4' APO Refractor Shootout

A 4" apochromatic refractor is a very nice telescope for astrophotography. With several on the market, it can be hard to pick one. In this video, I conduct real-world tests of four popular models to help you decide which may be the right telescope for you.

🔭 Telescopes Tested 🔭

💻 Data downloads 💻

❤️ Patreon ❤️

==Contents==
0:00 What I'm testing
1:10 How I test & disclosures
3:43 The importance of the mount
4:37 Physical characteristics
25:56 Imaging tests

Channel Disclosures
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Video Disclosures
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[NebulaPhotos]

Corrections: 1. For some reason, I kept saying millimeters when I meant to say centimeters when measuring the length of the first 3 telescopes. To be clear the length of each telescope with dew shield extended: Askar 103 APO - 77cm, Founder Optics FO106 - 69cm, ZWO FF107 APO - 76cm, SW Esprit 100ED - 64cm
2. Pricing of the Askar 103 APO is promotional pricing only good through the end of the month - forgot to mention that. Other prices are current USA (non-sale) prices.
3. Askar informed me that since the 103 APO and accessories they sent me were still prototypes, the interior of the 1.0x flattener was an issue with my sample only, and the mass production version shouldn't have that problem with the paint.
4. Not a correction exactly, but something I should have emphasized better in the video: I did use the additional spacer and correct backfocus arrangement with the Esprit 100ED. The elongated stars are only in the extreme corners. If you crop in about 500 pixels on each side (9500px -> 8500px in the horizontal), the stars will look perfect across the field. A link to download the FITS data (both single frames and calibrated stacks) is now in the description.
Hopefully, that's it. I'll update this comment if I notice anything else.

[ColeDedhand]

The Askar really holds its own against the more expensive scopes. It looks like a great option for getting to a 4" refractor without taking a second mortgage.

[jonrbryan]

I am on my second night out with the Askar 103 and 0.8x reducer, and I'm thrilled with it. I immediately noticed that I had pinpoint stars in my OAG. They were terrible with my previous scope, and I figured it was probably the OAG (I'm relatively new to this), but that doesn't seem to be the case. Askar's spot diagrams show the 103 outperforming the 107PHQ (same as the ZWO 107) by a wide margin at the edge of the field. I splurged and got all three flattener/reducers, and I'm looking forward to trying them out.

Askar seems to have gone with an optical design that gives up a small amount in the center of the field to get better performance at the edges on all of their new APOs (103/120/140/185). From my initial experience that seems like a good design decision, especially if it made them so much less expensive to produce.

[nikaxstrophotography]

That Askar scope looks the goods, maybe not with an 0.6 reducer but with the 0.8 it seems like a great investment

[amgc]

Provide an secondary viewpoint on the Askar 103 APO as I just got mine. The issue with the focuser is resolved by a slight allen screw (2) adjust, very smooth and no noise. I got all three of the flattners/reducers all were in perfect condition. You must have received preproduction models because mine have orange writing. Oh, and my knobs were attached!!. Thanks for your shoot-out Nico!

[DrewJEvans]

Excellent review. The Askar 103APO is phenomenal, espcially as it's price point I have had a lot of success with it at native FL and with the reducers testing so far!

[goose]

22:55 - I think the captain's wheel on the Esprit is installed incorrectly. There is a much larger gap at the top than the bottom of the frame. It looks like it has skipped a thread on one side. That would explain why it was so stiff and scratchy. This would also potentially introduce tilt to the system, and may be why it was very difficult to rotate the photo properly, and may also have affected the quality of the final image.

[MichaelA-jk]

Great review Nico! I'm purchasing today the Askar 103 with 1.0 and .8x flatteners...it perform well from your review at a much lower cost than the rest of the field!

[vicinvesta]

The smoothest talking drug dealer. This guy. 😂

[janossowski]

Thanks for this, very helpful. One thing that might be worth mentioning is that the zwo apo series is simply askar PHQ series sold under zwo brand so in reality 2 of these scopes were askar :)

If anyone would ever be trying to decide between the 2, simply go for the one which is currently cheaper/ on promo, or the one which is more appealing to you color wise

[fouriousbanana]

Great review! I was looking for someone to do an in-depth review of 4" ED refractors for astrophotography. I'm definitely going to get the Askar, not only being the best for it's price, it's the only semi-proffesional refractor I can buy (because others are more expensive)...

[simonthorp]

I have been following you for several years now and find your videos compelling. This video in particular inspired me to purchase the Askar 103 with both the .8 and 1x FF/Reducers. It helps that you are an absolute clone of my son! Hair and all…Love what you’ve done and will become a patreon supporter in the new year.

[darrellburke]

Thanks Nick. That's helped me a lot. Being budget conscious and with financial limitations - this a no brainer now. At $1000 compared to $2500 - $3000+ I'll be going ahead with my pre-booked Askar purchase (All-Star up in Canada). That it has some minor build quality issues is to be expected at that price point and nothing that can't be fixed or worked around ... I have lots of allen wrenches :) The fact that it was close to/equal to or even superior to the others on the various tests was a pleasant surprise. I already have a Starfield 0.8 reducer flattener so unless for some reason there are issues mating the two - all should be well.

[CoVoltage]

Askar scopes generally have very good support for large image circles, but I did notice they produce slightly hazy stars compared to FPL-53 scopes (and chromatic aberration when stars are saturated). They're surely a great budget option, and I'm honestly surprised about the pricing for the 103apo (plus the preorder option where you can get 3 reducers+guidescope for 1600). Esprit 100 are known to have astigmatism on corners for full frame sensor, so you are not wrong about the back focus. Although Esprit 100 is a great premium scope, I did find its dew shield to be a lot sloppier than the Askar.

[KingLoopie]

Another cool scope shootout for me to ponder on. Great reviews, Nico! 👍

[doramason]

Great review Nick!

Just to give a video idea maybe next time you can make a review of different Chinese manufacturers: Sharpstar, Long Pern (Founder Optics), Synta(Sky-Watcher), Kunming United(William Optics) and Jinghua Optical(Explore Scientific).

[dasimcoes]

The stellarvue svx 102 is a great scope and stellarvue will list the strehl rating of their scopes.

[steveb.]

Hi Nico
Thank you for your laborious work. The number of parameters that influence the image quality is diverse. The SkyWatcher Esprit image result at minute 30:45 looks more like a typical backlash tracking error. The EQ6 is known for this due to the gear transmission. The AZ EQ6 with belt drive is less vulnerable. Nevertheless, I have gotten into the habit of never bringing the telescope into exact balance.
I also have to say that manual focusing is hopelessly inferior to automatic focusing. In my opinion, you can make every effort and still not achieve the result of electronic focusing. The same applies to polar alignment. In my experience, conclusions about optical performance can only be reliably assessed when all of these criteria are exactly met, regardless of the camera.

[davidheflin]

Great video, I was interested in the ZWO, was. Definitely helped my decision.

[larkop]

Only just discovered your channel, i think a lot appreciate your work because you try to be impartial and fair. Just a small suggestion that you can ignore, sometimes a tabulated summary of your findings can help viewers get to the details quickly for comparison. Otherwise I think your work is definitely valuable and well received by people who are genuinely looking to understand the options available to them.