Re: RAT NOTES - TEC 200 F9 Triplet Apochromat - 09/01/04

From: Leonard (ngc7789_at_citynet.net)
Date: 09/02/04 

Date: 2 Sep 2004 05:53:18 -0700

ratboy99@aol.comet (Ratboy99) wrote in message news:<20040902004456.17374.00000097@mb-m27.aol.com>...
> RAT NOTES - TEC 200 MM F9 TRIPLET APOCHROMAT - 09/01/04

        Hi Rat ,

             Nice report , thanks for sharing with us . Boy that TEC
,they are fast becoming the place to go for that very fine instrument
of distinction .
             Please keep the reports coming , with much focus on your
observations of Jupiter this year .
                                    Top of the day , Leonard

              

 
>
> Well, it's been a long journey to get all the way from my first 8" SCT, to the
> Televue Ranger, through three Dobs, and another 2 (8" - again, and 11") SCT's,
> of course interspersed with three (or four) more refractors, and finally here
> - my very own 8" APO refractor.
>
> Why don't I just save the suspense and say it up front:
>
> Holy Cow!
>
> I first inquired about this scope with TEC 23 months ago. Received it last
> Monday, not bad actually, given the apparent dynamics of creating such an
> instrument.
>
> The outer box looked more as if it had been kicked by UPS all the way from
> Colorado rather than being driven here by truck, but the scope was well packed
> in bubble wrap in an inner box with another outer layer of peanuts, which
> protected it completely. Once opened it appeared to be unharmed.
>
> Some time ago, I received the mount; a Losmandy Titan. I had a few weeks
> playing around with it using my 6" Tak as a guinea pig. It is a nice big mount
> and I figured that it would be adequate to the task. As it turns out, there are
> some idiosyncrasies (as well as something of a learning curve) to it. I am
> still waiting to get a pair of stainless steel worm covers, as the supplied
> aluminum ones are subject to expansion / contraction when the scope is
> subjected to changes in temperature. It is a nice fit for visual use with the
> big OTA.
>
> Here's a good place for a side note: One thing I realized when it came time to
> set up this monster, is that I am damned glad that I have already owned and
> become well acquainted with 2-3 EQ mounted refractors. I still remember the
> time I took a dive in the snow to catch the AP Traveler as it accidentally slid
> out of the dovetail plate. This is not one of those scopes that I am going to
> be taking a dive for; I can barely lift it. The listed weight of the OTA is in
> the ~50 lb range. I've been consistently eating my Wheaties and lifting weights
> so that I would be up to the task when it came time to hoist it onto the mount
> (I'm 6'3" 205 lbs, and I bench 3 sets of 8 @ 165 lb, and curl 3 sets of 10 @ 40
> lb each arm - 3x week).
>
> Anyway, after I got the box opened and the rings in place on the mount, I went
> about the matter of lifting the OTA into the rings. I'm glad it is only 50 lbs,
> because it feels like 70. I am able to carry it up the step ladder into the
> heavens and lift it gingerly into the rings, and have so far done so twice, but
> I will probably try to rig up some sort of hoist for moving it between the
> mount and the case, because it is a bit too precarious to balance for my taste.
> I fully intend to NOT damage the scope, so I need to come up with procedures
> that do not take 90% of my strength to execute.
>
> After the scope was on the mount, I commenced to worry.
>
> I must have tightened every knob 3 times. I was particularly concerned (read
> paranoid) that the dove plate was not properly set in the dovetail assembly. I
> worried about this until the day before yesterday, when I was mounting the
> scope for the second time (even though that first night, I visually confirmed
> using a flashlight that it was properly seated). I also immediately ordered a
> case for the OTA from Scopeguard. But I still don't know which is worse,
> leaving it on the mount or moving back and forth to the case all the time.
>
> Another good side note: Why would it be necessary to have mounted it twice in a
> few days? I'll tell you why: The doorway for rolling the mount out had an
> opening that was 74" high . I say "was" because after that first night of
> sitting on the ground (on my ***) to observe the Zenith, I decided that I
> would be needing to enlarge the door again (for the second time). I spent two
> days brushing up on my rudimentary carpentry skills by adding a third, top door
> opening on hinges that gave an additional 10" of available height (87" total).
> Now I have to climb even higher to get the thing on the mount.
