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Istar 204mm f5.9 review

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#1 39.1N84.5W

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Posted 14 September 2016 - 01:07 PM

Finally got this little beast under some proper dark skies last week. This review is by no means an authoritative critique; rather a gentleman's observation of some very affordable and very nice glass.
First off here's the business end, followed by a home-built OTA cut down for binoviewers. Total weight fully loaded is 29lbs. The feathertouch focuser is a great counterweight to the large objective.
rps20160914_131101_615.jpg
rps20160914_131434.jpg

My interest in big refractors comes from owning and using all kinds of telescope designs. High contrast and pinpoint jewel-like stars always give me goosebumps. Some years ago I had a Meade 178mm refractor. Unfortunately the weight, size, and focuser left me less than satisfied. About 6 months ago I came across the istar company. A few emails to Ales, the owner, and I was on the wait list for a 204mm f5.9 objective.
My astronomy buddy Jeff Blazey offered to see this project to it's completion and I am very thankful for his help!
Down to the main question: false color? Fully opened at 8" there is some color on the brightest objects, but not near as much as a Synta achromat. Stopped down with a 6" aperture mask and the color quickly faded away. Saturn sits against a hard black background, definitely reminding me of the better "ED" refractors from William Optics.
But planetary observing isn't the main reason I bought a 8" objective. Star fields and low power DSO are my main targets. I set my alarm for 3am, mounted the scope on a surveyor's tripod with Giro IIDX alt/az mount, and started out with a 40mm Pentax.
The Pleiades with nebulosity (no filter), thick roping edges and a lace-like curtain of M42, smaller bursting star clusters inside the Double Cluster, and then finally the Andromeda Galaxy at the zenith, now 4am.
Here's where words stop and pure emotion kicks in. I've never seen the Andromeda field with such contrast, definition, and glimmering beauty. The dust lanes were very obvious, with both m32 and m110 showing their own structure. Overall I was covered in goosebumps and shaking my head.
"This isn't a poster, or an image."
I am glad I took a chance with istar and waited for delivery. Refractor objectives of this quality don't come along that often, and the price range puts it in pocketbook of many amateur astronomers.

Attached Thumbnails

  • rps20160914_131305_790.jpg

Edited by 39.1N84.5W, 14 September 2016 - 09:01 PM.


#2 mikerepp

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Posted 14 September 2016 - 03:34 PM

Very nice!   What is your mount for this beasty?  Did you buy it with the feathertouch our was that an add on?



#3 39.1N84.5W

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Posted 14 September 2016 - 04:14 PM

This is an ATM project. My buddy Jeff B assembled it, built the baffling, cut the tube down, painted it, etc.
I mentioned the mount in the review. :)

#4 junomike

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Posted 14 September 2016 - 08:02 PM

What's a ballpark cost and is Jeff currently taking orders!?!?  :wron:

 

Mike


Edited by junomike, 14 September 2016 - 08:02 PM.


#5 39.1N84.5W

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Posted 14 September 2016 - 08:23 PM

The objective sells for just under $2000. As far as Jeff filling orders.... I will let Jeff answer that.

I believe istar sells a fully assembled OTA with sliding dew shield for under $5000.

Edited by 39.1N84.5W, 14 September 2016 - 08:33 PM.


#6 stevew

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Posted 14 September 2016 - 08:55 PM

Interesting review. Thanks for posting.

Glad your enjoying your new scope.

 

Steve



#7 Traveler

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Posted 15 September 2016 - 12:37 AM

Wow, never thought that such a big telescope can use with a Giro II mount.



#8 39.1N84.5W

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Posted 15 September 2016 - 06:29 AM

The giro IIDX has the option of counterweights on the other side, and advertises itself as being rated for 30lbs.

#9 mikey cee

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Posted 15 September 2016 - 09:34 AM

I can fully attest to these comments as very true indeed! Nothing can beat an Istar lens whether factoring in cost or not! :cool:  Mike



#10 havasman

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Posted 15 September 2016 - 02:27 PM

I want to hear your experience observing M33 with that scope. I expect you'll get to it pretty soon. That should be something to see. Sounds like a great scope! 



#11 39.1N84.5W

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Posted 15 September 2016 - 03:15 PM

Yes I did observe M33. It showed a strong circular structure, just on the edge of definition. I was in a green to blue zone... at a black site I'm confident that the increased contrast will really help with dust lanes.

#12 TH1

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Posted 19 September 2016 - 12:41 AM

Just awesome. Is that a 3035 on there?

#13 GlennLeDrew

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Posted 19 September 2016 - 01:23 AM

We're the observations described conducted with a binoviewer installed?



#14 39.1N84.5W

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Posted 19 September 2016 - 07:43 AM

Most of my observations were with the 40mm Pentax. I did a little Binoviewer observing, but felt like keeping the Pentax in.

#15 39.1N84.5W

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Posted 19 September 2016 - 07:44 AM

Just awesome. Is that a 3035 on there?


