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ES Twilight I with 100 mm F9 refractor

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#1 Billy Bl.

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Posted 23 May 2019 - 08:51 PM

I have read both that such a long OTA is a problem and is not a problem with this mount/tripod. I need a larger sample size. Does anyone have, or has anyone used, this combination?



#2 jaraxx

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Posted 23 May 2019 - 10:01 PM

Does OK with a 102mm f7.5 - at least for visual.


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#3 vtornado

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Posted 23 May 2019 - 10:12 PM

Hi Billy, 

 

I have a orion ed100 f/9 on a porta mount.  It works but barely.  If there is a breeze it will not settle.  Focusing is a bit tricky at high power but can be done.  I  just picked up a ES twilight I, if you wait a few days I can tell you if it can handle the tube.

There is a mod to the tw1 where you cut some plywood pieces that altitude arm and stiffen it up.

I haven't done that yet.

 

VT.



#4 Berny

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Posted 23 May 2019 - 10:17 PM

I used with a TV NP101 and it was very shaky. I guess different people have more or less tolerance for that.



#5 Redbetter

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Posted 23 May 2019 - 10:53 PM

I haven't used this combo.  The long focal length means a substantial portion of the weight is near the end of a long lever arm.  This makes it more difficult to damp vibration from even small perturbations (breezes, focusing, touching the slow motion controls.)

 

There are some basic adjustments that you can make which will help the Twilight mount, but a tube this length poses more challenge than for a 600-700mm focal length.  I have an 80mm achro with 900mm focal length, modded with a 2" focuser and I have found this much less steady than a heavier but shorter 80ED (f/7.5, 600mm) which does well at 150x.  The ES mount would be more stable if it could be used in the vertical position rather than recline.  This might be practical for planets, but won't be for targets high in the sky.  I wish there was a 45 or 60 degree setting than the way-back 30 degrees.  I have not yet done the arm stiffening plate.

 

  • One of the things I have done is swap out one of the longer slow motion cables with a shorter one from another mount.  I did this because I was noticing a lot of vibration induced by that one long cable when touched.
  • There was also thread about these mounts that included rotating part of the mount screw/attachment in the base to reduce some of the potential for movement relative to the gear set and arm.  I vaguely recall having done this, but don't remember the particulars other than opening it up.
  • Something I did recently was to replace the bolts that attach the legs to the tripod.  This was suggested by another user recently.  The problem is that the supplied bolts don't have shoulders that fully span the ears on both sides of the tripod.  This means that the end of the bolt with the nut on it is actually somewhat undersized and supporting some of the tripod on the threads.  This introduces some unnecessary play into the system.  I replaced this with bolts that had shoulders that fully spanned the length of the ears, but I did have to cut them down a little since they were somewhat long.

I haven't checked this final mod closely, but I did a recent session on Jupiter with the 80ED and it seemed sturdier.  It was enough that I didn't even put the VSP's under the feet as is my normal habit.  I need to recheck with the 80 f/11.3... 



#6 Simon B

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Posted 24 May 2019 - 01:37 AM

You wanted a larger sample size so here's my opinion, no way jose!

 

I mean.... low power, maybe it's usable, but it's just going to jiggle a lot in general. The Porta II is more stable than the TWI, and even that will not hold a 100 F9 too well.


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#7 David_Ritter

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Posted 24 May 2019 - 03:47 AM

Having used both, I agree that the Porta-II is more stable head than the Twilight. And the Twilight is quite susceptible to vibration on long scopes as well.

 

I normally use my Twilight with an 80mm f7 ED refractor as well as a GSO 150mm f6 newtonian.

 

The Twilight works fine with the little refractor. It is a bit shaky when focusing at the higher powers, but nothing that causes any real problems. But when I put the longer and heavier newt on it, it's barely usable.

 

The slightest bump, or some wind or adjusting the focus causes serious vibrations that take a while to settle down. It's very hard to focus in fact and is basically unusable in a steady wind. But in calm weather, it does carry the newt and once it's focused and settled, it does do the job.

 

To help cut back on the vibration, I added an aluminum plate to stiffen up the metal parts connecting the alt axis to the az axis. For the little refractor, this helped a lot and it's actually quite nice to use now. But the newt still overtaxes the mount and so the stiffener plate didn't really solve the problem there.

