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#51 davidpitre

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Posted 30 April 2014 - 09:40 PM


Makes sense. A reflector would have to have enhanced coatings to even come close to the refractor's transmission (if using a dielectric star diagonal),

I certainly wouldn't argue with anyone's personal experience, and don't want to highjack the thread into a reflector/refractor war, but indeed a Newtonian with newer enhanced mirror coatings (97-98% on the primary and secondary) does come very close to a refractors transmission. I think the limiting magnitude difference with the reflector at best case scenario would be negligible and hard to distinguish. My point is that I believe the time has past from when a refractor could always take you "deeper" than a reflector of the same aperture

#52 galaxyman

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Posted 01 May 2014 - 01:07 AM

I agree David with the new coatings. I had an 8" f/5.3 with high quality optics plus coatings, and was able to pull in some real faint galaxies, though not quite as faint as the refractor. Still wish I had that scope though.

For the $$$ a newt (dob) is best by far, and my 12.5" and 22" dobs are a testament to that for me. Both are optimized with high-end optics, coatings, and small secondary mirrors.

Anyway, any recent reports from the owner of this 8" Istar? That's what I would like to read.


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#53 Jim Curry

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Posted 01 May 2014 - 06:06 AM

Post deleted by Jim Curry

#54 PhaedrusUpshaw

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Posted 01 May 2014 - 02:58 PM

One could discuss the merits of telescope design and characteristics till the cows come home, however when all is said and done weather Reflectors, SCTs or Refractors, we are ultimately discussing a matter of personal preference. Personally I prefer the amazing contrast and depth of focus achieved by long focal length refractors. Of course this is simply my opinion and we each have one of those. Having said that I find myself dividing my time at the eyepiece, pretty much equally, between my 5 inch long focal length refractor and my 10 inch Dob which of course has twice the objective size...
Remember what Jack said, "Keep looking up!"
Bill

#55 michiel

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Posted 02 May 2014 - 05:43 AM

Hi James,
nice review. I recognize your thrill just as I had when I had first light on my 8 inch f9 APM achromat, the same as Karl has. There is something magic in the view through a big refractor that is missing in other telescopes. having owned, and still owing various telescopes, the big refractor remains a favourite toy, albeing it less practical than my 14 inch DOB. Big refractor performance is most bashed down by people that did NOT look through them, must be something psychological. The CA in your 204mm destroys apparently all viewing pleasure, but you just do not realise this.(sarcasm)
Enjoy :jump: :jump: :jump: :jump: :jump: :jump: :jump: :jump: :jump: :jump:
Michiel from Holland

#56 norcaltakguy

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Posted 03 May 2014 - 01:08 PM

Hi James,
nice review. I recognize your thrill just as I had when I had first light on my 8 inch f9 APM achromat, the same as Karl has. There is something magic in the view through a big refractor that is missing in other telescopes. having owned, and still owing various telescopes, the big refractor remains a favourite toy, albeing it less practical than my 14 inch DOB. Big refractor performance is most bashed down by people that did NOT look through them, must be something psychological. The CA in your 204mm destroys apparently all viewing pleasure, but you just do not realise this.(sarcasm)
Enjoy :jump: :jump: :jump: :jump: :jump: :jump: :jump: :jump: :jump: :jump:
Michiel from Holland


Hello and good health from California Michael...

You can easily tell when someone "hasn't" looked through a 8" refractor, they can't come to any reasonable conclusion only "arm chair" their voices using whichever scope they have had the most experience with...I will agree totally that a big " Dob" rules the skies, but looking through 8 inches of glass is really a treat, it's just that simple...The sky conditions here totally "reek", not good enough to get my Istar out, but I did manage to try out my newest set up, I simple dub my Double Barrel set up ( Astro Telescopes 152 f/5.9 and my Astro Telescopes 102 f/11 planetary killer )

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#57 michiel

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Posted 06 May 2014 - 07:43 AM

Nice rig you have

#58 norcaltakguy

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Posted 13 May 2014 - 09:27 AM

