Eyepiece question

[Esseth]

Ok so i have had my 8' scope and i'm loving it even though i only have the generic 10mm and 25mm eyepiece's.

I've been trying to read alot about eyepices but i can't find a simple answer to my question. One thing i have noticed is that the higher mag you go the smaller the eye hole is, i was wondering if there are EP's that are high mag, but also have larger holes to look through.

[dannat]

there are a few, especially as the price goes up. At the cheaper end the WO spl series at 6mm has a fair bit of glass, as do the baader hyperion & vixen lvw if i remember correctly. (ordered from cheapest to dearest)

[mental4astro]

Hi Esseth,

I know I harp on about my dislike of barlows, however, I am nothing if adaptable. Here goes...

Here is an EP & barlow combo that will really put some punch into your scope, and give you the 'big eye lens' you are looking for:

GSO Superview 15mm & the GSO 3X barlow, and change left for $100 from Andrews.

I have this 15mm EP, & I love it. Very inexpensive & it works so, so well. Its eye relief is good too, though might be a little tricky with glasses, but not squashed up to it. I work this EP in combination with its bigger brother, the Superview 30mm, a 2" EP. Both have brilliant 68degrees field of view. If your focuser takes 2" EPs, I highly recommend this EP too for your dob. They perform exceedingly well for their price.

The high power EP I use is a Meade Series 5000 Plossl 5.5mm, which does have a relatively small eye lens, but not as small as the standard Plossls. Much, much easier EP to use than my Vixen LV5mm, & half the price. The Vixen has a large eye lens,but no eye relief in comparison, & a much more restircted field of view, 40deg's compared to 60. makes for much easier use at high power with a dob. Bintel has this diminuative EP at $129.

Just my current experience with my EP collection. All these perform well in all my scope, except only my big dob has a 2" focuser. I don't need much else right now. Hope it helps.

[slippo74]

Hi Alan,

There a lot of possible and valuable combos which you can play across UW, barlow, 2", etc...
Personally I did soooo many tests between cheap, medium range and expensive EPs, bothering all friends of mine who I know having better telescopes and equipment. So I've borrowed and tried a large range of EPs that goes from generic plossl, to Orion, Meade (4000 and 5000) up to TV Radiant, Nagler (and one Ethos last night).

I have to admit that in the end you get what you spend for and it is a reasonable things to do if the investment is a long time one.
So I've moved in buying 2 EPs Nagler series and I can't go back to any other alternative. I have now a 17mm 2" and a 13mm 1.25" Nagler IV series and I'm not using anything else with the exception of a good barlow (IF and WHEN required).
The quality of these EPs does justify their price and the comfort is same than to look into a wide 26mm .

However take my advice based of my personal and modest experience as I'm not an expert (not yet!).

Cheers, Cris.

[dpastern]

There's lots of choices out there, I'm no expert on Vixen, Pentax and other designs, nor am I an expert on Televues. That said, after viewing through several Televues, they're on my hit list to buy. That's a personal choice. For the time being, Alexander's advice is a good'un - the GSO 15mm plossl is a good eyepiece. Andrews sells them for $29, which is a bargain imho. I actually have this eyepiece, and it's one of my faves. If you have a 2" focuser, I'd also recommend the Andrews 30mm 82º eyepiece. It's not super sharp to the edge, nor is it perfect, but for the price, it's a cracking lens imho. Get a 2x GSO barlow and you've got some variety.

If you want a brighter eyepiece and more magnification, then you don't have much choice other than to go for the more expensive designs. I've included a link to a page that I found helpful, hope it helps you:

http://www.bpastro.org/index.php?page=selecting-eyepieces

Dave

[Paddy]

I'd add Orion Stratus to this list as a cheaper option bearing in mind you do get what you pay for. One suggestion I have is to consider how much you will use the eyepiece. If you go for magnifications over 250x, you won't use it a lot due to seeing limitations and remember that 300x is about the maximum except on remarkably good nights. So I'd suggest working out which fl your likely to use most and spend more on that. When I had my GSO 12" dob, I bought a 5mm Stratus which was not a bad ep but at 300x I hardly ever used it. My shortest fl ep now is a 9mm Nagler (250x) and I don't get to use it a lot. So in your shoes assuming your scope has fl 1200mm I'd perhaps go for a 2x Barlow and the 10mm to get to 250x for good nights and think about upgrades for the two eps that you have. A barlow is a little more fiddly than a stand alone ep, but you may not be using it heaps. Mind you, I'm on a hill with lots of trees about which may impede my seeing conditions. If you're in a site that's more cleared, you might be able to use higher mags more often. Suburban roofs would not help though.

