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OPTICSTAR 80mm F7.5 achromat refractor - Review


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I recently asked about this scope in another thread and whilst there was plenty of feedback about the other focal lengths and objective diameters avaialble in this range, there doesn't seem to be much information regarding this particular scope. So, I thought I'd record my observfindings for anyone considering purchasing the same scope and will update with first light report and further observations etc.

Firstly, the whole lot was reasonably well packaged. Whilst I think the boxes are a little thin, there's plenty of padding - outer box - inner box - bubblewrap - carry case - more bubble wrap - scope!

Pulling the scope from the bag, I first noticed the weight being considerably more than the ST80, which this is replacing. However, the presence of an adjustable tube ring should better allow me to balance the scope on my Orion Tritech II fluid head. The ST80 always wanted to tip back due to the lightweight tube and objective cell not countering the weight of the cast focuser, diagonal & EP.

The tube appears to be machined as opposed to rolled steel and has a mottled off-white finish. I'd read comments about this finish previously and wasn't sure whether I'd like it. Saying that, whilst it is not the prettiest, compared to a gloss black or white tube for example, it appears durable and the raised bumps offer some additional grip. It all feels quite substantial in hand.

The focuser is a crayford, but does not conform to the norm I have experienced in as much as with the locking screw set loose, the drawtube slides in and out freely (loose). I would have thought some pressure should be maintined on the focus tube, even with this screw loose. I will investigate adjustment, but it does not seem to have the usual adjusment screws of a typical crayford. With the screw tensioned some, focus movement feels as smooth as a standard SW crayford to me, which is more than satisfactory provided it does not require overtightening of the lock screw to prevent slip with diagonal & EP fitted.

The draw tube is retractable and slides very smoothly with a satisfactory amount of resistance, it did not slip when pointed at Zenith. The Opticstar logo is printed on one side of the dew shield only. The dew cap is a metal screw on item and the threads seem well machined and of a decent pitch as to prevent cross-threading.

The objective lens looks rather attractive with an apparently evenly applied deep green coating, though it looks bluer on camera. I struggled to see much detail inside the tube such as baffles due to it being very dark in there, suggesting it has effective anti-reflection paint. It will require a brighter light source to inspect.

That's about all I've had time to look at so far, tonight I will get it balanced on the mount and test the focuser with accessories attached. Suffice to say that for the modest price of £149, I am so far impressed. I also considered the 365 Astronomy version of this which is £50 more expensive, but appears to have a superioir focuser, however I discounted it due to having large machined rings (extra weight) and no finder shoe.

Here's some initial pics...

 

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Nice purchase. These scope are little hidden gems. It will provide a satisfying observing session, and being 7.5mm FL quite tolerant on may EP's!. I really like mine, and has been my grab n go scope for some time. i did some basic imaging through it back in the early days.. sure it was more a test than a serious approach, but it did very well!. Have fun with it.

Rob

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Got the scope mounted on the Tritech II tripod now. Safe to say I would not dare load this mount up to it's rated 6kg, this scope is more than enough for it! I've had to drop the centre column to reduce vibration and it's not too bad with only the centre leg sections extended. Will definitely need to observe sitting down, which is no bad thing.

I have to move the scope fully forward in its ring in order to reach balance when pointing at a middling altitude, as per the pics. Any lower or higher needs a nip of clutch to prevent over shooting but it still runs smoothly with clutch engaged.

I took a better look at the coatings and they look really good, very even in colour with no obvious under or over coated spots. I had to use flash photography to get a good view down the tube, which shows a REALLY evenly applied flat black paint, with no scratch marks in it like I've seen so often in SW scopes, and two knife edge baffles.

A quick look out the window at the dusk moon showed some nice sharp results and high mag on a TV aerial across the street displayed very little CA, I will somehow attempt to quantify this later on.

Skies are clear now and forecast to stay that way, we could see first night first light here! Hope to star test and test CA and ability to take mag tonight. Watch this space.

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So I managed to get first night first light! I set the scope up outdoors around 7pm but there was scattered low cloud, however, I managed to look at the moon in order to quantify the CA. I have to say I'm very pleased with the low level of CA, none on the terminator and only fleeting glances on the limb, which were either yellow or blue depending on focus, very much on par with my old 90mm F11, so very good for an F7.5 achro. Testing at higher mag with the Baader zoom set to 8mm providing x75 mag, focus snap was crisp and I briefly studied craters along terminator. I was impressed by the detail visible in what I think was Tycho, with the central peak very well defined. Cloud rolled in at this point so I retired indoors for a while.

