Would you buy a 15mm eyepiece?

[knightrider]

Hi guys, just after some quick advice.

My scopes both have 1200mm FL.
At present my set consists of:

30mm GSO Superview yielding x40
25mm Skywatcher Super Plossl yielding x48 (quite nice actually given it came with the scope)
9mm Orion Expanse (copy) yielding x133
6mm Orion Expanse (copy) yielding x200
4mm TMB Planetary II yielding x300

At present my 3 most used that get taken out every session is the 25mm/9mm/6mm without fail. The 30mm only sometimes if I'm looking at large Nebula, and the 4mm on exceptional nights.

I've been wanting to get the 15mm GSO Superview for quite sometime, and although not an expensive purchase have held back from doubts I'll even use it that much.

So I already have 5 eyepieces, 3 used without fail. Will this even change with the purchase of the 15mm? Keep in mind I view both DSO's and planetary with my scopes...

Thanks for you comments...

[MattT]

Absolutely....yes. 14 15 16 17 or 18 would be good...just have to find the right one for you. Budget mostly comes into it.
Matt

[sopticals]

The 15mm GSO Superview is an ok eyepiece with 70deg FOV and 80x in your scopes. I have a pair for use with my WO Binoviewer. Don't think you would be disappointed at the price level.

[SkyWatch]

80x is a nice magnification, and the GSO SV's are good value at $59...
It will fill a hole in your magnification range, so if you have the budget I would say go for it! (Or it could be a nice Christmas pressie from a significant other...)

[dannat]

if it were me id be looking at the 11-13mm eyepieces, i find the 100x a better overall usable mag for me

[barx1963]

I have the GSO 15mm Superview. Mainly have used it in my solar scopes and my 8" f4 travelscope. It is a nice little EP for the money. Nothing special but at low power it works fine. Pushing it up to 80x or 100x may reveal issues, but in my 8" at 53x it works OK.

Malcolm

[The Mekon]

Daniel is correct. The magnification I use most in all my scopes is in the 100x to 12Ox range. So a better choice would be 11mm or 12mm

[knightrider]

Hmm this has helped throw a different perspective. Maybe a 13 mm would be better to fill the gap

[mental4astro]

My fellow IISer's have given you very good, sound advice. The 15mm SuperView is a very good eyepiece for the price, and will perform very well in an f/5 reflector. I've had mine for several years, and its 30mm stablemate.

For the eyepiece range you have, a 13mm would slot in a little better than a 15mm, I agree. This is where I'll throw in my 2c worth...

The modest end of the eyepiece line is awash with poor eyepieces for fast Newtonians. They are either designed for other scope designs, like a refractor or SCT, where they will perform really well, but in a Newt they usually are poor performers, or if they were designed for Newt's (like the Plossl), they were designed when Newt's were typically f/6 and slower, so pushing them to f/5 and faster, and these eyepieces begin struggle, focal length dependent too, and they can become very difficult to use (tiny eyelens and no eye relief).

Among all this, there are a few gems. Longer focal length Plossls are great in Newt's of f/5. They have a big eye lens, and great eye relief.

You've already found the TMB Planetary Type II's. Their original design was revolutionary, and while no longer made under the original TMB banner (after Thomas Black died), these eyepieces are so inexpensive to make that the 'clones' are flaming excellent. Big eye lens, and long eye relief in all the models. The only runt in the family is the 6mm, which was problematic in the original line too, and continues being. But these are 9mm and shorter focal lengths.

I have struggled to find a decent mid-range focal length eyepiece though, in the modest end of the market. So far the only clear gem is the 15mm SuperView. Remember, I am talking fast Newt's. Big eye lens, and great eye relief. I agree with Malcolm that it does a decent job in an f/4 Newt too.

