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Ode to the XT6

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#1 AlienRatDog

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Posted 12 March 2019 - 09:47 AM

Last night we FINALLY had a nice clear night! I decided to use my daughter’s XT6. I did a quick collimation using an Orion Laser collimator deluxe (my Astrosystems barlowed laser is 2” and the XT6 has a 1.25” focuser) and double checked with a Cheshire, it was close enough. I put the scope on the porch during dinner so it cooled down for like 1.5hrs.

First object we looked at was the moon. It was marvelous, razor sharp. I put in my ES 6.7mm 82 def eyepiece with an Orion Shorty Barlow (I have no idea where the heck I put my powermate!) and the view was still sharp at 358x. The dob motions were ok, a little jerky at this power (but better than my DSVM Mount). I didn’t miss tracking, I was fine with manually tracking. I literally stayed on the moon for an hour.

Next was Orion, at 179x, the trapezium E and F stars were plainly visible (no averted vision needed), the stars we pin pricks! So much detail in the nebula. I also was checking out Meissa A and B (cute double). I also tried to see Sirius B, it was hard since there was a diffraction spike right where it was, I though I got a few glimpses (I kept at it for 30min). Rigel was cool too. I also checked it the cluster in the Rosette Nebula (looks good in my ES 68deg 24mm eyepiece) and Pleiades.

These views rivaled the sharpness of my 120mm ED scope and easily is sharper than my 8inch Edge (I never get a chance to use that scope cooled down). I also discovered that I prefer the use a manual dob while sitting, no motor drives to fuss with, completely silent, much more intimate experience with the sky (my wife keeps saying it’s because I’m getting old). We use the Nexstar Evolution for outreach or when family is over, but by myself, I just want to take my time and get lost in space. I’m thinking a manual 12 inch dob (maybe 16 but 12 looks manageable) may be next on the wish list.
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#2 KerryR

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Posted 12 March 2019 - 10:14 AM

Cool report! As a fellow Michigander, I too was please to finally see the stars last night!

I've always been impressed with the Synta 6" f8 Dobs.

If you go for a 12 or 16", you'll most likely be back in the never-gets-cooled-down world again. Even with a fan, my 16" loves to display the boundary layer all night. There are ways to deal with it more effectively than I do, but the complexity and power requirements go up dramatically.

 


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#3 JGass

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Posted 12 March 2019 - 10:25 AM

Before your next session, check the collimation with the barlowed laser technique. 

 

Also, have a look at the diffraction spikes around Sirius (or Regulus, or ...)  Are they sharp and do they clearly display the diffraction orders?  If so, that plus the pinpoint stars suggests the collimation is v. good.

 

 

 



#4 CollinofAlabama

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Posted 12 March 2019 - 11:43 AM

This telescope is on sale now.  I completely agree that a nice 6" F/8 dob has all the resolution a 120mm refractor can put out for a fraction of the cost (much better for DSO's, btw, but equal on solar system bodies)   The 6" F/8 dob has a much more agreeable mount setup -- much quicker, easier & more simply employed.  The SkyWatcher, unlike the Orion, comes with a two inch focuser, so barlowed laser collimation is possible, but honestly, at F/8, this is all you need.  Now the 2" rack and pinion focuser the SkyWatcher ships with needs some work, as it's too stiff.  Those with the patience, poverty, and time can do a number of things to fix it, but lazier folks like me simply replace the R&P with a dual speed Crayford.  If you're particularly cheap, you could get by with a single speed.  Even with the dual speed Crayford, you're spending a fraction of what a 120mm refractor-plus-adequate-mount will cost (these days, over $2k).  With all this, why get a refractor?

 

The only real answer to the 6" F/8 regarding refractors is TFOV.  Well, AP, of course, but I'm talking only visual.  For visual astronomy, outside of a larger true field of view, refractors have so little over the 6" F/8, it makes them hard to swallow.  Now falling temperatures through the night can bedevil cooling for any mirror, making it nigh impossible to reach equilibrium, but that doesn't happen commonly.  Folks, I own four refractors, so I love them, too, but it's always difficult to find a reason NOT to take out the 6" F/8 vs any of my refractors.  They're simply the unsung hero of visual astronomy.  If more refractor people owned them, they'd realize what Abe, the poor post-doc, has revealed to you, the telescope using public, this very March 12th, 2019.  Hear ye, hear ye!