 

So I have to agree with the other posters who say a longer, heavier scope will be difficult to use with this mount. But for a lighter, shorter scope, it does actually work very well. It's also lightweight, easy to set up and has a fairly solid tripod. I also like the slo-mo controls but do agree that handling them can set off vibrations.



#8 WyattDavis

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Posted 24 May 2019 - 05:06 AM

I have a Porta II and consider it to be too lightweight for my f/9 100ED. I have also read similar posts to those above that at best put the Twilight I in same league as the Porta II. I just went through a search to find a lighter mount for my f/7 102mm refractor and ended up with a heavier setup despite best efforts. I settled on a Stellarvue M2 + CGEM tripod, and it is very stable. The difference in stability for that size instrument is pronounced, with the lighter setups just being too shaky in my opinion.



#9 Redbetter

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Posted 24 May 2019 - 05:13 AM

Tonight I did some observing of Jupiter with the 80ED and the 80/900 achro.  No breeze tonight, so this was a mild test.  As usual the Twilight handled the 80ED quite well at 150x (and beyond, but I prefer this mag for planets with this scope.)  With the LT 80 achro I needed the VSP's for faster damping and to allow easier focus adjustment  and use of the motion knobs.  I again had the impression that the changing of the leg bolts has made the tripod stiffer and helped the mount to perform better, but this was without wind, and that makes a substantial  difference with long tubes.  I took the magnification up in increments of 129, 150, 180, 225, and 300x.  All were quite useable up to 225x which was acceptable, while 300x was marginal to poor and not pleasant to use.  (The quality/detail of the image was best at the lower powers, but that is a different matter.)

 

I haven't tried putting the 110ED f/7 (770mm focal length, 10lb OTA) on the Twilight since I optimized it.  I have only done some quick tests with that OTA early on to conclude it is bulky (diameter, mass, etc.) when on the mount and was not something I wanted to do, although it worked.  I already had the CG4 at the time, and the Twilight was purchased to go with the 80ED, not the 110.

 

A lot of this comes down to individual preferences for mount rigidity when focusing, etc.  What works for one can be unacceptable to another.  I can do "real time" focusing for planets and double stars with mount/OTA combos that some others consider unacceptable--VSP's are an important factor in that.  But there is also a threshold beyond which vibration and failure to damp in a reasonable period become frustrating to me and hamper observing. 



#10 Billy Bl.

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Posted 24 May 2019 - 08:08 AM

Thanks to all who have replied. Lots of relevant information. VT, I will definitely await your verdict. The consensus seems to be "maybe, maybe not", which is essentially where I started. I have an Atlas EQ6 that I got for my 200 mm F6 Newt, but I then got the refractor, mostly for solar-system objects. I just want a (perhaps marginal) grab-and-go setup for quick looks without spending too much. I have also considered the Porta II, but again the consensus seems to be "maybe, maybe not". I don't want an equatorial or goto. I've also tried to find information about putting a Twilight I or Porta II mount head on my Atlas tripod without requiring a trip to the local machinist (which for me is >100 km away), but unsuccessfully. I can get the Twilight I or Porta II for $400-500 (with taxes and delivery), up here where the Leafs will probably never win the Cup again before I die, and I really do not to spend any more than that.



#11 MalVeauX

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Posted 24 May 2019 - 12:25 PM



I have read both that such a long OTA is a problem and is not a problem with this mount/tripod. I need a larger sample size. Does anyone have, or has anyone used, this combination?

Hey Billy,

 

It'll be a struggle. Will it hold it? Yes. Will it be a pleasing experience? Not sure, but probably not. Depends on what you are doing with it. You can totally tweak the Twilight I to perform better. You can replace the legs with something more sturdy. You can brace the arm and it will be more rigid. You can extend the pier so that it's taller and easier to use to look through visually with a long refractor. But all of this is modification, costs more, and really after you're done you could have just gotten a bigger, better mount to do it all out of the box.

 

That said, I like the Twilight I. It handles my smaller scopes quite well. It really is comfortable with my 80mm F7.5 and smaller scopes.

 

My Twilight I is modified, the arm is braced, the legs are replaced with beefier ones. It still struggles with a 120mm F8 refractor. First, it's wobble city. It's the physical length of the scope, not the weight. I compared this with a C8 Edge which weighs more and it wobbled less! The physical length of a long refractor is what will torture the Twilight I's arm because of the much larger moment arm that is generated by the refractor. This is only a 1000mm focal length. A 100mm F9 is practically the same length. It will struggle on the Twilight I. It will be ok at very low power, but using it at anything medium to higher power is not going to happen without extreme frustration and patience. Focusing is just not enjoyable at all. At low power, it works though. The other issue is how long the scope is, after balancing, it could put your eyepiece so low to the ground that you are not comfortable viewing it. Long refractors need fairly tall mounts so that the eyepiece is in a suitable location to comfortably view. Keep this in mind.

