6mm TMB II

[paul mc c]

Is any one using one of these in a 12'' f5 dob and if so how do they find the view.

[Adz]

From my experience Paul because you have such a large fast scope, you are going to get quite a bit of distortion at the edges. Some people can live with it, some people cant. On the good side, an object is going to take longer to travel across the view. But when you buy a large dob, the need for better eyepieces is almost expected.

HTH

[paul mc c]

Thats right Adam tried it out last night and the view wasnt good ,a good 50% at the edges was distorted,i just sold an 8mm clone of this eyepiece which showed very little distortion.

[Adz]

Yes the clones are of a higher performance from what people say on here, the step down in magnification slightly could have helped too. You can speak to Spaceboy on here, he has a lot of experience with clones in fast Newtonians.

[Mr Spock]

I have a TMB II 6mm. Works great in the f10 C9.25, really sharp. With the 250mm F4.7 Newt I had it wasn't so good - edges were dreadful and the rest not as sharp as it could be.

[mdstuart]

I have the 6mm TMB on my 250px F5 and to be honest it seems fine to me. Maybe I am not so fussy?

Mark

[John]

I think the original Burgess / TMB Planetaries have better edge performance than the later clones and the Mk II's. The nearest I've found to the original ones are the TS Planetary HR's offered by the German dealer Telescope Services - these are the ones with the blue screen printing on them rather than the more rounded ones with white lettering that they also offer. Unsurprisingly, they are a bit more expensive than the clones and the Mk II's.

[paul mc c]

Thanks every one for the replys,obviously this eyepiece just isnt suited to my f5 scope so will have to replace it with another as i couldnt live with edge view it gives,now what to replace it with!

Paul

[John]

Thanks every one for the replys,obviously this eyepiece just isnt suited to my f5 scope so will have to replace it with another as i couldnt live with edge view it gives,now what to replace it with!

Paul

How about a Tele Vue Radian ?

The TMB's were billed as a "poor mans Radian" when they came out. The Radian's are tested down to F/4.

[Mr Spock]

What about waiting a few weeks for a 6mm Delos?

You could try it out and let us all know if they are any good... ;p

Quite fancy the 10mm myself

[cs1cjc]

TMBs planetaries sell for less than £50 and in some cases less than £40. It is perhaps unsurprising that the Radian at 3 to 4 times the cost gives a better performance as I am sure will the Delos at 5 to 7 times the cost! The planetaries give clean views with reasonable eye relief and are comfortable with no kidney bean effect at night. I have found they give less contrast than an equivalent length abbe orthoscopic, but I am now tending to the view that this is because the large eye lens of the TMB is rather prone to stray light.

Thomas Back, the designer of eyepiece optics wrote:

I tested the eyepieces down to f/6, and the edge of the field still showed a clean Airy disk. The design on the computer shows that it will be very clean even down to f/4. Now remember, a Newtonian will show coma, astigmatism, and curvature of field. So, you have to separate the primary's off-axis aberrations, from the eyepiece, to see how good the new BO/TMB planetary eyepieces are. But at very high powers, you don't use as much field, so you may even find that you don't need a TV Paracorr, with your f/4 and the new TMB planetary eyepieces.

[Adz]

I had kidney beaning with my Planetary, just letting you know...

[andrew63]

The BST Explorer range are very well received by members, i have a 8 and 12mm perhaps the 5mm is one you could consider - but try to get some feedback of users with fast scopes - mine is f9 so hardly a challenge!

andrew

[paul mc c]

I had the BST range which were a very good eyepiece but i was then using a 8'' sct,so dont know what they would be like in a fast scope.

I think i may hold out for a Radian though maybe a 8mm which will probably get used more than the 6mm eyepiece.