Need a good lens supplier.

[RAJAH235]

Hi guys 'n' gals,
I would like to replace the 4"/102mm, f6, achromatic lens in my "replacement" refractor.
T'is a bit "fuzzy" around the edges & the brighter objects "flare."
(Sorry for the texhnical talk.) ;)

Would like a nice, little better quality lens, if available.
I've a'Googled my fingers almost to the bone....but cannot find anything suitable.

Anyone know of any suppliers, makers etc?

Might be interested in an Apo but all depends on cost.

Ta mucherly.

Regs, L..

[ausastronomer]

Hi,

Firstly, let me tell you that nothing 1/2 decent is going to be cheap. Secondly, the likelihood of finding something to fit straight in to your existing mirror cell and with the right focal length, will be about as easy as climbing Mount Everest. I would think it would be a far easier, cheaper and better option to sell that scope and buy one of the cheap Chinese APO's, which perform very well for what they are. With a 4"/F6 refractor its focal length is way too short to excel as an achromat, for higher power work, so you are limited there for starters. The Chinese APos are 4"/F8's and work quite well considering their price.

Contact D & G optical. Their smallest size is 5" but they also do custom work. They only do achromats but as good as an achromat gets. Lovely lenses plenty of $$$$

http://www.dgoptical.com/objective.htm

Bob Royce makes custom replacement refractor objectives.

http://www.rfroyce.com/restoration%20work.htm

Slightly cheaper would be Antares Optical in Canada

http://www.antaresoptical.com/atm.htm

Cheers,
John B

[anj026]

Good Day

I agree with John, good lenses are not cheap even at the 102mm aperture. I have made telescopes with lenses from D&G, Antares and Istar and recommend them. I would expect to pay over $350 for a good 4" lens unless you are lucky enough to find a secondhand bargain.

Istar do 4" f10 and f12 lenses but not f6. As John says you may be better off selling the scope and upgrading to a different model. :)

It may be worth investigating whether the lens you have cannot be improved with cleaning and adjusting?

[anj026]

Here is a nice Apo lens, 107mm triplet f6.5. However the cost is 835 Euros plus postage from Germany.

http://www.apm-telescopes.de/apo-107mm-f-6.5-lens-in-cell_proinfo_11329.html

If it was my money I would pay the extra and buy the whole telescope.

http://www.apm-telescopes.de/apm-telescope-apo-astrograph-107-700mm-f-65-with-25-focuser_proinfo_14007.html

Alternatively there is the Skywatcher 102mm f5 achromat for around $400 AUD, 102mm f10 achromat for a bit more, or the 100mm f9 ED for around $1100 AUD. All good scopes for the money, you get what you pay for so to speak.


Or else settle for a homemade achromat using one of the other lens suppliers mentioned above. :thumbsup:

Andy

[anj026]

Here is a surplus B grade 102mm f6.9 lens in cell from Stellarvue for $149 USD. Scroll down the page to see the lenses.

http://www.stellarvue.com/surplus.html

Andy

[jjjnettie]

The Surplus Shed
http://www.surplusshed.com/pages/category/achromats_1.html

[RAJAH235]

Thank you for your replies, John, Andy, jjj.
Will take all under consideration.
(Don't want to sell it, as it's a "gift" (replacing my drowned 10" dob) from a friend who built it & is a member of our club.) ;)

We are looking for a slightly better objective.

Ta muchly.

Regs, L..