Thanks Michiel...It actually meets both uses, deep sky and planetary...I had originally purchased the 102 back in 2009, but sold it wanting more aperture...after a good friend of mine ( Alvin Huey of faint fuzzies fame)told me how good it was ( I only used my twice), I had to have another one...Sad part is this scope type won't be offered in the near future...Word has it that it's production cost just went up, making it over priced in today's telescope market :-(

#59 norcaltakguy

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Posted 30 July 2014 - 08:53 AM

I actually NOW use a Minus Violet filter aka " fringe killer"...I do have to say it brings another dimension to how good this scope truly is, meaning; IT Kicks Some Serious BUTT, planetary and DEEP SKY!!! I use all the Explore 100 degree eyepieces, down to the 5.5mm, nothing I look at gives off a "marginal" view, more so it brings out more of what I look at, BS on the fringe aspect, If you haven't looked through a 8 inch refractor, YOU have nothing to base your opinion on...Northern Cal has not had decent skies, even last weekend we had to deal with smoke from a fire east of our location...all in all, the 204 was exceptional, I spent a great deal of time resolving the Elephants trunk and the Iris nebula but the skies wouldn't cooperate, but the quadrants we spectacular, pin point stars and vivid dark space...MORE to follow!!

#60 astroneil

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Posted 30 July 2014 - 09:59 AM

Hello James,

I really enjoyed your piece on this telescope and I understand the hostility that some have thrown at you because I've been there myself. Istar produce fine achromatic lenses; beautifully corrected at peak visual wavelengths. I have a wonderful 5" f/12 model that ticks all the boxes. I also have a 6" f/8 Istar achromat that I have to finish evaluating but from what I've seen thus far, it's an extraordinary performer! To hell with CA! :lol:

I hope it continues to bring you joy!

All the best,

Neil. ;)

#61 droid

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Posted 05 August 2014 - 05:59 AM

 Chromatic aberration.......In my experience depends on the observer(s) , I've never owned the top end refractors, but I have a couple, the Orion 120 ST IS THE CURRENT.

Is there  Chromatic aberration, sure. Is it horrible, well depends.

I never drag this scope out for planetary, lunar or other bright object observations. Its strictly for those moon free few nights when I want to see star clusters, galaxy's etc.

I will admit, minor CA doesn't bother me, much, at all. How ever I've had friends who were repelled by it.

Maybe depends the eye?, experience level? I dunno.



#62 stevew

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Posted 07 August 2014 - 12:41 AM

A "Complete" Viewing report is coming, be patient group!

Any more updates on your 8 inch Istar?

 

Steve



#63 aa6ww

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Posted 16 August 2014 - 04:07 AM

Hey Jim, the next time we go out, and you take your 204 F/6, I'd like you to show me both the Elephants Trunk Nebula and the Iris Nebula. What eyepiece were you using to see these objects? We have only had 3/5 for transparancy most of the year out there in Rancho Cordova.

I say that because since we are observing in the orange zone, those skies are not dark enough to detecting dark mater, even with my C14. Ive read it takes some of the darkest skies on earth to detect the elephants trunk visually, nothing we have in this area we observe in Sacramento.

But never say never. I think at best, we would be able to disect the entire area and find the stars within the elephants trunk, and go from there. Locating the Garnett star would be where we should start, since we can see that with our naked eye.I can see the Garnett star even in my front yard with a streetlight nearby. so thats a no brainer.

Theres no way we would see any brightness around those stars to actually detect the dark mater making up the trunk. Its way more difficult to see than the Running Man and Flame nebula, both of which we cannot detect in the skies we observe in. We can't even see the nebulosity of the Rosetta nebula at the site we go to, we cant see the bubble nebula, and we cant even make out the bubble of thors helmet where we go. Heck, half the time, we have trouble even seeing the milky way because of the glow sky glow from Sacramento.

I have no idea why your claiming to see those objects, we have never seen even the Iris nebula except once I showed it to you up in Fiddle town 3 years ago with my C14 and those are darker skies than where we have been going since you got your refractor.

Nevertheless, it should be an ideal time since both the seeing and transparancy will be excellent. All we can do is try.



