TecnoSky 102mm F/7 FPL-53 refractor - Ongoing review

[Victor Boesen]

Wednesday I placed an order on a TecnoSky 102mm F/7 refractor which is/should be the same scope as the more known Altair Starwave 102ED-R and TS-Optics 102mm F/7. I received the telescope from Astroshop.eu Thurdsay about 30 hours after the order was placed. Talk about fast delivery!

Unboxing the scope 

I've purchased this scope after a couple weeks of debating what to do with my 10" dob. The entire thread and first impressions of the scope can be found here:

First light

My subconsciousness must have set an alarm this morning cause I woke up at 3:20AM (without setting an alarm) and looked out the window and I was greeted by a beautiful view of the moon. I considered if I should bring out the new scope and not a lot convincing was required:) I grabbed a couple of eyepieces, the scope and my tripod and went down to the parking lot. My first target was obviously Mars as it would only get lower on the sky as time passed. It was quite cold outside so I expected the telescope to require some time to cool down. Nevertheless, I grabbed my highest power eyepiece (4.7mm) and pointed the scope at Mars. I focused the image as good as I could and the surface details where very apparent, and Mars looked very bright compared to the view through my smaller Evostar 72ED with the same eyepiece(90X). The brighter Hesperia hugged by Syrtis Minor and Mare Cimmerium was very defined and the seeing felt really good. Syrtis Major was also visible on the far right side of the planet (image is flipped horizontally because of my diagonal) and in brief moments the limb at Syrtis Major looked cloudy/hazy? The polar cap was really small but still visible.

Please note the image above should be mirrored in both axis compared to the "real" orientation. The view through the eyepiece was the same as the above but mirrored on the vertical axis.

Next target I went for was the Moon, illuminated about 60% but very high in the sky. I still had my 4.7mm eyepiece installed and I was shocked at the view. I knew from experience with the Evostar 72ED that refractors give a different view of the moon than I get through my dob but I was amazed with the contrast of the surface. The dynamic range of the slight difference in brightness of certain areas was very obvious and I would call the texture of the surface "soft" but very sharp which I know sounds a little weird I switched to the 14mm eyepiece for a little while and the view through the eyepiece was still very satisfying even at only about 50X. "False color" I hear you say? It's definitely there, but only at higher magnifications on Mars and brighter objects like the Moon. Even moving in and out of focus the false color is very subtle, to the point where I can't tell for sure if the false color is introduced by the scope or my diagonal/eyepiece.

The pictures really aren't good at showing the capabilities of the scope, but I know you want them anyways;) The blue fringing around the limb wasn't visible through the eyepiece, instead the false color through the eyepiece was more like a very subtle yellow tint around the limb, which is the same color I noted when trying the scope on an antenna in the daylight at 152X. On Mars the false color consisted of a slight blue/red-ish color at the limb of the planet. I will, however, mention that the false color on Mars seemed to worsen as the seeing became worse, therefor I really can't tell if it's the scope's fault. NO false color was seen on the surface of the Moon and Mars and I didn't have any problems with floaters at an exit pupil of almost 0.5mm.

I found that focusing was really easy and I really like the R&P focuser. I tested my 2" 24mm eyepiece once again, but I for sure can't reach focus (need outwards travel distance). I did, however, try straight trough viewing with my 1.25" eyepieces and none of them were able to reach focus without the diagonal. I would therefor expect I should be able to reach focus with a 2" diagonal?

I have about 1.6cm of travel distance left when using my 1.25" eyepieces. The Takahashi diagonal is known for its short light path so other diagonals would probably leave more available distance.

After fiddling with my eyepieces for a couple of minutes I decided to try some of the more famous DSO available. M31 and M110 were easy to find, and they looked good through my 14mm eyepiece. I could imagine it would look great with my 24mm eyepiece under dark skies!! I aimed the scope at M45 which was a little large for the 14mm eyepiece, but the stars looked very sharp and the star field looked beautiful. The only thing I noticed was that the field didn't look completely even, and the stars in the outer 30% of the FOV were a little "comet-like" but moving your vision to them and adjusting eye position fixed most of the distortion. Again, doesn't have to be a problem with the scope since it could just as well be a problem with my eyepieces!