Edited by CollinofAlabama, 12 March 2019 - 03:36 PM.

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#5 Binojunky

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Posted 12 March 2019 - 12:06 PM

I picked up one of these last year, on sale through Amazon Ca for the cost of a couple of cheaper eyepieces, only got limited use before winter set in, bought it mainly for the moon as LP has made pretty well everything else nearly impossible, cracking good performer, minor complaint is the plastic focuser though it works fine for visual use,D.



#6 alnitak22

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Posted 12 March 2019 - 12:49 PM

Last night we FINALLY had a nice clear night! I decided to use my daughter’s XT6. I did a quick collimation using an Orion Laser collimator deluxe (my Astrosystems barlowed laser is 2” and the XT6 has a 1.25” focuser) and double checked with a Cheshire, it was close enough. I put the scope on the porch during dinner so it cooled down for like 1.5hrs.

First object we looked at was the moon. It was marvelous, razor sharp. I put in my ES 6.7mm 82 def eyepiece with an Orion Shorty Barlow (I have no idea where the heck I put my powermate!) and the view was still sharp at 358x. The dob motions were ok, a little jerky at this power (but better than my DSVM Mount). I didn’t miss tracking, I was fine with manually tracking. I literally stayed on the moon for an hour.

Next was Orion, at 179x, the trapezium E and F stars were plainly visible (no averted vision needed), the stars we pin pricks! So much detail in the nebula. I also was checking out Meissa A and B (cute double). I also tried to see Sirius B, it was hard since there was a diffraction spike right where it was, I though I got a few glimpses (I kept at it for 30min). Rigel was cool too. I also checked it the cluster in the Rosette Nebula (looks good in my ES 68deg 24mm eyepiece) and Pleiades.

These views rivaled the sharpness of my 120mm ED scope and easily is sharper than my 8inch Edge (I never get a chance to use that scope cooled down). I also discovered that I prefer the use a manual dob while sitting, no motor drives to fuss with, completely silent, much more intimate experience with the sky (my wife keeps saying it’s because I’m getting old). We use the Nexstar Evolution for outreach or when family is over, but by myself, I just want to take my time and get lost in space. I’m thinking a manual 12 inch dob (maybe 16 but 12 looks manageable) may be next on the wish list.

As a refractor weenie I must chime in. I’ve had an XT6 since 1997. Mine is a Guan Sheng scope with 19% CO, but performance sounds similar to yours. My TV85 and friend’s Tak 78 are really good small refractors and super sharp....but they lose/lost to the XT6 each and every night for astronomical targets. My friend with the Tak was so impressed with the performance of the Dob that he brought over his Tak FS102. Well, that lost too. So he brought it back several times and the result was always the same. I mean it was fairly close, a premium 4” APO is a nice scope, but fine lunar and planetary detail was easier in the 6”. And deep sky was not as close as lunar planetary. With a 7 Nagler at 171x in the Newt on M13, the eyepiece is literally filled with stars. His 102 showed 40 -60 at similar power, which surely ain’t bad, but the difference is apparent. And the Newt cost me 300  bucks! I got my TV85 a few years after the Newt...not because I thought the 85 would beat it..I knew it wouldn’t. And besides, Al Nagler told me it wouldn’t beat it the very first time I talked to him on the phone about scopes. I got the 85 for it’s versatility as a travel, solar, nature and astronomy scope. But as I’ve said for years, as a purely astronomical platform, a good 6” f/8 Dob is the best bang for the buck going. 300 bucks!


