Sharpstar CDK

[billdan]

Sharpstar are releasing a CDK 260mm F5, 1,300mm focal length telescope, looks pretty.
If its easier to collimate than the GSO RC's, it may be worthwhile getting one.

[gregbradley]

Any suggestions of price?

It could be a nice alternative to the GSO RCs.

Greg.

[glend]

There is a thread running on this scope on Cloudy Nights,

https://www.cloudynights.com/topic/714213-sharpstar-optics-cdk/

A couple of post claim it to be a copy of the TAK CCA.
Sharp star is, of course, one of the brands that is put out by Kumming, who make the TS scopes as well. It is possible that TS is seeking this scope. Is it an alternative to the DSO RCs?
Personally I do not think much of the bright primary colours, seems to be a marketing gimmick. I note Bill's comment on it "looks pretty". Time will tell if that is enough.

Greg price discussed on CN was around $4000 USD.
Supposed deliveries later this year.

[Stefan Buda]

This will be good competition for the Beamtech CDK250.

[Camelopardalis]

Bah humbug, Glen :P nothing wrong with a bit of colour, not like we see it much anyway :lol:

Might be an interesting “upgrade” from the pesky newt, if the collimation isn’t too frustrating :shrug:

[glend]

Now Dunk, is there not a theory that certain colours affect emissability of heat radiation into the night sky? I seem to recall an example or a white tube verses a black tube.
Of course if your one of the Corflute insulation fans, it might be covered up anyway. ;)

[Camelopardalis]

:lol: :rofl: :lol:

Does this mean the red one would be better for IR viewing and the blue for UV? :question:

[billdan]

It would be interesting to know the size of the secondary.

When AG Optical in the US made their Convergent series of CDK F5 astrographs the secondary obstruction was 57% (in diameter). That's a lot of light not reaching the primary. Their 10" version was US $9K, and $10K for the 12 inch.

In that CN post that Glen linked, the TAK CCA secondary is about 50% obstruction.

[gregbradley]

F5 seems very fast for a CDK. Unless they are using reducers to achieve that then other optical factors are being sacrificed to achieve the F5.

I remember the Planewave guys saying you could get faster F ratio at the expense of increased vignetting. The CDK's tend to have slightly more vignetting than other scopes but its not much. F5 though may have a lot of vignetting.

Greg.

[FrancoRodriguez]

true that. I wonder what their vignette limited flat image circle was. At native f5 I bet it's no way near as much as a CDK is, even with their reducer. I'd bet it would be less than 42mm

[Camelopardalis]

Maybe so, but at that focal length, you’re not going for wide field...

[Stefan Buda]

When I designed my CDK250 it became clear that if I wanted to make it any faster than f/5.8, I would have to use three corrector lenses instead of two.

Sharpstar are using three rather large lenses and so vignetting should be no issue but I doubt that the corrected field would be much bigger than 42mm.

[sharpiel]

I'd prefer Beamtech anyday. Hand made by a true local artisan. One with a trusted Australian presence and tried and tested excellence.

No competition at all in my experience.

[Slawomir]

Hand-made Beamtech CDK's ? It sounds very interesting.

[glend]

As far as I know all telescopes are hand made to some extent, unless Boston Robotics has developed a new robot to assemble them.
I will be the one to point out that if you search Beamtech, it is a headlight brand. No evidence of a telescope production business that I can find, other than mentions in this thread.

[Atmos]

There is one out there currently; in Mount Macedon I believe.

[AnakChan]

The external may look like the Takahashi CCA250 but the optical design is different. The CCA250 electronic focuser moves the secondary mirror, whilst the SharpStar CDK has a rack/pinion or Crayford focuser. I asked on FB that if the SharpStar CDK corrector elements are fixed or if they are part of the drawtube and it seems that the corrector elements are fixed.

[gregbradley]

Is there a website for Beamtech? Is that your business?

Greg.

[billdan]

The Beamtech CDK is the one that Stefan designed and built.

You can follow the construction details here :-

http://www.iceinspace.com.au/forum/showthread.php?t=165877

[Stefan Buda]

Beamtech has been registered as a business in Australia in August 2000 and has the ABN #: 40 376 505 689, but until recently only manufactured laser equipment.


No website yet, still focused on product development.

[Stefan Buda]

I use the prototype as a test bed and the first production unit went into a fully automated observatory in Terip Terip, Victoria.
https://www.astrobin.com/kgj0jw/?nc=user

[Slawomir]

Images look very good Stefan :thumbsup: Might be something protruding light path in a non-uniform way a tiny bit. Just to clarify - I am aware that there is a secondary :lol:

Is there a hope for a mini production happening sometime in the future?

[Atmos]

Ah! I remembered the direction north of Melbourne wrong :thumbsup:

[Stefan Buda]

Hi Slavomir,

SN002 should be finished this coming spring and most likely two more will follow next year.

Regarding the star images produced by SN001: The Strehl ratio I achieved is only 0.9 because there were problems with the glass I used. I intend to replace the optics in that scope.
For SN000 I used old Pyrex and achieved a Strehl of 0.96