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TEC 200FL #001 Has Arrived

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#51 Kent10

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Posted 07 October 2019 - 12:20 AM

Today I tightened up the screws on the mount under the plate and on the plate to try for more stability.  I don't think there was much room for improvement there.  Stability depends on the position of the scope.  Sometimes it is better than other times.  Once I get the finder from Yuri that will put more weight on the focuser end and then I can move the scope up a little.  I'll see if that helps stability.  The finder won't be ready for another month.  Yuri has to make a longer arm so it doesn't interfere with the wheel.



#52 fate187

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Posted 07 October 2019 - 01:00 AM

Hi Kent,

 

congratulation on your new scope! A very special one for sure. What I find quite remarkable is, that you are observing "almost every night". That is something people would love to do. But weather, job, family and also the appetite for astro need to align. I think this way you really get the most of your scope(s).

 

best wishes

Michael



#53 Kent10

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Posted 07 October 2019 - 01:05 AM

Hi Kent,

 

congratulation on your new scope! A very special one for sure. What I find quite remarkable is, that you are observing "almost every night". That is something people would love to do. But weather, job, family and also the appetite for astro need to align. I think this way you really get the most of your scope(s).

 

best wishes

Michael

Thanks Michael.  I am fortunate to be out almost any night I want.  The summer here is monsoon season so there are nights I can't observe.  But even then I find myself out under the clouds looking for holes and with lightening in the distance.  That is fun too.  My 180 is so quick and easy to setup.  Viewing with the 200 is a completely different experience and I will have to slow down to view with it.

 

You have some great scopes too.  And congratulations on your new Tec 140.  I would probably also own a Tec 140 if I didn't have the TV-140.


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#54 Kent10

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Posted 07 October 2019 - 08:54 AM

In comparing the 180 and 200, one other thing I have been comparing and looking forward to is less field curvature in some of my eyepieces with the F8 (200) vs F7 (180).  I think I see a nice difference but I haven't compared directly yet.  I expect to see a small difference with my TMB monocentrics which are eyepieces I really like.



#55 SandyHouTex

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Posted 07 October 2019 - 09:19 AM

Here is a picture of Nick Petrunin, Yuri's son, who made the lenses for the 200.  Dew shield not extended.

I'm not sure it's a great to be standing that scope on the focuser, but it is a beautiful scope for sure.



#56 Kent10

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Posted 07 October 2019 - 09:57 AM

I'm not sure it's a great to be standing that scope on the focuser, but it is a beautiful scope for sure.

It is a lot of weight going onto the focuser.  That is for sure!



#57 George9

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Posted 07 October 2019 - 10:37 AM

Let me just say that we are all living vicariously here, and thanks for sharing it. You definitely have more experience than me with large refractors, but as I think of things I throw them in in case it is helpful. I think with a little work you will be able to optimize it nicely.

 

Maybe remove the ATS extension just to see if that significantly stabilizes the scope. You won't need to observe that way; it's just a diagnostic.

 

Also put the ATS legs all the way out to create the widest base.

 

The fact that it behaves a little differently in different orientations may tell a lot. My double stack on the Mach1 vibrated east-west but not north-south, and I figured it was the shape of the Mach1 stalk. The AP1100 solved that for me. (Vibration was less than 2 seconds on the Mach1, but I just wanted it more stable.)

 

Whether the scope is hanging by the rings (pointing due south) or somewhat resting on the saddle (due west) might make a difference. Also might try weights up just to see what happens (then it's really hanging by the rings).

 

If you have to go for a wider pier, there is the 10" and 12" ATS. There is also a used PWT Monolith, and many newer high-stability piers. (Someone who used both the ATS and PWT said the PWT was prettier and rated for more weight but they liked the settling characteristics of the ATS more).

 

George



#58 Kent10

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Posted 07 October 2019 - 11:00 AM

George, I appreciate all the help you have given me.  I view often with larger refractors but the AP mount is very new for me even though I have been reading the manual in preparation for the day the 200 would arrive.

