Big eyepiece .......

[John]

And you thought that the 31mm Nagler was a beast

The middle one is a Zeiss 4" fitting 100mm focal length eyepiece. It's for sale on a certain US forum. I'm not a member there so I can't see the asking price but it does include a 2" adapter.

This would definitely affect both the balance of your scope and your bank account ........

[Damo636]

That is one big beastie I'm thinking 4'' concrete block to counter balance it and even then my focuser would probably whimper like a baby before falling to the ground in defeat! I would imagine the price would be truly astronomical.

[michael.h.f.wilkinson]

What a beast. For a 5 mm exit pupil it would require an F/20 scope , was it made for the Yerkes Refractor (F/18.9)?

[spaceboy]

LOL and here's me complaining about how big the 31mm Nagler is. I want to see a picture of a 5mm BGO next to it

[michael.h.f.wilkinson]

At least it has a 2" adapter, so I could fit it to my C8, or even the 80mm

[Charon]

OMG it's a monster

[Adz]

Woa thats huge!

[Rob1961]

Arrgh it's going to take over the world run for the hills, seriously that is huge

[Doc]

Ugly critter as well

[Vali x]

that's not an EP,that's an WW2 hand grenade ! jeez...

[michael.h.f.wilkinson]

that's not an EP,that's an WW2 hand grenade ! jeez...

The hand grenade is the Nagler, this is a 105mm mortar shell (or anti-personel mine)

[johninderby]

How about the Siebert 70mm 4.3" eyepiece shown beside a Pentax XL 40mm 2" eyepiece?

http://www.siebertoptics.com/SiebertOptics-eyepieces-observatory.html

Or if you only need a 4" they do an 80mm eyepiece.

John

[Stephen]

Monsters!!!!!

#omgweareallgoingtodie

[twotter]

That's no eyepiece....that's the air filter from a Ford pickup

[Collyer911]

mmmmmmmmm

you know you want to!!!!!!

[pastiche]

That looks bigger than my telescope!!

[BAZ Senior]

Probably snap my scope in two, that's just greedy!

[spaceboy]

Would a large EP of 4" bring there own problems like CA into the mix ???

[umadog]

I think any eyepiece can potentially add CA. I think the degree to which this is likely to be a problem depends on how steeply it's bending the light. More bending means a greater degree of potential aberrations. That's why the olde refractors were all really long focal ratio. Many aberrations become tamed under these conditions. That's the same for mirrors, by the way: less coma at longer f/ratios. That leads me to wonder if, in fact, a long focal length eyepiece such as this would have less likelihood of CA. It's the extreme wide-field designs which are most likely to suffer. They, of course, are carefully corrected for CA.

[Peter Drew]

I recently made a 100mm focus Plossl with 2" fit for a 8" F25 achromat. The eyepiece composed of two 50mm binocular objectives still had the usual 50 degree AFOV but there is no CA and images are very bright and pin sharp across the field.