Askar 151 PHQ Review - Part 2: Optical Test

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  • Опубліковано 10 січ 2025

КОМЕНТАРІ • 92

  • @darkskygeek
    @darkskygeek  Рік тому +1

    Support the channel by using the affiliate links below if you want to purchase anything from Agena Astro, my favorite astro retailer :)
    -----------------------------
    Affiliate Links
    -----------------------------
    Agena Astro: bit.ly/487tmnj
    Askar 151 PQH: bit.ly/3RQFFyJ
    Askar .7x reducer for PHQ series: bit.ly/3Q9uvnC
    Askar M54 T-Ring for Canon DSLR EOS Cameras: bit.ly/40gsXvp
    Askar M54 T-Ring for Nikon F-Mount DSLR Cameras: bit.ly/40cbIvj
    Askar M54 Backfocus Adjuster: bit.ly/40c0qal
    Askar M54 Female to M48 Male Backfocus Adjuster: bit.ly/3QA5sKx
    -----------------------------
    My equipment
    -----------------------------
    * iOptron CEM70 Center Balanced Equatorial Mount: bit.ly/3PzUMuP
    * iOptron Tri-Pier: bit.ly/3RhDzYz
    * Antlia V-Series LRGB Pro Imaging Filter Set: bit.ly/3LHcRVJ
    * Antlia SHO Narrowband 3nm Pro Imaging Filter Set: bit.ly/3Rj3yii
    * ZWO 8-Position Electronic Filter Wheel: bit.ly/488uvuW
    * ZWO ASI533MM Pro Cooled Monochrome Astronomy Camera: bit.ly/4887g4b
    * ZWO ASI174MM Mini Guide Camera: bit.ly/469sJYv

  • @neilhankey2514
    @neilhankey2514 Рік тому +6

    You know, I forgot how much I enjoy watching proper astronomy channels. Thanks for the video's.

  • @jimbub1001
    @jimbub1001 Рік тому +7

    One of the best and most thorough telescope reviews that I have ever seen! Well done - the qualitative AND quantitative analyses are outstanding. As a fellow 151PHQ owner, this review is representative of my experiences with the scope as well. Nicely done and THANK YOU!

  • @southbronxny5727
    @southbronxny5727 11 місяців тому +2

    The review was so excellent, I think you sold it all out on the site. I wonder how it compares to their new 185apo which I hope they send you to test also. 2 Thumbs up for the video. Thanks.

  • @The-Chaos-Shack
    @The-Chaos-Shack Місяць тому

    Fantastic review, Although a lot of the more technical stuff in this is a bit over my head, I have definitely learnt a few things from you. I will be having a look at your other videos. I didn't know that Askar made a scope bigger than the 130PHQ. The 151PHQ looks great and as a proud owner of the 80PHQ I know this series of flatfield astrographs don't disappoint. I wonder why they didn't stick with the distinctive green and white colour scheme of the others in the PHQ series.

  • @surgeon1000000
    @surgeon1000000 Рік тому

    Congrats on the thorough optical test and wavefront estmation. Probably the only channel doing that. Keep it up!

  • @Martincohenphoto
    @Martincohenphoto 3 місяці тому

    Another awesome video. Thanks for creating consistently great content!

  • @tostativerdk
    @tostativerdk Рік тому +2

    Love your extremely high bar for testing equipment, keep it coming :)

  • @ronconovoa7566
    @ronconovoa7566 2 місяці тому

    great info thank you i hope more people will follow you i did your indication now i am hook in

  • @Astro_Px
    @Astro_Px Рік тому

    I am just in awe at this wonderful presentation. Wow, I cannot say enough! Just perfect speech/pace - invaluable thorough review with great information. Learned so much about aberration. I was wondering if you would consider a follow up or maybe in the future about a quantitative/qualitative comparison of actual images taken with the scope, such as tilt, flatness. Again, I would like to really congratulate you on such a great video. Sometimes it is hard to follow because people (without experience) tend to speak way too fast and it makes it hard on the listener to latch on to all the details - you pace is perfect - Just really impressed - THANK YOU SO MUCH for putting this together.

    • @darkskygeek
      @darkskygeek  Рік тому +1

      Thank you for the kind words. I may do a follow up in the future, once I’ve had more experience with the scope. CS!

  • @markrussell7069
    @markrussell7069 5 місяців тому

    Thanks for your very detailed analysis. It was interesting to find out about these refractors.

  • @hael8680
    @hael8680 Рік тому +1

    Great review!! You are more critical of corners than I am...

