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Televue 22T4 Question

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#1 daveingu

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Posted 31 January 2013 - 07:04 PM

In my quest to find an eyepiece in the mid 20's range, between a 13E and 36QX for my 12f4.9 and 7f5.7 dobs, I have acquired a 22t4 and ES24/82. I have only tried the t4 in the f5.7 and was not happy with the view(but I also loved the immersiveness), the f4.9 is tucked away till spring. The coma never bothered me with the ES24 in either scope but I would like a little more eye relief.
My question is, is it worth The price of admission for a Paracorr (used) to keep the 22t4 OR should I just look for a 27 Pan or ES28 and go with the slightly lower mag? I have not noticed the coma with the 13E and only slightly with the ES24/82.
Supplementary question, will a Paracorr help with the Meade 36QX, I know my astigmatism comes into play at this focal length? I do like the option of wearing my glasses for the longer focal lengths if I need to.
Thanks
Dave

#2 Mike B

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Posted 31 January 2013 - 09:30 PM

I have only tried the t4 in the f5.7 and was not happy with the view(but I also loved the immersiveness)


Hi Dave-

You don't say exactly *what* it is about the 22T4 you didn't like... i'm presuming the coma? If so, it'll be even more pronounced in the F4.9 scope. But that should hold true for any & all EPs of that design & FL.

The difference *might* be that the highly corrected nature of the T4's design is SHOWING you the scope's coma better, more clearly?... the slightly less-corrected (i'd assume) ES24-82 might be hiding/masking some coma with its own astigmatism? This is a guess.

In my own (F4.55) Dob, the coma of the 12T4 Nagler never bugged me too much, whereas the 17T4 needed the coma correction, and even moreso the 22T4. A 28mm SWA-type EP would likely have a similar degree of coma, yet the lower magnification provided would tend to mimimize its appearance.

The 22T4 *plus* a coma-corrector should prove visually stunning! The ParaCorr reduces the naturally occurring coma by a factor of 6x- and with the EP being otherwise near 'bout perfect, your views with the P/C in place should be delightfully sharp pretty much from edge-to-edge. A lesser-corrected EP should, likewise, have the coma removed with the P/C, yet any other design imperfections (ie. astig.) would remain visible in the view. The ES EPs are pretty decent, tho, so i'd imagine the views between it & the 22T4 *should* be pretty similar with a P/C in place.

But personally, i'd probably still give the nod to the 22T4. It is an awesome EP! The P/C simply frees it up to be what it is, unhindered by the scope's coma.

In addition to all the above, a P/C will clean the coma out of ALL your EPs when used with the Newt optics- the coma really is still there, all the way until you get to ridiculous-high magnifications... we're mainly just not visually sensitized to its presence above a certain magnification range- i think that's probably normal. But a P/C will scrub it away universally! This becomes even more a factor if/when/should you ever venture into "hyperwide" (ie. 100*) EPs.

The good news is used ParaCorrs are floating around the used market for around $200, if not even less... so for less than the cost of the 22T4 you can kick its performance up to where it was designed to operate! You'll see it right away... and if you're like me, you'll wonder why you waited so long to pull the trigger!
:grin: mike b

#3 Scott in NC

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Posted 31 January 2013 - 09:31 PM

Dave, I find the views through my 12" f/4.9 dob using my Nagler 22T4 and type 1 Paracorr to be well worth "the price of admission" (to use your words). I'll add that I bought both of those off the used market.

#4 daveingu

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Posted 31 January 2013 - 10:15 PM

Okay, It is coma I am seeing, it wasn't as bothersome in the ES24/82 but it is there, never noticed it in my 13Ethos though (even at 4.9). I think my astigmatism is minimal at a 4mm exit pupil. I guess a Paracorr it is because I really like looking through the 22t4 and would like to see what it will look like at it's best.
Thanks for the replies.
Dave

#5 Mike B

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Posted 01 February 2013 - 12:49 PM

Hi Dave-

If & when you get there (a P/C ;)), please post back re: your impressions- could be very helpful for others on a similar journey!
:grin:

#6 Starman81

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Posted 01 February 2013 - 01:17 PM

Hi Dave-

If & when you get there (a P/C ;)), please post back re: your impressions- could be very helpful for others on a similar journey!
:grin:


Yes, I would like to know as well. One day soon, I may be in a similar position, if I am lucky.

#7 daveingu

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Posted 01 February 2013 - 02:55 PM

Ok will let the masses know, I have found one for sale locally, should have it in a week.
Starman 81... I see you have a 22T4 an 8" dob (i would guess F6) . How does the T4 work for you ?
thanks
Dave

#8 Starman81

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Posted 01 February 2013 - 05:12 PM

Ok will let the masses know, I have found one for sale locally, should have it in a week.
Starman 81... I see you have a 22T4 an 8" dob (i would guess F6) . How does the T4 work for you ?
thanks
Dave


The 22T4 is GREAT, especially since my dob's f/6 mirror has no 'noticeable' coma. I had one previously, liked it very much but had a problem, sent it back to the seller, then waited for another one to pop up on the used market and pounced on it. 82* AFOV and 19mm ER is a winning combination. It will mainly be a low power/finder EP with the higher magnification yielding a darker, more pleasing background in the light-polluted environs I usually find myself in. When I feel like it I will barlow it for some nice, medium-power views.

#9 daveingu

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Posted 01 February 2013 - 10:31 PM

That is interesting because my 7" dob is f5.7 and I see very noticeable coma when I put in the 22t4...........! I never really noticed it being objectionable with the ES24/82 or a Meade 5k 28mm. I will have to do some more comparisons to see how much more I notice it with the t4.
Dave

#10 Mike B

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Posted 01 February 2013 - 11:44 PM

That's one of the funny things about *good* optics in ONE part of the train... it may reveal shortcomings elsewhere. :lol: It *may* also be that you are blessed with particularly good eyesight- you spot subtle stuff many of us are simply glazing over?

I would be interested to hear your side-by-side comparos in the F5.7 scope using BOTH ultrawides, A-B, prior to obtaining the ParaCorr... or heck, after too!
:grin:






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