 

At some point I could remove the extension just for a diagnostic as you say.  Obviously I need that extension.  I do have a smaller 6 inch one but I like the 12" one so the scope won't hit the legs at zenith.  I asked the owner of ATS if the extension plus shorter pier was less stable than getting a taller pier the same height and he said no.

 

I have a little room to extend the legs out more and could try that.  I don't think the instability is coming from the pier though.  I have tapped and pushed the pier in several places and there is some movement but not much and it dies quickly.  I think the instability is in the mount and the long moment arm.  When I tap or hit the scope there is a "lot" of movement but I do think the amount of movement depends  where the scope is relative to the counterweights.  Weights pointed down or mostly down and it might be better.  When the weights are at the side then more instability, but I still need to think about this more.  I am going on what I think I recall.  I will try to think about this more this week as I view.

 

I wonder, too, if I need to balance everything better.  I have been doing a rough job so I can start viewing.  In the AP manual they talk about better balancing.

 

I think if I add weight to the focuser end with the finder and perhaps something else if I really want to try, then the moment arm will be less and I should get less movement.  Too bad I have to wait a month for the finder. 

 

Interesting about the PWT piers.  I always thought they might be better but the ones I have seen for sale used weren't tall enough for me.  I wonder if a 10" pier vs the 8" I have would be better but I still think the instability I am seeing is in the mount.  The Tec 200 must be at the limit of what it can carry, not so much by weight but by length.

 

Thanks for all your help!



#59 Kent10

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Posted 07 October 2019 - 11:03 AM

To add to my post above.  With my Tec 180 on the DM-6, it is quite stable.  But when I add a binoviewer and the setup gets longer it is not nearly as stable.  The moment arm or length of the scope seems very important, more so than the weight.



#60 George9

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Posted 07 October 2019 - 12:17 PM

I agree with you on the 8" vs 10" question. Going into it, I didn't think it was the pier width. But the total length of the pier can make a bigger difference. At Black Forest SP, someone with a large refractor commented on the total pier length being key (I was asking advice about my planned pier). Therefore, even if the pier extension is solidly attached, you might see a difference.

 

I wonder if the AP 10" pier with its wide legs and turnbuckle supports would be better, other than perhaps interfering with some zenith viewing. Bottom line, if it is the pier, then there is a solution.

 

On moment arm, are you saying that by adding weight, you push the focuser closer to the mount to rebalance so that your focus adjustments have less leverage? On the other hand the total moment of inertia of the scope will go up when you add weight (as you will push the lens further from the mount, and even with radius squared, it is still a net gain of inertia). So not sure whether it will help or hurt to have more weight.

 

George



#61 Kent10

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Posted 07 October 2019 - 12:46 PM

The 10" inch pier has a slightly wider base overall so you would think it would therefore be sturdier, but how much sturdier I don't know.  That might only help a little.  It is also a little heavier but not much because I have the double thick version of the 8" so it is getting closer to the 10" weight.  The thickness is the same as the 10" on mine.

 

The height of the pier must be important too.  ATS did tell me that I should not use the 12" extension and the 6" extension at the same time or else it would be too unstable.  But I do need this height to view at zenith.  Higher yet might even be better for me especially with a binoviewer attached but I think once I get the finder I can then move the focuser end forward to balance.  That might only be an inch or 2.  I don't know.  Maybe not even that with the heavy objective.

 

I think you are right though.  When I add the finder and move the tube forward to balance, there is more weight overall.  The length of the scope focuser side to the mount will be less but it will be heavier so that may not change anything.  And it will be longer on the objective end from the mount.

 

The AP 1100 manual discusses offsetting the weight so the counterweights move down slightly and the focuser end also moves down slightly.  I may give this a try.  I can fully disengage the Worm and Worm Wheel to test the balance.  I haven't done that yet.  I hope this will help.



#62 Codbear

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Posted 07 October 2019 - 02:02 PM

Kent,

 

It is amazing what 15 extra inches and 14 extra pounds between the 180 and 200 does to the mix. Good feedback on the width of the rings.

