TEC APO 160 costs $12,000 ??

superior to Ohara FPL-53? In what ways will the Flourite triplet
outperform, or have advantages over a properly designed, and properly
figured FPL-53 triplet?

I think I know the answer to this question. The Fluorite is an F8, it is a
shorter OTA than the F9. It also has better color correction in the
photographic wavelengths. So it will exhibit less color in photographs.

No, the real answer is that you cannot get FPL53 in that size. Ohara refuses to
make it larger than 7". I have tried for years to get it, and they refuse
because they say their yield drops rapidly above that point.

Fluorite is now available in much larger sizes, in fact I just got information
about a 300mm diameter size. The drive behind these sizes is not amateur
astronomical, rather it is mainly aimed at the semiconductor industry for
stepper lenses. larger sizes = finer resolution of line widths. Used to be that
6" stepper lenses were the norm, but now ever larger sizes are being ordered.

Roland Christen

Subject: TEC APO 160 costs $12,000 ??
From: (Chris1011)
Date: 10/16/2004 1:26 PM Eastern Daylight Time
Message-id:


Do you think adding fluorite would make your scope any better? Yours does not
even have FPL53 in it.

Roland Christen
**********************************
To some people Fluorite is the magic lens.
I dont buy it! I've owned enough APO's without fluorite, a older 6"f/9 AP
Starfire and a Brandon 94mm with AP lens and a few others. Also i've ownd a
few Taks with fluorite, and the older coated non fluorite AP's were just as
sharp and contrasty.

Why in the hell anyone would pay double the price for fluorite in 7" plus size
lens beats me!!!

Chas P.

rat,

leaving aside the difference in aperture between your TEC 8" and your Tak 6"
and, if possible, the difference in color correction, how do you rate the
TEC's optics versus the Tak's optics? That is, do you think the figure and
polish of the Tak are comparable to the figure and polish of the TEC, or is
the TEC distinctly better?

bill g.


"Ratboy99" wrote in message
...
This information now begs the question, "Why will the Flourite ED be
superior to Ohara FPL-53? In what ways will the Flourite triplet
outperform, or have advantages over a properly designed, and properly
figured FPL-53 triplet?

I think I know the answer to this question. The Fluorite is an F8, it is a
shorter OTA than the F9. It also has better color correction in the
photographic wavelengths. So it will exhibit less color in photographs.

The F9 is optimized for visual use, due to the the narrow sensitivity of
the
human eye to the visual spectrum. I can see a bit of color out of focus on
bright objects, but even on bright objects, such as Vega, I have to work
to see
the false color when the scope is in focus. For example there is no false
color
in focus on the edge of the Moon. Vega is the only single object that I
have
been able to detect a fleeting purple fringe on, and I mean fleeting. Any
other
color I've seen in it (such as on Venus) has plainly been due to
atmospheric
refraction, not false color in the objective. I think with perfect seeing
I
would be able to focus the color on Vega right out of view.

It outperforms myTak 6" in this respect by leaps and bounds, and trust me,
the
Tak is no slouch. It also gobbles up eyepieces better than the Tak. What
is
amazing is splitting .53 arcsec doubles to the Dawes limit at 600x. This
scope
does things performance-wise that none of the other 12 scopes that I have
owned have been able to even approach, regardless of aperture or optical
figure.
rat
~( );

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Do you think adding fluorite would make your scope any better? Yours does not
even have FPL53 in it.

Roland Christen

No, I don't, at least for visual purposes. It would make it a bit more
portable, but I am perfectly happy with its size.
rat
~( );

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rat,

leaving aside the difference in aperture between your TEC 8" and your Tak 6"
and, if possible, the difference in color correction, how do you rate the
TEC's optics versus the Tak's optics? That is, do you think the figure and
polish of the Tak are comparable to the figure and polish of the TEC, or is
the TEC distinctly better?

bill g.


For some reason (my eyes, optical figure, rare good seeing conditions), I have
been able to push the TEC much higher in terms of x per inch than I have been
able to with any other scope.

Incredibly tight doubles (.53 - .58 arcsec) are being pleasantly observed at
600x.

Best I've been able to do with the 6" tak is .9 or so. But then I haven't tried
that hard. I need to get it on some .75" doubles and see how it does.

First look at Saturn the other night with the 200 was awesome at 383x with a
binoviewer.

It's weird, kind of put my ideas of what I thought possible with my eyes into a
new perspective.

Jupiter will be the real test object. If I am able to use in excess of 225x on
a regular basis I am then going to have to say it is the scope.

