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Old 04-07-2020, 02:00 AM
Kurt
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Advice: Sharpstar 100Q II v Sky Rover 115 ED APO

Hi team,

Iím in the market for an APO Refractor around the 550mm - 700mm Focal Length for astrophotography and am tossing and turning on either of the below, and could really use some varying points of view.

Sky Rover ULT 115 ED Glass Triplet 115mm APO
https://www.astronomyalive.com.au/pr...tor-telescope/

Sharpstar 100Q-II
https://www.testar.com.au/collection...sharpstar-100q

I donít have any experience with APOs, but have done a tonne of reading these past few months, enough to do my head inÖ but plenty to understand the gist. Iím a regular photographer with DSLR gear and have been using a SIGMA 150-600mm, and others, on a HEQ5 Pro with both a 7D I and 5D IV, guided; but am now looking to upgrade to my first APO and dedicated focal length in what I would traditionally refer to as a prime lens, but for far less cost in comparison. Iíd also like to buy local.

I like the idea of wide field, though prefer that 600mm-700mm range for Nebule etc, with something acceptable weight wise that would still suit my HEQ5 pro, and then ease of use with my Full frame 43mm sensor DSLR.

Will look into dedicated cooled astro CCD later on, baby steps, and minister of financial affairs approval etcÖ

I know thereís a few things to consider with a nice APO, price, weight to suit mount, double v triple v quadruple design and quality, flatteners v inbuilt for the quad, resulting FL, flat field and ease of use etcÖ

Iím also aware through these forums and others that the Sharpstar is re-branded and sold under other aliasís all over the world, but similarly with the Sky Rover 115, there arenít a huge amount of reviews singing their praises, but not trashing them either, so itís actually been difficult to make a decision. Plus, Iíve even considered the SW 100 Esprit, it gets some really great reviewsÖ but is that APO just a more ďpopularĒ choice, not superior? Iím still researching a lot, but thought Iíd throw it on the table for a few more opinions if thatís ok.

Weight wise the SW 100 Esprit clicks in at 6.3kg, so that added with guiding equipment, filters and DSLR, weíre now loading up the HEQ5 Pro payload, but I have read about others who use this setup just fine and get great results, so that sounds promising. It averages around $3500.00 in Oz and itís a triplet (or doublet with a field flattener) with an FL of 550mm at f5. Itís on the shorter FL end out of the three Iím considering, but acceptable. It comes with a D Losmandy type bar, so would need an ADM bracket or similar plate to allow it to fit on my vixen head for the mount.

The Sharpstar 100Q II (second version of this variant) clicks in at 5.2kg, which gives me a little more headroom on the HEQ5. I can get it around $3800.00. Itís advertised on Testar as an Petzval quadruplet, but on Sharpstar it says itís an quartette doublet air-space design (I assume thatís the same) as in the ďcorrectorĒ or ďflattenerĒ is inbuilt, so itís a more of a plug and play APO without having to worry too much about spacing in the imaging train compared to a triplet where backspacing accuracy is required!? The 100Q II FL is 580mm at f5.8 with a FF flat field of 44mm, perfect for the 43mm 5D IV sensor. Testar also details that the objective lens includes one FPL53 Ohara glass, whereas the Sharpstar website only mentions ďspecial ED lensĒ. Not sure if that is the same thing? In addition, Sharpstar website says you can use a F4.3 full-frame reducer lens (but Michael Fong from Sharpstar confirmed that there actually isnít a reducer for the 100Q II yet) so Iím not sure why thatís advertised. I may or may not use one anyway, but would be cool to have the versatility.

The Sky Rover 115 APO is a triplet which clicks in at a similar 5.1kg, so thatís also nice for the HEQ5 and comparable to the Sharpstarís 5.2kg which for my setup with guiding, filters and DSLR seems to make sense. Price at $3000.00 sounds great, especially for the native FL at 805mm at f7. It would be reduced with the 0.8x reducer/flattener to an astrophoto flat field of 42mm FL of 644mm at f5.6, also perfect for the 5d IV 43mm FF sensor. So the way I see it, the Sky Rover 115 APO gives me the greatest focal length and decent aperture at the cheapest price and it's the lightest. I just wonder if the advertised ďPremier Japanese Triplet ďEDĒ Extra Dispersion glass lensĒ is on par with the others FPL53?

So I really like the price and extra FL of the 115 APO and definitely the added flexibility being able to use it at 805mm for visual and then 644mm for FF flat field Astro, so I like that versatility. Itís supplied with a vixen dovetail so that will mount straight onto my HEQ5. Iím just not sold on ease of use though compared to the 100Q II Quad, and instead having to use the flattener and getting correctly spaced for focus etc. (Only because I have no experience doing this).

