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BST 4mm Eyepiece 58°


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I am considering adding a 4mm EP to my collection and was wondering if anyone has had experience of the BST 4mm:

http://www.ebay.co.uk/itm/1-25-4mm-58-Degree-BST-Wide-Angle-Eyepiece-/160889646462?pt=UK_Telescope_Eyepieces&hash=item2575c52d7e

I seem to recall that members of this site have reccommended BST EPs in the past as being value for money so any feedback on this EP would be appreciated. I realise that at this price I can't expect wonders but I suspect that, as a fixed fl EP, the performence would be better than the combination of my Baader 8mm Hyperion and Celestron Ultima 2x Barlow. Also a physically smaller EP like the BST would be more suitable for my Heritage 130 than the Baader/Barlow combination!

There is also this option although more expensive - any experience with the Vixen LV 4mm?

http://www.ebay.co.uk/itm/Vixen-Optics-Lanthanum-LV-4mm-1-25-Eyepiece-Product-Number-3715-/221320250134?pt=UK_Telescope_Eyepieces&hash=item3387b70316

I should mention that I am considering a 4mm eyepiece for moon and planetary observation mostly although smaller DSOs might benefit from the higher magnification - always assuming we get some decent skies sometime this century!!!

Obviously any other (printable!) suggestions are welcome.

Kind regards

Roger

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I think that 4mm BST is the same EP I got (under different brand name) for my kids' miniDob. Same specs, same look. I have only tested it on terrestrial targets briefly, so my experience is limited, but it seems very nice. When the kids get first light on stars I could say a bit more. I had two LVs in the past (7 and 9mm) and they were very nice and comfortable EPs. In terms of performance, my two LVs were a close match for the TV Radians I got later (but they have the performance over 60 deg rather than 45-50 deg). The Radians were ousted only by the Pentax XWs and an XF.

Whether 4mm is a focal length you will use a lot depends on your scope. In your 6" F/5 it should be very useful on planets and the moon, and perhaps on the brightest planetary nebulae (I used my XW7 in my F/10 scope on the Eskimo Nebula, but that was pushing it; the XW10 was OK, however).

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I think that 4mm BST is the same EP I got (under different brand name) for my kids' miniDob. Same specs, same look. I have only tested it on terrestrial targets briefly, so my experience is limited, but it seems very nice. When the kids get first light on stars I could say a bit more. I had two LVs in the past (7 and 9mm) and they were very nice and comfortable EPs. In terms of performance, my two LVs were a close match for the TV Radians I got later (but they have the performance over 60 deg rather than 45-50 deg). The Radians were ousted only by the Pentax XWs and an XF.

Whether 4mm is a focal length you will use a lot depends on your scope. In your 6" F/5 it should be very useful on planets and the moon, and perhaps on the brightest planetary nebulae (I used my XW7 in my F/10 scope on the Eskimo Nebula, but that was pushing it; the XW10 was OK, however).

Thanks for that Michael.

The BST is speced at 58° but I guess it depends on how much of the FOV is sharp?

I kinda expected the Vixen to be better quality and not just because of the price but maybe the limited FOV rules it out?

I am pretty new to this but if you have a 8mm and use it with a x2 barlow its the same as a 4mm..I think it could be pushing it with a 130 though..

SG2013

As I said in the original thread, although I could use the 8mm+2xBarlow it seems to be the general opinion that a fixed focal length EP beats a Barlow combination on performence.

Also the Baader Hyperion is massive when attached to the 130 Heritage and outright ridiculous when a Barlow is added. The scope is totally nose-heavy and unbalanced and the weight is probably bending the "flex".

Kind regards

Roger

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