[Esseth]

Thanks guys, I never even thought about using a combination... shows how much i have to learn, however something ill defiantly look into.

I think the other half is looking into getting some eyepieces or a set for me for xmas, but i need to push her in the right direction lol.

[Paddy]

Yes I think this is a purchase that is best done in a very informed way. I would highly recommend going to a club night or other gathering of astronomer and looking through various eyepieces in your scope. A few well chosen high quality eps are things that you will have for a long time, so its worth waiting and investing some time. And finding out which magnifications you will use.

[WadeH]

Hi Esseth,

Thats the thing about our wonderful pastime, always learning!

My thoughts on eyepieces that hasnt already been commented on by others.

Remember that most of your observing will probably be done with one or two wideangle eyepieces eg: my 21mm Denk. (47X), gets a huge amount of work on all the deep sky fuzzies.
For planetary work a moderate size eyepiece is good and if closer work is wanted combine it with a good barlow or powermate. eg: I use a 13mm Nagler (76X) and 2.5X Powermate (192X). It is rare that more than this is needed with my 8".
Reguarly check out the IIS classifieds. I have got lots of good stuff there including my 21mm Denk. at great prices!!
With these setups the eyepiece hole is more than enough for viewing through. I do have 10mm and 5mm Super Plossls but they dont often get used mostly due to coditions.

Hope this helps,

Wade :2thumbs:

[slippo74]

Hey Alan,

Probably a picture is better than 1000 words :)
The 17mm Nagler compared to a generic 15mm.
Using a 2x Barlow you got an 8mm with such big lens in which enjoy the sky.
65675

[barx1963]

I'd probably stay away from eyepiece sets as they are usually just sets of plossls, and the one you end up using are the 25 and 10 anyway! Get a good quality EP with nice eye relief and you won't regret it.

[Wavytone]

Yes, expensive ones. A larger eye lens is typically found with eyepieces that have (a) a long eye relief, and (b) wide field of view.

Eye relief is the distance between the eye lens and your eyeball, which as you will be aware is painfully short with cheap eyepieces and those of older designs (orthoscopic, plossl, kellner).

Examples that provide long eye relief and are very comfortable to observe with include:

a. Vixen LV or NLV eyepieces, all have 20 mm relief and 50 degree field of view, sharp, moderate cost, they are small and lightweight. The LV's are obsolete and you'll have to find them secondhand, the NLV's are easily bought new.

b. Vixen LVW eyepieces, all have 20mm eye relief, 65 degree FoV, but much bigger, heavier and significantly more costly. In focal lengths down to 3.5mm.

c. cheap knock-offs of the LVW's (and inferior too) - Baader Hyperion, Orion Stratus...

d. TeleVue Panoptic, Radio, Nagler, Ethos... Wide field of view, big and heavy like the LVW's, and a lot more $ too.

Ultimately you really only need 3 eyepieces - low, medium and high power, maybe 4 at the outside.

[wavelandscott]

I'd recommend that you visit http://www.televue.com/engine/page.asp?cat=2 as part of your reading journey...while I do not always recommend Televue eyepieces, I think that the information here is top notch and worth reading.

Generally speaking, don't forget that in eyepieces like all things "you get what you pay for" and while initially you might not recognize the difference between high quality eyepieces and lessor quality eyepieces if you stay in this hobby a long time you will. I subscribe to the idea that a few highquality eyepieces are better than a case full of low quality one (I usually only use a few (2 or 3) in any one evening anyway.

Visit a viewing night or two with other people and look through as many different types of eyepieces as possible...become an informed consumer.

