72065Re: off-axis guider and filter wheel
- Dec 1, 2012I have had experience with the TS-OAG.
Its true that it takes up 9mm.
I have nothing against TS-optics and I have bought many many items from them. They do make some great stuff but there are major issues with the TS-OAG.
Eventually after raising the following issues the dealer/manufacturer agreed to take it back.Inherently the design is in my opinion flawed for the following reasons.
The screws holding the main adapters in place are small, thin and very fiddly. This means it is very difficult to get it rock solid, and hence it is prone to flexing, as was apparent in subs over time.
Next, the main imaging adapter only has three positions that you can position it on, these three positions are spaced 120 degrees apart and fixed, hence one has often needs to rotate the entire adapter to frame the object correctly. If used with a Canon camera, there is only position as the screws used to tighten the adapter plate block mounting the camera in 2 of the three positions.
Next, the pickoff prism only rotates a small amount, when combined with the above, framing the object and selecting a guide star is much more difficult than the orion or celestron off-axis guiders (which I also happen to have and use).
The off-axis adapter is not strong enough to hold an imaging train with filter wheel etc. Its too hard to get it tight enough and hence you will notice flexure over time depending on the OTA position.
--- In email@example.com, Mark Striebeck <mark.striebeck@...> wrote:
> I want to get the starlight xpress h694 monochrome camera. With that, I
> will need a filter wheel and I also wanted to get an off-axis guider.
> My initial inclination was to get the USB filter
> wheel<http://www.sxccd.com/sx-usb-filter-wheel>from starlight xpress
> and the off-axis guider for it. I liked the idea to
> have everything from one company to avoid adapters and such.
> But then I researched more and came across 2 interesting off-axis guiders:
> 1. TS OAG <http://www.optcorp.com/product.aspx?pid=17671>
> I like that you can move it around to find a better guide star, and that
> you can focus it independently of the camera. Plus with 9mm it's even
> smaller then the SX OAG (which has 13mm)
> 2. TS combined flip mirror and off axis
> You can also move it freely around - though with 35mm it's rather thick. I
> would have that much space in my light path, but I wouldn't be able to put
> everything else into it.
> What's interesting about the latter one is that it would allow me to do
> alignment without disassembling everything. I have to setup my scope from
> scratch every time, i.e. I have to do the whole alignment procedure every
> With regards to the filter wheel, I need to use 2" filters. Most 2" filter
> wheels only support 5 positions. How much of a restriction is that? FLI has
> a 7 position filter wheel for 2" filters (FLI
> but it weighs 2.9 lbs - that sounds rather heavy.
> Does anybody have experience with these? Or any other ideas?
> Any feedback is welcome - I'm nervous spending this much $$$!
> [Non-text portions of this message have been removed]
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