(I may also not really need to benefit from the 115 APOís 805mm for visual though anyway, as I already use a Celestron C5 at 1250mm for some visual fun in that arena, albiet at f10Ö)

I also really like the sound of the Sharpstar 100Q II too, mainly because of itís ease of use, flat field for 43mm Full Frame sensor straight out of the box, plug and play basically, I like the top handle for Guide-scope placement and it too ships with a vixen dovetail bar for mounting, plus itís locally bench tested here in oz and itís a comparable price against the SW Esprit 100, but itís the most expensive out of the three.

The Sharpstar price compared to the 115 APO confuses me a littleÖ.. would there be $800 worth of quality difference between the Quad compared to Triplet? Is ease of use worth $800? Am I missing something? Or perhaps thatís really the only decision I have to make?

All three seem to list good focusers with 360 rotation for image composition, so thatís handy too. Form factors between the 100Q II and Esprit 100 are all pretty similar, the 115 APO comes in a little longer.

At the end of the day, there may or may not be a right answer here, and maybe I canít really go wrong for amateur astrophotography between either of these three, which is ok, but I would really appreciate some thoughts or your experiences on the above, which for me, might give just a little more comfort in the decision I take in the end :-)

Thanks muchly
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Old 04-07-2020, 06:11 AM
glend (Glen)
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The Sharp star 115 is likely the exact same scope as the Teleskop-services TS115 APO. Sharp star are a brand. You can read plenty on the TS115 on the Cloudy Nights forum in the Refractor sub forum. I used to own a TS115 and can say without reservation, it is an excellent imaging scope, and would suit your requirements with the TS reducer corrector added.

https://www.teleskop-express.de/shop...g-sensors.html

The reducer fits directly to the female M68x1 thread of the apo.

The triplet objective combination of (Lanthanum glass and FPL51) is equivalent to a triplet objective using a single FPL53 element. Colour rendition is not a problem with this scope.


https://www.teleskop-express.de/shop...P-focuser.html

Update, I sold my TS115 to Alex.

Last edited by glend; 04-07-2020 at 07:34 AM.
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Old 04-07-2020, 07:19 AM
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xelasnave
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I am the very proud owner of Glens 115mm and say it is a great scope.

I am not too sure that the heq5 is happy carrying it however.

I first used the scope on M31 on the heq5 unguided with no problems however in the last couple of weeks I have been after M17 and find that the mount is very sensative to re balance such that I have to move the counter weights after some time as trails start to appear. Unguided but the trails suggest auto guided would not cope well..nor should it a mount should run close without guiding you don't want the auto driving it but making adjustments..in my view. Now this may be just a problem unrelated to the carrying capacity of the mount but last month I had no such issues with my 80mm ran unguided happily with no adjustement of counter weights.
To make it more confusing I have in the past carried my 8 inch f5 Newtonian with success.
All I suggest is to look hard for material to support or not the suitability of the heq5.
I am running unguided but you should not get the trails I am seeing and such a dramatic need to adjust counter weights..To me it suggests the scope is too much for the mount.
Maybe load up your mount with similar weight and see how it handles the weight..your cameras and a block of wood maybe.

Alex
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Old 04-07-2020, 08:31 AM
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Atmos (Colin)
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They’re all good to be about the same performance wise I’d imagine. The Sky Watcher and Sky Rover both use FPL-53 and I think the Sharp Star does as well but I haven’t looked.

With back focus for flattener, if he reducer has a 55mm back focus then your Canon should simply work with the M48 EOS adapter. Canon has a 44mm back focus and then the adapters are usually around 10mm as well.
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Old 04-07-2020, 10:52 AM
Kurt
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Thanks Glen, I'll have to get in some more reading on the TS version of the 115 for peace of mind. What did you move onto since your 115 and why? Cheers.

Alex, great to hear you love your 115 from Glen. Sorry to hear of your recent troubles though. I guess the only thing I've really thought about with the 115, or any APO in this class is the weight, and given the 115 is in around 5kg, surely this would nicely suit the payload limits of the HEQ5...

The 115 is quite long, so perhaps it indicates that correctly balancing, especially so in DEC, is so critical?

Thanks Colin. How would I go placing in an ZWO filter drawer in front of the DSLR with the 115 APO? Does that go straight after the APO, or the corrector, and how would it affect the back focus length required to accurately focus? Unless the filter drawer is exactly 10mm, I haven't checked.

Admittedly, in reference to my OP, in Australia, there's also the Meade 6000 ED 115 and the Orion EON 115 in the same class as the other three APOs I've already mentioned above, but I haven't read much up on either, so I'm happy to take additional counsel.