 

Since mine will be a permanent setup I will be able to spread the rings out farther on either a 14" or 16" dovetail.

 

Also mine will be mounted on a 10Micron AZ2000, the orientation will be "sideways" so to speak, which makes me wonder if, in my case, or ultimately in both of our cases, we'd be better off with some rings from Parallax. I used a set from Parallax for my 14" Edge and they were fantastic...solid as a rock!



#63 Cotts

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Posted 07 October 2019 - 04:52 PM

I just took possession of my new TEC 160 so I'm getting a kick out of this thread.

 

Two thoughts:  

 

First, a warning - the cam mechanism that closes and locks each scope ring is attached with 4 very small screws.  Check their tightness!  Mine arrived with all 8 screws loose - one of them had fallen off completely in the case.  The original owner had never checked them but i noticed a wiggle in the mechanism.  I have now tightened them all with blue Loktite so that they are unlikely to come loose again...

 

Second, regarding the feet of your tripod on turf.  I have found that turf is springy/spongy even when compressed with the weight of the scope/pier combo.  What works best for me is some sort of pointed foot that jabs right down into the soil below the sod.  This really reduces vibration.  The exact opposite is true for 'pucks' or flat surfaces of any type.  They actually slide around laterally on top of the partially compressed turf... the turf itself is spongy and allows much vibration.   Making a solid mechanical connection with the substrate is vital.

 

An option which works is to buy three 12"x12" patio stones and counter-sink them into the soil by removing the sod and very carefully packing them in place so that the feet of the pier can rest on the stones...  But piercing the turf with pointed feet is better.

 

Dave 



#64 Kent10

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Posted 07 October 2019 - 05:40 PM

Dave, congratulations on your 160.  I have been following your acquisition of this scope.  You'll love it!

 

I have done more testing.  Sam, I think that is it.  The extra weight and length make a huge difference.  More than I expected for my setup of a good pier and mount.  I noticed this even on my 180 on the Rob Miller tripod.  It is quite solid, very very good.  But when I add a heavy binoviewer and extend out, it is now not very good.  I think the length might be more important than the weight because I use heavy eyepieces and they don't seem so bad but on the other hand they are mostly low power so I wouldn't notice the shakes.

 

George, I did more tapping and pushing on the scope and all over the pier, top and bottom.  I think the height of the pier is a big part of the problem.  It bounces around more when hitting at the top of the pier than at the bottom.  But unfortunately, I need it to be high.  I will at some point push the legs out more to see if that helps some.  But then I go even lower than I would like.  Of course, with the finder I can push the scope up slightly.

 

I rebalanced the scope with the precision balancing in the AP manual and I don't think that helped for stability.  Minimal if at all.

 

Dave, thanks very much for your suggestions.  I think I will try without the pucks once I take it down.  George has shared his experience with that too in an early post in this thread.  I am not sure how I will get pointed feet but perhaps the rubber of the ATS pier will be better than the pucks.  Of course this lowers the mount some more too.  More difficult to view at zenith but I do want to address the instability.  I have seen pictures of Yuri's scopes at star parties and he uses pieces of wood under the feet.  Pieces of wood or stone as you suggest, would also raise the scope up for me.  You are right that the turf is very spongy.  This could be a big part of my problem.  With my dob, I have instability problems too and I attribute it to the unevenness and sponginess of the turf.  I put a round piece of wood underneath but it sometimes rocks.  I think I need 3 separate pieces instead.

 

Dave, thanks for the cam mechanism warning.  I noticed mine were fairly loose as shipped and I tightened them about as much as I could so the lever is very difficult to close.  I don't want those coming undone by accident.  

 

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#65 Allan Wade

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Posted 07 October 2019 - 06:27 PM

It’s fun to follow along in your journey Kent. I’m sure you’re not too worried about getting your TEC tuned perfectly, it will happen in good time. I waited three years for my 32” and it needed a bit of tuning when I received it to get it to a level that I was happy with. That took several months. It’s now two years on and having shifted it permanently into its observatory I’ve done a couple of upgrades that make it even better. The moral of my rant is that big setups will take more time and expertise to get fully optimised, but when you achieve that level of performance it’s hugely satisfying.

