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Orion Short Tube 80 f/5 (ST80) OTA

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Orion ST80

  • type : air spaced achromatic doublet refractor (multi-coated)
  • clear aperture : 80mm (3.1")
  • focal length :  400mm (f/5)
  • eyepieces : none
  • other included accessories : mounting plate and StellarVue enhanced 1.25” diagonal
  • finder : 6x26mm Orion correct-image metal finder on dovetail bracket
  • mount : none

After using the 15x70’s for about a year, I began to miss my lightweight 3” newt and its easy setup for those casual nights of stargazing when I just did not feel like lugging around my 17-18kg EQ newt. I also yearned for a more diverse range of magnifications. Take nothing away from the binocs as they will always be my ultimate grab and go and airline travel scope. I just wanted something that will allow me the luxury of more magnification every now and then. I wanted sharp contrasty views only a refractor could give. I also wanted to stay within my budget and hence my search on Astromart. After looking around for a while, I found a suitable Synta made Orion (USA) 80mm short tube (ST). There are several 80ST incarnations current being sold but they are all dodgy (clones of the original Synta made ST), save the original Synta optical tube assembly (OTA). This one garnered excellent reviews in its category of cheap but good scopes. It had respectable optics (can’t say it’s the best since its not an APO or semi-APO scope and never claimed to be one) and every part was made of metal save the focuser knobs.

This was one of the draw cards for this OTA for me anyway. Although its not one of the more expensive scopes around, it just felt so solidly constructed. When I first opened the box, I was struck by how nice the scope looked. It also had a quality feel to it. I was also elated to see that the main objective was fully multi-coated and not just fully coated as Orion stated on their website.

 The first night I got the scope (it came in time for my birthday which was nice) the skies were unusually clear, so I gave it a test run. As it did not come with a mount, I mounted it on my Optex T-560 photo tripod, the tripod that usually sees use with the 15x70’s. While not a Manfrotto, it serves its purpose for the time being. When I put everything on, including the star diagonal, the 6x26 finder and the 32mm Plossl, I immediately realized that, when pointed near zenith, the scope had to be balanced. So I grabbed one of my dumbbell weights and used that as a counter balance (see pic above). I have since been able to get it out on several other occasions including a shootout with my buddy Andrew’s 4” ST (also made by Synta). The 80ST held its own against its bigger brother.

So what do I think of the scope after having owned it for a good three weeks now? Well all I can say is that it performs as I had expected it to be, after some minor tweaking. When I got the scope, the optics seemed to be pinched (stars did not focus down to a point but were rather triangular in shape). This was easily remedied by removing the dew cap, loosening the plastic retaining ring, keeping the scope upright and then tapping the tube gently to allow the objective to sit nicely in the cell and then tightening the retainer ring to finger tight. Also when looking down the barrel of the OTA, I was immediately struck by how “shiny” the inner tube was (much like how my 6” newt was before I flocked the upper tube). But it did have a single baffle midway down the OTA. I once again unscrewed the retainer ring, removed the objective doublet, blackened the frosted lens edges of the objective lens and flocked the upper tube (up until where the single baffle sits). Now when looking down the barrel, the OTA is pretty dark save the focuser and its three shiny screws (a job for another time perhaps). Even then it is nowhere near as shiny as it originally was. A second Synta 80ST OTA (this one was a blue SkyWatcher) which mistakenly made its way to me looked markedly brighter down the tube without the mods I made.

These mods made a whole world of difference under the stars. Views I got of M42 were more contrasty, even without the UHC in place. The Eta Carina Nebula was magnificient, partly due to the huge FOV (well in comparison to my newt). With the UHC in, I could probably spend hours lost in its many dark lanes, rifts and tendrils. Stars focused down to a point and there were definitely more stars resolved across 47 Tucana’s face then before (same effect I got when I flocked my newt!). Also there was surprisingly very little chromatic aberration in this fast achromat. Sure the views were not as true colored as the views I got in my newt (Saturn and the moon looked a little more yellowish) but they were not as bad as I though they would be. And true to its configuration, the views were sharper and more contrasty than the newt. Saturn was a revelation, even at 66x. Cassini’s division was easy even at that magnification and looked even better at 133x. The difference in color between ring A and ring B was also very evident, as was the cloud band on the disc and the darkened poles. I could even make out the crepe ring (though not as easy as in the newt). Jupiter was not as contrasty or as sharp as Saturn. My guess is because it is much brighter than Saturn. In any case, it was sharper than my newt and showed the two main equatorial belts with two thinner bands (I have to date seen up to 5 bands during a night of excellent seeing with some detail in the one of the main equatorial bands). I have yet to get a very good view of Jupiter but my guess is that I will be able to make out some smaller details on the face. More on this later. Also the trapezium in M42 revealed a very faint, but definitely present e component (much better seen in Andrew’s 4” ST). One thing to note however was that the 15x70 still gave much better images of extended objects. There was more nebulosity seen in M42 through the binocs than in the 80ST (without the UHC though). Goes to show how much more you can see with both eyes!!!!

The accessories it came with were also respectable. The Orion 6x26 correct-image finder was nice and solidly built. It was all metal, maybe save the eyepiece portion and the metal bracket was great as well. Lenses were all glass and fully coated with a nice bluish sheen to it.  It gives correct-image views and I just simply love the “no brainer” finder bracket. My only gripe is that the views are markedly dimmer than my 6x30mm finder on the 6” EQ. The StellarVue enhanced diagonal was great as well. Felt pretty solid and came with a nylon tip to prevent marring of the eyepiece barrel, a nice touch. It is claimed that the enhanced diagonal reflects more light than the standard, almost 10% more. Have not been able to confirm this yet though. More testing required. My gripe with this diagonal is that it does not have a recessed ring to prevent it from slipping out of the focuser tube when fully loaded with a Barlow and heavy eyepiece. I also have a gripe with the focuser tube as 1 thumbscrew was not sufficient to hold the diagonal tight enough. I had several heartstopping moments when the diagonal just turned on its own and almost dumped my eyepieces onto the concrete! This was later remedied when I purchased one of Mercury System’s VFA125 1.25” visual backs. This screws on and has a nice brass compression ring to prevent marring of eyepiece barrels. Also the focuser was nowhere near as smooth as the one on my newt!

Review by Darren Wong (dhumpie). Discuss this review on the IceInSpace Forum.

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