Yes

#16 denis0007dl

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Posted 20 September 2016 - 01:23 AM

Finally got this little beast under some proper dark skies last week. This review is by no means an authoritative critique; rather a gentleman's observation of some very affordable and very nice glass.
First off here's the business end, followed by a home-built OTA cut down for binoviewers. Total weight fully loaded is 29lbs. The feathertouch focuser is a great counterweight to the large objective.
attachicon.gifrps20160914_131101_615.jpg
attachicon.gifrps20160914_131434.jpg

My interest in big refractors comes from owning and using all kinds of telescope designs. High contrast and pinpoint jewel-like stars always give me goosebumps. Some years ago I had a Meade 178mm refractor. Unfortunately the weight, size, and focuser left me less than satisfied. About 6 months ago I came across the istar company. A few emails to Ales, the owner, and I was on the wait list for a 204mm f5.9 objective.
My astronomy buddy Jeff Blazey offered to see this project to it's completion and I am very thankful for his help!
Down to the main question: false color? Fully opened at 8" there is some color on the brightest objects, but not near as much as a Synta achromat. Stopped down with a 6" aperture mask and the color quickly faded away. Saturn sits against a hard black background, definitely reminding me of the better "ED" refractors from William Optics.
But planetary observing isn't the main reason I bought a 8" objective. Star fields and low power DSO are my main targets. I set my alarm for 3am, mounted the scope on a surveyor's tripod with Giro IIDX alt/az mount, and started out with a 40mm Pentax.
The Pleiades with nebulosity (no filter), thick roping edges and a lace-like curtain of M42, smaller bursting star clusters inside the Double Cluster, and then finally the Andromeda Galaxy at the zenith, now 4am.
Here's where words stop and pure emotion kicks in. I've never seen the Andromeda field with such contrast, definition, and glimmering beauty. The dust lanes were very obvious, with both m32 and m110 showing their own structure. Overall I was covered in goosebumps and shaking my head.
"This isn't a poster, or an image."
I am glad I took a chance with istar and waited for delivery. Refractor objectives of this quality don't come along that often, and the price range puts it in pocketbook of many amateur astronomers.

Impressive scope!

I always wanted to look through 8" refractor, but have never chance....

I am sure you enjoy in it!



#17 39.1N84.5W

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Posted 20 September 2016 - 01:25 PM

From end of focuser, all the way in, to end of objective: 40"
With dewshield: 50"

#18 39.1N84.5W

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Posted 27 September 2016 - 02:03 PM

rps20160927_150154_486.jpg In the wild.



#19 Peter Besenbruch

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Posted 27 September 2016 - 05:30 PM

In the wild.

I heard your poor mount whimpering. ;)



#20 39.1N84.5W

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Posted 27 September 2016 - 06:08 PM

She's doing just fine.

#21 Edwin

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Posted 28 September 2016 - 05:59 AM

Nice scope ! I use a 152 F5.9 achro (fully loaded 22 lbs)  on my Giro II DX without any problems. I'm curious about what you can see extra with this 2" bigger aperture.


Edited by Edwin, 28 September 2016 - 06:02 AM.


#22 39.1N84.5W

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Posted 28 September 2016 - 06:03 AM

I had been using a 150mm f8 Synta and the difference is jaw dropping. A key point is to install a Losmandy saddle on the Giro arm for increased stability and reduced shaking.

Edited by 39.1N84.5W, 28 September 2016 - 06:07 AM.


#23 Jeff B

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Posted 28 September 2016 - 10:21 AM

What's really cool about this scope is that you can use aperture stops.  I noticed the lens was very sharp with 5" and 6.5" stops and of course the CA was significantly reduced as well.  This makes it well suited to high power use.  Me thinks a 140mm stop to be about ideal with this lens.  Even a 7" stop is quite useful though.  

 

Nothing like having 3-4 scopes of different aperture and focal ratios in one that you can choose between at will!  

 

I can only imagine how the double cluster and M42 look through this beast when bino-viewed.

 

Jeff 



#24 jrbarnett

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Posted 28 September 2016 - 10:26 AM

She's doing just fine.

"Just bear down, girl.  Bear down!"

 

:grin:

 

- Jim



#25 BillP

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Posted 28 September 2016 - 10:46 AM

What's really cool about this scope is that you can use aperture stops.  I noticed the lens was very sharp with 5" and 6.5" stops and of course the CA was significantly reduced as well.  This makes it well suited to high power use.  ...  Nothing like having 3-4 scopes of different aperture and focal ratios in one that you can choose between at will!  I can only imagine how the double cluster and M42 look through this beast when bino-viewed.

 

When achormat discussions arise, I find it interesting how so many have the immediate bias on CA and often think of it as a showstopper.  I find it interesting from a psychological perspective; and I often fall into the higher magnification rabbit hole.  But as my observing habit continues to improve and evolve, I also notice that I tend to now shed magnification.  So for the most part, excluding the planets and the Moon of course, I tend to view more in the 50x-100x range than anything else.  And there is certainly no shortage of targets for these low magnifications.  Heck, I have a list of over 2500 doubles where no more than 100x is needed, and to that I can add a list of a few thousand DOS!  Even on smaller DSO while they are briefly interesting at higher powers, they just look much better with their surrounding context so even things like little tiny M57 is simply stunning at 50x or 75x.  Seeing the nebula sitting in its field of space surrounded by other stars really gives it the context necessary to "see" it more effectively for what it is and where it is.  So IMO these super fast achromats are in fact really underappreciated and rare gems because they really do provide incomparable views with beautiful pinpoint star rendering that only unobstructed designs can achieve most easily.

 

Anyway...fantastic looking scope!  IMO, this 8" f/5.9 Achromat teamed with a 100-120mm Apo would be a killer lifetime refractive pairing!


Edited by BillP, 28 September 2016 - 10:47 AM.



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