>
> So I took the scope down, mount and all, and reassembled it with the legs
> further extended. Now at the Zenith, a 7 mm Pentax hangs about 33" off the
> ground at focus. Not bad, I can pretty much look in while seated on a low bench
> (read inverted milk crate). Closer to the Horizon, I pretty much need to be
> standing, unless I am willing to crank my neck, or better still, stand my Air
> Chair precariously "on top" of the milk crate. Not a bad solution, as I have
> decent balance, and if I were to fall off at least the scope would not be in
> much peril, as the mount would surely be capable of receiving my form in motion
> without the OTA so much as moving from its target.
>
> Appearance:
>
> I don't have all the measurements in front of me, but it is around 5.5 feet
> long with the dew shield retracted. The paint is white with a durable, rough
> texture. This will be very effective in hiding finger prints and also makes the
> tube less slippery when it has dew on it (I handle the tube using "rubber dot"
> type photo gloves for grip and to keep oils off of the assembly). It
> incorporates a black anodized, high quality Feathertouch dual-speed focuser.
> The lens cell is nicely appointed with the technical specifications of the lens
> (F=200 mm, F/L=1800 mm, etc, etc) laser-engraved thereupon. Very Nice.
>
> The lens itself is pretty amazing. I wish I knew more about how a lens cell is
> designed to compensate for temperature changes. I am also curious to see at
> just how cold of an ambient temperature that this telescope can be used and
> still maintain its figure. We typically see substantial periods where the
> thermometer at night appears to be perpetually stuck at 5 degrees F. It would
> be nice if the scope would be able to handle such a cold temp, but there was no
> guarantee given that it would at the time I placed my order.
>
> Speaking of which, I would have, for the sake of long term maintenance,
> preferred to have ordered an air-spaced unit, as being non-technical, I am
> superstitiously distrustful of the long term utility of an oil spaced
> objective. Just the same I have been assured to my satisfaction that it is a
> non-issue. It was also the only option available to me at the time that I could
> afford, so it is what it is.
>
> It is possible to see something of how the cell is constructed, but as I said,
> being non-technical, it is difficult, even looking through clear glass, to see
> clearly what is going on there.
>
> Did I mention the glass? 200 mm of clear aperture…aaah!
>
> It is a big lens to an amateur such as myself. Perhaps I shall dispense with
> waxing poetic about the coatings rendering the glass "invisible." I will only
> say that the coatings are considerably lighter than on the 6" Tak (which has a
> very dark coating), they are more like the coatings on the Traveler, if I were
> going to pick an equivalent.
>
> As eluded to before, the dew shield is of the sliding variety, it is nice and
> snug and I assume that it will move smoothly after it has been operated a few
> more times. The lens cap is of aluminum and attaches directly (as opposed to
> "screwing on", and is held in place with foam spacers - very nice, actually).
> The interior of the tube is flat black and supports 4 baffles. The inside of
> the focuser tube is lined with black felt. The 2" focuser cap is laser engraved
> with the TEC logo and the logo also appears on the focuser. There are two decal
> lettering type labels on opposite sides of the baffle reading "TEC APO 200 ED."
> With the baffle extended and the focuser engaged the overall length is in
> excess of 6 feet, it is a most imposing instrument sitting up on top of the
> Titan mount.
>
> At any rate, I still need to pinch myself, as I must surely be dreaming.
>
> First Light:
>
> So after a couple days, I had it together enough (and the weather had cleared
> enough) for me to take it out for first light. First light ended up being
> Polaris, using a 31 mm Nagler. The view consisted of a bright star with bright,
> undulating spikes; on bright stars at low power my eyes are crap, highly
> astigmatic. It was apparent as being a double star, something the scope would
> see a lot of over the next few nights. I used the opportunity to attach a new
> Telrad, and get it aligned. I was in business. I had a look around; M13 -
> washed out by the near Full Moon, the near Full Moon - way too low to the
> horizon and stuck in the muck -seeing was horrible, and then Vega for false
> color (still having a hard time really being able to see any at all "in
> focus").
>
> And then of course the double-double. Well, at 257x, that thing was incredible.
> (Don't ask me what the hell I was doing at 257x, I don't think I've used less
> than that practically the whole time I've used it - except to locate objects!)
> I had never quite noticed how apparent the magnitude difference was with the
> one pair - the pair that is parallel in line with the larger grouping of all
> four stars. The Airy Disks were quite apparent and surrounded by 1-2 faint and
> symmetrical diffraction rings. The outer one was fainter, and came and went
> with the seeing.