Lastly, encourage those that want to support your Astro interests at Birthday/Christmas to consider buying a gift card instead of an "unknown" eyepiece.

Having said all of that, use what you have for a while before spending more money...

For example, I would recommend that you get the proper gear and gain the skill of collimation before splashing out on quality eyepieces...a great eyepiece in a poorly collimated scoipe will look horrid!

Good Luck and Clear Skies!

[mental4astro]

"Visit a viewing night or two with other people and look through as many different types of eyepieces as possible...become an informed consumer."- Wavelandscott.

I couldn't agree more before laying your money down!

It also comes down to how much you want to spend.

You need to keep in mind too the optical properties/capabilities of your scope. For instance EPs with >80degree field of view will introduce noticable, if not intolrerable coma distortion into the outer edge in anything faster than f/5. These EPs demand the use of some type of coma corrector in fast scopes. In my case of an f/4.5 scope, that makes for significant top heavy situation that warrants careful thought into counterweights/rebalancing. These EPs also are so wide that your eye cannot see the whole field without moving. Sure they give the 'falling into space' effect, but they are not for everyone. You really, really owe it to yourself to test these EPs objectively, & THEN decide.

I've tried one of these giant 100degree puppies in my dob. Too much coma distortion & way too top heavy, & that's without the coma corrector. I'm happy to limit my selection to 68 to 70 degrees. That also opens more possabilities, optically & practically.

Yes, better quality does cost, however, keep an eye out for those little gems that use clever, inexpensive designs. They do exist. For instance, I mentioned the GSO superiview 30mm. Good for my use now, but I will be getting my mits on a TMB Paragon 30mm- better quality, but also not a mortgage buster. The 15mm I won't change- I won't improve much on quality keeping in mind optical properties. I'm looking through the scope, not at it.

[Manav]

Hi Alex - In my case Focal/# = focal length/aperture = 1200/254 = 4.7 so getting a Explore Scientific 14mm 100 Degree Eyepiece or a Televue Ethos 13mm is not a good idea without a Paracorr?

[mental4astro]

Hi Manav.

If you use this type of EP & not use a coma corrector you will just be cheating yourself of the best the eyepiece can offer. You may as well limit your EP selection to a max FOV of 68/70 degrees as this tends to be the limit that unassisted good eyepieces can offer sharp to edge of field. Remember, we are talking of the inherent optical properties of fast reflectors and different eyepiece designs. These are not defects of manufacture. Its like using standard petrol in a dragster instead of nitrous oxide- it will go, but you will always lose every race.

The Paracorr is not the only coma corrector either. Baader Optical also makes one especially designed for f/ratio 3.5 to 5, their 'Multi Purpose Coma Corrector'. There are others available.

[mac]

I'm also thinking about buying a high quality eyepiece to go with my F5 10" dob... I'm leaning towards a Nagler, but am not entirely sure which focal length to go for.

At present, I have 9mm, 15mm, and 26mm GSO plossl eyepieces, and a 2x ED barlow. Would a 13mm Nagler be the best bet?

[jjjnettie]

I'll second that.
This particular eyepiece has received very good reviews over the years.
I only use 2 eyepieces, and this is one of them.
I pair it with either a 2.5x gso barlow or my 2"Big Barlow. I've even doubled up both the barlows for some very up close and personal viewing of Jupiter.

[jjjnettie]

Note that we're talking about the "Superview" plossl. You're definitely not looking through a pin hole here. That's why it pairs so well with a barlow. (or two)

[Paddy]

I find that my most used magnification is about 130x. Does not require excellent seeing and shows good detail on galaxies, planets, planetary nebulae in my experience. I also like it on larger nebulae for picking out details like small clusters in eta Carinae neb, Tarantula, Eagle etc. If your fl is 1250mm then a 9 mm nagler T6 would give you this. Good price at the moment and they are a nice small eyepiece as well. That's what I'd go for. Another option would be 17mm T4 Nagler and 2x Barlow or powermate. Then you have a excellent eps at 2 focal lengths. The 17mm T4 is quite a bit weightier and pricier. And I haven't used one in a barlow, but I assume there should not be a problem.

[mac]

Thanks for the suggestions, Patrick!