My photo tripod and AZT6 mount head did surprisingly well carrying the scope, although I am looking forward to receiving the AZ4 mount with a steel tripod;)

Next up was M42 and under Bortle 7/8 skies I was surprised to see a decent amount of nebulosity through an unfiltered eyepiece. Nebulosity in the core was easily visible and the inner parts of the "arms/wings" were also visible with averted vision. What really caught my attention though, was the Trapezium. I only had a look through my 14mm eyepiece but the four stars were pin-point sharp in the middle of the nebulosity.
I ended my DSO-hunt with the galaxy pair M81 and M82. My star hopping was a little rusty since I haven't observed these two galaxies for a while! With the aid of sky safari it took a couple of minutes until I noticed the slight blob-shaped glow from M81. I adjusted the FOV a little and M82 emerged from the background. If I recall correctly, I remember my 10" dob showed the oval shape of M81 better, whereas it still looked a little more circular rather than oval/elliptical through the refractor. The view was still very surprising considering the aperture of the refractor and my local light pollution levels (which you can probably tell from the picture of the telescope!).

I really look forward to do more testing of the scope, but the first light seems very promising. It seems like the scope meets all of my requirements I was looking for: Portable, good planetary/lunar performer and capable on DSO's. The view of Mars was perhaps the best I've had before, and I was definitely not let down by the contrast of the scope on the lunar surface and subtle albedo features on Mars!

I will continue to update this thread as I gain more experience with the telescope, and I hope to release a video in a couple of days of my initial impressions of the scope, unboxing it and getting my hands on it for the first time!

I hope someone will find this thread helpful, since I noticed there wasn't much info about this scope to be found online. I'd happily answer some questions about the scope if you have one!
Clear skies!

Victor

Edited October 9, 2020 by Victor Boesen

[Alfian]

Great write up, looks like its going to be a scope with a high "grin factor"!

[JeremyS]

Super report Victor. And so glad you achieved first light so quickly 👍

Sounds like you have a "keeper" in that scope 👌

[Victor Boesen]

5 minutes ago, Alfian said:

Great write up, looks like its going to be a scope with a high "grin factor"!

Thank you Ian, definitely happy with it

[Victor Boesen]

2 minutes ago, JeremyS said:

Super report Victor. And so glad you achieved first light so quickly 👍

Sounds like you have a "keeper" in that scope 👌

The weather must've heard your prayers last night It sure seems like a great all around performer!

[Highburymark]

Great report Victor and what a terrific first light. There is nothing that compares with a nice apo refractor on the Moon. As you say, it’s almost shocking. I can pretty much guarantee that the colour you saw around Mars was not the fault of the telescope. I use a Takahashi FC-100 for planetary and I haven’t had a single session this opposition that hasn’t shown a blue aurora around Mars. Similarly I’ve used ED scopes that show colour on the Moon one day, and not the next day. Atmospheric conditions and eyepieces play a big part. Look forward to hearing more about the new scope.

[Victor Boesen]

34 minutes ago, Highburymark said:

Great report Victor and what a terrific first light. There is nothing that compares with a nice apo refractor on the Moon. As you say, it’s almost shocking. I can pretty much guarantee that the colour you saw around Mars was not the fault of the telescope. I use a Takahashi FC-100 for planetary and I haven’t had a single session this opposition that hasn’t shown a blue aurora around Mars. Similarly I’ve used ED scopes that show colour on the Moon one day, and not the next day. Atmospheric conditions and eyepieces play a big part. Look forward to hearing more about the new scope.

Thank you Mark, it was a great session! It's very reassuring to know that the "false color" is likely due to the conditions! Weather doesn't look good, but tomorrow, Monday and Tuesday might give some more opportunities to try out the scope again;)

[CraigT82]

Great write up👍. Yes I agree that the colour you saw around mars was atmospheric dispersion, which is always red one side and blue the other. Sounds like a really nice scope would like to get my hands on an ED frac one day! 