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#7 gwlee

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Posted 12 March 2019 - 01:05 PM

This telescope is on sale now.  I completely agree that a nice 6" F/8 dob has all the resolution a 120mm refractor can put out for a fraction of the cost (much better for DSO's, btw, but equal on solar system bodies)   The 6" F/8 dob has a much more agreeable mount setup -- much quicker, easier & more simply employed.  The SkyWatcher, unlike the Orion, comes with a two inch focuser, so barlowed laser collimation is possible, but honestly, at F/8, this is all you need.  Now the 2" rack and pinion focuser the SkyWatcher ships with needs some work, as it's too stiff.  Those with the patience, poverty, and time can do a number of things to fix it, but lasier folks like me simply replace the R&P with a dual speed Crayford.  If you're particularly cheap, you could get by with a single speed.  Even with the dual speed Crayford, you're spending a fraction of what a 120mm refractor-plus-adequate-mount will cost (these days, over $2k).  With all this, why get a refractor?

 

The only real answer to the 6" F/8 regarding refractors is TFOV.  Well, AP, of course, but I'm talking only visual.  For visual astronomy, outside of a larger true field of view, refractors have so little over the 6" F/8, it makes them hard to swallow.  Now falling temperatures through the night can bedevil cooling for any mirror, making it nigh impossible to reach equilibrium, but that doesn't happen commonly.  Folks, I own four refractors, so I love them, too, but it's always difficult to find a reason NOT to take out the 6" F/8 vs any of my refractors.  They're simply the unsung hero of visual astronomy.  If more refractor people owned them, they'd realize what Abe, the poor post-doc, has revealed to you, the telescope using public, this very March 12th, 2019.  Hear ye, hear ye!

I am a big fan of 6”f8 Dobs, but the Skywatcher weighs (40#) only 1 pound less than an Orion 8” f6, so I returned mine. Much prefer the Orion XT6 that weighs 34#. Unfortunately, current production XT6 Dobs have a cheesy plastic focuser these days, so I am hunting for a good used XT6 with a slightly less cheesy all aluminum focuser. 


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#8 Ed D

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Posted 12 March 2019 - 01:46 PM

I had a 6" f/8 for over ten years.  Never realized how good I had it until I sold it.

 

Ed D


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#9 AlienRatDog

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Posted 12 March 2019 - 01:46 PM

The plastic focuser is not too bad, it handles all my eyepieces fine. My only gripe with it is that when it’s cold, it gets stiffer than I like.

#10 AlienRatDog

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Posted 12 March 2019 - 03:06 PM

Before your next session, check the collimation with the barlowed laser technique.

Also, have a look at the diffraction spikes around Sirius (or Regulus, or ...) Are they sharp and do they clearly display the diffraction orders? If so, that plus the pinpoint stars suggests the collimation is v. good.


They seemed pretty good, I don’t recall seeing anything other than the main spike

#11 CollinofAlabama

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Posted 12 March 2019 - 05:55 PM

I am a big fan of 6”f8 Dobs, but the Skywatcher weighs (40#) only 1 pound less than an Orion 8” f6, so I returned mine. Much prefer the Orion XT6 that weighs 34#. Unfortunately, current production XT6 Dobs have a cheesy plastic focuser these days, so I am hunting for a good used XT6 with a slightly less cheesy all aluminum focuser.

