2" eye pieces

[steviebee]

I have just returned from an 18 day break in south West France. To say I was disappointed is a bit of an understatement. Out of all that time I could only get out for 3 nights( rain and overcast  ). Even so I enjoyed what I could view. Managed to see Saturn's Cassini Divide and 2 possibly 3 of her Moons. Some excellent views of our Moon ( haven't got a clue what I was looking at, must get a good book) I have 3 eyepieces, a SW 25mm and 10mm, both came as standard with my scope (SW 200p). I also purchased a SW 6.3mm SP series super Plossl( all eyepieces 1.25"). My problem is I managed well with the 25mm and the 10mm was ok, but could not see anything with the 6.3mm. I wear glasses for distance( I tried viewing with and without glasses, same result). I was wondering if I used 2" eyepieces for the scope it would help with what I can see, or should I just use wide field of view eyepieces.  Please bare in mind that I am very new to this Astro stuff, so go easy on me with your replies  .

Steve.

[John]

HI Steve,

The only advantage with 2" eyepieces is that they can show a wider field of view than 1.25" ones of the same focal length. Their advantage in this department only really kicks in when the focal length of the eyepiece exceeds around 18-20mm or so.

The 6.3mm plossl should have given you very nice views of the Moon and Saturn at 158x - very much well within the capabilities of the scope and I can't really understand why you could not see anything through it, especially as the 25mm and 10mm were working OK.

Better quality eyepieces do show clearer views but you should be seeing reasonably well with all the eyepieces you currently have. Probably best to sort that out before you invest in more eyepieces.

After you get, say, the Moon nice and clear with the 10mm eyepiece does it just literally disappear when you tried the 6.3mm plossl on it or did you see something but it was not obvious what it was ?

[ronin]

Not sure the eye relief is better with 2" eyepiees, also they are big. Literally coke can sized.

Take a look at eyepieces like the BST Starguiders or the Celestron X-Cels, they both provide reasonable eye relief.

I have glasses and have the set of BST's.

They also give a bit wider filed of view then the ones you have.

[steviebee]

Thank you for your Quick replies. To answer you question first John. I just could not see anything out of the 6.3mm, not even any brightness. I tried with and without my glasses. Sorry forgot to say I also used a 2x Barlow with all lens's and kept it on at all times. I am thinking now could it have been too much Magnification with the 6.3mm? Ronin, I am seriously thinking of getting a set of wider field of view one's, but just want to make sure it is not something I am doing/not doing that is causing the problem first. As I said earlier I am very new to this hobby, and I know you guys and girls will point me in the right direction to ensure I enjoy it. I don't want to spend lots of money if I don't have too (already in the dog house over getting my Cannon Camera for it). My problem now is I will have to wait until October before I can use the scope again as I have left it at our home over there. I am sure it is a case of just getting use to it. Thanks again for your help.

Steve.

[ghostdance]

I also used a 2x Barlow with all lens's and kept it on at all times. I am thinking now could it have been too much Magnification with the 6.3mm?

Steve.

From my limited knowledge (new at this too) I think it's the lighter seasonal skies: this summer most times I've had exactly the same experience using high power EPs with a Barlow, too dim, too low contrast, muddies everything up - I've put the high-powers to one side frankly til darker skies get here. Very happy tho with my 30mm Vixen through a TeleVue 3x Barlow. Nice

Steve (coincidentally, 'steviebee' is my family nickname, & usually my forum name, lol!) 

[John]

Steve,

The barlow will be doubling the magnification given by all 3 eyepieces. 317x with the 6.3mm plossl + 2x barlow is a bit too much most of the time although you should still see something there on the Moon or Saturn, an enlarged but fainter and more fuzzy view. You would get much sharper views if you use the eyepieces without the barlow in place though.

[steviebee]

Hi John, thank you. I was wondering if that was the case. Just have to be patient now and wait till October and try it without the Barlow.

Steve.

[steviebee]

Hi Ghostdance, must admit on all 3 nights it was very bright (Moon). cant wait till October, only a few lights in our village so will be nice and dark. I have had 'steviebee' since 1998, Steve is my first name and the 'B' is the first letter of my surname. I come from South East London originally.

[ghostdance]

Hi Ghostdance, must admit on all 3 nights it was very bright (Moon). cant wait till October, only a few lights in our village so will be nice and dark. I have had 'steviebee' since 1998, Steve is my first name and the 'B' is the first letter of my surname. I come from South East London originally.

Yes, that old moon gets things lit up!  I've been wondering about finding a local dark site ( somewhere nr Epping Forest mebbe) but with no car I'm planning a bino trip first. Indeed, roll on the Darkness!

Nice to know there's two steviebee's around (mine's a familial contraction of 'stevie-babes' but that's too much information!)

Oh, and the 200P is my shortlist for when I can afford a bigger scope. Looks good

[bingevader]

Hmmm, I've 2x barlowed my 7mm EP in the slightly longer skyliner at 342x on the moon very successfully, I wonder what the problem can be?

In October, you'll have to try it without the barlow and make sure that there isn't something up with the EP itself.

I'd suggest you might struggle with glasses and the eye relief on a 6.3mm plossl.

