6mm BST, initial thoughts.....

[Orange Haze]

I've had three viewing sessions with this new EP since I received it and thought I'd share my initial thoughts and hopefully get some opinions of others who have also used this EP.

Firstly, it's a size step up from the supplied 10mm EP. Photo below.

Before anything, I should say I ordered this from Sky's the Limit and the service and delivery time were superb.

The EP itself however has so far been a bit of a letdown. It's early days and I need to persevere but..

Jupiter. Was really looking forward to seeing this beast at x200, but of each occasion so far, the best I've seen is the two main bands. The GRS remains elusive, even on a clear moon free night. It has appeared soft, hard to focus and despite the supposed wide field, I find myself chasing Jupiter continuously I attempt to keep the planet fairly central. Anything outside of centre loses clarity very easily.

The Moon. Initially I was fairly impressed, moon had a nice texture about it. However on repeated viewings with and without a polarised moon filter I have found it to be an average view. I've preferred to use my 15mm vixen npl with a Barlow. Again it's softish with a heat haze effect (I'm sure that has a proper name).

Stars. I split Mizar, an easy target I know first session, but so far pretty much every star I point at seems glaring, not sharp at all. I thought maybe this was a collimation issue, but stars are sharp in my other EPs so I am not so sure. It's not been a pleasant experience with stars so far, although the trapezium seemed clearer, maybe the nebula diffused the glare for me. Thanks M42!

Using the EP is also a bit of a pain. Move a mm and bang the view is gone. Again I am sure this has a technical term, exit pupil??, I am still learning the terminology of astronomy so forgive my words here. I've tried adjusting the EP using the smooth twist control, but struggling to make it work for me.

So overall, is it the EP or me? As I say, it's early, only three sessions so far and I may yet find it's sweet spot, any suggestions on how this is done are welcome. I don't mean to do it down, but so far I have been pretty underwhelmed.

Clear skies. Lee.

[ronin]

Sounds like you have the eyepiece in the 250PX and at f/4.7 it will not be exactly friendly to eyepieces. I wonder f that is where the problem lies. Fast scopes tend to need better eyepieces - is there anyone at Sidmouth with an 8mm TV plossl or something better still that is designed for faster scopes?

Alternatively would someone let you drop it into an f/5 or f/6 200P to determine the performance.

One "odd" aspect is that the BST Wideangle is narrower then the BST Staguider, 58 compared to 60 so not a lot but odd to be the "wideangle".

[Orange Haze]

Thanks Ronin. I am lucky to be near the Norman Lockyer observatory so I may see if someone can test it up there for me. As an EP at the budget end I wasn't expecting anything amazing, just not quite as poor as I've experienced so far.

Perhaps the wide angle is something of false advertising..

[AlexB67]

It could just be seeing conditions, I found it very variable tonight during the GRS transit, though some short moments of good seeing.  Give it a few more goes in time and see what you think. I got the 8mm BST starguider, while it is very good, the more I have observed with that and the 6mm Radian,  which if anything should blur the view more is a step above for planetary work in my honest opinion.

What can work quite well in fast scopes depending how friendly/unfriendly this eyepiece is to a fast ratio, try to keep the planet fairly centred in the view. On axis you will get the best results.

[NGC 1502]

Hi Lee. If you are using the 6mm eyepiece in the 250px, then that's 200x.  In good conditions, 200x should give good views, but so often the atmosphere is far from steady,

and a soft view is the result.

Sunday evening I was viewing the double shadow transit on Jupiter with my 10" Dob. The 'seeing' was poor, and I mainly used 120x, and got good views. In better conditions,

the same scope gives sharp views of Jupiter at 170x and 200x, and very rarely indeed 240x.

I'm willing to bet that as long as your scope is well collimated and cooled to ambient then you will get good views of Jupiter at 200x,

but only when the atmosphere co-operates, and that doesn't happen too often. Best views will be with Jupiter not too far from the centre of the field of view.