 

It’s interesting to compare the two large TEC setups I’ve used this year. The 200 f/9 was on an AP1600 and Rob Miller tripod sitting on grass. It was a very unstable setup, and touching the focuser required several seconds for the vibration to dampen.

 

The 250 f/8.8 was only mounted to an AP900, but was sitting on a large pier solidly attached to the observatory and the whole deal was configured by an engineer who had no time constraints to get it all perfect. In use the TEC250 was very solid with almost zero vibration even when I tapped on the focuser.

 

I know you are all over it, but I think Dave and others have made a good suggestion. Get the foundation below the mount as bullet proof as possible.


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#66 Kent10

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Posted 07 October 2019 - 06:38 PM

Thanks Allan.  Good to hear from you.  I recall you mentioned the instability of the 200 F9.  I had forgotten it was on an AP1600 mount.  That might demonstrate that it really isn't my mount that is the problem because the 1600 should be easily enough for the 200 F9 I would think.  And that the 250 was solid on "only" a 900.  It must be my pier and turf then causing the problem.  I don't think my shakes are several seconds unless 3 is several.  It might be 2-3 for me depending how I hit it.  Focusing isn't great either at high power.  But then it settles and I really enjoy the tracking. 

 

I do worry about getting precise focusing if it is shaking though.  I don't enjoy that.  So I am going to work on the pier and see if that helps.  I might wait until there is a chance of rain though which might not be for a while.  I don't want to set it up again and I just want to enjoy some viewing for a while.

 

Thanks again.


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#67 John Fitzgerald

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Posted 07 October 2019 - 06:42 PM

What a scope!  I would permanently mount that in an 11 foot dome.



#68 Kent10

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Posted 07 October 2019 - 06:51 PM

What a scope!  I would permanently mount that in an 11 foot dome.

Thanks!  If I had the space I would build an observatory.  I have a very small back yard and I move the scope around depending what I want to see.  Not the same night but from season to season I shift where I view from.



#69 Jeff B

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Posted 07 October 2019 - 07:50 PM

Kent, a lot of good suggestions concerning damping of the system.

 

What you're basically trying to do is use the pier and mount structure as a mechanical diode to drain away, in one direction into the ground, vibrational energy and reduce mechanical "ringing" of the system from stored energy bouncing around.  You're damping the spring nature of the system.  

 

Another suggestion if you plan on keeping it outside is to use a thicker walled Hastings tube cut to the length you want to get the eyepiece height off of the ground you want at zenith, plus another 3-4 more feet which will be buried in the ground in a good sized cement plug.  The tube is filled with play sand all the way up to the adapter you will need for the mount.  The play sand is exceptional at damping any pier induced vibrations and draining them into the earth.  It also helps with vibrations from the spingy-ness of the mount and OTA system. 

 

The other feature is to put three eye bolts in the tube wall as high as you can but avoid any contact with the star diagonal with in the OTA range of movement.  Use chain and turnbuckles to connect the eye bolts to rods pounded into the earth then tighten the chains with the turnbuckles (you can actually tune the system with the chains).    You can see a similar arrangement in the pictures Allen Wade posted of the 250 installation in California.  

 

https://www.cloudyni...erving-session/

 

A bit of work but well worth it with a pier that is quite literally "as solid as a rock"...but better damped too.

 

Jeff


Edited by Jeff B, 07 October 2019 - 07:57 PM.


#70 Cotts

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Posted 07 October 2019 - 09:53 PM

Kent, here's something else that may be helpful to suppress vibrations and has not been mentioned yet:

 

Hargreaves Strut.

 

Dave



#71 Kent10

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Posted 08 October 2019 - 01:44 AM

Dave, the strut looks interesting.  Something to consider in the future.

 

Jeff, also something to consider.  However, I usually move my scope to different places depending on what I am observing.  I have a small backyard and there are some trees.  Something permanent wouldn't have the flexibility.  Too bad really.  I would like something like that.