... Ralph

 

I actually NOW use a Minus Violet filter aka " fringe killer"...I do have to say it brings another dimension to how good this scope truly is, meaning; IT Kicks Some Serious BUTT, planetary and DEEP SKY!!! I use all the Explore 100 degree eyepieces, down to the 5.5mm, nothing I look at gives off a "marginal" view, more so it brings out more of what I look at, BS on the fringe aspect, If you haven't looked through a 8 inch refractor, YOU have nothing to base your opinion on...Northern Cal has not had decent skies, even last weekend we had to deal with smoke from a fire east of our location...all in all, the 204 was exceptional, I spent a great deal of time resolving the Elephants trunk and the Iris nebula but the skies wouldn't cooperate, but the quadrants we spectacular, pin point stars and vivid dark space...MORE to follow!!


Edited by aa6ww, 16 August 2014 - 05:15 AM.


#64 davidpitre

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Posted 21 August 2014 - 06:48 PM

 

I say that because since we are observing in the orange zone, those skies are not dark enough to detecting dark mater, even with my C14. 
 
 

I sometimes observe from a black zone site, and still haven't been able to visually observe dark matter. ' Guna keep on trying , though.


Edited by davidpitre, 21 August 2014 - 06:51 PM.


#65 Starman1

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Posted 21 August 2014 - 11:45 PM

 

 

I say that because since we are observing in the orange zone, those skies are not dark enough to detecting dark mater, even with my C14. 
 
 

I sometimes observe from a black zone site, and still haven't been able to visually observe dark matter. ' Guna keep on trying , though.

 

Uh, you mean dark nebulae.  By definition, dark matter is invisible because it doesn't interact with normal matter.



#66 jrbarnett

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Posted 22 August 2014 - 11:07 PM

Here's a short review he did.

FYI he owns some other very serious scopes like a 22" f/3.6 dob and a AP 5" APO to name a few. Also as with most of CAS (yes thanks to me), he's more of a dedicated DSO observer, and most of the time the large refractor is used for that.

APM 180 mm F/6 Achromat Deluxe :


I couldn't stand it any longer finally broke down and set up the 180 on
my deck last night on the G11 in manual mode. Using the scope's rings as a
1x reflex finder I went hunting! It was like pointing a cannon at the sky!

Without a minus violet/Fringe Killer, the Moon was awesome (36 ortho, 24
Pan, 0-18 SMC ortho, 0-12 SMC ortho and the 3-6 TV Zoom set at 3mm (360x)!)
Obvious chromatic aberration at the bright limbs either side, but tolerable.

With the Fringe Killer, it's APO like!!
I have never seen so much surface texture and detail on the Mare, subtle
contrast was amazingly detailed.

Bands of clouds kept me away from the DC and UMa galaxies and Orion was
obscured by the house (I was set up on my deck blocking the southern
horizon)! But, over head, I got M37 and M36 in Aur and M35 in Gem. Pinpoint
stars, just like diamonds on black velvet! And the COLOR of the different
stars was extremely obvious, reds and blues and orange tints.

And then my heart stopped and I had a religious experience: Saturn!

Only about 1.25 degrees below the Moon, high clouds and lousy seeing, but at
180-360X with the TV zoom, planetary banding obvious and the Cassini
division winked in and out with the seeing. Five moons easy even in the
moonglow and skyglow!




Karl
E.O.H.


Chesmont Astronomical Society - www.chesmontastro.org
Galaxy Log - http://www.youtube.c...r/GalaxyLog4565
Galaxy Log Blog - http://galaxylog.blogspot.com/
HASB - http://www.haveastellarbirthday.com
Telekit (Swayze optics) 22" F/4.5 Dob
Homemade (Parks Optics) 12.5" F/4.8 Dob
Vixen 5" f/5 reflector (new)
TMB/APM 8" f/9 Refractor”The Beast”. One great DEEP SKY achro
ES 6" f/6.5 achro. Good one
Celestron Omni XLT 102 refractor.
Celestron 10x60mm Binos

Gee whiz!!!!!

