Help finding objective lens

[Rich486]

Can anyone help me with a missing objective lens from my old telescope? Any advice would be helpful. Can I get one made if I can’t find one or could it be a standard lens size. Focal length is 1400mm Not having much luck finding spares as telescope is an old one. Thanks 

[Kev M]

Do you meam "mirror" as this is a reflector ?

Or do you mean eyepiece lens ?

 

[Rich486]

No it’s got both mirrors and eyepieces but this telescope is meant to have a lens at the bottom of the focus tube. It will only focus 3 meters away with out it. A few people advised me of this from this forum. It has a thread at the bottom of focus tube so makes sense now

[Kev M]

Just read your other post, it appears to be a Bird-Jones design and its the corrector lens that is missing,

As others have said this will be difficult to source seperately.

It would be possible to get focus by moving the mirror further up the tube ( bit of mechanical work involved ) but the spherical aberration ( it would be a bit blurry )  would  be very bad without the corrector lens.

 

[Rich486]

Ahh ok. Do you think it’s a correcter lens missing at the bottom of focus tube just for my reference? Would that be concaved ? And in your opinion do you think that’s something I wouldn’t be able to buy or get made? Thanks or you help, I am wondering if telescope can be saved or best for the scrap pile!

[johninderby]

Unfortunately finding the right part is going to be nearly impossible and you shouldn’t pay more than a few pounds for one if you could find one.

For comparrison purposes a complete new Skywatcher 114 newt OTA can be had for £40.00.

https://www.astroboot.co.uk/search.php?needle=SW+114

Edited July 20, 2019 by johninderby

[Ricochet]

Given the reports on the quality of that style of telescope it isn't worth looking for a corrector lens. In fact even if you had a complete one the advice would still be to scrap it and buy something else. 

[Rich486]

yes the more I am finding out the more I think it’s not worth the trouble. Luckily I only paid £20. Seems like a nice telescope but what’s the point if it won’t do the job. Thanks for all advice and astroboot link

[johninderby]

There is an old saying.....Don’t throw good money after bad. Better to save up for something a bit better. Say a Skywatcher Heritage 100P at £100.00 or a bit more for a Heritage 130P.