Keep in mind, all these will display some types of aberrations. Coma is unavoidable, but tolerable (seen as little comet tails flaring out, most noticeably at the edges). Astigmatism is often present too, and is the single greatest tell-tale sign of an optical mismatch (seen as 'seagulls' along the edge). It is the control of astigmatism that is what too look for in the modest end of eyepieces. Astigmatism does not mean there is something wrong with the eyepiece. Not at all. What it means is the eyepiece is not meant for use in a Newt. The SuperView line is not designed for Newtonians! These are essentially Erfle eyepieces, which are used in Binos and other scopes with a lot of internal prisms. But they still do a bloody good job in Newts. They do show more astigmatism as the focal ratio gets faster and faster.

If someone has found a gem in the 15mm to 13mm modest range for a fast Newt, please let us know! It is a very rare fish this one...

[MattT]

The thing I'd consider buying is a Coma Corrector. The single best thing I bought that changed my 10" Newt into a nearly refractor views.

See my thread on the ES 14mm 82º in the eyepiece section. A big thank you to Morton for the sale :thanx:

Not sure if this falls into Alex's modest rare fish gem...but I like it.

Matt

[ZeroID]

My 15mm GSO SV is probably one of the most used EPs in my small collection.
Wide enough to give a good fov but enough mag to get some detail. Works OK in the 10F5 Newt and the 102F7 Lunt and 80F11 Refractors.
At the price it is it is worth just having for an option.

[knightrider]

So the 13mm has limited options, and appears to be pricier to get hold of. However the 15mm although less suitable, easier and cheaper to get. I'm going to have to do some thinking on budget I think.

I've absorbed all your comments. It's a great help. I might resort to getting the GSO. Thanks again guys :)

[mental4astro]

Don't think of it as 'less suitable'. The scope design the 15mm SuperView is made for may not be a fast Newtonian, but it DOES work very well in one. Just that it is not a perfect optical match, does not mean it is crap. Just be aware of its limitations, which for its price, makes it a gem. A 15mm Plossl may be a closer optical match than the GSO, but it doesn't hold a candle next to it in terms of overall performance and ease of use. Think of it instead as 'best for purpose' ;)

Matt, the Explore Scientific 14mm IS a gem, just priced more like one! :lol:

[SkyWatch]

Has anyone tried the Long Perng 12.5mm or 14.5mm? They might do the job for you.
I have the 9mm, and it works very well in an f5 Newt. Not "gem" priced either: used to be around $99, but are now $79...

- Dean

[knightrider]

The Long Perng 12.5 looks interesting, however if I'm correct it only has 55degree AFOV. I understand these are the same as the Orion Edge On series?

[SkyWatch]

I believe so, yes.

The thing about AFOV is that sometimes you find that the extra width isn't particularly useable anyway, with the view fuzzing out towards the edge (especially if you don't have a coma corrector). BTW, I just discovered Mike Salway's review of the GSO here: http://www.iceinspace.com.au/42-236-0-0-1-0.html This is an old review, so I don't know if they have improved at all...

[astroboof]

Hi there,
It almost enevitably turns out that the best eyepiece for the job is often the one you sold last year or passed up. A good 15mm EP will be useful for almost any amatuer FL telescope at some point for some objects, so yes it's worth it.

Shame you can't spring for something better corrected than a 15mmSV, so I'm pleased to read your rethinking the budget. If you do enough visual, sooner or later the spherical aberations of affordable 15mm widi-ish EP's will become obvious, esprcially at f4-5, and you may soon long for something sexier/flatter as you sweep the heavens.

With patience you may pick up a decent deal online, but until then a budget 15mm will do the job and you can always sell the bugger here- they are quite saleable. I think I have converted two of the Bintel 15SV's into illuminated reticle finder ep's, they are a good FL for short 300-600mm finderscopes.

Have fun shopping. :)

[MattT]

For some reason ES eyepieces still sell at less than half the new price :confused2: Anyway :cheers: Morton :D

So buying used, specially now, is the only way. I won't be selling any of mine...like them too much.

I have also used an Orion LER 12.5mm. 55º AFOV and going from memory the only minus was transmission, or lack of it....a bit darker than other eyepieces I own. On the plus side easy eye placement, flat field no coma that I remember. Good for a Newt. Andrews sell the Long Pern for a low $79 I think, which is great value.