Around 10pm I looked out to clear skies so I wrapped up warm and went back out. First up was a star test. With the scope having been outside for 3hrs, I was satisfied it was cooled sufficiently! The OTA was dewy, but dew straps were on and had been running on low with caps fitted, so no dramas there.

I'm pleased to say that the scope appears to be in good collimation, with perfectly concentric diffraction rings. Inside of focus the rings were very defined and remained colour free, outside of focus the rings were softer and more colourful, but still defined and concentric. One thing I did note was that the pattern inside of focus was not 100% circular, rather slightly oval in the vertical plane and the opposite outside of focus, slightly oval in the horizontal plane. This effect was VERY minor, like single figure percentage points and I thought I saw it come and go, so it may have been atmospheric. The only thing I can relate it to is astigmatism but this was on-axis. In focus, the airy disc was resolved nice and round as far as I could tell.

I then went on to observe some old favourites. Pleiades, Orion, double cluster, Bodes Nebula and Andromeda. I obviously noticed the lack of aperture compared to my previous 120mm frac, however this little 80mm still threw up some good views reminding me very much of the ED80 I once owned. In Orion, I could distinguish quite extended nebulosity and Trapezium A, B, C & D resolved well with fleeting glimpses of E, which is as good as I've ever seen. I suspect there's more to be had under better skies too as I was suffering from lots of sky glow last night, with LP being drawn up from the city in the moist air.

Mechanically the scope is good. I had no issues with the dew shield drooping and with the focuser tension screw set, the focuser lifted and held the 1.25" diagonal and Mk4 Baader Zoom near Zenith with ease. Coarse focussing is not as smooth as my previous scopes but the fine focus was rather impressive, smooth and very light to the touch. The scope is quite weighty and is pushing the limits of this little mount, however, with the central column retracted and only the centre leg sections extended vibrations during focus were not too bad, especially when fine focussing. I'm reluctant to upsize to an AZ4/5 because that would negate the beauty of this setup, that being that when I was finished observing, I simply picked the whole lot up in one hand and went indoors!

First impressions then certainly satisfy and justify the very modest outlay of £149. This scope has achieved exactly what I wanted, which was to improve over the ST80 with respect to control of CA and provide sharper, higher mag images. Overall I am very pleased with this purchase so far and on the occasion that something did not feel quite as premium as I have been used to, I simply reminded myself of the cost and suddenly, I was laughing out loud :)

 

 

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Edited by parallaxerr
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Nice review there. Its a very capable scope I have to say. I find mine better than the skywatcher range in this size, the 7.5 fl proves its worth with pushing the CA down to non distracting at all (as you claimed). Fit and finsh does look nice on the new model. Mine is the older version, but I have fitted a single crayford.

Good stuff.. enjoy!... Rob

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5 minutes ago, Rob said:

Mine is the older version, but I have fitted a single crayford. 

Out of interest Rob, was finding a replacement focuser easy enough? I've only ever replaced a 3 screw SW with a Moonlite but don't know what the attachment method is on these. I wondered if it may be compatible with one of the Baader Steeltrack adapters, M90x1 for example?

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On 14/12/2018 at 09:37, parallaxerr said:

Out of interest Rob, was finding a replacement focuser easy enough? I've only ever replaced a 3 screw SW with a Moonlite but don't know what the attachment method is on these. I wondered if it may be compatible with one of the Baader Steeltrack adapters, M90x1 for example?

Ok. this was a bit of mission to be honest. I sourced a Agena Astro GSO Adapter, then because I had a non GSO crayford I had to get the very edge of shim/flange lathe skimmed to allow the crayford to be attached. Fun little project!

Theres a few images in my album on here

 

Edited by Rob
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And here's a singe shot (1min 30sec) with 300D + LPR Filter camera I took using the AR80. I'm no imager.. just dabbled a little back then, however looking to start again. As you can see its very capable!

 

Edited by Rob
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My AR80S arrived this morning, so I thought I'd post a quick pic of it on my AZ5 mount.

First impressions are that it is very light yet substantial, and feels very well made for such a budget price. First light has consisted of pointing at a TV aerial to line up my finderscope; image is crisp and clear with just a hint of CA either side of focus.  I guess that, despite being an achro the focal length of f7.5 helps with this.

It is a little 'back heavy' with finder, diagonal and eyepiece but the mount holds it ok 

The Crayford focusser is a little 'sticky' in coarse mode, but fine focus is smoother.  It's not as smooth and the 10:1 Crayford on my Revelation dob, so may need some adjusting.

Can't wait for a proper first light if the clouds ever roll away!

 

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Edited by wheresthetorch?
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1 hour ago, wheresthetorch? said:

My AR80S arrived this morning, so I thought I'd post a quick pic of it on my AZ5 mount.

