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Collimation on the cheap


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#1 Andyfx

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Posted 06 August 2013 - 08:38 PM

I recently went back to a reflector and needed a new laser collimator and, while browsing, came across this:

http://www.amazon.co...aser collimator

 

For just £19.99 I thought it was worth a punt, and I'm happy to say it's well worth the money. It can be collimated via three grub screws hidden under silicone, and has adjustable brightness. Mine was only a fraction out on testing, and most likely due to shipping.

 

If you couple it with a Revelation 2" Self Centering Adaptor then you effectively have a 2" Hotech at around 1/3 the price:

http://www.harrisont...ce_Adaptor.html

 

Both items are still £20 cheaper than a Baader Laser Collimator, so it can't be bad really can it! :D

 

I agree that Seben scopes aren't up to much, but the collimator is a different story.


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#2 Neil

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Posted 07 August 2013 - 09:32 AM

Laser collimator's are a very useful tool but you do need to be careful with them.

 

First, you need to check the geometry of the primary and secondary and then use the laser collimator to fine tune the scope. Too many people believe that this device will solve their collimation problems when it won't, well at least not by itself. Perhaps this should be the subject of a video in the near future? It is entirely possible to have a screwed geometry and the laser to tell you that everything is OK.

 

As someone who has build a newton, I have experienced this issue first hand. I would highly recommend anyone with a newton telescope to make a peep-hole out of an old 35mm film case to check the geometry of the primary and secondary mirrors first before using your laser collimator.

 

Clear Skies

 

 

Neil.



#3 Andyfx

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Posted 07 August 2013 - 09:38 AM

I completely agree Neil. The secondary needs to be perfectly aligned to the draw tube before a laser collimator is really of any use. Astrobaby's guide is still invaluable to those staring off, but there's nothing like practice. I managed to collimate an F4 500mm by eye and was near enough dead on when checked with a chesire and laser.
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#4 astrodoc71

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Posted 07 August 2013 - 02:14 PM

Definitely practice is key like you say. Everyone has their system and many paths to success. I like the mechanical collimation with Cheshire or similar to get as close as possible, then rather than laser I use software in the field. (CCDinspector from CCD Ware)
Regards
Dave

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#5 Andyfx

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Posted 07 August 2013 - 04:25 PM

Never thought of that, what a great idea :-)
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#6 astrodoc71

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Posted 07 August 2013 - 04:54 PM

One plus is that you can actually quantitate your collimation error in terms of arc sec. That's helpful to me anyway :)

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#7 Andyfx

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Posted 07 August 2013 - 05:08 PM

That's what i love about this hobby, you learn something new everyday :-)
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#8 Starlock

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Posted 08 August 2013 - 09:58 AM

After checking that the secondary is centred in the focuser I use the Hotech you gave me Andy with a 2" self centering adaptor to adjust my secondary so the red dot is centred on the prImary, then I switch to the Chesire colli (again with the self centering adaptor) for pure primary collimation. I then proceed with a final visual check by defocusing a star at high mag to check that the doughnut is concentric.

 

Chris



#9 Andyfx

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Posted 08 August 2013 - 03:29 PM

Yup, we all like nice round doughnuts..... Preferably covered in icing though ;-)

#10 Aenima

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Posted 09 August 2013 - 10:54 AM

I have the cheap seben one, cant complain at the price and alongside a cheshire it does do what its supposed to :)

 

Many bad things have been said of Seben, but this particular laser can be adjusted if need be, and the rest is straightforward light beams really. :D

 

Worth the money.

 

Regards,


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Aenima

 

 

SW 200p/EQ5 + Canon 300D(IR removed). Spc900nc - LX-toucam (as guidecam/finderscope) - 3X Tele-vue Barlow - SW 2" LPF - 10mm 25mm EP's - Bahtinov mask - 1.25" Skyglow moon filter. 

 

 


#11 Andyfx

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Posted 09 August 2013 - 12:49 PM

Yea you have to ask yourself what's so special about the more expensive laser collimators so warrant the price. Do they do anything more than the Seben? Probably not. End of the day this can be an expensive hobby so saving a few quid here and there helps, either to save up for the next item, or just keep her indoors happy lol.
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#12 klaatu2u

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Posted 10 August 2013 - 03:00 PM

I avoided mirrors for so long after starting with them 'way back'.  Started with Newt's (19060's), then to SCt /MCt, then to refractors, and now again a big (at least for me) Newt.  Interesting to me is the reliance placed on the laser these days.  The human eye is pretty ideal and understanding what collimation is all about and a sight cap / centering adaptor can do all you might need for visual only.  Star testing I think you need to be very careful about for the final nudge, lucky person that has reliable skies for it, I normally don't.  For imaging I really like Dave's (astrodoc71's) CCD inspector method / suggestion as it would allow for adjusting with the CCD/camera in place.  I've so far avoided Newt type reflector  / astrograph for imaging but that may change soon, Dave thanks for that idea!


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Jim in Portland, OR.  Some images I've taken

14" Orion goto Dob that amazes me for visual, Lots of eyepieces, and a few binoculars

A few nice refractors and 8300M CCD with full set Astrodon filters 5nm Ha, 3nm SII and OIII -->Veloce RH200 f/3 on order :)

A 'ROR' and a concrete pier in my white LP zone backyard observatory where I image from (yes, in the city!)

TheSky6, Skytools3 pro, MaxImDL pro, Photoshop CS5, PSP7 with PhotoX2, many shelves of Guides, Atlas, handbooks, you name it...


#13 Andyfx

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Posted 10 August 2013 - 03:29 PM

Seems that many of us are starting to use newts for imaging now, I think the deciding factor is low cost and performance really.
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