>
> By this time I have recognized the folly of trying to scrutinize "out of focus"
> star patterns with APO refractors. I'm no expert, but I do know that the
> phenomenon of bringing all of the colors together to the same focus, but never
> being able to quite do it completely is known as spherochromatism, and that
> these colors interfere with each other when out of focus, and that I can
> basically throw out Suiter's star testing book of pretty fresnel patterns when
> it comes to evaluating Spherical Aberration in such an animal. Except, perhaps,
> for the "in focus" images in the book.
>
> I have become something of a backyard expert at evaluating optics via the star
> test method by simply leaving the stars "in focus"(!). It doesn't take a rocket
> scientist to know that if the energy is properly concentrated in the Airy Disk,
> and the seeing is good that the remaining diffraction rings will be few and
> faint. Through experience, I have seen otherwise, so it is pretty easy to
> evaluate SA in an optic using such a method, once it is based on personal
> experience.
>
> Spherical Aberration? Coma? Astigmatism? What are those? We'll have none of
> that here. This lens is one (or is that 12?) of a kind…
>
> Another side note: I have spent a great deal of time trying to determine what
> would be the perfect aperture for my location. A good part of this has been
> conjecture along with testing my eyes, to see exactly what it takes to see all
> a given aperture has to offer. There is much information, as well as
> disinformation on the Internet regarding maximum and minimum useful powers. I
> like the oft repeated maxim that for low power it is best to use the highest
> power possible that frames the object being observed. That is why I finally
> ponied up for the 31 mm Nagler, and especially the pair of 24 mm Pans for my
> Binoviewer, which will not yield much of a wider fov than my 32 mm Plossls, but
> are certain to give a darker sky background with its attendant increase in
> contrast, and hence, fainter objects visible.
>
> As for high power, I don't know why it is, but I am coming to the conclusion
> that I can see all that an objective has to deliver to the image plane at 30x
> per inch of aperture. I have revisited this rule of thumb over and over, in one
> telescope after another. That (30 x per inch) is where the Airy Disk becomes
> visible to my eye in the scope, and that is where I can see the full resolution
> of the instrument.
>
> This is an important point. My eyes have some floaters (flotsam and jetsam
> floating in the vitreous humor), the larger exit pupil I can use, the more
> clearly I can see. Also, contrast decreases with increased magnification. Being
> a Jupiter watcher, using the lowest magnification that will reveal all the
> detail that an instrument can resolve, will also maintain the highest level of
> low contrast detail visible in that fully resolved image. Seeing, also, may
> limit the high power utility of an aperture, and by matching the aperture and
> its full resolution to the environment, care may be taken to insure that the
> instrument is well suited for its purpose. In a nutshell, the largest aperture
> that can get under the local seeing.
>
> That said, I have often had some difficulty pushing much past 225x on Jupiter
> (my favorite object) at my house in the Rockies, and I have come to theorize
> that I can fully resolve a 7.5" aperture at that magnification, so going much
> beyond 8" is going to yield diminishing returns for observing Planets.
> Diminishing returns on various respects: Cost, portability, seeing limitations
> (BTW, I do use an 18" Newt for DSO's so please don't get the wrong idea). Now
> 8" is not generally considered an overwhelming amount of aperture for Planets,
> so this explains why, for my purposes, I decided to go with a refractor.
>
> Being limited as to maximum aperture useful for the application I could then
> concentrate on getting everything possible from that 8" of aperture. At 8"
> aperture, I can see resolve what the scope has to show at 250x, as will be
> demonstrated later. By keeping it down to 250x, I can theoretically squeeze
> more low contrast out of the system than running at a higher magnification.
>
> Did I mention yet? This is a nice scope, it's a keeper.
>
> Second light:
>
> So, I go out a couple of nights ago and think I'll try for a couple of test
> objects. I spent some bedtime reading looking over close doubles in the Night
> Sky Observer's Guide (nice books by the way), and came up with a couple of
> appropriate candidates in Cygnus.
>
> Siegfried and Bob were both over (Siegfried is caretaker for a 9" Clark
> Refractor, Bob has the second 8"er that is coming to this state (!), pretty
> amazing when you consider that out of the 12, several of which are shipping out
> of the country, that two would be coming here.
>
> We were looking at stars and splitting a lot of doubles with the new TEC APO.
