3.2mm BST Explorer/Starguider eyepiece- Any good?

[John]

That was quite a night

My 12" dob has excellent optics (1/9th wave PV) but with Jupiter the best contrast and detail are invariably seen between 200x and 265x. I've only had a couple of nights in the past 18 months when when my next step, 318x, was really sharp and contrasy on the giant planet. Saturn and Mars are different, but not Jupiter. I'm typically using Ethos and Pentax XW's.

I see floaters when I use my 3mm Radian eyepiece but they are on the right side of accepable. I've owned a 2.5mm Nagler but, lovely though it was, the floaters dominated the views. It was also too much power for the scopes I owned then, and now for that matter.

[Charic]

I put the Dob outside, wow! its bright in my garden tonight,  what with the direct street lighting and the full Moon, but what the hell, Jupiter is  so enticing, and I wan't to test the 3.2mm on the Moon. The 3.2mm worked as well as expected on the Moon considering the conditions, plus the Mrs has the exhaust pipe out the back door from the tumble dryer, so far from perfect conditions.

With Jupiter,  I could see the two weather bands, but I wasn't able to discern   any real detail tonight, and my scope was only fast cooled for 15 mins, using my own fast cooling pipe. and de-focussed,  little turbulence was observed?

I  also Barlowed my WO6mm and compared with  the 3.2mm on Jupiter, but seeing was not so good., but I felt the 3.2 was brighter! maybe less glass in the optical train?

On the Moon, the 3.2mm was what I wanted, and don't regret the purchase.

What has surprised me tonight is the clarity offered by  my new Plossls?  £33 for three  EP's. Their  just  stunning under the present conditions, nice sharp/clean image for my  eyes, and yet  I turned down a TeleVue 8mm? 

I hope to get to a truly dark site soonest, weather/time  permitting before the nights start getting lighter here, to give all my EP's a full comparison. 

Nothing technical in my tests, they either work for me or they don't. 

[FLO]

What has surprised me tonight is the clarity offered by  my new Plossls?  £33 for three  EP's. Their  just  stunning under the present conditions, nice sharp/clean image for my  eyes, and yet  I turned down a TeleVue 8mm? 

For overall performance <£50 at around 9mm or longer nothing - nothing - beats a well-made Plossl. 

Steve

[John]

I was getting a nice crisp image of Jupiter here tonight but the hazy cloud layer prevented my 4" refractor from cutting through to the finest Jovian details. The GRS transit was nice though

I was comparing my 3mm Radian with the 8mm TV plossl and the 2.5x Powermate (3.2mm). Nothing much in it apart from 10 degrees FoV and around 14mm of eye relief !. Nice views from both combos at 207x and 221x

Glad you are pleased with your new plossls Charic and had the opportunity to give them a run out

Edit: Back on the topic Donkeiller's original post, I reckon your 90mm triplet will be able to make good use of a 3.2mm eyepiece. When the seeing conditions are good it would be very useful for the Moon, double stars, Saturn, Mars and possibly even Jupiter when the seeing is very good.

[Charic]

Steve.......When I tried the 8mmTV, the conditions, apart from the winds, were much darker and just better all-round.

First and foremost though, the eye-relief was too short for comfort, compared to my BSTs, yet I feel totally comfortable with this 9mm Revelation Astro Plossl.

I would have thought the TeleVue to be the better EP, perhaps it is! but at the end of the day, telescope optics, the eyepiece itself and your own eyesight are what counts.

[John]

The GSO 9mm plossl has eye relief of 6mm wheras the TV 8mm plossl has 5mm. Those are pretty much the standard specs for plossls of whatever branding / manufacture, + or - half a mm.

The stiffer eye cup of the TV plossl will not help access it's field of view either.

If you are not comfortable using an eyepiece, it's optical quality becomes irrelevent.

By trying things out you learn what works for you

[Donkeiller]

I was getting a nice crisp image of Jupiter here tonight but the hazy cloud layer prevented my 4" refractor from cutting through to the finest Jovian details. The GRS transit was nice though

I was comparing my 3mm Radian with the 8mm TV plossl and the 2.5x Powermate (3.2mm). Nothing much in it apart from 10 degrees FoV and around 14mm of eye relief !. Nice views from both combos at 207x and 221x

Glad you are pleased with your new plossls Charic and had the opportunity to give them a run out

Edit: Back on the topic Donkeiller's original post, I reckon your 90mm triplet will be able to make good use of a 3.2mm eyepiece. When the seeing conditions are good it would be very useful for the Moon, double stars, Saturn, Mars and possibly even Jupiter when the seeing is very good.

