Re: [tec-scopes] Re: TEC 6 CO


Dec 11, 2004

 


----------------------------

#6106 Dec 11, 2004

Can anyone offer the CO size and/or percentage on this scope? Thanks!



Mark



----------------------------

#6107 Dec 11, 2004

Mark the CO is 29%



Ed



--- In tec-scopes@yahoogroups.com, "Mark Rieck" derklaus@c...>

wrote: >

> Can anyone offer the CO size and/or percentage on this scope?

Thanks! >

> Mark



----------------------------

#6108 Dec 11, 2004

Can anyone offer the CO size and/or percentage on this scope?

Thanks!



According to literature that came with mine the co is 29.6%.



Thanks,

Vahe



----------------------------

#6112 Dec 11, 2004

--- In tec-scopes@yahoogroups.com, "vahe352" vahe@f...> wrote: >

> > Can anyone offer the CO size and/or percentage on this scope?

> Thanks!

>

> According to literature that came with mine the co is 29.6%.

>

> Thanks,

> Vahe



Thanks Ed and Vahe. I had REALLY hoped that the I-M 615 I had waited

months for earlier this year could have been a solution. It was

initially advertised as being an f/15 with ~25% CO. After the wait, I-

M released the scopes at f/15, but with a 31% CO. It's secondary is

actually larger than the 715's! Before that, I tried to contact Yuri

about getting one of the last TEC6's being made, but never got any

answers back. Because it had been announced no more would be made,

prices on used units went through the roof.



One fellow that barely beat me to the punch on one this Spring for

$1400, sold it 6 months later for $2400. The way some folks are

jacking up the price of used scopes lately just doesn't sit well with

me, so I had to pass. I saw that again just a week or two ago. I

bought a Mewlon 180 for $1500(that price held steady with the 2

previous owners, both of whom I know), sold it for $1300(since I had

put holes in the tube for a fan). The guy who bought it from me sold

it recently for $1200. The newest owner listed it for $1800 a week

later! OK, sorry for the rant.



If anyone is considering parting with their TEC6 at a reasonable cost

(even what you paid for it), please drop me a line.



Mark



----------------------------

#6113 Dec 12, 2004

I had REALLY hoped that the I-M 615 I had waited > months for earlier this year could have been a solution. It was

> initially advertised as being an f/15 with ~25% CO. After the wait,

I- > M released the scopes at f/15, but with a 31% CO. It's secondary is

> actually larger than the 715's!



Just one comment on the CO size on various reflectors. Over the years

I have noticed that number of manufacturers specify the size of the

secondary mirror and leave out everything else, Meade Maksutov is

just one example, what we all want to know is the net size of

everything that makes up the secondary, including the cell, baffle or

whatever the forms the "shadow" on the primary, that is what counts.

The TEC6's CO. is not small, but perhaps it is right at the limit for

producing reasonable contrast on planets, anything over that size

would be just a little too large for my taste.

As for prices going up like crazy, I do not know what to say about

that, this is going to happen with all high quality scopes that are

in short supply. Did you follow the auction of that AP180 f/7

recently, someone paid 36.6K for that scope, totally absurd, but then

in a culture where a baseball bat can bring a million this is a

pocket change for someone with disposable income, and for heaven sake

a lot more fun to own and use.



Thanks,

Vahe



----------------------------

#6129 Dec 13, 2004

--- In tec-scopes@yahoogroups.com, "wilcoxmilton" mewaz@n...> wrote: >

> Hi Mark & Vahe,

>

> First of all, I agree 100% with you Mark about the compounded effect

> of a CO in less than perfect seeing. I believe you were the first

to > make this observation on another group.



Hi Milt,

Funny how lessons learned some time ago are coming up again with more

clarity than the first time(for myself anyway). I'd be will to take

more f/l(within personal preference limits), so long as the CO is

low. The ability to get wider fov with shorter f/l is ok, since

you're going to have to trade-off for bigger CO. That's why the TEC6

makes for a nice balance IMHO. I have not however, had the chance to

use one.