  • @KingLoopie1
    @KingLoopie1 8 місяців тому

    Alright, Alright.... You got me about halfway through. New sub! I love optical analysis and you're making it understandable for an uneducated id such as myself! 👍👍

  • @MountainFisher
    @MountainFisher 10 місяців тому

    Interesting to see how the testing is performed. I used Agena all the time, I'll use your link next time I buy something.

  • @physmc1
    @physmc1 Рік тому

    Comparing to the RC was an excellent idea. I'm convinced the spectrograph test is a very good assessment of the CA performance.

  • @Rob_1472
    @Rob_1472 Рік тому +1

    Sometimes I don’t comment on videos but this was actually a very balanced review given people good insight to reflect on. Hope all manufacturers send more to you. Sharpstar Z4 next. 100mm refractor at a fair value for its aperture and 6 lenses. Sharpstar if you’re watching, send him the OTA for review.

    • @darkskygeek
      @darkskygeek  Рік тому +1

      Thank you for the kind words 😊

    • @hael8680
      @hael8680 Рік тому

      I tend to believe more reviews of material sent by a dealer than a manufacturer. Manufacturers will send their best sample while dealers don't have the means to test as much before sending something to a user for testing and review. The youtubers ( this one included 😉) are for the most part honest in their reviews.

  • @wallbke
    @wallbke 7 місяців тому

    Really excellent and interesting. Adding pieces to the puzzle for my next scope. Thank you!

    • @darkskygeek
      @darkskygeek  7 місяців тому

      If you order this or another scope, feel free to use one of my affiliate links in the description of this video 😉 Thanks! 🙏🏻

  • @RajahChandrasekhar
    @RajahChandrasekhar Рік тому

    Awesome video as always!!!

  • @nikaxstrophotography
    @nikaxstrophotography Рік тому

    Great review than you for taking the time to do so.

  • @JoepsAstronomy
    @JoepsAstronomy 2 місяці тому

    EXCELLENT!

  • @comeraczy2483
    @comeraczy2483 Рік тому +1

    Thanks a lot. Best telescope review ever! By any chance, would you know if the WinRodier code is available anywhere? The team doesn't seem to be responsive at all. I believe it's Pascal for old Windows but I'm sure it would be easy to rewrite for gtk+ to get it to work smoothly with other astrophotography tools on a raspberry Pi.

    • @darkskygeek
      @darkskygeek  Рік тому

      I think that project is no longer active. The last release dates back 10 years ago. It’s a miracle it still runs! Thank you for the kind words 😀

    • @WilliFromEarth
      @WilliFromEarth Рік тому +1

      I found a paper from Bharmal, Busher, Haniff, “Near-focus high-sensitivity wavefront sensing“ from 2005. They are measuring the Zernike coefficients from the two images. With that information you can calculate the Strehl ratio, as long as it is above 0.1… which should be the case here ;-). This could be a good base for a new code.

  • @anata5127
    @anata5127 Рік тому

    Very nice video!
    Tak FSQ refractors, especially 85 version, are the past.
    Nowadays, flagship refractors are Tak TOA, due to novel correction flatteners.

    • @darkskygeek
      @darkskygeek  Рік тому

      I’d love to test a Takahashi TOA refractor 😁

    • @anata5127
      @anata5127 Рік тому

      @@darkskygeek It could have been great to have such independent report.
      Ask Askar to get it for you. Their can afford! Tell that you want to see whether their scopes are better than Tak flagship scope 😉

    • @ddierick
      @ddierick Рік тому

      @@darkskygeek I have owned two, they are the best corrected refractors in the world in all aspects, but heavy... (have owned several AP's, TMB's, many Tak's, several WO's, you name it ;))

  • @williammitchell3586
    @williammitchell3586 10 місяців тому

    Simply excellent video.

  • @CMOS-Astrophoto
    @CMOS-Astrophoto Рік тому +1

    Thanks for the video, nicely done as usual. BUT, an image test with that kind of vignetting and looking at stars that far from the corners is not representative. And no mention of the spot size data sheet from Askar? Other tests shows color misalignment in almost all Askar products as the glass used is not up to premium standard.

    • @darkskygeek
      @darkskygeek  Рік тому

      Unfortunately, that is the best I could do with what I had. The vignetting was not horrible at F/7 so I am confident with the result. However, with the reducer, I agree that further into the corners, the stars would have looked even worse. And thus, my conclusions stand. As far as the spot diagrams, I don’t pay attention to them. They are just claims made by the manufacturer, and oftentimes are just simulations, based on the optical design, not real measurements. CS!

  • @WilliFromEarth
    @WilliFromEarth Рік тому

    Excellent! I am very happy with my ZWO FF130, believed to be a rebranded 130 PHQ.
    Did you ever check out an APQ Jena refractor? They use CaF2 lenses.