Can't speak to the weight of the SW6 compared to the Orion XT8, but I own a GSO Zhumell 8", and it's a LOT heavier than the SW6.  I absolutely love my Crayford dual speed, mare than I hated the 2" r&p it came with.  Sold it on CN Classifieds very quickly, however.  I DID have to drill two small holes in the tube.  The GSO dual speed Crayford's four holes are a little farther apart left-to-right, but way too long top-to-bottom.  I drilled two small holes just below and slightly out (left & right) from the two existing bottom holes, and forced the screw through for the top two, which are tight but can be made to work without further drilling.  I only put a plastic baggie over my secondary!  But I removed my primary and then used a portivac to suck up all the metal shavings.  The existing hole is more than enough for the dual speed Crayford focuser to go through, if you need that kind of infocus for a particular eyepiece.  After I installed the GSO dual speed I put flocking opposite the focuser and around the primary area.  I also checked the center spot (dead on, or dead on enough, awful close, and not enough off that I could easily detect it, but I used rulers and my eye, not an inferometer or anything scientific).  I blackened the edges with a sharpie and measured the reflective diameter -- 147.5mm for my SW6, so, really a 5.8" objective, but close enough.  Gives me a very forgiving F/R of 8.14.  The SuperView 42mm provides a relatively comfortable 2º FOV, is under $75 shipped, and provides a nice 5.16mm exit pupil.  That's $420 for scope and 2" dual speed Crayford upgrade, not bad.  I ordered a $25 Orion 1 lb counterweight, cause I needed it, but again, even after flocking, you're gonna have trouble spending more than $500 for this setup, and it'll kick refractor derrière, pardonne-moi.  And you can't even get a 120mm achromat With Mount for this price, and even if you got one used for similar cost (which isn't fair since these could be picked up used, too, of course) the mount and setup will always be about 3 times the hassle, not to mention what will happen to both scopes in any kind of wind.  Dobsonians have it all over every other design in terms of wind.  And I know.  I live in West Texas.
 
The 6" dob is ‘da bomb’ for relatively light weight, easy to use, power-packed astronomy -- easy to collimate and maintain with excellent results at the eyepiece.  They're winners, and the 2" Crayford focuser is icing on the cake for me.  There is no better value in astronomy, and at F/8, you really don't have to worry about a coma corrector.  Although the entire field in NOT coma-free, it's close enough, and noticeably better than F/6.  Refractors can still produce those oh-my-god 2.5º-plus fields that aren't possible in a 6" F/8, but the moon?  Jupiter?  Most DSOs which are smaller than 2º?  Refractors that can beat the very portable 6" F/8 are mostly found in observatories.

Edited by CollinofAlabama, 12 March 2019 - 11:39 PM.

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#12 stargazer193857

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Posted 14 March 2019 - 12:34 PM

I don't know what brand 6" f8 I used, but it was so light weight that there was no reason not to take it out every clear night, unless you just really don't like the views. There are nights though when I don't feel like carrying out the 8".

I've looked through a 6" and 8" side by side at 53x each. The 6" did very well against the 8". You have to be looking at the right objects to be wowed by less than a magnitude jump.

The low price of the 6" or used 8" guarantees that almost anyone can a cess the sky.

That said, I want the best of all worlds.

#13 alnitak22

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Posted 14 March 2019 - 12:53 PM

I don't know what brand 6" f8 I used, but it was so light weight that there was no reason not to take it out every clear night, unless you just really don't like the views. There are nights though when I don't feel like carrying out the 8".

I've looked through a 6" and 8" side by side at 53x each. The 6" did very well against the 8". You have to be looking at the right objects to be wowed by less than a magnitude jump.

The low price of the 6" or used 8" guarantees that almost anyone can a cess the sky.

That said, I want the best of all worlds.

My XT6 weighs around 35 lbs. I carry it fully assembled in one hand up and down two flights of steps to get to my roof. A little Target stool which I observe with is in the other hand. I’m 62 and in good shape, but this is an easy grab n go operation. It needs 30 minutes in the dead of winter to give its best lunar/planetary views, but is usable at low power right out the door. And it’s no prob to spend 25 or 30 minutes panning around the winter sky at low power. When it’ll split Rigel at 40x, it’s ready for high power.


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#14 SeattleScott

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Posted 14 March 2019 - 01:47 PM

The drawback to me was always the narrow FOV. When I only have 30-45 minutes I don’t want to be hunting around with a little 1.3 degrees FOV. Good to hear the Skywatcher has a 2” focuser. I wasn’t aware of that.

Scott

#15 alnitak22

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Posted 14 March 2019 - 01:58 PM

The drawback to me was always the narrow FOV. When I only have 30-45 minutes I don’t want to be hunting around with a little 1.3 degrees FOV. Good to hear the Skywatcher has a 2” focuser. I wasn’t aware of that.

Scott

I understand. But with a 24 Pan or 35 Ultima, I don’t have any trouble. But out in dark skies I do want more FOV. Which is why I have a TV85.


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