has anyone Hyperstar converted their SCT?

[bus_ter]

I fancy the idea of f/2 imaging with my SCT. Has anyone bought one of the Hyperstar conversions? Does it affect the collimation swapping the lenses around?

[Kai]

I know SteveL had a hyper star , colimation proved very very tricky from what I remember

[JamesF]

I know SteveL had a hyper star , colimation proved very very tricky from what I remember

He's the only person I can immediately recall who has done it. Haven't seen him posting for some time though.

James

[bus_ter]

It sounds good on paper. Basically turning the ideal planetary scope into the ideal DSO scope. F/2 would be a dream for DSOs. There must be some trade offs somewhere?

[JamesF]

As Kai says, my understanding is that the collimation is absolutely razor edge.

There are also other issues, such as what do you do with the cabling for the camera, which must pass in front of the corrector/mirror?

James

[cfpendock]

As James has indicated, there are other issues, although I don't believe the cable is the biggest problem. I was going to try this but didn't in the end because it seems that focussing accurately at f2 is almost impossible even when using specialised focusers such as crayford, featherlite and others. I did a lot of research on this - Dean Koenig Starizona (who make the hyperstar) suggested their micro-focuser, but this still moves the main mirror. By fractions of microns in order to achieve focus.....

I think it should be better to move the actual hyperstar lens assembly in much the same way as the Feathertouch draw tube /rack and pinion system moves the eyepiece when fitted to the rear of the scope, but this was getting too complicated for me, and discussions with Wayne Schroeder at Starlight Instruments suggested that their Feathertouch Crayford focuser would NOT work with the hyperstar.

But good luck if you do it - some people have achieved some pretty spectacular results with hyperstar. There is a chap on this site, perfrej from Sweden who has used one. He is GOOD, and I take the liberty of pasting his comments to me when I was considering the project:

Having one for my EdgeHD 9.25, I can vouch for its quality. It is great to be able to image with a light bucket and photon sucker like that. On the Edge series scopes, the system becomes f/2.3 - certainly good enough.

Finding focus is not that difficult if your mirror flop is small. I actually bought a Micro Touch mortorized focuser for mine and that helps a lot. I haven't tried it with FocusMax yet but will soon.

The Hyperstar can be rotated without losing collimation. Collimation is simple and straight forward but it is a very sensitive system. You collimate on a de-focused star, real or atificial, and it is not difficult nor rocket science in any way. I have found that it retains collimation between sessions and even between changes to secondary mirror and back to Hyperstar. Build quality is extremely good and Starizona are very nice to deal with. You get the camera adapter of your chioce with the unit. Behind the camera adaptor is a standard 2" filter spot and you have to take the adapter off in order to change the filter.

I found that handling the cabling to the camera is an issue. It does create diffraction spikes and I chose to put fake vanes for the cardinal directions that do not carry cables,thus emulating a standard four-spoke diffraction pattern in a uniform way. I put the cabling and fake spokes in the dew hood.

The camera I was recommended was the SX M26C. It doesn't add to the obstruction which is good and OSC is good for this light bucket.

All in all, the Hyperstar is pretty cool and doesn't really raise any obstacles if you are careful and accept that initial collimation and tests will take a little while to get right (I still haven't done the fine tuning on mine, but then I live in the land of eternal summer light so I'm just getting back to business after a 3½ month involontary pause).

Don't hesitate to get one, but forget about unguided unless you have a really good mount, like the 10Micron, AP, Mesu or Paramount.

Best of luck with it,

Chris

[kirkster501]

What would worry me about HS is the corrector plate holding the weight of the HS and a camera. And also, were the scope to swing down corrector end first the camera/HS assembly would smash into the forks and crack the corrector. Without HS of course the scope would just swing in the forks were you to accidentally do this. Sooner or later this mistake is going to occur - IMO it is an [expensive] accident waiting to happen