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Понедельник, 21.08.2017, 17:02

Levenhuk Strike 90 Plus

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My main telescope is 200-mm Meade LT-8 SC, and I love it. But, alas, I cannot take it with myself wherever I go, 'cause a backpack with the telescope is rather heavy (near 30 kilos) and huge. Even to pack – it takes a rather long time (OTA, a tripod, a dewshield, a battery, a notebook, a camera etc.). Well, it's really good astronomical instrument, but not of a “grab and go” style. The second problem that would be pleasant to resolve - Meade's f/10 focal ratio restricts a field of view, so I can hardly watch vast objects, alike Pleiades (M45) or Beehive (M44) clusters, or M31 (Andromeda galaxy). Even with 40-mm 1.25" eyepiece I get FOV ~ 0.9 degrees. So I decided to purchase some light and compact astronomical instrument, alike 90-mm aperture Maksutov (I owned one long ago) or refractor (but not as expensive as typical APO). After all I decided to buy Levenhuk Strike 90 Plus – it has 90 mm aperture, 600 mm of focus (f/6.7), it is light and (last but not least) inexpensive. Some sellers indicate that this model is for kids – okay, think I am a kid *lol*

I purchased the telescope online and payed 230 USD (including a doorstep delivery). A real bargain, I'd say. Inside a box I have found OTA, alt-azimuth head with a counterweight, a tripod, a soft transportation bag, 3 eyepieces (6 mm, 20 mm and variable 7-16 mm), 3x Barlow lens, a diagonal mirror, a compass, 3 posters and two books – user's manual and star atlas (a Russian translation). The last two I found to be useless and full of mistakes. But, in fact, one doesn't need a manual for this telescope. An assembly process is easy as a pie – you can fully assemble/disassemble pack/unpack this telescope in 5 minutes. It is really light (I can grip a tripod and easily hold a whole construction with just one hand). With the counterweight (that can be detached, by the way) it weights near 8 kg, without – just 6 kg. If to compare – my first 90-mm Maksutov-Cassergraine with equatorial mount EQ1 weighted 12 kg, my present alt-azimuth Meade LT-8 SC weights 17 kg. So this Levenhuk Strike 90 Plus – it is the lightest 90-mm instrument I've ever seen. Such a light weight makes you think that this is just a toy. But it is not so.

To test the new telescope we (me and 2 friends) took a ride 180 km (112 miles) far from the city under a really dark sky (it was a new Moon night). I packed everything inside the included bag (there was even extra place for a photo tripod) and put it inside a trunk. The road was really, really bad (bad roads – it's a secret Russian weapon to destroy enemy's tanks, do you know? *lol*), a jolting was awful and there were several moments when I thought our car will fall to pieces (it didn't, but the right taillight did). To tell the truth, I was afraid that this small Levenhuk will not survive such a trip. Goddamn, no! Not a single scratch! More, April nights in Russia are a bit chilly – our thermometer showed -11 Celsius degrees (12 ºF). The frost is a really good test for plastic details and badly built electronics – a cheap plastic becomes fragile, like a glass. Nevertheless, this Levenhuk passed this test also. Even the Red Dot finder worked perfectly all night long! (For example, a Red Dot finder of my Meade LT-8 SC died of the first October frosts). Well, this toy is not a toy at all, it is a really well-built telescope!

Included eyepieces are made of plastic and I didn't like the picture inside. 20-mm eyepiece is still rather good (if you have no better eyepiece in your pocket), but 6-mm and 7-16 mm eyepieces are absolutely useless. The picture inside is dark, strongly colored and blurred. But I did expected genuine eyepieces to be something cheap and basic, so I put 'em aside and took from my suitcase a 40-mm and 12-mm Meade 4000 Superplossl eyepieces and 2x Barlow lens. The following change was not just evident, it was simply breathtaking.