First impressions are that it is very light yet substantial, and feels very well made for such a budget price. First light has consisted of pointing at a TV aerial to line up my finderscope; image is crisp and clear with just a hint of CA either side of focus.  I guess that, despite being an achro the focal length of f7.5 helps with this.

It is a little 'back heavy' with finder, diagonal and eyepiece but the mount holds it ok 

The Crayford focusser is a little 'sticky' in coarse mode, but fine focus is smoother.  It's not as smooth and the 10:1 Crayford on my Revelation dob, so may need some adjusting.

Can't wait for a proper first light if the clouds ever roll away!

 

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Looks great on the AZ5. I'm looking forward in hearing how this performs...

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9 hours ago, wheresthetorch? said:

My AR80S arrived this morning, so I thought I'd post a quick pic of it on my AZ5 mount.

First impressions are that it is very light yet substantial, and feels very well made for such a budget price. First light has consisted of pointing at a TV aerial to line up my finderscope; image is crisp and clear with just a hint of CA either side of focus.  I guess that, despite being an achro the focal length of f7.5 helps with this.

It is a little 'back heavy' with finder, diagonal and eyepiece but the mount holds it ok 

The Crayford focusser is a little 'sticky' in coarse mode, but fine focus is smoother.  It's not as smooth and the 10:1 Crayford on my Revelation dob, so may need some adjusting.

Can't wait for a proper first light if the clouds ever roll away!

 

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Looks great, I'll be interested to hear how the AZ5 works out, have been considering one myself.

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Thanks to  a recent gap in the clouds while the moon was up and an unexpected clear night last night, I've now had the opportunity for first light with with AR80S on the AZ5.  

The scope's performance on the moon was really impressive.  There was a hint of CA on the limb in the form of a yellowish tinge, but no hint on the lunar face and the terminator was beautifully clear and crisp through my BST Starguiders.  

Last night I cruised around some familiar DSOs while I got used to the scope and mount - M42, M43, M45, M31, M35, Double Cluster and some double stars in Orion (Struve 747, Struve 745, sigma Orionis and iota Orionis).  I was really pleased with the views - stars were pinpoints across most of the view with just a hint of distortion at the extreme edges.  At just 40x I was able to see all three components of iota Orionis, and they were easily split at 75x.  Similarly, stars D and E in sigma Orionis were easily separated from the main ABC stars.  Overall, the telescope is perfect as a 'grab and go' small achro with limited CA.

Unfortunately, I'm less impressed with the AZ5 mount.  It's really not very steady at all, and any attempt to fine tune the focus led to the view jumping around and taking a good 2-3 seconds to dampen down.  It was a still night, and I hate to think what the view would have been like had it been windy.  I got the mount used on eBay, and it lacks the pillar extension - I've therefore ordered one from FLO in the hope that having to extend the tripod legs less might improve its steadiness.

Anyway, there you go.  In summary - scope good, mount less so.

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  • 4 months later...

Just thought I'd bring this thread back life!. How are you guys finding the AR80S, Keeper?. Are you finding that short sessions are just a pleasure Opticstar?.

I still use mine for 1 in 3 sessions TBH. I love the ease & quickness of setup, with fantastic views. Sometimes it is hard to believe you looking through a £150 Achro!. I still feel its a hidden gem of a scope.

Rob

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I was a bit put off the Opticstar achromats by a report from Neil English where he found the 80mm F/5 Opticstar achromat objective was of mediocre optical quality. He replaced it with an objective from a Skywatcher ST80 which proved a good performer and transformed the Opticstar 80mm F/5 into a good scope. 

Perhaps Neil was unlucky ? :dontknow: 

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I've got an AR80 and AR90 short versions and to be honest they have been great little perforners. Have used both as grab and go scopes and together as guide scope and imager. 

For a cheap achro I can't fault them. I'm only selling mine now as I've just got an apo and something has to go. 

Well worth the money in my opinion. 

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13 hours ago, John said:

I was a bit put off the Opticstar achromats by a report from Neil English where he found the 80mm F/5 Opticstar achromat objective was of mediocre optical quality. He replaced it with an objective from a Skywatcher ST80 which proved a good performer and transformed the Opticstar 80mm F/5 into a good scope. 

Perhaps Neil was unlucky ? :dontknow: 

Maybe John?. That said I've not looked through the f5 model, just the f7.5 which seems to just have a sweet spot on performance. I think also if your on a tight budget you just cant go wrong with these. I'm tempted by the 90S at f8.8.

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Yes, still very happy with mine.  Been getting some good white light solar views recently as well through it.

It's my first refractor (had a Mak before and my 'main' scope is a Dob) so I have to admit I've not really got a baseline, but I find the views pleasing. 

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