Apparently one lesson that has yet to become clearer is being

exhibited by once again wrestling with trying to get performance out

of a cat in the Winter. I just can't seem to get one to accept mid to

high mags here. I've come full circle by running a C8 paired side-by-

side with an 80mm apo. I've settled with accepting low to mid mag

only out of the cat, but feel that there must be a solution to get a

bit more aperture than can perform. Another similar situation I had

was in '01. I ran an I-M 603 all Summer with fantastic results. I

used it close to 100 nights on Mars and other objects. When Winter

came, I'll be darn if I could ever get it to go over 100-125x. The

same now seems to be happening again with the C8. Granted the seeing

here is unsteady most of the Winter, but both the 80mm and a 115mm

apo can take more mag easily.



Neither the 150mm or 200mm cats produce very sharp planetary images

even at 100x. Cooldown is not the problem as far as I know. I've

given them both hours before use and run them for a few hours more

until they dew up. I can remove the dew to get another hour or so to

no avail. I know their larger apertures are more affected by unsteady

seeing, but feel that with the mags I'm achieving with the apos,

seeing may not be the only limiting factor at work here. For

comparison, I've run Mak-Newts at the same time as the MCT's and

SCT's and have been able to achieve sharper images and higher mags

just like the apos. Problem is, with this particular application, I

need short/light tubes.



Optical quality? Well, the 603 was able to reach 175-250x and remain

very sharp in the Summer. CO? That's the only big difference left.



Mark







----------------------------

#6131 Dec 13, 2004

--- In tec-scopes@yahoogroups.com, "Mark Rieck" derklaus@c...> wrote: >

> I'd be will to take

> more f/l(within personal preference limits), so long as the CO is

> low. The ability to get wider fov with shorter f/l is ok, since

> you're going to have to trade-off for bigger CO. That's why the

TEC6 > makes for a nice balance IMHO.

>



Mark, I have never owned a cat of any kind, but I have looked through

many SCT's and a few Mak's and have not been that impressed. My best

views have come from apo's and small CO, superbly figured Dob/Newt's.

IMO the TEC6 would be a good performer not just because it is a Mak

or has a 29% CO or hit the sweet spot in f/l, but also because of the

TEC optical quality!

>

> Neither the 150mm or 200mm cats produce very sharp planetary images

> even at 100x. Cooldown is not the problem as far as I know.



I have recently measured the temperature gradient in Sedona. It has

been running roughly 4.F per hour during the time I normally

observe. It seems like a cat would be able to keep up.

> Optical quality? Well, the 603 was able to reach 175-250x and

remain > very sharp in the Summer. CO? That's the only big difference left.



Don't forget the quality of the optical figure. My intuition (you

started me down this path) is that the more energy you take out of the

Airy disk and put into the diffraction rings - whether it be from a

large CO or optical aberrations - the more affected the scope will be

by poor seeing. If you buy this theory, a TEC APO200 would walk all

over your C8 in ANY seeing conditions, not just 9/10.



Milt



----------------------------

#6139 Dec 13, 2004

Don't forget the quality of the optical figure. My intuition (you

> started me down this path) is that the more energy you take out of

the > Airy disk and put into the diffraction rings - whether it be from a

> large CO or optical aberrations - the more affected the scope will

be > by poor seeing. If you buy this theory, a TEC APO200 would walk all

> over your C8 in ANY seeing conditions, not just 9/10.

>

> Milt



You buyin'?....had to try.



When I had my 140, there were plenty of nights when the seeing didn't

let even it do it's thing. I recall making posts about how the 80

could outdo the 140 on poor nights. Some folks called me nuts(I am,

but that's beside the point). Pairing the 140 next to a very good 8/7

Newt I had just completed a year ago showed that in some instances,

aperture will indeed rule. It's along those lines(and self imposed

spending limits to be honest), that I'm pursuing another compound

scope. Some day, a 180mm apo. For now, something else.



I'm a bit torn about the fate of a TMB 115 I've acquired recently. It

runs a pretty tight race with the old hand-me-down orange tube C8 on

dso's. I had expected the apo to be able to resolve finer whispy

details on M42, but the C8 surprised me. Contrast isn't bad either,

but I have yet to run on anything but a Moonless night. On other

nights(and at high mag), the 80mm apo rules. This past weekend, I ran

the 80/600 apo and the C8 on a twin arm Gyro. If kept at 66x(6.3 r/c

and 19 Pan), it makes for a nice counterpart to the little apo.