Even very expensive EPs lose a bit on bright objects if away from the centre of the FOV, when used in a 'fast' scope.

HTH, Ed.

[ronin]

Perhaps the wide angle is something of false advertising..

Not by Alan, they are Wide angle on the Barsta site as well, and Barsta make them, so I guess they all come out marked UWA and no-one has a choice.

[AstroAdam]

5mm in a 250p is definitely right on the edge of usability most of the time in the UK, edging gore towards the soft that the sharp most of the time.  I tend to keep to 8mm or more in my 200p, and that's f/6...

[AstroAdam]

Sorry - I meant 6mm...

It's a pain not being able to edit!

[Orange Haze]

Not by Alan, they are Wide angle on the Barsta site as well, and Barsta make them, so I guess they all come out marked UWA and no-one has a choice.

No certainly not by Alan. Found Alan and the overall service excellent, will use them again. Meant more as a niggle over the manufacturer. But only a niggle.

I think my key will be patience and to pounce on any stable atmosphere one night. Of course it does mean that I am now itching to get another EP between the 6-15 mm range. Poss a 8mm. Astronomy, where the spending never stops. .

[ronin]

Not sure why Barsta mark then UWA, their web site has 2 sets under "Wide Angle" the other is 65 degrees - actually have a useful looking 6.5mm in the group. Wish they gave construction details.

Spending is one side rarely warned of.

When it came to eyepieces I have the set's of BST's, TV Plossls and the WO SWANS.

Then I stopped, decided I had all I really needed, no great urge to get ones like the 82 or 100 ES's or TV's.

A few other individual ones running round that were collected, or came with scopes, but that is it.

[faulksy]

when i had a couple of bsts, they looked a lot different to yours are you sure thats the right model ?

[Paul73]

Keep at it Lee.

I was very disappointed when I got my 8mm. It has taken a couple of months for me to get used to the idea that, for £50, it is always going to have limitations that will be ruthlessly exposed in a fast scope. I expect that those limitations will be even more marked in the 6mm.

Expectations lowered, I am starting to enjoy it more. Saying that, The stray light bouncing around the innards every time you look at something bright is always going to wind me up.

Thanks for the report. I was thinking about the 6mm but will maybe hold off after reading your thoughts.

Paul

[rwilkey]

when i had a couple of bsts, they looked a lot different to yours are you sure thats the right model ?

Hi Faulksy, there are a couple of designs with the BST label on them.  Probably the ones you are familiar with are the BST Explorers/StarGuiders, which are quite different and far superior to the BST UWA's in my opinion.

[faulksy]

Hi Faulksy, there are a couple of designs with the BST label on them.  Probably the ones you are familiar with are the BST Explorers/StarGuiders, which are quite different and far superior to the BST UWA's in my opinion.

didnt realise these were the uwans. your correct robin i was thinking of the exploreres

[chris1485]

Hi,

I have the 4mm version of this eyepiece and in my Zenithstar ED80 (x136) I was dissapointed. It didn't focus very well, the image was soft and appeared a little washed out.

My 15mm NPL plus 4x image mate beat it on Jupiter showing detail the 4mm couldn't resolve.

I have heard though that these eyepieces can be marked up with the wrong FL. I could well believe mine is in fact a 3.2mm. This would explain the poor image. ie. x170 being a little too much for my scope on most nights.

Just my recent observations.

Thanks,

Chris.

[great_bear]

It's probably atmospheric conditions, an uncooled mirror or poor collimation.

Saw a nice quote on CN the other day: "Rule of thumb: If the image isn't sharp, it's probably not the eyepiece..."

Check the online jetstream weather forecasts - if the jetstream is overhead, you can forget planetary viewing for the night.

The BST UWAs may not be as sharp as a good Ortho, but they're not going to look visibly unsharp outside of a critical a/b eyepiece comparison shootout.