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Making own eyepieces

kev100

By kev100
in Discussions - Eyepieces

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kev100

kev100

Posted
Posted

Hi there,

I've been looking to upgrade my eyepieces, and reading hundreds of reviews, forum posts, Amazon reviews, spec pages ... and then I thought, 'I know, what about making my own' ... just for a bit of fun.

I found this – http://www.dma1.org/~wagner/eyepiece.htm - which looks pretty straightforward, but then ran into the issue of which lenses to buy (and from where). I found this site – http://uk.alibaba.com/product/1926526557-achromatic-objective-lens.html - which seems reasonable, and wondered if anyone has an experience in this respect.

Cheers,

Kev.

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kev100

kev100

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Hiya, the fact that there's hundreds out there is kinda the issue. I've been planning to upgrade for a while, and I'm dizzy with the options/things to consider. 

Just thought it might be a fun project.

:)

Kev 

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LeeB

LeeB

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I love making my own eyepieces, you get to choose exactly what you want, and while buying is great as well , try buying a 64mm 2inch plossl or a 37mm 2 inch or etc....and they look great in turned walnut.

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kev100

kev100

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Hi dude_with_the_tube, LeeB,

Okay, budget-wise I'm thinking about £50 a pop, for a planetary (perhaps 4mm), then a 10-15mm, and then a 25-30-ish mm). I want to get decent, sharp views of planets, neulae and globs, and good wide views of larger DSOs. SO, I've been looking at BSTs, Vixens, TMBs, William Optics/GSOs, that sort of thing. Currently my Revelation plossls are okay, but I'm getting a lot of distortion at the edges on my 25 and 30mm EPs, and though the 9mm is pretty good, I'd like a little more mag when skies allow. I also like the idea of a 2-incher ...

A few years ago, a friend loaned me a home-made EP, I have no idea what its spec was, but the views (through my old 130p) were amazing, and much better than the stock Skywatcher Eps (obviously). I'll try and track him down again and see if I can get its details. Mag wasn't particularly high (I suspect it was in the region of 30-35mm. The fitting was 1.25in, but the body of the EP with the lenses in was easily 2in! I still remember the view of the Plieades through it was staggering, with blue nebulosity, and pin sharp stars ...

Anyway, LeeB's point (thank you, by the way) is exactly what I've been thinking lately. Something in the region of a 30-40mm, 2-inch EP. From what I've read so far, attempting anything with a higher mag is too difficult to do at home, but I've see (on't internet), several pretty good looking examples of the type I'm thinking, and or a lot less than a TeleVue!

Cheers,

Kev.

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NGC 1502

NGC 1502

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Hi Kev, pardon me for saying this, but in post # 7, you mention the possibility of a 4mm eyepiece, and with the SW 250 Dob in your signature, that's 300x.

Most of the time, the atmosphere is not steady enough to give sharp views at 300x.  I think that 200 / 240x is a "more useful more often"  top magnification to have, so for me, I'd be thinking of a 6mm or perhaps a 5mm EP for high power.

Not everyone will agree of course, just my view for what it's worth.

Regards, Ed.

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kev100

kev100

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Hi,

I do agree that going to 4mm might be too much, so yes, 5 or 6mm would probably be better. Still researching at the mo, and as I said in my earlier posts, there's soooo much to consider.

Kev.

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Schorhr

Schorhr

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Hi,

I was considering buying some erfle kits at surplusshed, but for one set the postage was a downer.

Else a 6mm 66 degree UWA for 18-27£ is a great budget eyepiece even if not perfect for f/5, by increasing the distance of the bottom element you can make a zoom and get it to an equivalent of 3mm or so.

Astromedia kits are fun, building plössl/kellner/Huygens and so on, but nothing that matches commercial eyepieces.

with students I've build simple eyepieces out of Fresnel lenses, jeweler's loupe (pretty neat) and other things.

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AndyWB

AndyWB

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Hi,

I do agree that going to 4mm might be too much, so yes, 5 or 6mm would probably be better. Still researching at the mo, and as I said in my earlier posts, there's soooo much to consider.

Kev.

Yeah, I've a 5mm and a 6mm - and I tend to use the 6mm as my highest magnification. In fact, it was bought 'cos the 5mm (which is good still in the 130p) was too much in the 250px.

From what I've read, the distortion you're seeing is maybe unavoidable ? I find myself thinking coma correctors - http://stargazerslounge.com/topic/220519-will-i-need-a-coma-corrector/ - though it seems to bother different people different mounts. For me, I have to look for it to notice it - but I think maybe I don't use the edges of the field that much at low power.

