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Canadian Telescopes 152 F-5.9 Acromatic Refractor

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#76 WarrenM

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Posted 01 July 2012 - 09:29 PM

John:
I read your post above with interest. I have not noticed the red spot your seeing in star tests on my scope. Though, I have to admit, I have never done a star test with a high power eyepiece. When viewing stars or star clusters I'm normally using 64x or lower. The images inside and outside of focus look perfect to me at these powers and there is no sign of a red spot like your seeing. Tonight I'm going to set up my scope and do star tests using medium to high power eyepieces to see if I can duplicate what your seeing. I'll let you know what I find out tomorrow.

Warren

#77 John Miele

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Posted 01 July 2012 - 09:53 PM

Thanks Warren. You might need to use 200X to see it. I was using 225X. I missed it myself the first time I did a star test. But when I read about the other owner seeing it, I repeated my test and sure enough it was there. It take steady air and high power but it was there. If you see it it's only on one side of the focus...John

#78 WarrenM

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Posted 02 July 2012 - 02:45 PM

John:
Last night I set up my CT152 and did star tests for about two hours along with my 23 year old son (he's into amateur astronomy also). I used 3 stars for the tests. Polaris, Alkaid (in the Big Dipper's handle) and the bright star Arcturus. I used 3 eyepieces and a 1.6 power barlow to do the testing. They gave powers of 164, 191, 257, and 306. In all cases the out of focus star images showed a blue dot in the center surrounded by feint concentric rings. This was both inside and outside of focus. The images look textbook perfect to me. My son and I looked carefully for any sign of a red spot, but we never saw one. I'm wondering, did you see the red spot in more than one eyepiece? If not, you may be seeing a strange enternal reflection caused by the eyepiece/telescope combination. If more than one eyepiece shows the red spot then I think you have to assume that at least one of the two doublet primary lenses is out of collimation. Sense the crown (the front lense) and the flint (the rear lense) are separately adjustable on this scope the process for collimating them is somewhat of a mystery to me. My scope did not come with an owners manual. I'm assuming you didn't get one either. If you decide you need to collimate the scope, I think you would have to use the adjusting screws to move the red spot to the center of the star test image without moving the blue spot. Unless someone out there who knows how to do it sends us a post you would have to use trial and error. Wow, that sounds scary just saying it! I wish I could be of more help. If you have any other questions let me know.

Warren

#79 John Miele

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Posted 02 July 2012 - 03:14 PM

Thank you very much Warren :bow:. I'll check using some different EP's as you suggested but it sounds like there is most likely an alignment issue. What is amazing is that the star images still look good. I was able to split a 1 arc-sec double with the scope. I can't wait to see how even more amazing this scope will perform after I get the collimation really dialed in!...John

#80 Refractor6

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Posted 02 July 2012 - 03:56 PM

Thank you very much Warren :bow:. I'll check using some different EP's as you suggested but it sounds like there is most likely an alignment issue. What is amazing is that the star images still look good. I was able to split a 1 arc-sec double with the scope. I can't wait to see how even more amazing this scope will perform after I get the collimation really dialed in!...John


Did you check the focuser alignment yet John? A sight tube is best over a cheshire collimation tool for that one from my experience to see if the focusers alignment is a bit off. If the outer cell tube or perhaps a baffle seen around the optics aren't perfectly centered {the amount of black stuff you can see around the circular glass seen through the small hole of the pinhole sight tube} then your focuser is off for sure. The cheshire is good at showing you what's going on with the alignment of the optics at the other end.

Good to have both to check out the whole optical train. Start with the site tube in the back....

#81 mdowns

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Posted 13 July 2012 - 06:05 PM

I just found this thread and so I can only hope others continue with it. I recently bought an antares 1529 on cnights and was wondering if others have had similar results with thiers(Ant,Es,CTs). I found the 3 element barlows I had (meade,smart astronomy) were not very effective. However when I used an older 2x 2element long focal lenght barlow (parks made in japan)the improvement was dramatic (for planetary ca reduction). Has any one else had a sinilar experience? These scopes are of course wonderfull rfts, with the addition of the 2x barlow mine delivers really nice palnetary images moderately close to my c8. Anyone else?

#82 WarrenM

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Posted 13 July 2012 - 11:52 PM

mdowns:
I go into some detail on how I deal with CA when using my CT152 in my answer to Steve (above) dated 2/11/2012. If you haven't read it just scroll up to it. As far as barlows go, the only one I have been using with my scope is a short 2" 1.6 power Antares barlow. I have noticed it cuts down the CA some but not a lot. Your success with a 2 element 2 power barlow makes me want to try it. I have such a barlow that I haven't used in a while, so I'm going to give it a try and see what happens.

Warren

#83 AllanF

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Posted 18 October 2012 - 08:18 PM

In case anyone missed it there are two excellent reviews of this telescope in the current issue of Astronomy Technology Today (Vol 6, Issue 5 - Sept-Oct 2012). You must subscribe to read it on-line and from poking around their website i think you may want to just buy the print version rather than subscribing on line and same applies to iPhone version - buy print version.

Al

#84 WarrenM

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Posted 19 October 2012 - 05:23 PM

Allan:
Thanks for posting the info on that magazine article. I'm going to see if I can buy it at Barnes & Noble.

Warren

#85 Peteman

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Posted 22 October 2012 - 06:09 PM

Hello everyone this is my first post on CN. Great thread and thanks to Warren for the great review. Your reveiw is one of the reasons why I bought this scope - maybe Canadian Telescopes should consider paying you some commission!

I know this scope will not be the best for imaging but I gotta try. Does any one know what adapters to buy that will thread directly into the 3" focuser onto a DSLR t-ring. Are these a standard size thread/diameter?

Thanks!

#86 WarrenM

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Posted 23 October 2012 - 12:29 AM

Hello Pete:
I'm glad you found my review useful in helping you make a decision on your telescope purchase. I wish I could help you with your camera adapter question. I stopped doing photogrophy years ago when we were still using film. You might try calling the customer service department at Canadian Telescopes. They should be able to tell you which adapters to buy. Good luck with your new scope!

Warren






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