Help with eye pieces for a 60mm refractor please.

[Cazz]

We have a vintage/classic/ or is it just old, lol, refractor scope 60mm 900mm, which has only 1 eye piece, a Ke22mm and a 90 degree prism, the fitting is 0.965"

My questions are please:-

1) which size eye pieces are we best getting to start us off?

2) I see an adapter to convert it to 1.25" is available, is this worth doing in view of upgrading in the future, or will we loose something on this scope.

3) Which makes should we go far as regards good value, I'm aware there is probably some rubbish available, also our bank account isn't compatible with the best quality.

Many thanks for any help or links.

[Tribal-Wolf]

You don't say what make the scope is, with the price of a half decent scope for beginners at just over £100 it sounds like false economy to buy EPs for a 60mm old refractor uless it's of a decent quality.

[Cazz]

You don't say what make the scope is, with the price of a half decent scope for beginners at just over £100 it sounds like false economy to buy EPs for a 60mm old refractor uless it's of a decent quality.

Hi, It says on it, 'Hunter Astronomical' it looks similar to the older Tasco's, but I've not actually used either so can't comment on the quality. OH seems to think it wasn't cheap when he first had it in the mid eighties when he was 12.

I agree that it would be a waste to buy really good eye pieces, but equally I don't want to waste money on cheap rubbishy ones.

[John]

You need a 1.25" - .965" hybrid diagonal. You can then get the benefit of 1.25" eyepieces in the scope. Over about 20mm focal length the field of view will be cut off by the narrow drawtube but that's not a major issue I'd suggest.

The hybrid diagonals can be bought here in either a budget (plastic) or rather better form:

Star diagonals, Antares mirror and prism star diagonals

In terms of eyepieces, standard plossls would be a decent improvement over the eyepieces supplied with the scope. They can be bought from £20 here:

First Light Optics - Skywatcher SP Plossl eyepieces

You could try a 7.5mm, 12.5mm and a 20mm.

Total investment is around £85 assuming the better quality star diagonal. The eyepieces could be re-used if you get another scope.

[Cazz]

You need a 1.25" - .965" hybrid diagonal. You can then get the benefit of 1.25" eyepieces in the scope. Over about 20mm focal length the field of view will be cut off by the narrow drawtube but that's not a major issue I'd suggest.

The hybrid diagonals can be bought here in either a budget (plastic) or rather better form:

Star diagonals, Antares mirror and prism star diagonals

In terms of eyepieces, standard plossls would be a decent improvement over the eyepieces supplied with the scope. They can be bought from £20 here:

First Light Optics - Skywatcher SP Plossl eyepieces

You could try a 7.5mm, 12.5mm and a 20mm.

Total investment is around £85 assuming the better quality star diagonal. The eyepieces could be re-used if you get another scope.

Excellent, thank you, there's lot to think about, I think I will also look out for some pre used ones, that way if OH doesn't get fully rehooked it's not a big outlay.

He was saying that he used to have Barlow lenses with it, why do people not like these please?

[nightfisher]

have a look on the focuser, the label that will say some thing like d60 f910...if there is also a little circle with a K or T in it, its worth getting some £20 plossl`s for it, as this letter denotes the optic maker.

i would not bother with a barlow for such a small scope

[JamesF]

He was saying that he used to have Barlow lenses with it, why do people not like these please?

A barlow effectively increases the focal length of the telescope. If it doubles the focal length then given the same eyepiece you will get double the magnification. This may seem like a good thing, and sometimes it can be.

However, if you think about what's happening when you increase the magnification, you're spreading the light entering the scope (which will be the same for any given view) over a larger area to get a larger image. That means there's less light at any given point and you get a dimmer image. A barlow makes that worse because glass doesn't transmit 100% of the light that enters it, so every lens the light has to pass through loses some light and also makes the image dimmer. A decent barlow might have two or three lenses, each "stealing" a bit of the light you'd prefer to keep. Not only do you get a dimmer image because of the magnification, but it's dimmed even more because you have more glass in the way.