    • @darkskygeek
      @darkskygeek  Рік тому +1

      The ZWO FF130 is indeed made by Sharpstar. It is identical, except in its branding, to the Askar 130PHQ. I have never heard of APQ Jena. There are a few manufacturers, some are much more well known, like Takahashi, who still make fluorite lenses. However, fluorite does not have that strong of an edge over FCD-100, FPL-53, or FPL-55, and I read that it is more troublesome a material for lens makers, so it is usually more expensive. That being said, the next time I visit Tokyo, I might pay a visit to Starbase in Akihabara and buy a small Takahashi FC60, that would be a fun little telescope! CS!

    • @WilliFromEarth
      @WilliFromEarth Рік тому

      Indeed, CaF2 is very difficult to machine, because of its brittleness. And it is a very expensive material to begin with. Zeiss has a lot of experience with CaF2 glasses and hence APQ Jena builds on that experience. I have never seen nor own any APQ telescope. They are supposed to be extremely polychromatic. … that’s why I am asking. I would like to see your spectroscopic test on them. The FPL glasses have an Abbe number above 90 and a low refractive index close to CaF2, but they are much easier to machine. CaF2 has a very high transmission in the UV and DUV, the FPL glasses do not. I am actually wondering which of those FPL/FCD glasses are used by Sharpstar. Have they disclosed any this info? As a Chinese manufacturer they might even use something from Chengdu…. But I do not know.

    • @WilliFromEarth
      @WilliFromEarth Рік тому +1

      Yeah… I did look once through a Tak at a starparty and was blown away. I must say, however, the FF130 is amazing visually.

    • @darkskygeek
      @darkskygeek  Рік тому +1

      @@WilliFromEarth Sharpstar does not disclose the type of glass they use, for good reasons. I would do the same if I were them. Too many people don't understand that an optical design is a combination of compromises, and explaining those compromises in simple terms so that everybody can understand them is just mission impossible.
      As far as APQ Jena, if such a refractor were to be sent to me for review, I would gladly take a look at it ;-)

    • @WilliFromEarth
      @WilliFromEarth Рік тому

      @@darkskygeek Excellent point. Stellarvue made a long statement on their webpage about FCD and FPL glasses. While it is all true what they are writing, they might create more confusion than clarity for some people ;-). Always tricky.

  • @AshA-ww8hc
    @AshA-ww8hc 10 місяців тому

    Hey Julian. What kind of FWHM values are you getting in PI FWHMEccentricity script when using a Moffat function under good seeing conditions with a broad band and narrowband data?
    Thank you for the thorough review.

    • @darkskygeek
      @darkskygeek  10 місяців тому

      Unfortunately, I deleted the test subs I took while I was evaluating the telescope, back in September/October, and since then, the weather in northern California has not allowed me to do anything, so I cannot give you an answer at this time.

  • @hawkesworth1712
    @hawkesworth1712 Рік тому +1

    From the limited reviews I've seen I can't see the point of the Askar focal reducer on this scope - or any reducer on a PHQ scope for that matter.
    If the reason for the reducer is to reduce exposure time, the result is a shorter exposure with a slightly lower quality image.
    If the reason for the reducer is to widen the field of view then buy a 130PHQ and an 80PHQ for only a few hundred more than the price of the 150PHQ, and forget the reducer.

    • @darkskygeek
      @darkskygeek  Рік тому

      I think there is a point, for people (like me) who have cameras up to (and including) APS-C sensor sizes. It will reduce exposure times and increase FOV, which is nice. But that’s it. If you own a larger camera, then yeah, that reducer will be limited and maybe not so useful.

    • @hawkesworth1712
      @hawkesworth1712 Рік тому

      I should have added thanks for the excellent review.

    • @darkskygeek
      @darkskygeek  Рік тому

      @@hawkesworth1712 Thanks, Adrian!

  • @igorlitvin1779
    @igorlitvin1779 11 місяців тому

    Turbulent cells of air in the atmosphere limit the actual resolution of telescopes in the optical wavebands to typically no better than that obtained by a 20-cm telescope. The seeing at any location depends upon many factors and changes due to temperature, weather, pollutants and local microclimate. Good locations may achieve a typical seeing of 1 arcsecond but most sites are worse than this. Even the best sites rarely achieve seeing of better than 0.5 arcseconds. If the resolution a telescope achieves is limited by the seeing rather than its diffraction limit it is said to be seeing limited.
    It means 12 cm telescope (1 arcsecond resolution) is maximum what we must use and 150 mm is too much already because of the result will be not better than 120 mm.
    What do you think?

