Hi guys. I'm thinking about putting together a new widefield setup for the upcoming summer season. I focused on two instruments: Vixen 55 fl and Sharpstar 13028/TS hypergraph 130. The first is a refractor with a fluorite doublet with a focal length (with flattener/reducer) of 236 mm f 4.3. The second is a Newton f 2.8 astrograph with a focal length of 360 mm. The instrument will initially work with my current Asi 1600mm and 31mm Antlia filters, but in the future I plan to move to the 2600mm. In the case of the Vixen 55 I would have a wider field and greater ease of use at the expense of speed. In the case of the reflector I would have a focal ratio practically twice as fast at the expense of the FOV and simplicity. However, I really like my current Skywatcher 200/800 f4 and couldn't help but consider buying another newton. The setup would work mainly in a little ROR shed, under a bortle 6 sky. Since I have two very young children, the idea of traveling astrophotography is out of the question for now. If anyone has any good advice or considerations that I missed, I would be more than welcome.
New wide field rig - vixen fl55 vs. Sharpstar 13028/ts hypergraph 13028
New Wide field setup for nebulae season W/ mono camera
16% (3 votes)
84% (16 votes)
My vote between the two was for the Hypergraph… aka the Sharpstar HNT130, purely because (even though it's noted to have issues), it will still be better than a doublet.
The Hypergraph/HNT caught my attention when it was first released. There's alot of great photos produced by it, but I've also been reading alot of folks having issues keeping it collimated. F/2.8 optics are not forgiving. I tried running an F/3 newt at one point and kinda gave up. Looking back I probably could have collected some patience and got it working, but it wasn't for me. I like the turnkey, no frills ready to go aspect of my triplets.
Doublets in general are frowned upon for astrophotography.
The Hypergraph/HNT caught my attention when it was first released. There's alot of great photos produced by it, but I've also been reading alot of folks having issues keeping it collimated. F/2.8 optics are not forgiving. I tried running an F/3 newt at one point and kinda gave up. Looking back I probably could have collected some patience and got it working, but it wasn't for me. I like the turnkey, no frills ready to go aspect of my triplets.
Doublets in general are frowned upon for astrophotography.
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I have the HNT 13028, it's a nice little scope. It is a little tricky to collimate but when it is service I keep it in an observatory so I don't have to worry about collimation shifting.
Collimating the primary with the included cheshire can be difficult because the corrector is not removed and my eyes have a hard time focusing through it. My method now is to align the secondary with a laser, get a rough alignment of the primary, then mount the camera and fine tune the primary with a bahtinov mask. I made a zone mask for the bahtinov so you can work on one collimation screw at a time. Like this.
Collimating the primary with the included cheshire can be difficult because the corrector is not removed and my eyes have a hard time focusing through it. My method now is to align the secondary with a laser, get a rough alignment of the primary, then mount the camera and fine tune the primary with a bahtinov mask. I made a zone mask for the bahtinov so you can work on one collimation screw at a time. Like this.
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I'm a proudly owner of a FL55ss but I don't use the focal reducer. I use it in his native focal leght and I must say: The craftsman quality is the best that I saw so far which only can be matched by the Takahashi. I must say: Despite been a doublet (as most of the old school Takahashis are), that natural crystal flourite lenses are the best that humans made so far on the planet.
Observatório Astrográfico do Boqueirão:
I'm a proudly owner of a FL55ss but I don't use the focal reducer. I use it in his native focal leght and I must say: The craftsman quality is the best that I saw so far which only can be matched by the Takahashi. I must say: Despite been a doublet (as most of the old school Takahashis are), that natural crystal flourite lenses are the best that humans made so far on the planet.
I very much doubt that transparent "natural" CaF2 can be found in sizes large enough even for a 55mm lens in nature. Never mind the other requirements.
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Thank you all for the replies. I have owned several refractors in the past, and they are undoubtedly easier to use than a fast newton. @Mike Hamende how often do you have to recollimate? I practiced with my Newton f4 and the Ocal collimator. The 130 f2.8 will certainly be more demanding, but I hope it is compensated by the better mechanical quality. My skywatcher four was a nightmare at first, I solved it with the new spider and the Esatto focuser from Primalucelab
Yes, you have narrowed your search to the two scopes mentioned, but consider the Borg55FL F/3.6 Petzval refractor. No spikes. With blurXTerminator it will nicely handle a full frame sensor.
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Leonardo Landi:
Thank you all for the replies. I have owned several refractors in the past, and they are undoubtedly easier to use than a fast newton. @Mike Hamende how often do you have to recollimate? I practiced with my Newton f4 and the Ocal collimator. The 130 f2.8 will certainly be more demanding, but I hope it is compensated by the better mechanical quality. My skywatcher four was a nightmare at first, I solved it with the new spider and the Esatto focuser from Primalucelab
I collimate once when I set the scope up in the observatory and I don't need to touch it after that unless I take it off the mount.
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