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Why would you want a 6 inch Achromat?

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#51 mikeDnight

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Posted 13 January 2018 - 06:58 PM

I only have a Celestron AVX mount so maybe a scope like the ES 152 AR would be too much for visual use.  I am sure the CA would be there.  Probably takes a while for a big chunk of glass like that to acclimate, but I am thinking of getting one. Why did you get yours? Would you use it on the AVX? If you had it to do over, would you still get one?  Appreciate your input.

Thanks,

Dave

A 6" achromat with a relatively short focal length can be a great scope for sweeping up DSO's and comets. It's also a great scope for the observation of variable stars. (Read Starlight Nights, by Leslie C Peltier and you'll kill for a 6" F8 achro!)

The CA isn't that objectionable, and providing the spherical aberration is well controlled, it will be reasonable on the Moon and planets as well.

 

Mike


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#52 stevew

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Posted 13 January 2018 - 07:32 PM

 

As long as the lens has a good figure and is well corrected for c/a and s/a, a well made six inch achromat can be a lifetime scope.

 

Steve

 

Steve is that a Losmandy mount your long and luscious refractor is riding on?

 

Yes...

D&G six inch F-12 and Losmandy G11.

My boys are 6' 2"

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Edited by stevew, 13 January 2018 - 07:35 PM.

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#53 RickV

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Posted 13 January 2018 - 07:32 PM

I have three 900mm, 2-element-objective refractors:

1 - Orion 100mmED, f/9, 2 inch simple focuser,

2 - Canadian Telescope 152mm, f/5.9, 3 inch 10:1 focuser, and

3 - Orion Eon 120mmED, f/7.5, 2 inch 10:1 focuser

 

If I was to get rid of one, it would be #1, the 100mmED.

Why?

- No 10:1 focuser.

- The views through #3 (120 Eon) are superior.

- The views through #2 (152 CT) are inferior (chromatic aberration and not so sharp) as I experienced at a star party in a side-by-side visual test against a 6 inch Newtonian.  However the precision of that massive 3 inch 10:1 focuser is a joy to use.  Plus, the CT 152 is ideal for narrow-band H-alpha solar work (with an attached etalon) where being an archomat with chromatic aberration does not matter.


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#54 Simon Alderman

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Posted 13 January 2018 - 11:13 PM

I have a 6” f5 Jaeggers with an oil separated objective and 10 to 1 crayford on a dob mount. I have yet to find a scope that I like better for low to mid power sky sweeping. Just purchased a 31mm T5 that I can’t wait to use in it, though a Pan 19 is the usual ep. This scope is one of the very few that I’ll never part with. My favorite grab and go.


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#55 Ken Sturrock

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Posted 14 January 2018 - 11:44 AM

D&G six inch F-12 and Losmandy G11.
My boys are 6' 2"


Regrettably, I'm bookmarking this thread so that anytime I start daydreaming about a long focal length six inch, I can remind myself what that *really* entails.
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#56 John O'Hara

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Posted 14 January 2018 - 04:55 PM

Thanks guys for the comments, much appreciated.  I just ordered the ES AR152 version and an extra 12lb counterweight for the AVX.  Will let you know how it goes!

Clear Skies!

Dave

I might be mistaken, but I think Rod Mollise uses (or used) a Celestron AVX with his 6" f/8 achro, and was satisfied for visual use.  You might want to PM him (rmollise).



#57 Dave Ponder

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Posted 14 January 2018 - 05:29 PM

John,

Thanks.  I just read his blog about his AVX and 6 inch scope.  Looks like it will be fine.



#58 CHASLX200

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Posted 14 January 2018 - 05:38 PM

 

I know the older CG5 is way too small for a 6" F/8.  I would say a G11 would be much better.

If you're talking the older mounts prior to the CG-5A with the upgraded 2" stainless steel legs and upgraded ball bearing axes I agree.  But the CG-5A and ASGT (same mount just different electronics) handle the 6" f/8 just fine for visual, especially if you add the Orion 16" pier extension.

 

I was talking about the first run CG5 in 1996 like i had. Worst mount ever. I know they got better over the years.


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#59 mogur

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Posted 14 January 2018 - 05:52 PM

 

Thanks guys for the comments, much appreciated.  I just ordered the ES AR152 version and an extra 12lb counterweight for the AVX.  Will let you know how it goes!