Thanks John.

[jetstream]

For overall performance <£50 at around 9mm or longer nothing - nothing - beats a well-made Plossl. 

Steve

10mmBCO?

[FLO]

For overall performance <£50 at around 9mm or longer nothing - nothing - beats a well-made Plossl. 

10mmBCO?

The orthoscopic is a superb eyepiece and if we were assessing 'absolute optical quality' then a well-made orthoscopic beats a well-made Plossl, by a gnat's whisker. But, as Charic demonstrated, that doesn't amount to much if the eyepiece isn't comfortable. An orthoscopic has less eye-relief and less FOV than an equivalent Plossl and most (like the Japanese-made 10mm BCO) cost over £50 so for "overall performance <£50" I'll still vote for the Plossl

Steve

[YKSE]

 An orthoscopic has less eye-relief and less FOV than an equivalent Plossl and most (like the Japanese-made 10mm BCO) cost over £50 so for "overall performance <£50" I'll still vote for the Plossl

Steve

Are you sure about about eye-relief(ER) part? My impression is just the opposite, i.e. orthos have better eye-relief than plossls for the same focal length, better ER and a little advantage over the symmetrical plossls in central sharpness, making orthos slightly more favorite than plossls among planetary observers.

[FLO]

Are you sure about about eye-relief(ER) part? 

I was until you said that 

It has been a while since I have used Plossls but I still have my orthoscopics. Both offer eye-relief around 80% of the eyepiece focal length but, in my experience, my orthos offer a little less than the Plossls I have used. 

My impression is just the opposite, i.e. orthos have better eye-relief than plossls for the same focal length,

Okay

 

... a little advantage over the symmetrical plossls in central sharpness, making orthos slightly more favorite than plossls among planetary observers.

Yes, for absolute optical quality orthoscopics win. The design was originally developed for microscopy. Zeiss wanted an eyepiece with the lowest possible aberrations for precise measurements on a microscope slide. The ortho offers remarkably high contrast, colour correction and freedom of distortion, beating eyepieces costing many times more, but even if the eye-relief is near-identical to a Plossl the FOV is still restricted to around 42-degrees and the BCO orthoscopic mentioned earlier costs over £50. 

There are of course exceptions, modern designers have taken liberties with both the Plossl and ortho design, but for me to be more specific I'd need to start mentioning brands and I would rather not do that 

HTH, 

Steve

[nightfisher]

I have to say i have a good 6.3mm TAL plossl that i really dont like or get on with, but have used it in the past...........yet i can use a 4mm circle T ortho and regularly use my 5mm ortho 

[FLO]

I have to say i have a good 6.3mm TAL plossl that i really dont like or get on with, but have used it in the past...........

I found the eyecup was rather deep on that one.

Eyepiece choice is very subjective but I don't think I have ever been impressed with a Plossl with a focal length less than 9mm. 

yet i can use a 4mm circle T ortho and regularly use my 5mm ortho

Is that the volcano-top model? My first eyepieces were all secondhand orthoscopics. They were distinctly unfashionable so cheap as chips and readily available but optically very good

Steve

[nightfisher]

I found the eyecup was rather deep on that one.

Eyepiece choice is very subjective but I don't think I have ever been impressed with a Plossl with a focal length less than 9mm. 

Is that the volcano-top model? My first eyepieces were all secondhand orthoscopics. They were distinctly unfashionable so cheap as chips and readily available but optically very good

Steve

Yes plossl`s at 9mm and above are a joy to use, and i would agree that they are still superb value for money and very effective in so many different scopes

Yes the 4mm is a volcano top and very usable on the right nights, we just dont get many "right nights"

I think this highlights why eyepiece choice is so personnel and very subjective   

[Andy101]

Hi,

Just been looking for a Planetary eyepiece all day and came across the BST 3.2mm Starguider eyepiece in the attached review and bought it immediately. Picked it up for £39.99 plus £3.95 shipping. Looking forward to trying it with my 10 inch (f/5) Lightbridge.......

http://www.swindonstargazers.com/beginners/eyepieces.htm

 

[Charic]

My 3.2mm was bought more so to build/complete the set, knowing that I'd be pushing the limits of this scope, but found it works well on the Moon. If they produced another Starguider  this week I'd buy that too?