[knightrider]

Thanks for your comments Alex. I agree that for its price bracket they would be very hard to beat.



Thanks Dean. I know what you mean about the extra width. My 30mm GSO SV does a little of that around the edges also. Thanks for the link too, it was very informative.



I think I need to look at the 12.5mm/13mm range to really balance out my focal lengths.

I've found the Saxon 13mm SWA Eyepieces. They look ridiculously like the Orion Stratus eyepieces and same specs etc. It's fitting into my ideal requirements of a wider AFOV and FL.

Has anyone tried the Stratus/Saxon SWA eyepieces before? I know they're more expensive but not overly. Atropetes seems to have them priced fairly well.
http://www.bintel.com.au/Eyepieces-and-Barlows/Orion/Stratus/108/catmenu.aspx
http://www.astropetes.com.au/accessories.html

I just think if I went for the GSO 15mm SV I'll be thinking I could've put that money towards something more suitable...

[mental4astro]

If you ONLY have a Newtonian, DO NOT get the Hyperions, Stratus, or those Saxon SWA!!!

Remember how I said earlier that eyepieces are designed for a particular scope? The above line of eyepieces are specifically designed for use in SCT's, Maks and refractors. Used in these particular instruments, these make excellent eyepieces. That is because the these three scope designs produce a focal plane that is of the same shape - convex. Newtonians produce a concave focal plane. And the faster the focal ratio, the more severe the 'depth' of the concavity. The Hyperions, Stratus and Saxon SWA make for a dreadful match with Newtonians!

This trio of eyepieces are all essentially Baader Hyperions *, rebadged as Stratus and Saxon SWA. Many years ago, I too thought that Hyperions would make a good addition to my eyepiece collection, having also read many reviews stating how good they are.

BUT, what I did not know then, was the relationship of scope designs and eyepieces, and that eyepieces are primarily matched to a particular shape of focal plane that scopes produce.

It cost me a bomb to learn this lesson, as I only had Newtonians then. I purchased a 24mm Hyperion, and I had a major disappointment. The image was terrible in my 17.5" Newt, :( . I took it as a bad eyepiece. I then purchased a 13mm and 8mm. Again, crap image!!! I re-read the reviews, and I started to notice something - ALL the positive reviews were coming from SCT users! Not one single Newt! The one exception with this line of eyepieces is the 5mm. It is not of the same basic design as its other stable mates, and it actually is a great eyepiece in a Newtonian. It is the only Hyperion eyepiece in my regular kit. I've punched my little 8" f/4 Newtonian to 360X with this 5mm Hyperion, and it gave me the best view of Saturn I had. An f/4 newtonian will test ANY eyepiece.

Sound crazy? Not really. If you are in the imaging game, you will quickly find out that you cannot use a coma corrector with a refractor. Nor can you use reducer correctors made for SCTs in a Newtonian. This is because they are all scope specific. Same goes for visual.

There are some eyepieces that will work nearly as well in Newts as a fast refractor, & an SCT. But there are not many of them, and not all models of focal length work equally well in all scope designs. These are also more expensive lines too. For this reason, for my own eyepiece kit, I do not stick to the one 'brand' or 'line'. I cherry pick what I find works best in my scopes. But it also means that I have some eyepieces that are exclusively scope specific, and I don't use them in other scopes because I know they just will not work. And some of the eyepieces I have in my kit will surprise many people, because they are considered 'unfashionable' or the brand is looked down upon, but these EPs are flaming brilliant, and dead set bargains, but very much scope specific.

Unfortunately, eyepiece manufacturers do not tell us about these technical aspects of their eyepieces. They fear that it will impinge on sales. Thing is, by not telling us, one poor review of an eyepiece due to a mismatched coupling of EP to scope will have a bigger impact on sales. But the bean counters just don't get that...

It has long been an aspiration of mine to find those 'gems' of eyepieces that are inexpensive, but do a damn fine job in Newtonians. Fast Newtonians are just about the hardest of task masters on eyepieces. A good quality eyepiece is as much a matching of optics as it is our own personal understanding. If money were no problem, there are plenty of great eyepieces out there. But if one needs to watch pennies, the choices are not as wide, and we need to understand the compromises that we need to make so we then make the best selections.