 

:lol:

 

Please do NOT give him a 10" Dob or 11" SCT.  His old ticker might not be able to take it.

 

Gotta love the enthusiasm, but...

 

- Jim



#67 Mr. Bill

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Posted 23 August 2014 - 02:10 PM

"Gee whiz!!!!!

:lol:

Please do NOT give him a 10" Dob or 11" SCT.  His old ticker might not be able to take it.

Gotta love the enthusiasm, but...

- Jim"

 

Poetic license..... :grin:



#68 davidpitre

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Posted 25 August 2014 - 04:02 PM

 

 

 

I say that because since we are observing in the orange zone, those skies are not dark enough to detecting dark mater, even with my C14. 
 
 

I sometimes observe from a black zone site, and still haven't been able to visually observe dark matter. ' Guna keep on trying , though.

 

Uh, you mean dark nebulae.  By definition, dark matter is invisible because it doesn't interact with normal matter.

 

Uh, I was attempting a joke.



#69 Starman1

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Posted 25 August 2014 - 06:47 PM

Doh!

:foreheadslap:



#70 nicknacknock

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Posted 27 August 2014 - 03:04 AM

 

Gee whiz!!!!!

 

:lol:

 

Please do NOT give him a 10" Dob or 11" SCT.  His old ticker might not be able to take it.

 

Gotta love the enthusiasm, but...

 

- Jim

 

 

Enthusiasm is a good thing indeed and it is what keeps us active in this hobby. However, Jim's comment is spot on in terms of that "but..."

 

People are too liberal with the "APO like" description of an achromat with a minus fringe or semi-apo filter. Yes, the views improve but really, once you have used an APO and critically examined the views, there is no comparison. The contrast and clarity of image provided by APO telescopes must be experienced on a good night to really understand what it is that they offer, be it planetary, DSO, doubles e.t.c.

 

Not that I am trashing achros, I have a 120mm f5 achro myself which is strictly for low to mid magnifications (up to 75x and that's pushing it - usually with my Ethos 21mm at 28.5x and 3.5 degrees TFOV) and for the intended purpose of wide field low magnification views, it fulfils its role admirably. But a filter does not an achro into a planetary (with no CA or barely any CA) / high magnification (with high contrast and clarity of image) instrument make.

 

Still, a large achro must be a joy to use for DSO. Unfortunately I have only had the chance to own and use a very well corrected 152mm f5.9 achro which while impressive for its aperture and limitations in terms of it being an Achro, I could not justify the trouble of keeping it and setting it up at nearly 25 lbs for the OTA and rings and a full load with eyepiece, diagonal, telrad and RACI of nearly 30 lbs for the aperture.

 

I salute those who don't have back problems and can enjoy these large refractors, be it Achro, ED or APO  :bow:  


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#71 Jeff Morgan

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Posted 28 August 2014 - 01:23 AM

Still, a large achro must be a joy to use for DSO. 

 

It is.

 

Within the low power regime if the target is not overly bright they can be excellent, easily exceeding fast Newtonians.

 

But if you want to push the power up, the Newtonian (or apochromat) quickly becomes the better choice.



#72 starcanoe

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Posted 30 August 2014 - 09:11 AM

How does Istar's R30, R35, and R50 designation work?

 

If I have a 6" F8 R30 lens does that mean it has the same secondary spectrum as a 6" F11.4  (8/.7) standard achromat?

 

Or something else?



#73 galaxyman

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Posted 04 September 2014 - 10:54 AM

 

Here's a short review he did.

FYI he owns some other very serious scopes like a 22" f/3.6 dob and a AP 5" APO to name a few. Also as with most of CAS (yes thanks to me), he's more of a dedicated DSO observer, and most of the time the large refractor is used for that.

APM 180 mm F/6 Achromat Deluxe :


I couldn't stand it any longer finally broke down and set up the 180 on
my deck last night on the G11 in manual mode. Using the scope's rings as a
1x reflex finder I went hunting! It was like pointing a cannon at the sky!