I got a Maxvision 68 degree, 28mm as my low power, wider field eyepiece. It's a 2" one, and was a bargain at about 85 quid. It is lovely, though the eye-rest takes a lot of getting used to, and it does show some coma near the edges. But I guess I'm easily pleased. 

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John

John

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Lovely piece of work Tim, as was the refractor you made it for  :smiley:

Did the eyepiece use an optical design of your own creation or is it a conventional pattern mode to a larger scale ?

@ kev100 (the original poster): This chap seems to make his own eyepieces and seems to stock lenses of all sorts which might be employed to make your own:

http://www.irpoyser.co.uk/irpoysercatalogue4.php

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Reeny

Reeny

Posted
Posted

I found this lens supplier on Ebay.

http://stores.ebay.co.uk/Stock-Optics-Ltd?_trksid=p2047675.l2563

I needed to replace the plastic lenses in the cheap Seben Zoom.

It was hit and miss trying to select the correct focal lengths for the glass.

In the end I went for the cheapest Concave

http://www.ebay.co.uk/itm/110915520768?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649#ht_497wt_1162

and I bought a £2 jewellers loupe to rob out for the 21mm dia Convex.

I have tried it out today in daylight, and the Zoom eyepiece seems to be working OK.

But I wouldn't want to make a hobby out of it.

Too much can go wrong, and you know it's going to be an expensive mistake if it does.

The high quality, large diameter glass is £30 per unit.

So you can imagine the final price of a 7-element home made eyepiece.

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JRWASTRO

JRWASTRO

Posted
Posted

Hi there,

I've been looking to upgrade my eyepieces, and reading hundreds of reviews, forum posts, Amazon reviews, spec pages ... and then I thought, 'I know, what about making my own' ... just for a bit of fun.

I found this – http://www.dma1.org/~wagner/eyepiece.htm - which looks pretty straightforward, but then ran into the issue of which lenses to buy (and from where). I found this site – http://uk.alibaba.com/product/1926526557-achromatic-objective-lens.html - which seems reasonable, and wondered if anyone has an experience in this respect.

Cheers,

Kev.

Greetings Kevin,

Good to hear about your ambitions in this department. Please have a go at making monocentric ep's. if you are successful give us a price and I just may buy some off you.

Jeremy.

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kev100

kev100

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Hi everyone, and thanks for taking the time to post on this. By the way, I did a repost in the DIY astronomy section (thought it suited the topic better there).

I'm still looking at options at the moment, and I've had some good discussions with Ian at IR Poyser (very helpful). The idea began as a possible way of getting decent enough EPs without spending lots of dosh (which I don't have). However, as I don't have any machining facilities myself, I've been looking at what readily available components there are that I could make the barrel out of, etc. All in all, though, to make a 35mm EP using Poyser's lenses (which do seem very good) and some other bits and bobs would cost in the region of about £60-70. Already, though, that's getting into the price range where I could pick up something pretty decent and ready-made on ebay ... Also, there's no way of knowing how it would turn out (might just be a waste of money and time!).

Anyway, for now I've put it on the backburner, and will carry on with my Revelation plossls (they're okay, really). I'm thinking I'll wait till September's Astrocamp in the Brecons and see if I can try out some EPs in my scope, and take it from there.

If I do decide to go ahead with making on, I'll be sure to let you know.   :smiley:

Cheers again,

Kev.

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timwetherell

timwetherell

Posted
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Lovely piece of work Tim, as was the refractor you made it for  :smiley:

Did the eyepiece use an optical design of your own creation or is it a conventional pattern mode to a larger scale ?

Thanks John :)

Had to sell the big refractor to down scale for the move back to the UK but am working on another compact model :)

The eyepiece was a design of my own, though not a cleverly ray traced theoretical one - one arrived at by trial and error and a couple of very basic optical principles. I find the trouble with theoretical designs is that unless you have access to an optical shop, having come up with your design, it's tough to get a specified glass in given diameter and curvature. Also having gone cross-eyed in my youth over theoretical optics at Uni, I find there's a lot more fun in just playing with lenses on a bench than ray tracing on computers 

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timwetherell

timwetherell

Posted
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Lovely piece of work Tim, makes the 31mm Nagler look a bit on the small side, is the diagonal one of yours too?

Alan

Hi Alan. Yes, back when this was made there were few commercial options for a 3" diagonal. Actually I stuffed up a bit with the diagonal - made the two arms unequal under the erroneous assumption that I could simply tilt the mirror to adjust the light path to centre. Resulted in the axis being laterally displaced about 5mm. However, with the optically forgiving long focus eyepiece that wasn't of any great consequence. That's the trouble with art or home made stuff in general. Everything is a prototype. I guess a bit like life really. You make mistakes, mess it up and at the end you know what you should have done :)

all the best 

Tim

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