Random cheapo Newtonian to try collimation?

[TiffsAndAstro]

Missed out on an Orion star blast 4.5 for £35 was wondering about the one below. Not bothered about the mount.

Just thinking about a cheap non bird Jones F5 ish Newtonian to try out collimation before maybe buying something better that won't needs lots of fixing to make it good, in the future.

This OTA weighs 4kg so not impossible for my current mount.

 

Apologies for worlds longest URL

https://www.ebay.co.uk/itm/116256865754?_trkparms=amclksrc%3DITM%26aid%3D777008%26algo%3DPERSONAL.TOPIC%26ao%3D1%26asc%3D20240315132637%26meid%3D9d7e1fe2c60c4db8bbf5485b08b19ca4%26pid%3D102055%26rk%3D1%26rkt%3D1%26mehot%3Dnone%26itm%3D116256865754%26pmt%3D0%26noa%3D1%26pg%3D4375194%26algv%3DRecentlyViewedItemsV2MobileWithMLRV6RankerPricelessTop50Features%26brand%3DCelestron&_trksid=p4375194.c102055.m146925&_trkparms=parentrq%3Af42a24fa1900ad993dea692fffff0868|pageci%3Ac1d5d29f-4c13-11ef-9343-e6e005883b3a|iid%3A1|vlpname%3Avlp_homepage

[pipnina]

Were you going to use a newt for imaging or visual observation? For imaging you might find they all behave with their own character and an f5 will be a doddle to collimate compared to an f4. For visual, you can get it "close enough" and it will look fine, maybe you could be picky at high power.

But all the newts I've used have behaved differently. Some barely held collimation at all (8" TS Photon f4 flexed under its own weight, while my 10" dob and 5" PDS were like bricks and easy to adjust, and even survived some transportation without need for adjustment.

If you want to look at a specific newt for imaging or observing, maybe if they sell it on FLO you could pick it up anyway, with a collimating tool (my preferred is laser for fast primary alignment and secondary squaring, cheshire for centering the secondary). That way you get to see if the newt you want to end up using works for you, with the safety of the 30-day return?

[TiffsAndAstro]

9 minutes ago, pipnina said:

Were you going to use a newt for imaging or visual observation? For imaging you might find they all behave with their own character and an f5 will be a doddle to collimate compared to an f4. For visual, you can get it "close enough" and it will look fine, maybe you could be picky at high power.

But all the newts I've used have behaved differently. Some barely held collimation at all (8" TS Photon f4 flexed under its own weight, while my 10" dob and 5" PDS were like bricks and easy to adjust, and even survived some transportation without need for adjustment.

If you want to look at a specific newt for imaging or observing, maybe if they sell it on FLO you could pick it up anyway, with a collimating tool (my preferred is laser for fast primary alignment and secondary squaring, cheshire for centering the secondary). That way you get to see if the newt you want to end up using works for you, with the safety of the 30-day return?

Could try that but I don't like taking advantage like that. I'd only return stuff that I had to.

I quite like the idea of finding a small newt just to try out. Might even be light enough for my mount.

Imaging only btw

I didn't bid on the above item in case it was a bad bird Jones.

ALso I like idea of trying out collimation to help me decide if I should get a decent one. Plus the mount upgrade it would need

[happy-kat]

Do you like defraction spikes on images?

[TiffsAndAstro]

22 minutes ago, happy-kat said:

Do you like defraction spikes on images?

yes i think i do. at least 'nice' ones.  i don't like them enough to want to add them to my current images though

[ONIKKINEN]

Collimation of cheapo newtonians will be significantly more difficult than with decent newtonians, so not sure this is a good way to learn collimation if that was your main goal with getting one for cheap at first. Its because if the scope is mechanically unstable proper collimation will be impossible to do consistently, especially with models that have plastic focusers and no primary mirror center marker. My first scope, an Astromaster 130 was all plastic and practically impossible to collimate accurately, so didn't learn much with that scope.

The smaller Skywatcher PDS (130/150) scopes are not too expensive or heavy, and there are a lot of them out there so you might find a good deal second hand which would be my suggestion for a soft landing to the world of newtonians.

[TiffsAndAstro]

3 minutes ago, ONIKKINEN said:

Collimation of cheapo newtonians will be significantly more difficult than with decent newtonians, so not sure this is a good way to learn collimation if that was your main goal with getting one for cheap at first. Its because if the scope is mechanically unstable proper collimation will be impossible to do consistently, especially with models that have plastic focusers and no primary mirror center marker. My first scope, an Astromaster 130 was all plastic and practically impossible to collimate accurately, so didn't learn much with that scope.

The smaller Skywatcher PDS (130/150) scopes are not too expensive or heavy, and there are a lot of them out there so you might find a good deal second hand which would be my suggestion for a soft landing to the world of newtonians.

Didn't even consider the lack of circle on the primary. I think 130mm ones just a bit too heavy.

Focusers will be rubbish I guess.

Ty for the advice.

[TiffsAndAstro]

Er two more probably stupid questions sorry

Has anyone tried attaching secondary on a stick on end focus tube?

Also, do focus tubes always have to poke into the OTA so far or can they be cut down a bit once you know roughly where focus is reachable?