Re: Long focal length eyepieces at f/15 MCTs
- I avoided the specifics of my 715 since the focus of the discussion
was the eyepieces themselves, and namely the Paragon. Mine is built
with a 29% CO, thereby providing a larger illuminated field size.
--- In firstname.lastname@example.org, "Guilherme de Almeida"
>in a Intes-Micro M715 telescope, I reported the illumination drops to
> Hi, Mark Riek
> Good report about that eyepieces.
> However, testing some 40 mm >65 degrees apparent field eyepieces,
zero before the true edge of field of that eyepieces. That is, you
will have zero light at more than 5degrees from the true edge. I
tested the Aleph Lab 40 mm 70 degrees, the SWAN 40 mm 72 degres. I
found the field stop of these eyepeieces is far greater than the
illumination of the focal plane. There is not the case of only 60%
illumination at edge, or so, of field. No, ist is trully ZERO. Also
it is NOT a defect of these wonderful telescopes.
>with long focal lenght eyepieces:
> I have found we have only two sollutions about the M715 telescope
> a) For a 70º eyepiece, the maximum focal lenght is about 32 mm or
>be greater than about 55º.
> b) For a 40 mm eyepiece focal lenght, the apparent field cannot
>mm focal lenght eyepiece), it is uselless to have a wide angle
> c) To have 54x magnification available with the M715 telescope (50
eyepiece, because you will not see nothing at edge of field (or close
to the edge of field). We will not benefit from the greater field.
>degrees apparent field. The field stop is about 39 mm diameter. It
> For 50 mm focal lenght I choosed the Vixen LV 50, with only 45
may seem a bad choice, or a peep hole eyepiece, but it is the only
way to have a low magnification of 54x, for special low magnification
views, wh the turbulence is a little greater..The focal reducers get
> Did you also see this ???
> Very best regards, my friend
> Guilherme de Almeida
> ----- Original Message -----
> From: Mark Rieck
> To: email@example.com
> Sent: Wednesday, July 09, 2008 6:44 PM
> Subject: [tmboptical] Re: Paragons vs. the Empire
> I just finished picking one up not long ago, along with a UO 40mm
> to compare them against each other. My goal was to choose myfavorite
> for use in f/15 Maksutovs. As would be expected, both exhibitan
> relatively poor edge of field correction in faster scopes such as
> f/4.5 Newtonian I used them with. What surprised me is bothexhibited
> relatively poor edge of field correction in an f/6 MakNewt as well,source
> which provides great edge of field correction in itself, so the
> was most definitely the eyepieces.both
> The same rang true with focal ratios when using refractors. Where
> did perform admirably was in the scope they were obtained for usein,
> an f/15 MakCass. Image quality was quite similar between the twofavored
> regarding contrast, clarity, and light throughput. I found I
> the Paragon due primarily to it being one of the lightest 40mm40mm
> widefields made and an edge in comfort(since the UO I have does not
> have an eyecup).
> I have compared many of the less expensive widefields in the 30-
> focal length range, and found none have the edge of fieldcorrection
> the Naglers do at faster focal ratios. I must note I have not trieda
> side by side comparison with the 41 Panoptic. Other possiblecandidates
> in the 40mm range being comparable in price, weight, andperformance
> also include the Pentax(XL and XW) and Celestron Axiom. Every oneof
> perhaps 4-5 budget priced widefields have fared even worse. YMMVsince
> tolerance for edge of field correction varies.9/7/2008 18:32
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