    • @darkskygeek
      @darkskygeek  11 місяців тому

      If this were the only factor, professional astronomers would be using small refractors 😉 but in terms of deep sky imaging resolution at the amateur level, yeah, you’re not that far off. Also, don’t forget about image scale, it is critical in astrophotography. CS!

    • @igorlitvin1779
      @igorlitvin1779 11 місяців тому

      Professional astronomers use larger mirrors. This is correct, but I assume they use them in certain conditions. These are the mountains of Chile and so on. In typical European landscapes, this resolution cannot overcome turbulent shaking at 1 arcsecond. I'm new to this area and trying to understand the limitations. But I am an optical physicist (PhD) with 20 years of experience in theory and experiment.@@darkskygeek

  • @xMemn0nx
    @xMemn0nx Рік тому

    J'avais deja du mal a me retenir d'acheter ce telescope, et la ca devient encore plus compique haha. Je pense downsize et lacher mon RC 10" pour retourner sur quelque chose de plus simple et bonne qualite avec encore une bonne longueur focale. Je pense que le 151 PHQ est pile ce qu il me faut

  • @southbronxny5727
    @southbronxny5727 10 місяців тому

    Watching this again, one thing you didn't say and I couldn't find anywhere is, what kind of glass is in it? I'd assume not 53 or 55 glass because they would've boasted about it but my guess would be 51 glass. Do you know which glass it is?

    • @darkskygeek
      @darkskygeek  10 місяців тому +2

      Askar is probably using HFK95N. That probably is not telling you anything, and that is why they don’t communicate that. This information on its own is not helpful. HTH. Clear skies!

  • @fifififo5918
    @fifififo5918 9 місяців тому

    I have the AT 130 triplet and am a visual observer only. Besides the better CA performance, would you consider the Askar 151 much of a visual upgrade or not? Thanks!

    • @darkskygeek
      @darkskygeek  9 місяців тому

      For a purely visual observer, I would not recommend that upgrade. This is an astrograph first and foremost. CS!

    • @fifififo5918
      @fifififo5918 9 місяців тому

      @@darkskygeek ❤Thanks!

  • @joseborges8479
    @joseborges8479 Рік тому

    Wonder what the difference is between the PHQ series and the APO series?

    • @darkskygeek
      @darkskygeek  Рік тому

      The APO series requires a field flattener, which has a specific backspacing requirement, while the PHQ does not. On paper, that is the main difference. In practice, I am sure that the APO performance does not quite reach that of the PHQ, but the only way to find out would be to have Askar send me a unit of the APO 140 I guess 😁 CS!

  • @richardshagam8608
    @richardshagam8608 Рік тому

    What was the software you used for the wavefront analysis? As a retired optical engineer with a specialty in interferometry, I hadn't heard of that method before.

    • @darkskygeek
      @darkskygeek  Рік тому

      Look for a paper titled “Wave-front reconstruction from defocused images and the testing of ground-based optical telescopes” by Claude Roddier and François Roddier. It provides the theoretical foundation for the technique I used.

    • @richardshagam8608
      @richardshagam8608 Рік тому

      @@darkskygeek Thanks--I found the paper! I also discovered that PixInsight has a script which may be based on the same technique. I haven't tried it yet, however.

    • @darkskygeek
      @darkskygeek  Рік тому

      Great! Which script would that be?

    • @richardshagam8608
      @richardshagam8608 Рік тому +1

      @@darkskygeek Look under Script> Instrumentation >WavefrontEstimator

  • @clement_p2774
    @clement_p2774 Рік тому

    Merci pour cette excellente vidéo !

  • @williamgreen3408
    @williamgreen3408 Рік тому

    Would you recommend the 151 for visual use, leaving aside the cost and weight? I gather that you would not recommend it, given the contrast factor, or am i wrong? Thank you.

    • @williamgreen3408
      @williamgreen3408 Рік тому

      Maybe the 130PHQ would be better for visual use???

    • @darkskygeek
      @darkskygeek  Рік тому

      I absolutely recommend the Askar 151PHQ for visual use. The 130PHQ is also a fine scope. If you buy one of these models (or really anything else) from Agena Astro, please consider clicking on my affiliate links, much appreciated! 🙏🏻😁

  • @trench47
    @trench47 Рік тому

    In your first video you said the CEM70 may be a bit on the light side to handle the 151PHQ correctly. Do you still feel that way and are you planning on upgrading your mount to something with a bigger payload? I ask as I'm looking at a CEM70 as I run a 130 refractor but the 151PHQ may be in my future. Thanks for your informative videos.

