Megrez 102

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Czy wiecie co� wi�cej na temat tego sprz�tu ,czy jest wart 1250 Euro ,a mo�e kto� z forumowicz�w luka� przez ten sprz�t.

Niestety jeszcze go niem mia�em w r�ku ani w serwisie i raczej nie mam si� jak wypowiedzie� obiektywnie w tej kwesti, ale s�dz�c po jako�ci Megreza 80 my�l� �e to b�dzie bardzo dobry wyb�r w tej cenie 8)

bardzo zainteresowa� mnie ten sprz�t bo w�a�ciwie czekam na megreza 80mm f6.25, pomy�la�em �e to jest sprz�t, kt�ry m�g�by zakup du�ego APO odsun�� w nieokre�lon� przysz�o�� :D :!: , znalaz�em niewiele info na ten temat, ceny w walutach europejskich... :wymiotuje: , na oficjalnej stronie ani s�owa, po ameryka�skich info wnioskuj� �e w Stanach tego wi�cej nie sprzedaj�, je�li kto� wie co� wi�cej niech da zna�, prosz�

na william optics newsgroup znalaz�em ciekawy, chyba pouczaj�cy post, kt�ry niniejszym cytuj� (dla tych, ktorzy nie maj� czasu si� zarejestrowa� tam, sorki za spor� obj�to��) :

I agree also. Problem is there is a perception that you have either scopes
with a lot of chromatic aberration, like standard short achromats, and APO
scopes which come close to perfection in that area in most cases. The
problem arises from the vague definition of the term "semi-APO". If you mean
the term from today's usage it can mean any observable reduction of color
errors that is less than an F10 achromat, which seems to be today's
standard. By that definition any good F12-F15+ achromat from the 50-70's
would meet that definition. But current scopes aren't made in those ratios
much anymore. If you compare a Vixen F10 to a Sinta F10 you may find the
Vixen has noticeably less color than a Sinta, but the detail level between
them might be pretty close.
Or you can say a scope sold as ED is possibly a "semi-APO". If made at
F8-F10+ it can often rival a shorter focus true APO that is in the F6-F7
range, at least visually (QC issues aside look through a good example of a
Meade APO). But what happens is that the makers are so enamored over the
improved optics they shorten the F-ratio (that is what people want) and end
up increasing the level of color errors. Extremely low dispersion glass can
only do so much and when you shorten the F-ratio the light cone gets steeper
and harder to fully correct. That's why most true APO scopes have either 3-4
elements or one of which is a non-glass fluorite crystal (current champ for
Abbe distortion index) as opposed to ED scopes which generally use a
fluoro-crown element.
Problem is actually one of definition. Definition of APO (term is
apochromatic) is at least 3 of the primary optical colors are brought to a
common focus. Not all, just 3. Achromatic means 2. By the true definition
most ED scopes would meet the definition of apochromatic. However now people
use the term to mean all visible wavelengths, which only the highest
quality APO scopes can approach. So now the term "semi-APO" might mean the
same thing as the definition of APO where the 3 primary visual colors focus
at a common spot and the rest give it a little color.
But the term itself is so vague that people tend to at least hope that their
"semi-APO" is close to a true APO and when it isn't they get disappointed.
Basically they have unrealistic goals. What they really want is a cheap APO,
which by today's standards is not realistic.
Basically they would be just as well off buying a Sinta 6" F8 and a light
violet filter to eliminate the purple halo. And at that price range it is
hard for a "semi-APO" 100mm scope to compete. Especially against a 6" F5 or
120mm F5 for portability and performance for the dollar.
Kent Gittings

-----Original Message-----
From: dowen0@a... [mailto:dowen0@a...]
Sent: Saturday, September 01, 2001 9:31 PM
To: William-Optics@yahoogroups.com
Subject: [William-Optics] Re: Megrez 102 where are you?

OK, I'll be the one to disagree.

I think that there is a huge gap between the cheap Chinese import 4"
scopes at $375 and the TV/Tak 4" scopes for $2,100 (stripped down).
There is a market for a $995 - $1,000 scope that CONSISTANTLY
provides better optical performance (chrom. aber, astigmatism, zonal,
color control, etc) combined with upgraded mechanics (focuser) than
the cheap imports.

