Help! Is it my eyes?

[jabberwocky]

last night i tried out my new eyepiece for the first time, its a 32 mm skywatcher SP plossl.

my problem is im having isuues looking through it. as soon as i get my eye close to it, it goes black and i cant see anything through it, and it gets even worse if i use it with my meade shorty barlow, that combination is hopeless, everything goes black with my eye about 2 inches from it.

now i realise these arent the best eyepieces in the world but are at least a step up from the standard ones supplied with the scope.

so what is the problem?

my eyes?

are there any issues with it being a 32mm?

defective eyepiece?

what am i doing wrong?

[Adrian]

Sounds like 'kidney beaning' or eyepiece blackout. Search the forums and you should get some information.

Some eyepieces seem to be more sensitive to eye placement than others. A 32mm plossl will have quite long eye relief (around 24mm from the front lens) so putting your eye too close to the front lens will cause this - try looking from a bit further back.

[swamp thing]

Hi

That'll be, your getting too close to the eye lens.

A Barlow lens will exaggerate this effect, making it worse.

Just don't "crowd" the eyepiece so much.

A lot of longer focal length eyepieces suffer from this.

Regards Steve

[NGC 1502]

what am i doing wrong?

Would fully agree with previous posts.

Any eyepiece can give 'kidney beaning' if your eye is inside the

max eyerelief. But that is much easier to do if the eyepiece has

very long ER, like the 32mm Plossl. Eyepieces with very short ER

don't have this issue, because you cannot get your eye too close

to be inside the ER.

Just back off a bit from the 32mm, and you will be fine.

Regards, Ed.

Edit - this won't help you, but Televue recognise this issue, and

have this http://www.televue.com/engine/TV3_page.asp?id=158

to sort the problem.

[lw24]

I've got the same eyepiece, and have the same problem, I think it definately needs longer eye relief.

[jabberwocky]

'kidney beaning' discribes exactly what I'm seeing, thought it would be an eye relief issue but blimey how far away do I need to be? I need opera glasses to see down the eyepiece lol. Now I know it's not a faulty eyepiece I'll work at it and see how I get on, cheers guys.

[John]

The eye relief on my Tele Vue 32mm plossl is stated as 22mm - yours will be similar to that I reckon, plus or minus a mm or two. The rubber eyecup on the Tele Vue is not 22mm deep however so you need to "hover" your eye a little way above the eyecup which does take some practice.

I guess this is where eyepieces with twist up eye cups score - you can adjust the eye cup to be just at the right height so you can "hit the spot" each time, so to speak.

[jabberwocky]

Time for some DIY on the eyepiece me thinks.

You would think the adjustable eyepiece thingy would match the eye relief wouldn't you

[swamp thing]

You would think the adjustable eyepiece thingy would match the eye relief wouldn't you

That would make sense, but often they use the same rubber eye cups on a whole range of eyepieces ( cheapskates ).

Regards Steve

[John]

There are low cost eyepieces that use twist up eye cups. Off hand I can think of:

- Vixen NPL's

- TMB Planetaries and their clones

- BST Explorers

Plus there are probably others.

The mechanism is more complex to make than a simple rubber eye cup so it adds a bit to the price I guess.