Are Non-collimateble Newtonians bad? Experiences please!

[Nikolai De Silva]

Hi, Thank you all in advance.

I have a SW Starquest 130p and it comes with a Non-collimateble mirror. It is also noted in the FLO website. I haven't found any issue with it so far. 

Does anyone have any experiences with Non-collimateble Newtonians? If so, what are the comments? Are they good or bad?

Comments are highly appreciated!

Nikolai.

[Zermelo]

I have the SW 150i, and I expect your StarQuest has the same design.

In fact, the secondary can be collimated in the usual way, it is the primary that is fixed - it is adjusted in the factory and then glued into place within its ABS cell.

Some observers would not consider a scope with an unadjustable primary, "just in case". SW's view is that you won't need to, so don't worry about it. They have been using this design on some of their smaller scopes for several years now, and I'm not aware of any serious issues. I've had mine over three years, and all I've needed to do is tweak the secondary a couple of times. I've never dropped it, though.

If the primary does ever get badly out of collimation, apparently it is possible to undo the cell's securing screws and "crack" the glue seal, adjust the mirror, and re-tighten the screws. Obviously, this should only be attempted if it's really necessary.

[Nikolai De Silva]

Thanks @Zermelo May be a dumb question. But how to adjust this?

[Zermelo]

If you slacken off the central screw (anticlockwise) a little, it allows the three others to move in or out (they will likely be hex Allen grub screws, you'll need the correct size key).

You will then be able to tweak the three screws to adjust the orientation of the secondary relative to the focuser. It's hard to explain in writing what to do to achieve what result, it's easier to see what's happening when you try it. You can also move the secondary towards or away from the primary, by turning all three screws in the same direction, if the secondary is not opposite the focuser. Finally, you can use your fingers to turn the secondary on its axis, if it's not square to the focuser. When you've finished adjusting, tighten up the central screw again to fix the secondary.

There are many collimation guides on the net that describe how to check and adjust collimation. You just need to take note of the part relating to the secondary. Don't touch it if you don't need to, but then again, it's not difficult to correct it if you mess up.

[Mandy D]

@Nikolai De Silva Most small refractors do not have collimation adjustment and no-one complains about that. Why should a small reflector be different? If properly made and aligned at the factory, they should hold collimation well. I've not had to adjust the collimation on my 200P since I did it about 6 months ago. Maybe, I'm not as fanatical about it as some, but it certainly works very well for imaging the Moon.

[Zermelo]

Ah, I've just seen that you have asked about this in a separate thread, which will complicate your responses.  Someone there is thinking that your collimation screws are missing, whereas I thought they were just difficult to see in your photo. If they are missing for whatever reason, then I agree with the other comment, try to get some thumbscrews and then you won't need to use a key.