With the 40-mm eyepiece this telescope has a 3 degrees wide field of view. When I pointed the telescope onto the Milky Way in Sagittarius and Scorpius constellations, the show was really amazing. Do you remember a song “Stardust”? La-la-la-laaa... That's it. Shining clouds made of the finest dust I've ever seen, with darker fibers and areas between them, and here and there – gas nebulae, glowing from inside. My Meade LT-8 SC with it's typical FOV 0.8 degrees wide shows me the Milky Way just as an even star seeded field, without any structure. When I pointed Levehunk Strike 90 Plus onto Antares I began to dance – on the background of the stardust there was a brilliant Antares and right nearby - a globular cluster M4. Lagoon nebula (M8) – it was amazingly beautiful.

During that night I watched through this 90-mm telescope M4, M13, NGC457, C14, M103, M11, M8, M7, M17, M18, M22, IC4665, M57, M10, M12, M81, M82 and M31 with satellites. The picture was very, very fine, with a high contrast and sharp-edged juicy stars. When I showed NGC457 via 40-mm eyepiece (15x) to my friend, he laughed - “wow, that's the real owl!” and when I replaced the eyepiece onto 12 mm (50x), he exclaimed - “oh my, now it looks alike Terminator with glowing eyes”. The Ring Nebula (M57) is rather small (50x magnification), but looks perfect. I watched the Milky Way from Sagittarius through Scutum and Aquila and Cygnus until I reached Perseus – the picture was brilliant. Alas, a focuser of this telescope is made of plastic and I am afraid it cannot bear a DSLR with T-adaptor. I really wished to make a photo of what I had seen!

After watching stars I decided to set up a bigger magnification and check up planets. I watched Mars and Saturn via 12-mm eyepiece with 2x Barlow lens (100x). Well... No, it is not my choice. A strong chromatic aberration - it is just a part of the problem. The lightweight tube on the no less lighter tripod is so sensitive to any vibrations and even a lightest wind blows, that it was very hard to focus and watch. Rings of Saturn were visible good enough, but without a Cassini Division. On the reddish disk of Mars I saw no details, except some kinkle onto a polar cap presence. I think this Strike 90 Plus would be rather good for Jupiter and Saturn (for beginners) but not for Mars. This job my Meade LT-8 SC makes far, far better.

Watching of the Sun and the Moon, on the other hand, was really successful. Again, I do not recommend to use a short-focus eyepieces and high magnifications with this telescope. 50x, maybe 60x (10 mm) will be good enough. With higher magnifications the work with a telescope becomes uncomfortable, and the quality of picture strongly degrades, in my opinion. The Sun filter I made by myself – of carton, adhesive tape and Baader Astrosolar Visual film (I keep a roll since 2008th solar eclipse).

The image was bright and juicy, with very high contrast, sharp-edged black spots and bright active region faculae. The image was so clear and bright that I raised my smartphone camera and tried to make a picture... Wow, people, it worked! The cam autofocused successfully and took the image, here you are:

Later, when I watched the Moon, I did it again – just used a smartphone camera to make astrophoto. It worked perfectly! I guess this is not a masterpiece photo, but it is good enough for beginner, and if your kid will make several such photos for his or her scientific project, the teacher will be very pleased I think. Notice the violet border around the Moon - this is a chromatic aberration. But if you don't like it, just convert a photo into B&W that's all! :)

Later I discovered, that this Levenhuk telescope is a perfect instrument for watching Mercury right after a sunset or just before a sunrise. Mercury's phases are easily seen. The chromatism is rather strong, but Mercury is the object so seldom viewed... Let us forgive this chromatism *lol*

Pros: Grab-and-go masterwork. Extremely light and compact with a rather big aperture. Sturdy. Quickly assembled. Just add a good 20-40 mm eyepiece – and get very good quality of the image and very comfortable pointing and observing. A transportation bag included. Not expensive.

Cons: Not a best choice for high magnifications. Included eyepieces leave much to be desired. A plastic focuser cannot bear a DSLR.

Conclusions: I love this small telescope! This is the best "walkingscope" for watching Milky Way I've ever used. High contrast and a huge (3 degrees wide) field of view allow to locate Messier deepsky objects very easy. Very good for Moon and Sun (don't forget to add an aperture filter!). Good enough for viewing Jupiter and Saturn.