Where to buy 30 to 50mm objective lens

[PurpleFringe]

Hello SGL,

Anyone know where I could buy a 40 or 50mm objective lens to play with? I'm wondering about building my own finder scope. Preferably f5 or f6 - not too challenging for eyepieces.

Alternatively I could try buying a cheap second hand pair of binoculars, anyone know what focal length a typical 8x40 binocular objective has?

Many thanks

Andrew

[FraserClarke]

Binoculars are typically about 200mm FL I think (certainly the ones I have taken apart have been!). Probably the cheapest way to do it.

There are quite a few optics suppliers around. Some of the bigger ones, who certainly have the sort of lens you're looking for;

http://www.edmundoptics.co.uk/optics/optical-lenses/achromatic-lenses/

http://www.thorlabs.de/navigation.cfm?guide_id=12

[laser_jock99]

Old binoculars. Plenty of pairs of  bins on e-bay for 99p + postage.

[bambuko]

...Plenty of pairs of  bins on e-bay for 99p + postage...

You must be joking...    or using different ebay

The only stuff I can find there is usually "vintage" (with a price to match) or has £20 postage.

I have managed to get pair of 7x50 Prinz bins in a local charity shop for £10 though (perfect for the finder I guess?)

[Stu]

I've got a couple of old bino objectives you are welcome to have if you want. Nothing special, probably 40mm if I remember correctly, might just let you experiment without spending anything. PM me if you would like them.

Stu

[PurpleFringe]

Thanks everyone.

The lenses from edmund and thor are a bit pricey - maybe if I turn out to be really good at making finder scopes...

I did look at binoculars on ebay before posting, sounds like my second best option.

Stu - very generous offer, thank you. Sounds like an unbeatable option. I'll be in touch.

Andrew

[kc0yef]

 surplusshed

http://www.surplusshed.com/pages/item/l1913d.html

[bambuko]

 surplusshed

http://www.surplusshed.com/pages/item/l1913d.html

that's fine if you are in US, but original poster is from UK and afaik there is no equivalent shed in UK?

[kc0yef]

Surplus Shed will post it  try their ebay store and ask there if you can't go to the web site

http://www.ebay.co.uk/usr/surplusshed

[bambuko]

Yeah   it's not the first time I get this answer... same for other hobbies as well, and if you absolutely have no other choice than you swallow hard and pay, but...

by the time you pay postage, insurance, duties, handling charges, tax, bank charges, exchange rate charges, etc, etc it only makes sense for high value items (for small ones it can double or treble the final/delivered cost).

and... of course it's all fine if there are no issues, but as soon as you want ot return the item because of quality or other problem, you might as well not bother

I've been there many times before and my experience of long distance shoppping is "mixed"    to say the least...

In my personal view (YMMV) buying from abroad is a bit like investing - only get involved in it if you are prepared to loose a lot (all) money involved.

Having said so, this forum is international rather than purely UK, so your suggestion might be useful to some.

[kc0yef]

 I buy abroad all the time peoples experience is different however surplus shed's lens' are 

Item No: L1913D
Price: 60pence  

shipping would be £3

[PurpleFringe]

Hi everyone, just an update to this thread.
 
I ended up buying some 10x50 binoculars on ebay for £10 delivered. I measured the focal length of the objective as about 205mm, which makes them about f4, quite fast! The view through the binoculars is not particularly good, quite cloudy. I think the main problem is dust or grime in the prisms / eyepiece because the objective is reasonably clean and when I line up my own 20mm superview eyepiece the image is lovely and clear. And wider - which is what I wanted. Definitely not sharp to the edge though, f4 is a challenge my eyepiece isn't up to. Still.
 

I'm busy making an OTA from plywood for it now, square and oversized. If I ever finish it I'll post something about it.

Thanks for the post about surplusshed, always good to find new sites that could be useful someday.

[callump]

Sorry, came late to this thread, but might be useful for others... you could try I R Poyser  - quite a lot of optical goodies, uk based.

http://www.irpoyser.co.uk

Callum

[bambuko]

Another Surplusshed option for UK is this:

Phil Dyer Astrophoto

Apparently "...All of Surplus Shed's optics catalogue is available..."

It also promises "...UK and EU customers can purchase Surplus Shed items from this website, with considerable savings in shipping charges (post-free to the UK), and you will not have to pay VAT and import duties payable on delivery, or Post Office duty collection charges. 14 day money back guarantee, with returns to UK supplier..."

It all sounds very good, so I was wondering if anybody used the services of Phil Dyer and in particular surplus hed stuff?

[saac]

Another Surplusshed option for UK is this:

Phil Dyer Astrophoto

It all sounds very good, so I was wondering if anybody used the services of Phil Dyer and in particular surplus hed stuff?

I'm a frequent user of Surplus Shed having bought direct  from their US site, most recently components to build an interferometer and spectroscope. I would have no hesitation whatsoever in doing so again.  Items delivered are of high quality, arrive on time and are very competitively priced, shipping costs are fair.  Don't see why you would need to go through a third party, but that is just my opinion.

[NickK]

Binoculars are typically about 200mm FL I think (certainly the ones I have taken apart have been!). Probably the cheapest way to do it.

There are quite a few optics suppliers around. Some of the bigger ones, who certainly have the sort of lens you're looking for;

http://www.edmundoptics.co.uk/optics/optical-lenses/achromatic-lenses/

http://www.thorlabs.de/navigation.cfm?guide_id=12

Although expensive, I can vouch for thorlabs - fast (next day) delivery and beautifully made (as you'd expect!)

However I've been eyeing up some surplus shed optics for the initial optics.