>
> Needless to say, the Gemini GOTO was giving me fits, and a motor stalled. So I
> finally decided to just push it to the objects and save for later trying to
> figure out whether my problems were the mount or just my inexperience with it.
> Sidereal tracking was still working fine throughout the evening. Glad I still
> know how to star hop.
>
> Ended up with Otto Struve 403 at .8 arcsec, and Otto Struve 410 at .6 arcsec
> (according to The Night Sky Observer's Guide, both around mag 7, both are in
> Cygnus).
>
> Both split **clean** (no figure 8's or any of that crap), for all three of us
> (so I do have witnesses), at both 257x and 450x.
>
> Unbelievable! That .6 arcsec double is the closest double that I myself have
> ever seen, and starting to push the theoretical limit for an 8"er, if I have my
> facts straight.
>
> Even more amazing is that they both split clean for me at the 257x, there we
> are again at that magic ~30x per inch of aperture. Even at 450x, I could not
> see them much better, if anything they were a bit more disturbed by the seeing
> conditions at that extreme high power.
>
> Another side note:
>
> One thing that I have noticed is that it has taken me an inordinate amount of
> time to get my facts straight regarding optics. For one thing, I think the
> reason I was finally successful with the .6 arcsec double is that I chose one
> that wasn't so bright that it's diffraction pattern would overwhelm the
> separation of the Airy Disks. This and the fact that the stars were quite equal
> in brightness, which helped them to split clean. What a stroke of luck that I
> get a new scope, and sometime in the first week I am given the gift of sub-arc
> second seeing. I mean this thing split .6 mm like it was butter. It never even
> occurred to me, after all the hundreds of observations that I have now made,
> that this might be the exception, and not the rule. It just seemed
> so…natural.
>
> Third Light:
>
> Well, I had a lot of other questions still remaining, how about stray light,
> sky background darkness, contrast, etc? I brought out my old faithful 10" F6
> Zambuto Dob (Protostar 3 vane diagonal and quartz mirror, flocked tube), to do
> a side by side. I let both instruments cool down for two hours. By some freak
> of nature, the seeing cooperated for one more night. Not quite as good as last
> night, but still pretty damn good. Let's have a look at that Otto Struve 410 at
> .6 arcsec again. In the 8"er, there it was again, plain as day. Two tiny Airy
> disks, the outside surrounded by the faintest diffraction ring, absolutely
> beautiful.
>
> Now to try it with the Dob. Got collimated, Found the star with a 22 mm Nagler,
> switched to the 6 mm Radian (255x), holy cow, there it is; split!
>
> I spent the better part of an hour carefully comparing one scope to the other.
> I have come to the same conclusion as many others regarding diminishing returns
> as more money is spent on a telescope. In a nutshell, in my case, was it worth
> it?
>
> Absolutely, emphatically, Yes.
>
> There was perhaps a (WAG) 20% improvement in the aesthetic quality of the split
> double star. While in the 8" the stars were tiny, hard Airy disks, in the Newt
> they had something of a TV screen appearance to them. The diffraction rings
> were interrupting in such a way as to appear to make fine lines in the image.
> The star was still split clean, but it didn't have quite the same quality at
> all as the image in the refractor.
>
> Attempts to dsitinguish differences in background skyglow, contrast, light
> grasp, etc., quickly became an exercise in futility. Simple matters like trying
> to match magnifications and eyepiece designs became burdensome.
>
> Then, my 45 year old bones began to make a further observation. The Dob ain't
> that comfortable to use, it wobbles a bit at 255x, the objects fly across the
> fov (I have a tracking platform, but really…), "go find that star again",
> "yuck, that focuser", balance is an issue…
>
> I sat at the EQ mount and operated the hand paddle on the mount and the 10:1
> focuser. What a joy, what comfort, what a view! And that focuser!
>
> IF I lived at a better location (again we are concurring with conventional
> wisdom on the subject, and this is a big IF), I could perhaps see the utility
> of going for a large Cat type scope on an EQ for observing the Planets.
> Something like a 12" Mak would be great.
>
> As to using a Newt such as my 10" F6 on an EQ mount, I somehow doubt that it
> would work very well for myself, being awkward and uncomfortable. Sorry to say,
> I am even starting to like my couch more these days (but it ain't over yet!)