I know this is quite a long post. But there is much to understand.

Remember, I am not dishing Hyperions or Stratus. Not one little bit. They are GREAT eyepieces, but not in Newtonians (except for the 5mm, ;) ).

Lastly, knightrider, do not think that you need a single very specific focal length, like a 12.5mm/13mm. The actual difference between a 15mm and a 13mm is really not worth getting your knickers in a knot over. It really isn't. If what works best is a 15mm, get the 15. If you are fortunate to find a 13mm that fits the bill, get the 13. If you have a choice between the two, you are a very lucky person! :)


* Many people think that the Baader Hyperions are a copy of the Vixen LVW line. This is not the case one little bit. The may have a similar look, but that is as far as it goes. Internally they are totally different. Hyperions are crap in Newtonians, LVWs are brilliant in Newts, and one of the very few lines that also work very well in SCTs and Maks, and more than twice the price.

[mental4astro]

A Frankenstein 13mm eyepiece

There is one way to make a 13mm Hyperion work well in a Newtonian. It requires the 1.25" nose piece of a 24mm Hyperion though. Swap the nose piece of the 13mm with that of the 24mm - there is no lens in the nose piece of the 24mm Hyperion, where as there is in the 13mm. Now, screw into the nose piece of the 24 the lens of a 2X barlow. The Barlow lens is a different design and works in the opposite way that a Smythe lens does that is used in Hyeprions. The resulting 'Frankenstein' 13mm actually does a very nice job in Newtonians. Not perfect, but a hell of lot better!

[knightrider]

I understand where you're coming from.
Thanks for the extra information. There's not much else to choose from in my searching that have the extra angle in that range and budget. I was willing to go as high as $140 but after that it starts getting too expensive.

It seems I'll be settling for the GSO SV. I know I won't be disappointed with it. I just want to make sure I get it right the first time :)

Edit:
In my searching I did find multiple reviews of the Stratus 13mm and many of those had good things to say about their performance in newts. 2 had F6 and 1 had a "F4.5". Although in all of those they did mention kidney beaning in the outer edges, and whether or not this was acceptable is up to the preferences of the user. But otherwise they mentioned it worked quite well. Other thing I noticed was the size of the unit. They're pretty big, maybe too big.

All in all, I'm very appreciative of existing user experience of any of these. It all helps :)

[Cimitar]

+1 for 15mm eyepiece. I own a Meade Series 4000 QX 15mm and it's my standard quick go-to item for visual/polar alignment. I also have an 8.8mm high end Meade, but I can rarely use it due to seeing conditions.

My main eyepiece for visual use is the Baader Hyperion Zoom (Mark III). It's a fantastic eyepiece. It has capability of 8-24mm. Generally speaking, it's usually on either 16mm or 24mm, however I can ramp it up if I need to. I wish I'd bought it first, because in my opinion, it's all I ever need! :)

Cheers, Evan

[knightrider]

Thanks for ll your help guys, I ended up orderig the 15mm GSO/Bintel SV. I'll post in when I get it and test with my results :)

[knightrider]

I gave the eyepiece a test last night. It performs better in the F8 than the F4.7 as expected, but still quite nice. In the F4.7 stars begin to flare at about 70% out, but crisp in the centre. Which is fine as I place most objects in the middle anyway. In the F8 it starts about 90% out.

Overall I'm quite happy. For the price of it it's delivers a nice crisp image and is easy to look through :) Everything I need it to do.