    • @darkskygeek
      @darkskygeek  Рік тому

      I actually said that it was near the minimum required for serious imaging, but is okay, and I have gotten good guiding results with it (< 0.4” RMS using an OAG) Therefore, I am not planning to upgrade my mount. However, good balance is critical! CS!

    • @trench47
      @trench47 Рік тому +1

      @@darkskygeek Thanks for the reply. I thought the CEM70 should handle the 151PHQ but I somehow interpreted 'near minimum required' as 'on the light side'. I think I will go ahead with the CEM70, I hear is generally a good mount.

    • @darkskygeek
      @darkskygeek  Рік тому

      Yeah, go for it, I’m very happy with mine. Early versions of the CEM70 had quality issues, but iOptron has likely improved their manufacturing process since that time.

    • @Ghostnotes1221
      @Ghostnotes1221 Рік тому

      Seriously thinking about purchasing this.
      I believe my Losmandy G11 is capable of handling it.

    • @darkskygeek
      @darkskygeek  Рік тому

      @@Ghostnotes1221 I think it should work. If you go for it, consider using the AgenaAstro affiliate link I put in the description of the video 🙏🏻 It helps me keep the channel going at no cost to you. Thanks! And if you do decide to get this scope, don’t hesitate to share your experience with it.

  • @DSOImager
    @DSOImager Рік тому

    Very nice upgrade, congrats. Looks like an awesome scope. Are you planning to run the reducer?

    • @darkskygeek
      @darkskygeek  Рік тому +2

      Thanks, James. Yes, I am planning to use the reducer as well. It’s great up to an APS-C size sensor. I am currently using a 533MM Pro, but I am planning to upgrade to an APS-C camera some time in the future, maybe when the successor of the 2600MM Pro comes out. CS!

    • @DSOImager
      @DSOImager Рік тому +2

      @@darkskygeek lol.. that is how it goes isn't it? Shortly after I picked up the 1600mm the 2600 series came out.

    • @WilliFromEarth
      @WilliFromEarth Рік тому

      @@darkskygeek Any idea what camera/sensor that would be?

    • @darkskygeek
      @darkskygeek  Рік тому +1

      @@WilliFromEarth I don't have any inside information, unfortunately. Let's see. It might take a couple of years before the next generation sensors make their way into our astro cameras.

  • @allenbaylus3378
    @allenbaylus3378 Рік тому

    Please see if you can get the askar 120 apo to test.

    • @darkskygeek
      @darkskygeek  Рік тому

      Askar just announced a 185mm diameter triplet! If I take the time necessary to properly test a refractor (> 40 hours of work to create a video like this one), it would be the 185, not the 120 🤪

    • @allenbaylus3378
      @allenbaylus3378 Рік тому

      @@darkskygeek well then I will be patient and wait for the 185 review - I did not see the 185 but I did see the pre-release info on the 140APO - 980mm/f7 $1999 and the 151PHQ - 1057mm/f7 $4399.
      But since you mentioned this I did see the 185APO 1295mm/f7 $4799.
      This would be around the same price as a Celestron Edge-HD 11 with accessories $3750 plus Hyperstar $1299.
      I know that a SCT is a different creature but once you surpass the $2000 price you are starting to talk about real money.

  • @astrotimber8925
    @astrotimber8925 6 місяців тому

    Very Geeky. Excellent!

  • @MrChausner
    @MrChausner Рік тому

    Excellent

  • @cats-skog
    @cats-skog 11 місяців тому

    Too bad lens in the Ronchi test.
    They probably polished the lens quickly to reduce costs.

    • @darkskygeek
      @darkskygeek  11 місяців тому

      I did not do a Ronchi test for this review.

    • @cats-skog
      @cats-skog 11 місяців тому

      @@darkskygeek Oh sorry?
      Then you should do Ronchitest for this telescope. I want to know Askar performance.

  • @bakus-hobby-ch
    @bakus-hobby-ch 11 місяців тому

    It's a "Turndown edge" in Ronchi test. no good telescope.
    Asker has many good rifle scope products.
    But they are not good at making large lenses.

    • @darkskygeek
      @darkskygeek  11 місяців тому +1

      And yet it is able to produce great images 🤷🏻‍♂️

    • @bakus-hobby-ch
      @bakus-hobby-ch 11 місяців тому

      @@darkskygeek This is because computers process images with poor contrast by image correction. It looks worse when you see it directly with your eyes.

  • @Science_of_Mind_Magnet
    @Science_of_Mind_Magnet Рік тому

    Very detailed information, thanks. 👽🔭🪐🛸🌗🌚🌘