>
> Don't get me wrong, I am all for bang for the buck. And I like ALL telescopes,
> but I did want to drop this note and express just how pleased I am with this
> latest acquisition. Like I said before, I still can't believe that it is really
> here. It is safe to say that for 1/10 of the price a person, willing to accept
> some minor disadvantages and inconveniences, can get 90% to where it is
> (however, to my own consternation, 90% doesn't always cut it for me when it
> comes to eking out that final 5% of subtle detail in Jupiter's belts that I am
> Always Looking For). And like I said, if I lived elsewhere, it might be a
> different story).
>
> By all means, it is very easy to enjoy this hobby to a very high level with
> very modest means. But for me, with my years long quest for the perfect Jupiter
> scope (well OK, I like the Moon, Saturn and Mars, too), I think I may have
> finally found Telescope Heaven. This may very well be the closest thing to a
> perfect 8" aperture that I have ever seen.
>
> I can understand now what S&T meant, when they worked my patience over a while
> back while I was waiting, by saying the only thing they didn't like about the
> 140 was that they had to send it back after the testing was done. Fortunately
> for me, I don't have to send this one back.
>
> Yet another side note:
>
> Going through this latest comparison has put me in a bit of a sticky situation.
> For one thing, seeing the .6 arcsec star for the first time in my 10" right
> beside the 8" forced me to accept that I have to constantly remain open to
> learning about how these things work. Picking the fainter double (not buying
> the 8" refractor) was what really did the trick. I am seeing how different
> eyepieces affect background sky glow (and there are some differences out there,
> even among premium makes), I am further realizing that unless I properly clean
> the diagonal, it might be adding some scatter to the image. I am realizing that
> there are intangibles, such as comfort at the eyepiece, stability of the mount,
> the ability for a scope to stay put while changing eyepieces and remain
> balanced, the ability for the mount to track and keep a star centered for when
> I wander away and then come back later, that all have a bearing on what one is
> able to see.
>
> For the longest time I was content to simply nudge my Dob slowly across the
> sky. Now I just see aberrations wherever I look, even in my own eyes. So this
> is where the road to becoming a critical observer leads…
>
> I went through the same kind of thing one other time, when I was first getting
> started. I originally was so taken by the stars that I would just lie out in

> the yard and look up. Once I became obsessed with learning the constellations
> and my way around the sky, for a time, it became a burden. I didn't want to
> know anymore, I wanted to go back to ignorance, and just enjoy the sky for its
> beauty. I passed through the other side of that dilemma and now am quite
> comfortable both with the beauty, and knowing just a speck of what it is that I
> am enjoying.
>
> I feel the same way about telescopes now. As most of you here likely already
> know, this is not a new thing for me. I have obsessed over telescopes for
> years. I think (at least I hope) that I am finally reaching the point where I
> can see the 8" APO and the 10" Dob for the apple and orange that they truly
> are.
>
> I have done countless side by sides between all of my scopes, especially the 6"
> APO and the 10" Dob.
>
> I truly feel that this time between the 8" APO and the 10" Newt, there will be
> just the one night of comparison, I give up.
>
> A friend asked me if it was "worth the wait." Yes, it was worth the wait. This
> scope is finally good enough for me just the way it is, and I feel no
> compulsion to put it (or myself) through any more rigorous and ridiculous
> comparisons, or to spend another moment going over it with a fine toothed comb.
> It has passed its side by side, and its first nights out under the stars with
> flying colors. IOW, so far, so good and "good enough," for that matter.
>
> I even think I might have got more than I paid for, as odd as that may sound.
>
> Last side note:
>
> I think that sometimes it is possible to create an instrument that performs
> well on the bench, but the mechanics handicap its performance in the field.
> Based on what I have seen with this instrument so far under the night sky, I
> must say that it appears to be fully performing as well in the field, as it
> must have done on TEC's optical testing bench. The specs to which it was
> reportedly manufactured were exceedingly high, and for these specs to translate
> so well to my eye under the night sky at 40 degrees F and dropping, is a
> profound accomplishment; my hat is off to TEC.
>
> As far as this humble test pilot can ascertain so far, this telescope appears
> to be essentially a perfect instrument.
>
> Did I already say it? I'll say it again; I think I have finally found Telescope
> Heaven.
>
> Very impressive, TEC guys,
>
> I can hardly wait for Jupiter...
> rat
> ~( );>
>
> email: remove 'et' from .com(et) in above email address