[PSALM19.1]

All's well that ends well Knightrider! :) I hope you don't mind me asking Alex a question via your thread: I am also in the market for a new EP for my 8" Dob; I use my 6mm Orion Edge On and 32mm Bintel Plossl ALOT and that's pretty much it (my other EP's are a rarely moved out of the case!); the reason to get another is to either get a 3mm or 9mm EP and your recent talk about Long Perng and their similar look to Orion's Edge On series has got my interest! Due to the fact that they differ in price significantly, it would be a bonus to get the cheaper option! Now, my 6mm Orion works REALLY well in my scope; it is clear as a bell across the whole FOV - to go to a 9mm would be for those nights where I need to pan back a bit; and then, to buy a 3mm would be for those cracker nights - I wonder though, how well a 3mm would go in an 8" Dob...? Welcome comments from anyone, not just Alex! :)

[knightrider]

No problems Shaun. What other EP's do you have?

In my opinion I think 4mm will be the max you'll go in your scope. My 4mm hardly gets used except on rare nights when the sky allows. 6mm maximum on most occasions.

[SkyWatch]

Hi Shaun,

The 9mm LP is a nice eyepiece, and works well in my f5 scope- so it is certainly a well-priced option for you. I agree that 3mm is pushing the boundaries a bit. I am assuming your scope if f6? If you are getting really clear views in your 6mm then you might be able to go to 4mm, but it would be pretty rare that you could go further. Have you tried a barlow on the 6mm?
I find that there is always a limit beyond which you are simply magnifying the fuzziness of the object, and reducing the contrast. For planets this is usually around 150-200x unless you have exceptional seeing: and that would equate to your 6mm.

The other way of thinking about it is that it is not very often that you can go smaller than 1mm exit pupil: and for an f6 scope this is your 6mm eyepiece. A 3mm eyepiece will give 0.5mm exit pupil: and everything has to be just right for that to work well.

All the best,

Dean

[mental4astro]

Scope basics 101, magnification:

Max magnification - 50X per inch of aperture - this is a conservative figure dependant primarily on optical quality, and assumes decent quality.

Min magification - is a function of exit pupil given by 7mm X focal ratio of scope. This gives the longest focal length eyepiece that will give a 7mm exit pupil. The 7mm is the maximum dilation of the human pupil. This value though is wishy-washy at best. The largest exit pupil is to ensure that the maximum amount of light is entering the eye, but there is nothing to stop you using longer focal length eyepieces - just be aware that not all the possible light is entering you eye. ALSO, exit pupil is age dependant - as we age our pupils dilate less and less. I am not too fussed about this though. I use a 30mm in my f/4 Newt - I 'should' be using an EP shorter than 28mm with this scope. But I have a bucket next to me while observing to catch that light that spills out around my iris and I then donate this light to less fortunate astronomers than me... :D

Shaun, your 8" dob theoretically should be able to be pushed to 400X, which means a 3mm eyepiece. But as mentioned earlier, the opportunities to get to 400X are very few due to the atmosphere. Hell, I'd love to be able to regularly push my 8" SCT to 400X for my sketching, but I rarely can.

250X is more often than not the max I can take things. For your 8" f/6 dob, that means a 5mm eyepiece (I have not seen a 4.8mm eyepiece, :rolleyes:). If you are looking for a good but inexpensive short focal length EP, look at the TMB Planetary Type II line. Yes, today these are so-called 'clones' of the original, but they are still freaking good eyepieces. What made the originals so good, and also inexpensive then! was there fabulous design and coatings. So much so that it is just not worth the while to try to look to make them any cheaper as the design works so well as it is and IS inexpensive to make.

What also makes these EPs so good? Not just the price, but they have a really large eye lens (the eye lens is the lens that you look into, the field lens is the EP lens that faces out to the 'field'), and they all have excellent eye relief of some 16 to 18mm. No pin-holes here to look into that you need to park your cornea onto to see. AND they work very well in Newtonians!

The picture below is of a comparison between a 9mm TMB and a 9mm plossl. The longest focal length in this line is 9mm, and the shortest is 2.5mm. There is NO 14mm TMB Type II Planetary!

The only focal length of the TMB Planetary Type II to avoid is the 6mm. It was the runt of the family since they came out. The 6mm still works, but it is not as good as its stablemates.