If you're looking at something very bright, losing some light may be no big deal. It may not be if you're doing photography either, as you can potentially make up for the loss of light with a longer exposure. If you're physically looking at objects that aren't very bright however, you're after all the light you can get and it may be better to get more magnification by using a shorter focal length lens rather than by introducing a barlow.

I'm fairly sure it's not always the case, but many short focal length eyepieces have comparatively little eye relief (especially at the cheaper end of the market). I have a 7mm orthoscopic eyepiece that you almost have to climb inside, for example. If you need more eye relief then it can be useful to use a barlow and a longer focal length eyepiece (with more eye relief) to get the equivalent magnification.

So, barlow's aren't always evil, but they're not always a good thing either

James

[Cazz]

I've been reading loads on here, it's really interesting and I've learnt loads today.

Right, I've looked at the label and all it says is D=60mm F=600mm made in Japan, there is no letter in a circle at all, so I presume that means it isn't high quality.

When you are 12 years old and receive a present you've always wanted and are told it's expensive so you must look after it, your mind paints a different picture of the true value compared to an adult brain.

[Cazz]

James, thanks for that excellent explanation on barlow lenses, it makes perfect sense to me now.

[John]

When you are 12 years old and receive a present you've always wanted and are told it's expensive so you must look after it, your mind paints a different picture of the true value compared to an adult brain.

That is so true and a very good way of putting it

I started with a scope like yours and it certainly showed enough to get me hooked on the hobby.

I stuck with a 60mm refractor for a few years because the cost of upgrading back then was prohibitive on my megre income.

Today excellent scopes are available at comparatively low prices

thank goodness

On a practical note, as your scope has a focal length of 600mm (originally I thought it was 900mm) I'd suggest a 6.3mm eyepiece rather than the 7.5mm I originally proposed.

[Cazz]

On a practical note, as your scope has a focal length of 600mm (originally I thought it was 900mm) I'd suggest a 6.3mm eyepiece rather than the 7.5mm I originally proposed.

Sorry, well spotted, that is my speed typing, or was I distracted, it is a 900mm focal length.

It's my OH's scope and his idea to get back into it, after reading about them and the help I've had here, I'm also inspired, I think he will have competition for it.

Many thanks for the advice on the eye pieces.

[nightfisher]

can you post a picture of this scope, it might still be worth spending about £8 on a hybrid diagonal, also there is a website called uk astro buy and sell, on there you could pick up a couple of cheap plossl`s for about £15-20 for the pair

I recently had a little d60 f910 for lunar grab and go, with hybrid conversion it gave excellent lunar views, and showed jupiter with its 4 moons

[Cazz]

Hi, I put a pic a couple of days ago, I'll put a link up, so not to clutter the forum up with the same image. Sorry isn't a very good pic, it was taken on my phone in a confined space.

http://stargazerslounge.com/welcome/172224-hello-bewildered-cazz.html

That's interesting what you managed to see with yours, I'm definitely looking forward to my first ever look through one.

[AndyH]

Whilst it's of a unknown age or maker, the fact that it has a 'long' focal length for the lens size & being Japan made, is a big boost to it's probable optical quality.

I also heartily recommend a hybrid diagonal and good quality, but cost effective eyepieces. I reckon it should give very nice views.

If you can, post up some pics!

Andy.

[Cazz]

Here is a pic, if you need any more, just let me know.

I have tried to put a link to my hello thread, but it's not loaded for some reason, perhaps my computer skills are limited also, lol.

Apologises for the rubbish photo, it was taken on my phone in a confined space, it is currently mounted on our camera tripod.

[Cazz]

Some more pics,

[John]

Ah - so it does have a focal length of 900mm. I'll reverse my high power eyepiece recommendation back to a 7.5mm then. It looks sort of 1970's / 1980's vintage to me.

[Tribal-Wolf]

Very similar to a Tasco scope I had in the '80s and also my brothers old Prinz Astral 500, which was great for what it cost back then. He actually offered the Prinz to me the other week which is what got me back into wanting a new scope.