[Victor Boesen]

21 minutes ago, CraigT82 said:

Great write up👍. Yes I agree that the colour you saw around mars was atmospheric dispersion, which is always red one side and blue the other. Sounds like a really nice scope would like to get my hands on an ED frac one day! 

Thanks Craig The Skywatcher Evostar 72ED DS-Pro, which I purchased last summer, was enough to show me how great a decent refractor can be for casual observing. I really enjoy the tight stars, high contrast, portability(mostly true to faster APO's) and it doesn't really care as much about the atmospheric conditions as my dobsonian does. You should definitely try one yourself some time! But be careful, they can get addictive(and expensive) pretty fast

[JeremyS]

21 minutes ago, Victor Boesen said:

Thanks Craig The Skywatcher Evostar 72ED DS-Pro, which I purchased last summer, was enough to show me how great a decent refractor can be for casual observing. I really enjoy the tight stars, high contrast, portability(mostly true to faster APO's) and it doesn't really care as much about the atmospheric conditions as my dobsonian does. You should definitely try one yourself some time! But be careful, they can get addictive(and expensive) pretty fast

Now there speaks a true refractor-phile!   🙂 👍

 

[RobertI]

Nice first light Victor! Glad you enjoyed using the scope. I also found that the field was far from flat with my 38mm 2” eyepiece, it annoys some and not others. I imagine more expensive eyepieces would help eliminate this issue - perhaps others can advise? It’s been so long since I’ve been out and used my scope, it’s raining now but supposed to be clear later - here’s hoping. 🤞 

[Victor Boesen]

3 minutes ago, RobertI said:

Nice first light Victor! Glad you enjoyed using the scope. I also found that the field was far from flat with my 38mm 2” eyepiece, it annoys some and not others. I imagine more expensive eyepieces would help eliminate this issue - perhaps others can advise? It’s been so long since I’ve been out and used my scope, it’s raining now but supposed to be clear later - here’s hoping. 🤞 

Thank you Rob:) It really doesn't bother me much to be honest. It was nice having an opportunity to try it out the morning after it arrived. Doesn't happen often😅 I hope you'll have some good weather your way!

[Victor Boesen]

Had another great session last night with the Tecnosky. This time I brought my 2.5X barlow lens to try some high power observing. The sessions consisted of the following targets:

• Jupiter
• Saturn
• Ring nebula (M57)
• Dumbbell nebula (M26)
• Hercules cluster (M13)
• Pleiades (M45)
• Double stars
  • Almach (9.8" sep.)
  • Mesarthim (7.7" sep.)
  • Alsad (2.1" sep.)
• Mars

I'll categorize the objects for simplicity

Double stars

All double stars were observed with my 4.7mm eyepiece at 152X.
I have never been much into double stars, but I started observing some easy ones when I got my Evostar 72ED since it isn't as capable on DSO's. I knew about the double in Almach so that was my obvious first go. Focusing on the stars were a joy, the concentric rings snapped into two tight stars, the brighter one still showing a slight hint of rings, but the two were easily separated. I could also tell a difference in the color of the two stars, one being slight blue and the other a little orange.

Following skyandtelescope's list of double stars I looked for some more difficult options, and I decided to go with Mesarthmin, which I thought wouldn't be too difficult either, since they're also separated by e decent amount. Again, no problem splitting the two, and they looked beautiful.

I quickly became confident in the scope and I decided to go for Alsad, which is separated with 2.1 arc seconds, so I knew this would be a challenge. Nonetheless, I located the two stars, and they were definitely separated. At some points, I could also easily resolve a black gap between the two stars. The scope had no problem focusing these doubles into tight points of light, and despite not being a professional at double stars, I think a 2.1" split is pretty good at 152X.

Deep sky

I wanted to test the deep sky capabilities of the scope well knowing it wouldn't be the same as my 10" dobsonian, but I was quickly surprised. Staring with the ring nebula at 106X the ring was very pronounced, and with averted vision the shape became even more apparent. I would go as far as saying the view through the refractor was "comparable" to the view through the dob, and I am interested in giving this one a go with my OIII filter some day.