How to tell between an 'original' and a 'clone' TMB Type II? The original has the focal length quoted as "mm". The non-originals are "MM". Why are there 'originals' and 'non-original' (as I prefer to call them, not clones as they are made in the same factory as the 'originals'!!!)? TMB stands for the initials of Thomas M Black, a very talented optician who designed eyepieces and refractors. He contracted a Chinese company to make the eyepieces for him. When he died, this company tore up the contract and started selling the eyepieces directly, undercutting the originally marketed line.

Shaun, understand the magnifications limits, both practical and theoretical, and you can make educated decisions for your scopes. The best I can do is guide you to those eyepieces that work best in terms of ease of use and optical matching. Which focal lengths? All I can suggest here is to have four different focal lengths in your kit. Remember, that the shortest focal length EP you have (say a 3mm for your dob), will be the one you use the least. But for me it is worth the cost just for those few times when I can punch things along! :)

[PSALM19.1]

Awesome guys as usual! Knightrider: I have a 4mm (crap) plossl (leftover from my Celestron First Scope - my humble "first" scope!); a 15mm plossl (not too bad - Bintel brand), a 24mm 2" Bintel (also, not too bad) and a Bintel 2xBarlow and a Celestron 2xBarlow - and yes, I sometimes use both at the same time! (On extremely rare occasions, the view is reasonble at 800x:P)

Alex: yes, have looked at the TMB's for a while now and umm'd and ahh'd about getting one! I think the 9mm would be a good addition to my scope so will probably go for that one. My scope, around 50% of the time, throws up very nice views at 400x (Barlowing my 6mm Orion); I've watched galilean moon transits quite easily at 400x on occasion! On one occasion in a moment of complete insanity, I looked at Saturn at 800x (both barlows!) and the seeing that night was probably the best I'd ever encountered...sure, it was a little fuzzy, but still not bad considering....:)

[brian nordstrom]

:) my new, to me 15mm TV plossl arrived today and have it outside with my little 60mm triplet APO and man does it give a very sharp image :eyepop: It certainly does give a nice view , hope the clouds clear so I can view the moon tonight and report back , but terrestrially it really looks great.
Brian.

[SkyWatch]

Sounds great Brian: 28x and around 2 degree field should give really nice views!

Have fun!

Dean

[brian nordstrom]

:thumbsup: Yes Dean great sharp views at 28x , and with the ultima 2x barlow giving 56x still very sharp , huge detail seen last night on the moon , very nice together these two , awesome small APO and world class 15mm plossl , great stuff .

I believe you don't need to pay big bucks when eyepieces like this are readily available , only 52 degrees but sharp and flat to the edge .

Cant wait to try it out in the 127mm f8 iStar refractor a nice 67x should shine in this scope .

Brian

[PSALM19.1]

Brian, would that EP work well in my 8" Dob? How much did you pay for it? I dream of owning a TV but my scope isn't really needing an EP that costs more than it did...:sadeyes:

[brian nordstrom]

:thumbsup: Thanks for asking Shaun , I paid 95 dollars for it from the classified,s here. , they do pop up now and again but you have to be fast. .
Personally I would grab the absolutely amazing 15mm superview because as said before you have to spend a lot more to get a better eyepiece. , they really are that good.

To give you an idea , for a lark over about 6 months I gathered together a full set the 15 , 20 , 30 and 40mm SV,s just to compare them to my 15 , 19and 27 TV panoptics and 40mm TBM , these 4 are worth over a grand together compared to about 250 bucks for the SV,s .
Ok , yes they were not as good as the premium eyepieces but if I did not have these I would have been more than happy .

The 30 and 40 mm SV,s worked better above f8 but the jewel,s in the crown of SV,s are the 15 and 20mm they are probably 80% of the Panoptics , easily , that good .
Grab one , you wont be disappointed.

Brian.


GrabQUOTE=PSALM19.1;1215417]Brian, would that EP work well in my 8" Dob? How much did you pay for it? I dream of owning a TV but my scope isn't really needing an EP that costs more than it did...:sadeyes:[/QUOTE]

[PSALM19.1]

Thanks Brian; waiting on delivery of a TMB II 9mm so will have to look at the SV in the near future....:D