEC is practically perfect from the optical point of view. The Phantom FCL 140-6.5 is, therefore, a great all-round refractor, and the manufacturer has promised to remedy the minor mechanical issue with the amount of “grip” of the rotary lock. Therefore, iStar Optical can be congratulated on a very well made optical instrument.

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#2 weis14

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Posted 02 December 2021 - 01:49 PM

Excellent review and direct comparison!


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#3 Stargazer3236

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Posted 02 December 2021 - 02:21 PM

Too bad it wasn't cheaper, but alas, that's what you pay for excellence!



#4 lunardave

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Posted 02 December 2021 - 03:41 PM

Too rich for my blood. Sticking with my cheap by comparison TV85.



#5 coinboy1

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Posted 03 December 2021 - 05:33 AM

Great review, really nice scope and great shots. Thanks for the side by side comparison. It is definitely a game changer in the APO market and really the price is reasonably for what the performance is. 



#6 ABQJeff

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Posted 04 December 2021 - 02:20 AM

Great review! I actually read it before I did mine (yours was the one I was referencing). I agree the Phantom 140 f/6.5 delivers great performance especially given the price of competitors that it beats or equals.

CS!

#7 Terra Nova

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Posted 05 December 2021 - 12:56 PM

That is one extremely impressive refractor!



#8 Jon_Doh

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Posted 06 December 2021 - 09:18 AM

Thank you for your review.  The 140 is becoming the sweet spot for refractors it seems and now there are a lot of excellent offerings in that category making the decision of which 140 refractor to buy more difficult.  



#9 Christine_Z

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Posted 06 December 2021 - 01:15 PM

Thank you for the review...A 140 that can be reduced to f/4.2 that's kinda really appealing for smaller format cameras and EAA



#10 LMcKeen

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Posted 08 December 2021 - 08:45 AM

I would like to see a side by side comparison between the AP Gran Turismo, Takahashi has TOA-130NS and the iStar Phantom FCL 140. The first two are 10mm smaller and over $2K more expensive.


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#11 Psion

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Posted 08 December 2021 - 12:50 PM

Thank you to all. It would be nice comparison, it's a pity AP Gran Turismo and TAK TOA is out of stock.



#12 Gleason

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Posted 10 December 2021 - 05:36 PM

How about showing the wave front error profile, strehl ratio, and Ronchi on the TEC you used?  If it showed more CA, it would help to understand why.  Does not appear to be any quantative data to support the observation.  



#13 Psion

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Posted 11 December 2021 - 10:04 AM

TEC 140 ED (not FL) has significant more chromatic aberration because of used glasses - K10/FPL53/BK7 and RC index is 0.9, while RC index of Phantom is 0.6. Simply put, Phantom uses a better combination of glasses and modern optical design. You can see Airylab test, this TEC is little bit worst than my TEC.



#14 ISTAR Optical

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Posted 12 December 2021 - 02:25 PM

I would like to see a side by side comparison between the AP Gran Turismo, Takahashi has TOA-130NS and the iStar Phantom FCL 140. The first two are 10mm smaller and over $2K more expensive.

Hello, I am so confident about the modern design, quality of optical glass and superior quality of iStar's Phantom FCL 140-6.5 Super APO triplet that I would welcome such direct side-by-side comparison and testing. I am quite sure that our new APO triplet will either match or exceed the quality of all comparable models using comparable optical design (a triplet, regardless if air spaced, cemented or oil spaced).

 

best regards,

 

Ales


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#15 scoale

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Posted 24 December 2021 - 02:59 AM

Ales, congratulations on what appears to be a top tier scope.  Can you elaborate on why, given the degree of confidence you have in how your scope would compare to AP/Tak/Tec, etc., the strehl guarantee is only 90%?  Thank you. 



#16 Psion

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Posted 24 December 2021 - 04:27 AM

The standard Strehl value has Istar from 0.96 to 0.98. The manufacturer only guarantees a minimum value 0.90 in all circumstances.

 

Generaly - The acceptable level of wavefront aberrations is  value of 0.80 Strehl is conventionally used to define an optical system as “Diffraction limited”, as we know.



#17 Hobby Astronomer

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Posted 24 December 2021 - 08:37 PM

Very nice review with lots of detail.

 

Have to ask this most important question when a review is offered...

 

Do you own this scope? Will this be your primary imaging telescope going forward?

 

Again thanks for the work putting this together.



#18 Psion

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Posted 26 December 2021 - 02:49 AM

Thank you! No, the tested Istar telescope was my colleague's telescope, I have a TEC 140ED. A lot of people usually tries to praise their own technique, this is not my case. I have many telescopes and not one of them is primary for imaging.



#19 25585

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Posted 06 January 2022 - 04:17 PM

Sharpstar (& rebranders) sell a fast 140mm double ED triplet. The Istar seems similar...



#20 Psion

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Posted 07 January 2022 - 04:03 AM

Yes, Sharpstar has 140 / 6.5 like other manufacturers (CFF, TS-Optics, ES and etc.), but that's a different lens design and glass than iStar. Anyway, I'm a little disappointed with the Sharpstar Hypergraph8, it's a bad telescope. I've seen bad primary mirrors and the image quality isn't very good. Much better are Hypergraph6 and 130 (Hyperbolic mirrors) IMHO.



#21 Taeyoung

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Posted 11 January 2022 - 01:42 AM

Are  Istar's lens and OTA made by Istar?

I know the other APO similar to Istar Phantom  140.

These refractors seems twin...



#22 Qqbin

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Posted 12 January 2022 - 01:04 AM

Are  Istar's lens and OTA made by Istar?

I know the other APO similar to Istar Phantom  140.

These refractors seems twin...

iStar lens are made by them. I build a custom telescope using the iStar 140mm f6.5 APO lens, the same one used in the Phantom 140, and I am extremely happy with the performance of the lens. It is consistent with the review on this thread.



#23 Psion

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Posted 12 January 2022 - 02:45 AM

iStar has a proprietary and original optical design and there is no identical optical design from any other manufacturer. In this time has new optical design for 200 mm F6 Super APO and prepared also FF/APS-C reducer for F3.9!



#24 ISTAR Optical

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Posted 12 January 2022 - 05:08 PM

I would like to see a side by side comparison between the AP Gran Turismo, Takahashi has TOA-130NS and the iStar Phantom FCL 140. The first two are 10mm smaller and over $2K more expensive.

Hello,

a new customer from Poland is going to do side by side comparison with 3 or 4 similar models by Takahashi, APM, CFF and AP from what he said. They have their nation wide astro meetings coming up this spring and that is where all these scopes will be in one place. So Im curious about the outcome myself but if I had to bet, I think Phantom 140 will end up as a virtual tie or even above the image quality of some of these comparable models. 

I will ask him to post his review on CN.



#25 ISTAR Optical

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Posted 12 January 2022 - 05:11 PM

Ales, congratulations on what appears to be a top tier scope.  Can you elaborate on why, given the degree of confidence you have in how your scope would compare to AP/Tak/Tec, etc., the strehl guarantee is only 90%?  Thank you. 

Hello,

Psion's response to your question is spot on. I would write exactly the same. 




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