 

Twilight I (with HEQ5 legs, braced arm) with a 120mm F8 refractor + 38mm 2" eyepiece

 

This is a struggle bus setup. I don't recommend it. It will hold the weight. But it will not do it elegantly and it will bounce around and be not an enjoyable experience.

 

44861693964_1b2b6681d0_c.jpg

 

Twilight I (same setup as above) with a 80mm F7.5 refractor + 38mm 2" eyepiece.

 

This is very comfortable, it handles it totally fine. The moment arm is not substantial even with the big eyepiece weight, because the physical length is shorter. I can take this to higher power and it easily handles touching it to focus, so it's totally usable at all levels. Very well matched.

 

31021076147_b89264a539_c.jpg

 

++++++++++++++++++++++

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For larger refractors that are long (F8+), 4" and up, personally I would suggest something more like this:

 

https://www.teleskop...adjustment.html

 

Very best,



#12 AhBok

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Posted 24 May 2019 - 07:07 PM

I had that combination about a year and a half ago. Frankly, it was pretty bad in the grass and all but unuseable on pavement with vibe pads. That scope really likes the stability of a GEM.

#13 Billy Bl.

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Posted 25 May 2019 - 08:52 AM

It's looking as though I have a choice of insufficient, iffy, or overkill. Overkill will likely mean heavier and more expensive than I want, so I may have to opt for iffy, with perhaps some modifications (I do like to tinker). I'll continue looking for something between the two. My standards of usability may aslo be lower than average. I don't expect either the Twilight I or the Porta II to be unstable with no wind or touching, and I have the time and patience to wait a few seconds for any vibrations to dampen. I'll continue to wait for VT's report, though. Again, thanks for all the inputs.



#14 Hesiod

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Posted 25 May 2019 - 11:28 AM

I have a 100/900 refractor and the Porta 2 mount: my opinion about this setup is that it is almost unusable, even with an improved tripod.

 

A decent mount for similar-sized telescope is the T-sky (or SkyTee) mount, a coarse but solid contraption which is compatible with light Synta tripods (Eq5 and the like) and equipped with slow-motion knobs.

The head is around 5kg, has 2 clamps (even if one is planned for binos, so it is "oddly" placed), has a good payload which can be even "enhanced" by the use standard counterweights (not needed for the 4"), and sells around 300€


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#15 Redbetter

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Posted 25 May 2019 - 03:40 PM

I gave the 110ED f/7 some time last night on Jupiter and Saturn, in the back yard through hazy skies.  There was no breeze, so this was again a near "best case" test.  I was using it in the recline position though, which is the most sensitive to vibration. 

 

The good news was that it was entirely usable for this purpose (and splitting Antares.)  I started without VSP's since I had been using the 80ED on Jupiter at 150x.  With the 110ED I quickly decided I needed/wanted the VSP's to get back to the same effective baseline.  With them I used powers of 154, 193 and 257x.  Vibration from focusing and using the slow motion controls was definitely more noticeable at 257x, but still damped reasonably.  At 193x it was not an issue for me.  The few basic improvements I have made to the mount seem to be working well.   A breeze would likely be a problem though, and that might require a stiffening plate on the mount arm as some compensation. 

 

The bad news is that while this is workable, it is ungainly/doesn't look right.  It isn't a great configuration for this OTA and it would likely be irritating when used for objects high in the sky.  Keep in mind the 110 f/7 is a shorter tube at 770mm focal length, although heavier than the 100 f/9 ED.  The focuser end extends well back to balance the heavy objective out front, not an ideal set up for this mount. 


Edited by Redbetter, 25 May 2019 - 03:52 PM.


#16 ascii

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Posted 25 May 2019 - 03:53 PM

I have a 100 mm f/9 on the no longer available Unistar Deluxe.  If I had to replace the mount, I'd go with this mount/tripod package.  I've heard nothing but good about it in combination with 100 mm f/9 scopes.
 
https://www.stellarv...e-mount-system/



#17 Billy Bl.