The same story goes for the dumbbell nebula. The "core" shape was easily visible and with averted vision I could barely notice the dark patch inside the core, which I've previously noted on sketches with the dob. The OIII must also be tried on this target through this scope, but I definitely do not feel let down by its performance on deep sky after observing the ring nebula and the dumbbell.

M13 was another story though... The cluster looked good, but I noticed the scope didn't resolve as many of the stars as I remember my dob did. Again, this was to be expected, and I didn't feel like the vies wasn't enjoyable, in fact far from that. I spent some time observing M13 and the core slowly became more resolved. I was still very pleased with the performance.

M45 was beautiful! I noted on my first light that there was a serious field distortion when observing M45 with my 14mm eyepiece, but for some reason this wasn't the case last night. I don't know if poor focus was to blame on the first night, but I was surprised to see 90-95% of the FOV pin-sharp filled with bright stars.

Here's the scope set up with my Takahashi 1.25" prism diagonal, 2.5X barlow and 6.7mm ES, 82 degree, eyepiece giving a total magnification of 266X I was observing Mars when I took this photo.

Planets

With Jupiter and Saturn only 10-12 degrees above the horizon I knew I shouldn't expect much, especially from Jupiter. With that said, some shape was visible to Jupiter's main bands at 152X, and the moons were sharp but definitely affected by the atmospheric conditions.

Saturn was also quite wobbly, but the rings were very defined and the planet's shadow cast on the rings was also visible. Cassini division was visible in steady moments of good conditions. Titan was easily visible, and I may have seen Rhea some times, but I'm not sure.

As soon as Mars cleared a nearby tree I stuck my 4.7mm eyepiece in the diagonal and I was met by a beautiful and sharp disc with obvious albedo features on the southern half of the disk. Studying the planet for some time revealed a wave-like/moustache feature at the equator, and the polar cap was also visible but very small by now. Clouds/haze was also visible on the top right of the northern pole (view is horizontally flipped, so that'd be the north-western polar limb). Atmospheric dispersion was evident, and the disc had some blue & red fringing around it, which improved at good moments. Some subtle brighter albedo spots was also visible in the otherwise dark southern half, but this wasn't as obvious as any of the other features I have mentioned.
I tried adding my 2.5 barlow "for fun", but I was blown away when I looked through my 4.7m eyepiece and 2.5X barlow at a magnification of 380X. Surprisingly the wave-like/moustache albedo feature was still obvious, together with the polar cap and clouds. The image was comfortable bright but not dim, and floaters weren't a serious image, but apparent! I didn't gain any more detail, but the slightly dimmer image was somehow more comfortable. Switching to the 6.7mm eyepiece and barlow gave me a magnification of 266X, and the contrast was slightly higher and image scale was still very comfortable. After observing for a while and switching between the 6.7mm and 4.7mm eyepiece I think around 300X would have been the sweet spot with regards to contrast and comfortable image brightness.

For fun I had brought with me my DSLR and I tried recording afocally through the eyepiece where I, to my surprise, saw a beautiful image of Mars on the live-view screen with noticeable albedo features closely matching what I was seeing through the eyepiece. I took some videos, both with the 6.7mm and 4.7mm eyepieces, and had a look at them today after work. I am blown away with the quality of this scope, and I could've never imagined I'd be using 380X on Mars through 4" of aperture and still benefit from it!

Here's Mars imaged afocally at 266X with my DSLR and 50mm prime lens.

Link to the videos of Mars and final photos can be found here: (I'm pretty confident I caught Olympus Mons as well!)
https://youtu.be/oe7mw_s2uBc

Despite not performing as good on some deep sky objects as my dob I can still se myself using this instead, because of the tight star field, and from memory, the view of M57 and M26 wasn't much different than through the dob, only M13 wasn't as resolved. I'm hoping to try the scope under some dark(er) skies soon instead of my own bortle 7/8;)

 

Victor

[Highburymark]

Great report! Felt like I was there with you, and shows just how flexible and capable a good 4” frac can be. Excellent Mars capture too. 

