How do I source a WO 66mm F6 Lens ?

[astronobob (Bob)]

Hi Astro-lianos,

Im thinking of replaceing this lens as it has kinda seen bettera days !
I bought it relitively cheap many thousands moons ago as it already had some coating damage and has worsened considerably since.
Or maybe Lenses like these can be recoated
I havent even checked if its a double are triple lens system and if need replacing or coating - id assume it be done to only the front lens ?

Any insight/weblinks appreaciated muchies

[Steffen]

If it's a Petzval scope it'll have a doublet at the front and another doublet further back.

I'm not sure it'll be worth re-coating the front element, the whole scope would have to be sent in for the subsequent realignment.

Can you actually see the effect of the damaged coating at the eyepiece?

Cheers
Steffen.

[N1 (Mirko)]

You are certain the actual coating is damaged.

Otherwise I might have said this looks like it might actually clean off.

[dannat (Daniel)]

i think either lens/coating will be cost prohibitive, clean as best you can with something like acetone & just keep using- if the coating bothers you you might use something stronger like cerium oxide [but be careful using this]

[SteveInNZ]

What did Williams Optics say ?

[astronobob (Bob)]

Appreciate much all the responce guys !
The marks/issue as seen it 1st post pic is definately on the front surface of the main objective lens, i can feel it with fingers.
So i gave it a clean with some Lens fluid - it seems the marks are from where the coating has lifted as when I rubbed with lens cloth & fluid, more coating has come off - have nothing to loose really, so I just kept cleaning and all the coating is Now off Prob not the best move but
That was my choice and no fault of anyone but me & I can totally live with it, so, no dramas at all !
The Objective Lens now actually sports a high reflective appearance - like reflective Sunglasses or car window tint - cant see in, but can see out = one spunky scope but will obviousely be loosing the light that is reflected, not much i assume as it still looks ok through it in daytimg with eyepiece - ill get around to test it at night !

I wanted to know my options about correcting the issue as 400mm is a nice wide field, but will also be use as a guidescope with the ED80 with Reducer = approx 500m

Anyway, Here are some astro-pics I took way back in 2009 when 1st tested it - mind you I was definately just the beginner back then and only equipped with a 400Dslr
The images show some rather bad Blue Halos, at 1st thought, may have been fog/dewed lens but not the case, hence maybe the lifted Coatings were creating the halos - Would like to see now if it is, no coating at all

1st is full frame of Eta, no processing on any of these.
2nd is a full pixel crop of Eta
3rd is full pixel crop of the Lagoon taken next night

I havent spoken or checked out anything with WO guys tho I may have a squizz around if need & when time permitts
Thanx again and for any further insight guys

[dannat (Daniel)]

the WO 66 i had was certainly not APO -had blue CA when photograpng thru it

mind you WO is usually pretty good -i had a problem with a used binoviewer of theirs -sent it to them -they collimated for me & all i had to pay was return postage..pretty good seeing as though i wasnt the original purchaser -problem is i dont think they source 66mm lens anymore ..you could ask for a discount of the new 70/71mm units

[astronobob (Bob)]

Thanx Daniel - I may check it out

[anj026]

The 70/420 lens is available here; http://www.teleskop-express.de/shop/...ble-mount.html

The price of 199EU can be reduced by 19% as we don't have to pay their tax. Then you need to convert to AUD and add postage. I think you might get it for around $290 AUD landed in Australia. But then it might not fit your tube?

[Vostok-1 (Yuri)]

Convert the scope into a solar scope.

[ericwbenson (Eric)]

Originally Posted by astronobob

but will obviousely be loosing the light that is reflected, not much i assume

Only 4% loss per uncoated surface, and since it is the outermost surface it will likely not cause any haloes.
Best,
EB

[astronobob (Bob)]

Originally Posted by anj026

The 70/420 lens is available here; http://www.teleskop-express.de/shop/...ble-mount.html

The price of 199EU can be reduced by 19% as we don't have to pay their tax. Then you need to convert to AUD and add postage. I think you might get it for around $290 AUD landed in Australia. But then it might not fit your tube?

Yeah Thanx Andy - might be worth considering if it fits exactly - on the otherhand, doing mods to get it to fit is a bit daunting, speshly if that lens casing is biggier than the tube ?
Appreciate the link mate, and Ill prob see how it performs as it is for now, may be fine, may not ? Just need to get a chance
,
,
,

Originally Posted by ericwbenson

Only 4% loss per uncoated surface, and since it is the outermost surface it will likely not cause any haloes.
Best,
EB

Hey cheers for that Eric, Hope your right, on halo account

[RobC (Rob)]

I am only a novice , but suggest you use a UV filter to get rid of the blue halos around the bright stars. The blue halos are coming from the ultra violet (not visible ) end of the spectrum.

Cheers

Rob