The 6" Tak is usually best for Jupiter at about 180x, 200x max.

The 10" Zambuto Newt maxes out usually at 200x as well (sometimes able to use
225x to good effect).

But the one thing that I know for certain that I have never had a scope that
was just cruising on Saturn at 383x, especially using a bino...
rat
~( );

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Subject: Hey, rat! TEC 8" versus Tak 6"?
From: t (Ratboy99)
Date: 10/16/2004 3:04 PM Eastern Daylight Time
Message-id:



For some reason (my eyes, optical figure, rare good seeing conditions), I
have
been able to push the TEC much higher in terms of x per inch than I have been
able to with any other scope.

Incredibly tight doubles (.53 - .58 arcsec) are being pleasantly observed at
600x.

Best I've been able to do with the 6" tak is .9 or so. But then I haven't
tried
that hard. I need to get it on some .75" doubles and see how it does.

First look at Saturn the other night with the 200 was awesome at 383x with a
binoviewer.

It's weird, kind of put my ideas of what I thought possible with my eyes into
a
new perspective.

Jupiter will be the real test object. If I am able to use in excess of 225x
on
a regular basis I am then going to have to say it is the scope.

The 6" Tak is usually best for Jupiter at about 180x, 200x max.

The 10" Zambuto Newt maxes out usually at 200x as well (sometimes able to use
225x to good effect).

But the one thing that I know for certain that I have never had a scope that
was just cruising on Saturn at 383x, especially using a bino...
rat
~( );
*****************************************
Boy the seeing really limits you, i dont even get warmed up below 500x...

Chas P.

How about using N-FK56, then?


Schott is totally unresponsive about this material. They are not prepared to
quote me anything in reasonable sizes for astronomical objectives.

Roland Christen

I thought about it some more, Bill, and frankly it is impossible to "leave
aside the difference in aperture." The difference in aperture is by far the
overriding difference between the two scopes and there is no way to separate it
out in comapring theme, it is simply too great a factor.

As to your other questions, the figure and polish in both scopes are excellent.
There is some spherochromatism affecting the out of focus images using each
scope, so neither of them are easily evaluated for optical figure using the
handy dandy star test. I don't have a green interferometer on me, so...

Both scopes have very smooth, sharp optics that positively snap into focus.

From what I know of Yuri and his boys, I think they lavish a great deal of
effort on getting the TEC lenses absolutely perfect.

From what I've seen, I believe that TEC has developed a deep sense of personal
pride regarding the fact that they fabricate their optics "in house." Anyone
involved in producing a high quality product realizes that this pride is itself
is a fuel that drives the quest for perfection.

And while Takahashi subs their lens sets out to another company (a subsidiary
of Canon?) , they, too, obviously have optics that are fabricated to a very
high spec.

They are both great scopes.

In ending it is worth noting that I have not had the Tak out even once, even to
do a side by side, since having received the TEC two months ago.


leaving aside the difference in aperture between your TEC 8" and your Tak 6"
and, if possible, the difference in color correction, how do you rate the
TEC's optics versus the Tak's optics? That is, do you think the figure and
polish of the Tak are comparable to the figure and polish of the TEC, or is
the TEC distinctly better?

bill g.

rat
~( );

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No, the real answer is that you cannot get FPL53 in that size. Ohara refuses
to
make it larger than 7".

Yeah, I knew it wasn't FPL53 already. Yuri wouldn't tell me what it really is,
but when I am using the scope it looks more like FPL52.

rat
~( );

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On 16 Oct 2004 19:04:11 GMT, t (Ratboy99) wrote:

rat,

leaving aside the difference in aperture between your TEC 8" and your Tak 6"
and, if possible, the difference in color correction, how do you rate the
TEC's optics versus the Tak's optics? That is, do you think the figure and
polish of the Tak are comparable to the figure and polish of the TEC, or is
the TEC distinctly better?

bill g.


For some reason (my eyes, optical figure, rare good seeing conditions), I have
been able to push the TEC much higher in terms of x per inch than I have been
able to with any other scope.

Incredibly tight doubles (.53 - .58 arcsec) are being pleasantly observed at
600x.

Best I've been able to do with the 6" tak is .9 or so. But then I haven't tried
that hard. I need to get it on some .75" doubles and see how it does.

This must tie in with eyesight as I have no trouble under good seeing
conditions splitting 0.6" or slightly under equal doubles with a good
C8. Unequal doubles are another issue though.
-Rich