I also wear glasses for distance and don't have any problems not using them with the 'scope.

The moon is fab, try the Lunar Field Atlas and the Full Moon Atlas.

Cheers

[Charic]

steviebee........Hi,  http://www.ebay.co.uk/itm/1-25-18mm-BST-Explorer-Dual-ED-eyepiece-Branded-Starguider-/161049462890?pt=UK_Telescope_Eyepieces&hash=item257f4bc86a

I recommend you purchase both the 8mm and 18mm BST Starguider eyepieces at £49 each. Try these two EP's side by side. These would replace your supplied 10mm & 25mm. Its the route I chose. I have Compound Myopic Astigmatism? low short sighted and low astigmatism, which means I  cannot focus distance properly on my retina, without some minor correction. Its an old age thing???? I use prescription for driving and fishing and occasionally  watching the TV.

I choose not to wear prescription glasses when using the telescope. I can see fine through the eyepieces without glasses. The focuser corrects the myopia, but not the astigmatism, which is low in my case.  I get on great with BST lenses. But more interesting is that if you speak with Alan, his number is on the site, and explain your issue, he normally allows you to decide if the Eyepieces are  comfortable for you in use. If the EP's don't help you in any way, send them back and you'll get your full £98 back, the only cost to you is return postage! Great value and great lenses too. If they work, issue solved, if they don't, then at least you have discounted one brand before you manage to try another, and you get your money back.

Also a 6.3mm plossl Barlowed I think is 317x power on your telescope? far too much power to see most things. But the Moon should work. 

[steviebee]

Hi Charic, thank you for that. I bought a laser Collimator from him last month and was pleased with the service. I will definitely go down this route I think. Although I will have to wait till October because that is the next time I will be with my scope. I must try and convince she who holds the purse strings that owning a small refractor here in the UK would be a good idea. Thank you again.

Steve.

[Moonshane]

in answer to the original question re 2" or 1.25" eyepieces, assuming the same quality optically, there's is no difference other than potentially larger field as John says, plus weight (meaning possibly balancing problems or at best having to change the balance of your scope between eyepiece changes) and expense plus the 'faff' of adding an adapter for your 1.25" eyepieces.

I have two 2" eyepieces. a 40mm 65 degree eyepiece which gives me (almost) the widest field possible in a 2" eyepiece.  in my faster scopes the exit pupil will be very large at 9mm and then I use the 26mm Nagler. I don't feel I am missing much with the much smaller, lighter 1.25" versions. In fact I prefer simpler designs (like plossls and orthos) on solar system objects and double stars.

[Jim Steele]

I agree with other posters that the problem is likely the Barlow, you should see something on Saturn (all be it a blury blob) though it could be possible that its no longer in the FOV.

The Plossl design also means eye relief is much tighter with lower focal length eye pieces, a real problem for specticle wearers. Something like the Vixen SLVs might help in this regard, and John has given them a very favorable review.

Hope that helps,

Ben

[Lowjiber]

Thank you for your Quick replies. To answer you question first John. I just could not see anything out of the 6.3mm, not even any brightness. I tried with and without my glasses. Sorry forgot to say I also used a 2x Barlow with all lens's and kept it on at all times. I am thinking now could it have been too much Magnification with the 6.3mm? Ronin, I am seriously thinking of getting a set of wider field of view one's, but just want to make sure it is not something I am doing/not doing that is causing the problem first. As I said earlier I am very new to this hobby, and I know you guys and girls will point me in the right direction to ensure I enjoy it. I don't want to spend lots of money if I don't have too (already in the dog house over getting my Cannon Camera for it). My problem now is I will have to wait until October before I can use the scope again as I have left it at our home over there. I am sure it is a case of just getting use to it. Thanks again for your help.

Steve.

With a focal ratio of f/5, you were definitely overpowering your scope with a 2x Barlow on the 6.3mm eyepiece (effectively 3.1mm w/Barlow).  I am surprised that you nothing though.  However, when magnification goes up, surface brightness goes down, so (with the exception of the Moon) it is possible that your target just lost too much brightness to show up... especially if light-pollution and/or poor seeing conditions came into play.

If I could recommend one eyepiece, it would be an 11mm ES 82^o eyepiece.  With 15^o of eye relief, you'll find it very comfortable to use.  Additionally, at around two times your scope's focal ratio it will give a perfect "blend" of magnification and surface brightness.

Clear Skies

[steviebee]

Hi Lowjiber, many thanks for your reply. That ep sounds ideal, I will put that on my shopping list.

Regards.

Steve.

[O-RICH]

i find that using a barlow 2x with a 10mm with my 200p is the limit before i notice a degradation in quality (I'm guessing it magnifies the 'pollution' too). Id imagine 2x with a 6.3mm would make viewing rather tough, maybe better using the barlow with a 24/5mm.

[RCG]

When you say you "wear glasses for distance" does that mean that you only have refractive errors (no significant astigmatism) in your vision?

If so, leave the glasses off when using optics.

[steviebee]

Hi RCG. Yes I only have 'refractive errors'. I believe it must be as the OP's say that I am over powering my scope.

Steve.