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 (Stephen)]

Originally Posted by knightrider

Hi guys, just after some quick advice.

My scopes both have 1200mm FL.


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...

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 (Dean)]

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 (Daniel)]

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

[barx1963 (Malcolm)]

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 (John Briggs)]

Originally Posted by dannat

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

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 (Alexander)]

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

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

Matt

[ZeroID (Brent)]

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 (Alexander)]

Originally Posted by knightrider

...the 15mm although less suitable, easier and cheaper to get.

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!

[SkyWatch (Dean)]

Originally Posted by mental4astro

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...

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 (Dean)]

Originally Posted by 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?

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 (Steve McN)]

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]

Originally Posted by mental4astro

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

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

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]

Originally Posted by 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!

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

Originally Posted by 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...

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.

Originally Posted by 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.

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-a...8/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 (Alexander)]

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.