Without a minus violet/Fringe Killer, the Moon was awesome (36 ortho, 24
Pan, 0-18 SMC ortho, 0-12 SMC ortho and the 3-6 TV Zoom set at 3mm (360x)!)
Obvious chromatic aberration at the bright limbs either side, but tolerable.

With the Fringe Killer, it's APO like!!
I have never seen so much surface texture and detail on the Mare, subtle
contrast was amazingly detailed.

Bands of clouds kept me away from the DC and UMa galaxies and Orion was
obscured by the house (I was set up on my deck blocking the southern
horizon)! But, over head, I got M37 and M36 in Aur and M35 in Gem. Pinpoint
stars, just like diamonds on black velvet! And the COLOR of the different
stars was extremely obvious, reds and blues and orange tints.

And then my heart stopped and I had a religious experience: Saturn!

Only about 1.25 degrees below the Moon, high clouds and lousy seeing, but at
180-360X with the TV zoom, planetary banding obvious and the Cassini
division winked in and out with the seeing. Five moons easy even in the
moonglow and skyglow!




Karl
E.O.H.


Chesmont Astronomical Society - www.chesmontastro.org
Galaxy Log - http://www.youtube.c...r/GalaxyLog4565
Galaxy Log Blog - http://galaxylog.blogspot.com/
HASB - http://www.haveastellarbirthday.com
Telekit (Swayze optics) 22" F/4.5 Dob
Homemade (Parks Optics) 12.5" F/4.8 Dob
Vixen 5" f/5 reflector (new)
TMB/APM 8" f/9 Refractor”The Beast”. One great DEEP SKY achro
ES 6" f/6.5 achro. Good one
Celestron Omni XLT 102 refractor.
Celestron 10x60mm Binos

Gee whiz!!!!!

 

:lol:

 

Please do NOT give him a 10" Dob or 11" SCT.  His old ticker might not be able to take it.

 

Gotta love the enthusiasm, but...

 

- Jim

 

Hmm... how about a 22" SDM dob?

 

The owner of this APM 7" f/6 is actually a very avid CAS observer and is noted for going very deep. So more about his view at the eyepiece here.


Karl
E.O.H.


Chesmont Astronomical Society - www.chesmontastro.org
Galaxy Log - http://www.youtube.c...r/GalaxyLog4565
Galaxy Log Blog - http://galaxylog.blogspot.com/
HASB - http://www.haveastellarbirthday.com
Telekit (Swayze optics) 22" F/4.5 Dob
Homemade (Parks Optics) 12.5" F/4.8 Dob
Vixen 5" f/5 reflector (new)
TMB/APM 8" f/9 Refractor”The Beast”. One great DEEP SKY achro
ES 6" f/6.5 achro. Good one
Celestron Omni XLT 102 refractor.
Celestron 10x60mm Binos



 



#74 De Lorme

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Posted 06 September 2014 - 01:46 AM

Could the quality and manufacturing knowledge of {Meade, Celestron Etc.} fast 6" f/6-5 lens are inferior to Istar?  That's the only solution I can think of.

Remember Roland said that he had a hard time getting quality lens material{from China} not that it was exceedingly difficult beyond his or anybody else

who are experts in making refractor lens capability.  Roland did say that if Istar found a lens manufacture more power to them? 

Did he say anything about Istar didn't have the manufacturing skill.? 

I've yet to see a bad review from Istar.  I continue to hear of those saving there nickels to buy one. 

 

The owner of the APM 7" and James have had a lot telescopes and thus experience. Why not just believe them?

 

De Lorme


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#75 Mr. Bill

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Posted 08 September 2014 - 01:47 PM

Not all Istar purchases go smoothly....I bought a 6 inch f/5 lens set from Istar and received this sample which had scratches from poor cleaning that looked like somebody used steel wool.  :shocked:

 

Turns out this was a return that Istar apparently didn't bother to check out and sent it to me.

 

Sent me a second one that was perfect as far as surface polish but really makes you wonder.....

 

I also have the Celestron (Synta) 6 inch f/5 with much better optics (aspheric) than the Istar.

 

Tried to post picture but don't see option in editor??????


Edited by Mr. Bill, 08 September 2014 - 02:05 PM.







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