I guess where I'm really unsure, is the difference between going a quad over any triplet, for both better CA and flat field, and is that quality going to be worth it with the Sharpstar 100Q II in comparison?

Thanks again!
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Old 04-07-2020, 11:15 AM
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xelasnave
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The length no doubt or perhaps is the issue. At the moment it seems perfect but maybe it would benefit from some bias. Unfortunately I will not be able to address the problem for a couple of weeks ... anyways you must know in this game good or bad you will be looking for a better mount in no time.
Good luck ...just do it.
Alex
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Old 07-07-2020, 12:49 PM
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Manav (Yugant)
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I have a stellarvue SVQ100 and its same/similar and its pretty good. I'll post some pics for you on CN.
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Old 09-07-2020, 02:01 PM
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gregbradley
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As far as Lanthanum and FPL 51 combos go Roland Christen did an article on that. Basically that its inferior. I think though that article was referring to doublets.

Marketing blurb is usual to hide the factor a lesser grade of glass is used. FPL51 is the original ED glass and is old. Its really an area of dishonesty where they leave you guessing what type of glass it is. But my rule is if they don't say its FPL53 then it isn't. Also some companies falsely claims fluorite lenses when its FPL53 so there is a lot of lying and innuendo. FPL53 is weil known so they state as a sales point.

FPL53 is now somewhat outdated and FPL55 is now the latest best. My understanding is its performance is the same as FPL53 optically but it has better properties as a glass which I am sure is good for the optician to get a more perfect lens with.

Petsval potentially is the better imaging instrument so long as its well collimated and solidly built. The FSQ106ED has shown how powerful the Petsval design is. As to how good the quality of this particular scope goes you'd have to check with cloudy nights. Another way of checking is do a search on Astrobin for images made with those scopes and judge for yourself, much more solid ground than asking others.

Is the reducer included in the price for the 115? Or is it extras. Do both scopes come with rings? a case or bag?

Focusers vary a lot in practice and are often a weak spot for many scopes even high end scopes. I would check out that well. Also the focuser needs to be a minimum of 3 inches aperture for full frame. Any less and you are dreaming.

Full frame requires 44mm not 42mm so already 42mm is falling short which could mean wonky stars in the very corners. Ideally wider than you plan to use but perhaps that is not very realistic.

I would personally chose the FPL53 scope as all the top scopes over the last 15 years all use FPL53. All other things being equal.
I would personally prefer a petsval over a triplet with reducer if they were close in price and the petsval had no known issues.

As far as 100mm versus 115mm goes its a bit brighter at 115mm but at the end of the day these are widefield scopes. 800mm is a bit long in my opinion. That would be the territory of 130mm scopes.

Faster F ratio is valuable as well. Faster F ratio does put more pressure on the scope to be well built though.
Edit:

Looked at some images on Astrobin. They were Sharpstar 100Q not the ii model. Some were great some not so good. Tendency towards blue rings around bright stars. One image used a Sony A7rii camera which is a full frame sensored camera. Stars were distorted badly for nearly half the image. Not even vaguely capable of sharp stars to the corners. The best images were from KAF8300 sensored cameras which is micro 4/3rds in size.
So if you plan to use a full frame camera unless the later ii model is way better than the original its not going to do it. There were no images there for the triplet. But it has 9 good reviews. I also bought a high end scope from Astronomy Alive and found Cris Ellis to be very professional, truthful and good to deal with. I'd be leaning towards the triplet.

Greg.

Last edited by gregbradley; 09-07-2020 at 06:33 PM.
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Old 24-09-2020, 03:17 PM
Kurt
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Thanks again to everyone for their thoughts and suggestions. Just letting you know that I finally went with the Sharpstar 100Q II and have so far been very happy with my purchase.

- Sharp to the corners, no aberrations
- Suits my FF 5D IV perfectly
- Connects straight onto the HEQ5 Pro with the vixen bar
- Connected my guide scope on the top rail
- Suitable weight for the HEQ5
- No need for flattener/reducer
- No backfocus issues
- The focusser is very strong and sensitive
- Bench tested and local support
- Great Focal Length for large amount of targets

Now all that's left on the current wish-list is a dedicated astro-camera, an auto-focus and some dark-site imaging time, hehe. Oh, and maybe a second rig, lol.

Here's some quick images, and of my setup.

https://imgur.com/a/4HV1KuM


https://i.imgur.com/MiP83em.png

https://i.imgur.com/6L74aWj.jpg

https://i.imgur.com/GlWDxFn.jpg
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Old 24-09-2020, 04:24 PM
Xeteth (David)
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That shot of the Pleiades is absolutely gorgeous! You should definitely chuck these shots in the astrophotography section!
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