 

I had an amazing night observing.  For starters, in the late afternoon I compared my 180 and 200 on distant pine trees.  I was separating needles at very high power.  The 200 had the edge and didn't seem to be more affected by seeing.  Nice.  I could get higher magnification with a brighter image, just like I expected and without additional seeing problems as far as I could tell.

 

Then I compared the 2 at night.  Saturn was beautiful in both scopes.  I was able to get to higher power with a brighter Saturn in the 200 but the seeing wasn't able to show much advantage.  I could imagine the potential, however.

 

On the moon using approximately the same power, I could see the advantage in the 200.  More detail and more etched.  Copernicus was great.  I didn't have the seeing though to see the Alpine Valley Rille.  Maybe just a hint?

 

M22, M11, NGC 7789, several doubles, the double cluster, the Owl Cluster, M52.  I used the same power in each scope.  Brighter stars and faint ones more easily seen in the 200.  Slightly larger exit pupil on the 200 so the background was also a little brighter but everything looked beautiful.  I tried higher power on M15 but seeing had deteriorated.

 

I star tested both scopes.  Both great but I still think the 200 is better.  I think the scope is pretty much color free.  OK there must be some color but probably not very important.  The outer ring inside and outside focus is a slightly different hue of white but fairly equal in intensity.

 

On the star test of both scopes I noticed some swirling.  I remember experimenting with this before so I closed the dew shield and the swirling was gone.  Opened it and it came back.  So for the rest of the night I viewed with the dew shield in.  I had some reflections of the moon at times but I think it is better to view without the heat plumes.

 

I viewed Jupiter early on but it was so low I could see the atmospheric dispersion and it was not sharp at all. 

 

The night was a lot of fun.


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#72 George9

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Posted 08 October 2019 - 03:30 AM

On spikes, my pretty limited experience was that the mount felt much better to my hand with spikes on grass, but that looking through it, I had reinvented the tuning fork, and it never settled completely in the wind. With rubber feet it felt very spongy to my hand but looked dead, i.e., very good. That’s was with two 30-lbs telescopes double mounted on an AP1100 on an 8” ATS 42” pier with no extension. Maybe my spikes hit a rock or something else weird. Therefore, I would just try it both ways and see what actually looks better.

I am wondering about three 6” high platforms that are fairly solid maybe with spikes on the bottom of each for a good connection. Each weighing 10-20 lbs. Then put the pier with the 6” extension (instead of 12”) on top of those, one foot on each platform. Move the platforms each season.

Or else turnbuckles from the top of the pier to the feet of the pier, much like the AP pier.

Generally what has worked for me is a very solid structure that has exactly one point to absorb vibrations, generally the feet.

Also for diagnosis, how does the 180mm do on the 12” extension? (And would still be curious about the 200mm on the pier without any extension, say during daylight, just to see if that is the major factor, even if is not feasible for observing at night.)

(I like the strut, too.)

George

#73 contrailmaker

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Posted 08 October 2019 - 05:47 PM

So, does this new acquisition mean there’s going to be a TEC180 on the market soon? I’m going to need a bigger condo.....

 

CM


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#74 Codbear

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Posted 09 October 2019 - 12:55 AM

I recall that, when I took my 180 down recently in preparation for the arrival of my 200, I was shocked to discover the small screws were loose on each of the TEC rings.

 

After reading the above comments about the rings, I've decided I will special order rings from Parallax to fit the 210 mm O.D. of the 200's tube. As I said in a previous post, the Parallax performed incredibly well on my 14" Edge and I had nary a worry at all using them.



#75 Kent10

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Posted 09 October 2019 - 02:49 AM

So, does this new acquisition mean there’s going to be a TEC180 on the market soon? I’m going to need a bigger condo.....

 

CM

I don't think so and certainly not anytime soon.  The 180 is so easy to use.  The 200 on the AP mount takes lots of time to set up.  That is why I am working on a more permanent set up.  I already ordered a custom Telegizmos cover.




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