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Posted 28 May 2019 - 07:31 AM

If I had to replace the mount, I'd go with this mount/tripod package.  I've heard nothing but good about it in combination with 100 mm f/9 scopes.

Thanks for this, ascii. I didn't know about this mount, but I'm seriously considering it. It is compatible with my EQ6 tripod.



#18 vtornado

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Posted 09 June 2019 - 01:30 PM

Sorry to get back so late.  I have been busy with work and little league, and the weather is abysmal here.

Just look at the flooding reports coming out of the midwest.  Just about every day is cloudy.

 

I did a day light test today, I looked at a distant road sign at 180x.

This combo  (orion f/9 100mm ed, and tw1 mount head)  it is on the edge of usable.

My TW1 is on an aluminum tripod on good soft dirt.

There is a 3mph breeze today.

I can focus if done carefully. After twanging the scope with my finger it takes about 3 seconds to settle down.

The breeze does not jiggle the scope, but I would expect > 5 would

 

Some things to consider are,

1) I  am only using 1.25 inch accessories off the back.,  Big honking eyepiece will put additional stress on the mount, forget about a camera.

2) I am running a 30mm finder.  A 50 would be additional stress.

3) I have a crayford focuser, which may make focusing easier than a R&P.

 

A better tripod may take out some shake.  A steel tubular leg may me sturdier, but is heavier if weight is an issue.

 

There is a mod that puts a piece of plywood in the hollow space in the altitude arm.  Other members here say it helps.

  It is on my list of projects to do.

 

Another thing to consider is removing the dew shield, and replacing it with a foam one.  I have the orion ED f/9 100, my shield does not

seem to come off.  I'm not sure if it is stuck or glued.  I did this trick with a 6 inch f/8 (on a much bigger mount) and it helped stability a lot.

 

To me it seems like the azimuth axis is the shakiest.

 

INMH the scope is too much for the mount.   Unfortunately there is no low cost alt/az mount on the market for a 100mm long f/l scope.

It depends upon how finky you are. 



#19 clearwaterdave

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Posted 09 June 2019 - 02:28 PM

If you like to tinker.,go pipes.,very stable.,pretty cheap.,get the tripod of your choice and easily make a mount that works.,cheers.,

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#20 Jond105

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Posted 09 June 2019 - 02:35 PM

If you can get an AZ4 and slow motion isn’t important, an AZ4 holds the 100ED fine at 200x and higher in my opinion. This was my ED100 on the AZ4 with extension. I use this same set up with the 120ED as well

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#21 Jon Isaacs

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Posted 09 June 2019 - 02:58 PM

I have a 100/900 refractor and the Porta 2 mount: my opinion about this setup is that it is almost unusable, even with an improved tripod.

 

A decent mount for similar-sized telescope is the T-sky (or SkyTee) mount, a coarse but solid contraption which is compatible with light Synta tripods (Eq5 and the like) and equipped with slow-motion knobs.

The head is around 5kg, has 2 clamps (even if one is planned for binos, so it is "oddly" placed), has a good payload which can be even "enhanced" by the use standard counterweights (not needed for the 4"), and sells around 300€

 

I have both the Portamount and a Twilight 1.  I was hoping the TW-1 would be usable with my NP-101.. Definitely NO.  The Portamount is useable.  The gear boxes are interchangeable between the PM and the TW so I spent three nights trying to isolate just what it was about the TW1 that made it so prone to vibration.  There seemed to be several things but the support arm is a definite issue. 

 

The discontinued SV MG-2 appears to be based on the Sky Tee.  Hesoid's description is right on , coarse but solid.  Ready to go, the MG-2 weighs 19 pounds (I weighed mine ) and handled the 15 pound 120 mm F/7.5 Orion Eon with authority,  500 X on doubles. 

 

Eon in backyard.jpg
 
Jon


#22 Billy Bl.

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Posted 09 June 2019 - 05:52 PM

I eventually took ascii's advice and got a Stellarvue M2. I have it on my SW EQ6 tripod and am happy with it.


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#23 F.Meiresonne

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Posted 26 June 2019 - 12:41 PM

Yup, the TW1 can handle long tubes not well. I holds my 102 mm F/7 quite well but i would not mount F/9 scopes  even with smaller apertures. It is just not the weight but the length that counts in this case. Also important to tighten all bolts very well, also those that are not visible wich means you have to tearn down the mount a bit.

Still  i like the grab and go aspect of the mount


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