Clear Skies!

Dave

I might be mistaken, but I think Rod Mollise uses (or used) a Celestron AVX with his 6" f/8 achro, and was satisfied for visual use.  You might want to PM him (rmollise).

 

I used a GM 8 with mine. Certainly sturdy enough, but I could have used a tripod extender so I wasn't sitting on the ground for near-zenith observing. 



#60 rogeriomagellan

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Posted 16 January 2018 - 03:44 PM

I was looking at the Starwave 152mm myself and seems excellent. I would love one, but new the run a cool $1200 CAD. I can get a new 6 inch F8 at $700 CAD new. Not sure I'd be willing to spend an extra $500 on it. Then ofc there's the used market.

Hi. What brand? Celestron?



#61 Gofr

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Posted 16 January 2018 - 06:34 PM

Omegon from astromarket.


https://www.astromar...221?language=en

#62 Tyson M

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Posted 16 January 2018 - 10:20 PM

I think the istar 6" are attractive. There is a supercompact 150mm F5  Rich field achromat that has caught my attention.  


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#63 infamousnation

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Posted 17 January 2018 - 01:51 AM

To view dso



#64 rogeriomagellan

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Posted 17 January 2018 - 05:54 AM

Omegon from astromarket.


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Thanks for the answer.

 

Wouldn't the Bresser Messier AR-152L appeal to you more? It costs pretty much the same. IMHO, it comes with a much better focuser. It sounds a better deal to me.

 

https://www.teleskop...00-mm--OTA.html



#65 BarrySimon615

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Posted 17 January 2018 - 11:10 AM

Everyone who has been attracted to a 6 inch telescope has their own reasons based upon their likes, dislikes, living location, weather conditions, discretionary money, etc., etc.

 

Back in 1978, the year I got married, I felt like I wanted to grow beyond the excellent Sears 76 mm refractor that I had purchased used earlier in the year. As I was tool savvy, coordinated and patient I felt like I had the ability to follow reasonable instructions, enough so to assemble a reasonable telescope where the most serious part of this "surgery" that I would be doing would be cutting a tube to the proper length and squaring up the ends.  The various 6" refractor objectives with cells that Jaegers had to offer really appealed to me - but what to get?  I approached the problem logically, drawing out the different focal length tube assemblies and then considering transportation and mounting issues.  While the f/15 model would certainly have the "Wow Factor" and it's own special strengths, it would have to stay at home considering my vehicle (1976 Chevy Concours, basically a fancy Nova).  Additionally a mount appropriate for an f/15 six inch scope would likely at that time, mean a heavy duty Cave mount.  Quite expensive for a newly married 26 year old.  Accordingly I settled on the f/5 as I did not want to compromise, it would have to be long f/ratio all the way or the ultimate wide field 6 inch (760 mm focal length).  No regrets with this decision and with the shorter tube length there were no transportation issues and I could get away with the driven equatorial mount that Meade sold with their 6" reflectors.  My 6 inch Jaegers is still with me and has undergone several modifications over the past 40 years.  The tube has been shortened (a bit) twice.  The original focuser is gone and replaced with an early AP focuser and I have a second (longer) dew shield on the scope.  Internally it now has better aluminum baffles/glare stops via the use of Thousand Oaks solar filter cells.

 

On the sky it holds it's own.  Back in 1978 I saw the Veil Nebula for the first time at a club event.  It was the first time too for others there courtesy of my telescope.  Comparing it to a friend's FSQ 106 and using both scopes at low power, the Jaegers did quite well, being able to reach deeper.  No chromatic aberration issues noted at low magnifications when the view does not include a bright planet and 2nd magnitude or brighter stars in the field.  Used for photography it does fairly well.  To me bright stars with blue halos is not too much different from bright stars with diffraction spikes (reflectors).  Additionally if you add a nebula filter (Lumicon Deep Sky) it does a great job in removing blue halos.  So back in 1978 my Jaegers 6" f/5 satisfied my appetite.  Today I have both a TOA 130 and a TMB SS130 which are both optically better than the 6" Jaegers, so there would be nothing to compel me to build one today, but for where I was then, what was available then, it was great!

 

Barry Simon

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Edited by BarrySimon615, 17 January 2018 - 06:11 PM.