I'd  class a 6mm as my high powered eyepiece, but have found the 8 and 12mm BST's  get the most use, simply down to the conditions, but when its good, the 3.2mm does work well on the Moon, but I've not tried anything else, just too powerful, making tracking an issue.

The  3.2mm is close to  pushing your scopes  limit , the 5mm BST could also prove interesting, on  f/5 scope, but you may see the scopes coma at these power's.

From your supplied link, It was also Robins review that prompted me to buy the 32mm Panaview.
One thing for sure with the BST, you wont know unless you try. 

[Red Dwarfer]

BST are a great range - check out these Orthoscopic lenses on eBay https://www.ebay.co.uk/itm/Ascension-Super-Abbe-Orthoscopic-Eyepiece-4-8mm-UK/322899883041?hash=item4b2e553421:g:1x8AAOSwvR5aFteE

[Charic]

I've  tried the Baader BCO's, but look at that tiny eye lens on the Ascension, that would be uncomfortable.

[BillP]

On 1/29/2015 at 09:10, FLO said:

That is a good point, using both eyes does help  

 

Very true...I notice this when binoviewing.  However, I think exit pupil limits are highly variable, depending on the person and their physiology, and the target being observed as well.  When doing planetary observing, I will go to .5mm exit pupil, but prefer around .65-.75mm.  This is for Saturn and Jupiter.  Mars is a different story and it can take a lot of magnification and still show well.  So I will go as low as .3mm exit pupil on Mars, and find it highly enjoyable.  And the Moon is a different story still and I will push it to .2mm exit pupil for my Moon-walk experiences   I am in my 60's, but floaters are not a big problem.  When they do pop up it is usually more on Lunar observing as opposed to planetary.  And when they do float into view, especially dead center of the view, I just tilt my head and give it a few light bumps with the palm of my hand and that jostle moves them out of the view right away.

[Mak the Night]

If you mean this 3.2mm StarGuider:

I don't see why it wouldn't work in a refractor. It gives me an 0.53mm exit pupil on my Newtonian when lunar viewing. It gives a very sharp, clear and highly contrasted view. I recommend it.

[rwilkey]

The 3.2mm StarGuider, I have found, is only really useful on the Moon and gives good sharp views in my f/9.  Recommended if you like to study the Moon in comfort!

[Stu]

On 09/03/2018 at 00:53, Charic said:

on  f/5 scope, but you may see the scopes coma at these power's.

Coma is worse at lower powers, you are less likely to see it at higher powers.

[Stu]

21 hours ago, Mak the Night said:

I don't see why it wouldn't work in a refractor.

It totally depends on what sort of refractor you are using.

Stick it in an f5 Genesis and you get a useable 0.64 exit pupil and x156. Pop it in a f15 4" and you get a 0.21mm EP and a somewhat unusable x468. An eyepiece has to be taken in context with the scope it is being used with.

For the OP, x390 with 0.64 EP should be useable for lunar and doubles on very steady nights.

[Charic]

2 hours ago, Stu said:

Coma is worse at lower powers, you are less likely to see it at higher powers.

Yes your right. ( and looking back, not sure why I edited )

Coma does look worse at lower powers, but surely that's down to the field of view rather than just power in use?
Would a high power 6mm 72° afov not show any coma, I'm sure the Delos did on my scope? 
The larger the field of view, and the further off axis your view allows, many Stars may appear to show visually as little comets, unless the telescopes coma is controlled somehow?
I agree, coma can be less noticeable using smaller focal length eyepieces with their associated smaller fields of view, yet some folk may still find coma, if thy look for it!
 

[Stu]

1 minute ago, Charic said:

Yes your right. ( and looking back, not sure why I edited )

Coma does look worse at lower powers, but surely that's down to the field of view rather than just power in use?
Would a high power 6mm 72° afov not show any coma, I'm sure the Delos did on my scope? 
The larger the field of view, and the further off axis your view allows, yes, many Stars will/maybe appear to show visually as little comets, unless the telescopes coma is  controlled somehow?
I agree, coma can be less noticeable using smaller focal length eyepieces with their associated smaller fields of view, yet some folk may still find coma, if thy look for it!
 

I'm not totally sure of the answer Charic  

I believe, say, a 6mm 42 degree afov eyepiece would show less coma than a 6mm 100 degree, but I think that the focal length probably has more of an effect i.e. A 21mm Ethos would show significantly more.

Needing some dob boys to come to the rescue hear