[JeremyS]

What a super report, Victor. You have definitely bagged yourself a great scope. Impressive image of Mars too!

[Dantooine]

I’m so glad you have gotten a telescope you are very happy with. 

[RobertI]

Nice report Victor, you achieved a lot in one session! Interestingly I also tried my wide field 38mm again recently (see recent report) and like you found that the edge distortion was not as bad as I remembered. For your interest I have managed to split a 1.4” double and I think the scope could do even better than that, so keep at those doubles, I think you’ll find it addictive! I love your Mars images, very impressive - I think the higher magnification version shows more detail - do you agree?

[Victor Boesen]

Thank you @Highburymark, @JeremyS, @Dantooine and @RobertI!! I have been very lucky with regards to the weather since the scope arrived, but of course I don't mind

Rob I will definitely stick with the doubles, and I find they're great to explore under my light polluted skies at home! I just need to find them first😅 I do agree that the 380X image shows slightly more detail, for example the clouds on the northern limb. I do, however, think I prefer the contrast in the 266X image.

Last night I had yet another session with my new telescope under darker skies. I decided to meet up with some other amateur astronomers I have a good relation to, and we met at a dark spot just outside of the city (25min drive). I hadn't been there before, but I was surprised with how dark it was! The milky way was noticeable in the Cygnus region but not overwhelming, and I'd say the location is about a Bortle 5. I also had the opportunity to try out one of the other's 2" skywatcher diagonal, and I was happy to see that I could easily reach focus with all my eyepieces, the 2" included! I also brought my filters and I made use of the darker skies by looking for some deep sky objects.

M26 looked beautiful with my OIII filter screwed in the diagonal. I observed it with my 24mm, 14mm and 8.8mm and each eyepiece showed a different view. Through the 24mm it was very bright and comparable to the brightness of some of the surrounding stars. Because of the low magnification there was a lack of detail in the nebula itself, and it looked more like a glowing ball, although the core was slightly brighter. Through the 14mm the detail improved, and the core was now easily discernable from the outer nebulosity. Even more detail was visible with the 8.8mm, and the "shell" of the nebula was beautiful!

M31 was unfortunately located towards a dome of light pollution which was noticeable through the eyepiece. It did look very good through the 24mm eyepiece and M110 was also visible. I did notice the elongated shape of the galaxy was a lot more obvious at the darker sky compared to the view at home. The 24mm eyepiece seems great on these wide field targets and I can't wait to get my own 2" diagonal!

Next up was M81 and M82 through the 24mm again. The image was easy to compare to when I observed them from home last night, and the oval/ellipse shape of M81 was a lot more evident. M82's shape was quite sharp and defined, and I could definitely resolve more of its shape, eg. core and outer parts, compared to from home where it was mostly just the core and a slightly elongated shape.

I then swung over to the double cluster in Cassiopeia, and it was absolutely beautiful through the 24mm! I figured the rich star field would be a good way to test how flat the field would be. The field wasn't entirely flat, but I found that taking some time to adjust to the view and settle on good focus helped. After studying the double cluster for while I'd say that about 80% of the FOV remains sharp.

Pleiades was also buried in the dome of light pollution, but they looked great nonetheless with pin-point stars through the 24mm. No nebulosity was seen, and I expect that this would require a lot darker skies. If you've seen nebulosity in the Pleiades, what's your "requirements" with regards to aperture and darkness to see it?