I disagree with the comment that people expect APO performance at the
$995 price range. Sure, it'd be great to achieve. One problem, I
would suggest, is calling this scope a "semi-APO". That leads one to
expect something that the scope can't deliver. The other problem,
from what I can gather, is that the manufacturer couldn't produce
this particular model with the level of consistancy that the consumer
expected. I wouldn't be happy either if I'd paid over $1,000 for a
scope that a)had to be returned to get it fixed the day after I had
received it or B) performed optically no better than a Celestron
102HD.

All this seems obvious to me....but then I may be a minority of one.

David

--- In William-Optics@y..., "Robert Schmall" <mbschmall@c...> wrote:
> Eric:
>
> Regardless of our individual viewpoints, it appears that all of us
agree that the marketplace was not ready for this scope at more than
$1000.
>
> Bob
> ----- Original Message -----
> From: Eric Faust
> To: William-Optics@y...
> Sent: Thursday, August 16, 2001 11:27 PM
> Subject: [William-Optics] Re: Megrez 102 where are you?
>
>
> For what it's worth, as one of the few that purchased and
returned
> the Megrez 102, it was not color correction that was the reason
for
> return. It was a consideration though. I did not expect an APO,
but a
> semi-APO. If you accept the definition from "Telescope Optics" by
> Rutten and Venrooij, that should mean similar to a 4" f/13.6
achromat
> for the Megrez 102. My minimum expectation for the Megrez was
color
> correction equal to an f/10 achromat, and that is approximately
how
> the Megrez performed. The bigger issues for me were contrast and
light
> scatter. The mechanics were superb and it was tough to send it
back. A
> week after I returned the scope, I was camping at 10,000 feet in
Utah
> and wished the little scope was with me. If I had paid the
> introductory $1,000 price instead of $1,150, and not got stuck
paying
> CA 8% tax, I probably would have kept it.
>
>
> Eric
>
>
> --- In William-Optics@y..., "Herb York" <ztrmann@f...> wrote:
> > Beg to differ.
> > People spending $1000 + for a 4" scope want it to perform like
an
> Tak 102 or TV 102.
> > This is our experience. Not blaming anyone and not referencing
your
> experience. Collimation is one thing - color correction
expectations
> are another.
> > Thanks
> > Herb
> > Anacortes Telescope
> > www.BuyTelescopes.com
> > www.AstroMart.com
> > 360-588-9000
> > 800-850-2001
> > ----- Original Message -----
> > From: Robert Schmall
> > To: William-Optics@y...
> > Sent: Wednesday, August 15, 2001 10:58 AM
> > Subject: Re: [William-Optics] Megrez 102 where are you?
> >
> >
> > Herb:
> > With all good feeling for Anacortes, which has been most
helpful
> to me, the implication that the consumer is responsible for the
> failure of a product is going to be hard to sustain. As proof,
the 80
> is still selling, and the public's expectations for it are no
> different than for the 102--that it perform at its price level.
> >
> > Bob
> > ----- Original Message -----
> > From: Herb York
> > To: William-Optics@y...
> > Sent: Tuesday, August 14, 2001 9:20 PM
> > Subject: Re: [William-Optics] Megrez 102 where are you?
> >
> >
> > Our feeling was that expectations of performance
outstripped
> reality of the
> > price.
> > In other words we felt that it was expected to perform at
APO
> levels for
> > achromatic prices. We asked William to not provide it here
any
> longer.
> > Herb York
> > Anacortes Telescope
> > www.BuyTelescopes.com
> > www.AstroMart.com
> > 360-588-9000
> > 800-850-2001
> > ----- Original Message -----
> > From: <kjackson@g...>
> > To: <William-Optics@y...>
> > Sent: Tuesday, August 14, 2001 7:03 PM
> > Subject: [William-Optics] Megrez 102 where are you?
> >
> >
> > > Hi,
> > >
> > > I just noticed that the Megrez 102 appears to be
discontinued.
> All
> > > mention of it is missing from the WO and Anacortes web
sites.
> > >
> > > Anyone (William and Herb in particular) have the scoop?
> > >
> > > I certainly hope it is not lost for good!
> > >
> > > Keith
> >

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