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#66 Dave Ponder

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Posted 17 January 2018 - 05:30 PM

I just received my new ES 152AR and mounted it on my new AVX, rolling on JMI Wheelie Bars. Four inches of snow and 26 degrees outside, new scope curse strikes again!  Scope arrived in good shape except for a ding on the finder.  Too bad ES doesn’t have the finder in cutout foam, sure bet they get to replace these often!  Anyway, can’t wait to get a good night out and check out some DSOs.  Recouping from a broken leg, haven’t used a scope in months, but the Wheelie Bars will help!

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#67 John O'Hara

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Posted 17 January 2018 - 05:58 PM

Looking forward to your experiences, Dave.  It's a beautiful looking scope!  

​BTW, I purchased a Sky-Watcher 100 Pro ED 2 years ago, based largely on  your review.  I'm very pleased with it.


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#68 Dave Ponder

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Posted 17 January 2018 - 06:05 PM

Looking forward to your experiences, Dave.  It's a beautiful looking scope!  

​BTW, I purchased a Sky-Watcher 100 Pro ED 2 years ago, based largely on  your review.  I'm very pleased with it.

Thanks, the 100ED is excellent.  



#69 SandyHouTex

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Posted 17 January 2018 - 06:25 PM

I have two of the Celestron 6 inch f/5 Omni XLTs.  I plan to make a binoscope with them, but I tested them both when I got them and CA wasn’t as bad as I thought it would be.  Not as bad as my Meade LXD-55 6 inch f/8.  My theory is that since they’re so short the violet blur disk is so large it’s not visible.  On the Meade it was purple, purple, purple, especially on Jupiter.  The Omni XLTs also have an aspherical surface to better control spherical aberration.  The images are nice and crisp in them.


Edited by SandyHouTex, 18 January 2018 - 10:17 AM.

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#70 Gofr

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Posted 17 January 2018 - 06:52 PM


Omegon from astromarket.


https://www.astromar...221?language=en

Thanks for the answer.

Wouldn't the Bresser Messier AR-152L appeal to you more? It costs pretty much the same. IMHO, it comes with a much better focuser. It sounds a better deal to me.

https://www.teleskop...00-mm--OTA.html

Yes and no. Yes in that you're right, I would prefer the better focuser and white colour if the Bresser tube (white would be better for day time solar viewing). However it is still a $100 difference....

#71 photoracer18

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Posted 17 January 2018 - 07:42 PM

I used to have a rare Borg 150ED that worked well visually at star-parties on a Vixen SP. But my earlier Meade 152ED/APO and D&G built 6" F15 (Jaegers optics) both required more mount.

#72 stevew

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Posted 17 January 2018 - 10:53 PM

I also had a 6 inch F- Jaegers about 1991.

I still fondly remember the beautiful wide field views. M31, The Veil etc. It was also the first time I saw M108 and M97 in the same field. But it was not a great scope for the planets, however it wasn't designed for that.

My Antares 152 F6.5 while still not a great planetary scope is better optically.


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#73 bolide

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Posted 21 January 2018 - 09:51 AM

   Lots of reasons to love a 6" achromatic refractor, especially if it's high quality optically, and of f/10 or longer! I say this mainly because of chromatic issues, but also for bringing out the best performance it can offer in planetary and double star resolution and contrast. 

   Obviously, this length presents significant issues as far as securely mounting the OTA, observing positions as the scope is moved, wind issues, etc., not to mention storing it! But I can personally attest to having some spectacular views of the moon, double stars, and planets with my home built and fully baffled OTA using a 6" f/15 Jaegers coated achromatic objective.

   Hmm, maybe redesign the optics and tube for an unobstructed folded refractor!



#74 Jim Curry

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Posted 21 January 2018 - 01:14 PM

I built an f12 Istar. It gave sumptuous lunar views, wonderful 300x dbl star splits and detailed Jove, Mars, and Saturn observations.

Jim
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#75 39.1N84.5W

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Posted 26 January 2018 - 01:19 PM

Of all the filters I tried the Baader Semi-Apo filter did the most acceptable job of cleaning up CA. Aperture mask that 6" to 4.5" and you will get even better planetary resolution of Jupiter and Saturn.
I enjoyed a 31mm nagler most nights in my 6" f8 Achromat. Eventually sold it for an 8" f6 Istar.
Congratulations on your new scope!


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