After Cygnus had moved a little from zenith I decided now would be the perfect time to test if the Veil nebula would be doable through "only" 102mm of aperture. The only time I remember seeing it through my 10" dob was at a bortle 3/4 location with an OIII filter and 24mm eyepiece. I recall both the eastern and western veil being visible, but I wasn't "blown away" by the view, and I much preferred the view through my 15X70 binoculars with my OIII and UHC filter in the eyecups! At first I located the general area without the OIII filter in place, and I couldn't see anything, but I knew I was in the right spot. I then mounted the OIII filter in the 2" diagonal and the Eastern veil became obvious without the need to search around the FOV. The curved shape was easily visible, and I showed the four others attending our small "star party" the veil and they could all see it! After studying it for while it seemed like the southern and northern parts of it seemed brightest, but I couldn't notice many fine details expect the general shape and brightness. The western veil also became visible after some time, but it wasn't as impressive, which I had also previously experience, and it looked more like a faint glowing pencil brush right across 52 Cyg. Nonetheless, I was very satisfied with the view of the veil with my modest 102mm of aperture under, what some would not even consider, dark skies.
For fun, I tried one of the other's 40mm, 70 degree eyepiece on the veil, and I could fit the eastern and western veil in the same FOV, but I felt there were more details visible, mostly to the eastern veil, through the 24mm. Through the 24mm I can barely fit both parts in the same FOV.

I finished the session with a quick look at Mars, but it seemed that the conditions weren't as good last night as they were in my previous sessions, but I could still glimpse some details in the albedo features, and the polar cap, together with clouds on the northern limb, was still visible at moments of good seeing. I do think I may have noticed some slight yellow false color last night, but I figure this might be from the 2" skywatcher diagonal, since I haven't seen this yellow tint before on Mars or the Moon even.

I'm very pleased to know that a 2" diagonal would fix my current focusing issues, so I look forward to get my own some day. I just have to figure out which one
I continue to be amazed by the scope, and its deep sky capabilities are certainly not a joke. I look forward to bringing it to even darker skies this winter!

[Highburymark]

Great stuff!

You don’t need to spend a fortune to get a good dielectric 2” diagonal Victor. The Skywatcher (or equivalent) one is absolutely fine - just as good as the more expensive ones in my experience.

[Victor Boesen]

1 minute ago, Highburymark said:

Great stuff!

You don’t need to spend a fortune to get a good dielectric 2” diagonal Victor. The Skywatcher (or equivalent) one is absolutely fine - just as good as the more expensive ones in my experience.

Thanks!

I was surprised with the performance of the Skywatcher diagonal, but I would preferably want something a little "nicer" mechanically. After all I feel like my et of eyepieces and my current scopes deserve some good quality stuff(not that the skywatcher isn't, but you get the idea)

The 2" WO diagonal from FLO looks quite good to be honest, and so does the Baader 2" dielectric one with a click lock, which seems quite nice to have!

[johninderby]

I do like the WO diagonal which I’ve found to be a great diagonal. The Revelation Quartz is a best buy though for a top quality diagonal and just as good as the WO..Highly recommended. 👍🏻

https://www.harrisontelescopes.co.uk/acatalog/revelation-quartz-dielectric-diagonal-2.html#SID=566

The SW one is OK but has a bit less contrast as it’s mirror is not as smooth. OK if bought at the right price.

Edited October 12, 2020 by johninderby

[Victor Boesen]

2 minutes ago, johninderby said:

I do like the WO diagonal which I’ve found to be a great diagonal. The Revelation Quartz is a best buy though for a top quality diagonal and just as good as the WO..Highly recommended. 👍🏻

https://www.harrisontelescopes.co.uk/acatalog/revelation-quartz-dielectric-diagonal-2.html#SID=566

Good stuff! Unfortunately harrisontelescopes doesn't ship to Denmark, so I'll have to find another vendor. What is the most obvious difference between the WO and the Revalation quartz?

[dweller25]

Hello Victor,

Here is a drawing I did at x217 on October 10th which looks to be the same CM as in your video 🙂

[johninderby]

Also available from Bresser.

https://www.bresseruk.com/diagonal-dielectric-99-quartz-2.html

The WO is lighter and that’s about it. Build quality is similar.

[John]

I have a couple of the Tele Vue Everbrights which are superbly made things (machined out of a single block of alloy) and even the heavy eyepieces such as the Nagler 31 and Ethos 21 are held very securely in them. My Astro Physics Maxbright is none to shabby either. These gems are rather expensive though and the lower cost diagonals do perform pretty well too