where to find Refractor Lens?

kimo · Post by **kimo** » Sun Apr 10, 2011 9:18 pm

Hi,

I already made my Achromatic 80mm F10 refractor, now looking towards to make a larger objective telescope with shorter focal length. anyone know where can I get larger Achromatic / Doublet / ED lens with cell?

Thank you
Kimo

orly_andico · Post by **orly_andico** » Mon Apr 11, 2011 10:46 am

there's this guy on ebay who sells "ED" lenses from China. quality unknown.

istar sells achromatic lenses in various sizes.
http://www.istar-optical.com/istar_017.htm

the 5" f5.5 is $370.

although if i were you i'd just look out for a used ED telescope on astromart. you can get an orion 100ED/skywatcher 100ED for between $400 and $500 USD.

James Ling · Post by **James Ling** » Mon Apr 11, 2011 4:47 pm

Hi Kimo.....

Istar is now working on 150 F5 R75 Anastigmatic Doublets using the new Lanthanum glass.
This time they'll figure it to R75, when means the CA is 75% lesser than the std one.

The price for the lens cell is approx. in the 950-1100 dollar range, and the OTA price should be in 1600 dollar. The finalized price should be out by end of this month. Weight should be in 5-7 kilo range for OTA

The bad news is that the waiting time is aound 60 days, for them to build the first few pcs.

But if you are someone who have a big and tall mount, Istar has one last one left of the 160 F12 Lanthanum APO triplet lens cell.
Is offered to anyone at USD2095, regular price is 2875 dollars or possibly 2975 dollars.
160 F12 is Triplet, not doublet. It is APO triplet using rare Lanthanum earth glass (same glass used in Pentax eyepieces, Nikon lenses, etc..)

REgards

James Ling

orly_andico · Post by **orly_andico** » Mon Apr 11, 2011 6:26 pm

istar does make some good lenses.. but they are made in Eastern Europe and are, frankly, on the expensive side. Of course a 160mm triplet APO for $2100 USD is an amazing bargain (compare the $5000+ TEC 160FL which is also made in Eastern Europe).

but.. i can't justify spending $2100 USD on a refractor. so I will content myself with my 100mm ED.

MooEy · Post by **MooEy** » Tue Apr 12, 2011 10:15 am

i have thoughts of buying that 160 f/12, but where to put it!

James Ling · Post by **James Ling** » Tue Apr 12, 2011 11:14 am

ISTAR made 2 pc of this newly developed 160 F12 Lanthanum APO triplets, and the first buyer will produce a very extensive review and also this article will be published in ATT magazine, possibly Astronomy magazine.

But for our region, we should go for max around F8.

Below is what Ales , from ISTAR told me about my query to him.....

It is impossible to build 150 F5 Lanthanum APO triplet, it would not be APO but only visual semi APO, we can get APO performance at F9 and slower only.

If we have anyone around in our region like to get the F9, perhaps can make a special request to Ales to build for us....

REgards

James Ling

orly_andico · Post by **orly_andico** » Tue Apr 12, 2011 11:30 am

one thing to note is that a 160 f12 would be very challenging to mount.

there's this guy on C-N who was looking for a mount for his 130 f12 Mrozek APO-MAX and eventually settled on the $5K CGE Pro.

a 160 f12 would be even larger and longer. so you're talking about EM400/500 class or AP1200.

cloud_cover · Post by **cloud_cover** » Tue Apr 12, 2011 11:32 am

Actually, what's your budget?

And why do you want to DIY? (as in cost reasons, personal satisfaction, own specifications? etc.)
I think if I had the know-how and the storage space to put it as well as an outside balcony/backward, I'd be interested in the 160/1920 too!

orly_andico · Post by **orly_andico** » Tue Apr 12, 2011 11:40 am

yeah that 160 f12 would be a killer. mounting it... would also be a killer :-P

you'd only need a 210mm ID aluminum tube (hard to find.. the alu shop in King George sells maximum 6" / 150mm tube), some baffles, and a nice 4" Feathertouch focuser :-)

James Ling · Post by **James Ling** » Tue Apr 12, 2011 11:47 am

The 160F12 is almost 5" longer than my 6Ft 8" Istar scope.

I use the G11 losmandy , and the scope is almost touching the ground when it is pointing up.

So you will need to piggy back another scope at the back of the OTA, so as to move the scope further away from the viewing side.

The latest CGEM DX mount will be able to take this 160F12, as it will never be exceeding 40 lbs.

REgards

James Ling