Because the 80 can cut through muck better than the 115, and the C8

compares to it acceptably at low mag???? It's a tough call. The 115

did show considerably more planetary detail and accept higher mags,

but I have the 8/7 Newt for dedicated planetary observation(and ya'

gotta be dedicated to lug that monster out!).



So, at this point I may be getting closer to a companion for the

80mm. I had hoped the 115 could replace both the 80 and whatever

compound I matched with it, but for now I just don't know. I've been

through a C5, StarMax 127, Mewlon 180,(2)5" f/9 ED's, and now the C8.

I have yet to try another 150mm MC, although one has always been in

the running. Flashes of my 603 not being able to handle cold weather

has me wondering if a TEC6 would fare any better(or perhaps try

another reasonable priced alternative like a MK67). For now(due

mainly to limited observing time), this rig should remain portable

and quick to set-up. I'd sell them all for an even larger apo....if

then mounting it wouldn't add so much to the price!



Mark...in constant search of nirvana



----------------------------

#6143 Dec 14, 2004

Hi Mark,

You have allready found nirvana. It is called a 180mm

Mak-Newt. Hope all has been well with you, Thomas

--- Mark Rieck derklaus@...> wrote:

>

>

> > Don't forget the quality of the optical figure.

> My intuition (you

> > started me down this path) is that the more energy

> you take out of

> the

> > Airy disk and put into the diffraction rings -

> whether it be from a

> > large CO or optical aberrations - the more

> affected the scope will

> be

> > by poor seeing. If you buy this theory, a TEC

> APO200 would walk all

> > over your C8 in ANY seeing conditions, not just

> 9/10.

> >

> > Milt

>

> You buyin'?....had to try.

>

> When I had my 140, there were plenty of nights when

> the seeing didn't

> let even it do it's thing. I recall making posts

> about how the 80

> could outdo the 140 on poor nights. Some folks

> called me nuts(I am,

> but that's beside the point). Pairing the 140 next

> to a very good 8/7

> Newt I had just completed a year ago showed that in

> some instances,

> aperture will indeed rule. It's along those

> lines(and self imposed

> spending limits to be honest), that I'm pursuing

> another compound

> scope. Some day, a 180mm apo. For now, something

> else.

>

> I'm a bit torn about the fate of a TMB 115 I've

> acquired recently. It

> runs a pretty tight race with the old hand-me-down

> orange tube C8 on

> dso's. I had expected the apo to be able to resolve

> finer whispy

> details on M42, but the C8 surprised me. Contrast

> isn't bad either,

> but I have yet to run on anything but a Moonless

> night. On other

> nights(and at high mag), the 80mm apo rules. This

> past weekend, I ran

> the 80/600 apo and the C8 on a twin arm Gyro. If

> kept at 66x(6.3 r/c

> and 19 Pan), it makes for a nice counterpart to the

> little apo.

> Because the 80 can cut through muck better than the

> 115, and the C8

> compares to it acceptably at low mag???? It's a

> tough call. The 115

> did show considerably more planetary detail and

> accept higher mags,

> but I have the 8/7 Newt for dedicated planetary

> observation(and ya'

> gotta be dedicated to lug that monster out!).

>

> So, at this point I may be getting closer to a

> companion for the

> 80mm. I had hoped the 115 could replace both the 80

> and whatever

> compound I matched with it, but for now I just don't

> know. I've been

> through a C5, StarMax 127, Mewlon 180,(2)5" f/9

> ED's, and now the C8.

> I have yet to try another 150mm MC, although one has

> always been in

> the running. Flashes of my 603 not being able to

> handle cold weather

> has me wondering if a TEC6 would fare any better(or

> perhaps try

> another reasonable priced alternative like a MK67).

> For now(due

> mainly to limited observing time), this rig should

> remain portable

> and quick to set-up. I'd sell them all for an even

> larger apo....if

> then mounting it wouldn't add so much to the price!

>

> Mark...in constant search of nirvana

>

>

>

>











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