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2"-2x powermate observation?

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#1 dag55

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Posted 12 December 2012 - 05:23 PM

I have been using a Televue 2" - 2x powermate for about a year now. I can see image degradation when using it at high power. Example a Pentax 10xw in the powermate vs Pentax 5xw, I can see the image difference as the powermate image isn't as clear and sharp. I tried this in my Tak. 128 fs with the 1.6x tele extender in place which is installed before the diagonal resulting in 330x. I also tried this with a very good quality Newt. I put together with a total strehl at 98.9 1450 focal length resulting in 240x. I also tried the combination in my C-11 yeilding 560x just to compare and in each instance the Powermate combination wasn't as sharp. I use it on medium to low wide field EP's like Naglers with great results. Are the 2"-2x Powermate designed more for 2' EP's at medium to low power, and does the 2.5x-1.25" Powermate work better for high power viewing. One note I have a Siebert image amplifier 1.5x which doesn't seem to suffer from the aberations I descibed. Any one observed what I have desribed?I am considering getting a 2.5x amplifier for my setup and want to insure the best visual performance.
Thanks Dane :question:

#2 David Knisely

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Posted 12 December 2012 - 06:57 PM

Nope, the 2" 2x Powermate I have used was good and sharp in both my 9.25 inch SCT and my 14 inch f/4.6 Newtonian. Indeed, one of my favorite combinations for my 14 inch is the 20mm Nagler and the 2x Powermate, which gives me 188x and about a 26 arc minute true field of view (great for the larger globulars or smaller open clusters). In my 9.25 inch f/10 SCT, that combination is even better for globulars, as it kicks up the power to 235x with a 21 arc minute true field of view. The image quality was very good as long as the seeing was halfway decent. Clear skies to you.

#3 Tom and Beth

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Posted 12 December 2012 - 09:43 PM

This is a slim, but is there any possibility the added weight in your focuser is causing it to tilt? Honestly, searching for straws why you would be able to notice a difference with the same power in your scope (your example of 2X2 with 10MM, and 5 MM alone)

I have this accessory, and on those REALLY exceptional nights have used it up in "insane" magnification area.

#4 beatlejuice

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Posted 12 December 2012 - 10:50 PM

does the 2.5x-1.25" Powermate work better for high power viewing.



I don't know if it works better as I have no experience with the 2", but the 1.25"-2.5 powermate is great for high power viewing.

Eric

#5 Starman1

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Posted 12 December 2012 - 11:01 PM

Atypical.
I have used it with an 8mm Ethos (9 elements) in a Paracorr (5 elements), yielding 18 total elements at 456X with no noticeable loss of sharpness not related to the power used (i.e. seeing related).
If you are seeing on-axis reduction in sharpness, I would guess the lenses have something on them, or maybe there is a blem in one of the lenses.
I would return it to TeleVue for them to examine.

#6 johnnyha

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Posted 12 December 2012 - 11:14 PM

does the 2.5x-1.25" Powermate work better for high power viewing.



I don't know if it works better as I have no experience with the 2", but the 1.25"-2.5 powermate is great for high power viewing.

Eric

+1, absolutely.


#7 dag55

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Posted 13 December 2012 - 02:04 AM

Thanks , I don't think all the focusers on the equipement I have used is the problem they are really in good condition and rated for far more weight than the combination I am using. The possibility that the Powermate has a blem in one element though would explain the cause. I will contact TV and see what they recomend.
Thanks Dane

#8 dag55

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Posted 15 December 2012 - 10:49 PM

Thanks for mentioning the focuser, I used the 120mAPO tonight and located the problem . My diagonal has a raised area just where the 2" tube joins the diagonal mirror housing, and if I am not careful to secure the diagonal behind that raised area it will tilt with the added weight of the Powermate. Views are great with the 10XW + Powermate vs. the 5xw. Thanks for the suggestions, Dane

#9 GeneT

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Posted 16 December 2012 - 05:16 PM

I have been using a Televue 2" - 2x powermate for about a year now. I can see image degradation when using it at high power. Example a Pentax 10xw in the powermate vs Pentax 5xw, I can see the image difference as the powermate image isn't as clear and sharp.


This does not surprise me. However, I have not had this experience. I hooked up a 2X Powermate to a 12mm Nagler and compared the views to a 6mm Delos. The Delos was just a tad--just a tad--sharper. That said, I also prefer single eyepieces rather than an eyepiece, Powermate combination. Powermates/Barlows do come in handy for some situations, i.e. needing high magnification to split doubles. They also provide a means to extend the magnification for those who can only afford a few eyepieces.






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