Baader Hyperion 24mm vs Televue Plossl 32mm

[majapala]

After two very successful nights viewing here I west Wales, I am predictably ready to spend some money. I've been considering getting a good quality low power EP for my 127 Mak. I have been considering the two eyepieces mentioned. I understand that they both have the same AFOV, due to design difference, but that the BH shows a darker background which will be beneficial for spotting DSOs (which I would like). However, I hear nothing but praise for the TV.

Recommendations and advice is always appreciated and valued from you lot!

[michael.h.f.wilkinson]

Especially in the Mak, with its long focal length, both EPs would perform very well indeed. At F/11.8, the 32mm give an exit pupil of less than 3mm, which is fine, the Hyperion gives 2mm, which does give darker backgrounds, but the TV should often be OK. From a suburban location, I do find that many galaxies are detected more easily at a 2.2mm or 1.7mm exit pupil of the 22mm and 17mm T4 Naglers in my SCT than with the 3.1mm exit pupil of the T5 31mm (wonderful ep, nonetheless). On balance, I would say the Hyperion 24mm has a slight edge in this case.

[Stargazer_00]

That would've been what I was leaning towards as well, coupled with the versatility built into the hyperions you get more value for your money.

[M4lcs67]

I own the 24mm Hyperion and use/used it in my 127 SLT. Brilliant eyepiece. I was told that taking anything beyond 27/28 mm on a 127 you would start to see the edge of the tube so you might wish to reconsider getting something larger than that. The 24mm Hyperion cannot use the fine tuning rings though and is therefore fixed.

[Stargazer_00]

Maximum TFOV of a scope is: (maximum field stop for eyepiece size / focal length) x 57.3

TFOV delivered by eyepiece is: eyepiece AFOV / magnification

so you can work out for yourself if the particular eyepiece will breach the maximum potential TFOV of your scope.

EDIT: from memory (need confirmation here) maximum field stop of 1.25" is 26mm and 2" is 47mm

[michael.h.f.wilkinson]

I think the max field stop is 27-28mm for the 1.25" (3-4 mm less than the barrel diameter, just as with the 2")

[rwilkey]

Go for the TV 32mm Plossl, an exceptional ep and will work better in faster scopes.

[Andy_E]

Wish I could add some pearls of wisdom, but I'll be watching this post with interest as I'm facing a similar decision... all be it with a different telescope.

[Dunkster]

The TV is supposed to be an excellent EP but another thing going for the Hyperion as well as the darker bit is the apparent FOV is wider at 68 degrees, which just gives a different, more immersive experience same amount of sky, just presented differently.

Edited: I should add that the more immersive experience is subject to personal taste!

[John]

.... I understand that they both have the same AFOV, due to design difference, but that the BH shows a darker background which will be beneficial for spotting DSOs (which I would like)...

They actually have quite different apparent fields of view (AFoV) - 50 degrees (TV) V's 68 degrees (Hyperion) but the true field of view (TFoV) you get when you view though them is more or less the same.

The higher magnification of the Hyperion would darken the background sky a little.

I reckon the choice could depend on your future plans. If you will stay with F/8 or slower scopes then the Hyperion makes sense. If however you might move to faster scopes in the future (say an 8 or 10 inch dobsonian or newtonian) then the TV plossl is more future proof as it will continue to perform well across it's field of view even with faster scopes.

[michael.h.f.wilkinson]

Note that in really fast scopes like an F/4 big dob, a 32mm gives an 8mm exit pupil, which is too large for most of us, except if you are in a very dark location (and for preference have eyes like a bush baby)

cute, ain't it?

[alan potts]

On this one I agree 100% with Robin, buy the televue.

If you can get one secondhand you will never loose out. If you going to change your scope for a faster one, say F5 at a later date or add one, the TV will still be at the top of it's game. However if you were always going to keep the F12 ish scope then the Baader will perform fine but done expect it to give the same views in a fast Newtonian.

Alan

[majapala]

Your corrections and advice is greatly appreciated as usual everyone. I forgot to mention that I have every intention of upgrading my gear (when I look into it, however, it scares me a bit), so future proofing my choice seems sensible. Having said that, it's not going to happen for a while, so getting the best out of my current setup is a big consideration. Either way I feel that I will go into it in an informed way. Thanks again.

[Stargazer_00]

You'll probably find that the one constant in your armory as time progresses will be eyepieces so it will pay to future proof as much as possible and acquire the highest possible quality you can when you do purchase.

[Moonshane]

just as an aside, the best full sun and moon eyepiece I have is my 32mm TV plossl. it's just superb at providing a well magnified image with just enough space around it and simple optics create a sharp, contrasty image. I use it in scopes with focal lengths of 1200mm-1840mm (usually with an aperture mask for full moon). a 32mm plossl is a great eyepiece and would sit well in any collection.

[SkyGibbon]

I have an Orion Expanse 21mm, which is the exact same eyepiece as the hyperion. What others have said is true. In my f/4. 7 250mm dob it is not the best. To the point I very rarely use it. My super plossls are used more. On my f/8 6" dob it is used all the time. One of my favorites to barlow up.

[Lobotomik]

I was also wondering what eyepiece to choose for the widest TFOV in a 127SLT. I did not know whether the Hyperion 24mm would show its full 66 deg. AFOV, or whether it would vignette due to limitations in the 127SLT tube. I needed a good figure for what was the max TFOV from this scope, but it was nowhere to be found.

In the end, I emailed Celestron, asking whether an XCel LX 31.8 mm, with a 60 deg. AFOV producing a 1.3 deg. TFOV would be a good choice, and they responded immediately. Here is what they said:

"There is no X-Cel 31.8mm  eyepiece. The 127 has an opening in the rear baffle of approximately 27mm ID.  Just by coincidence the field stop diameter of the X-Cel 25mm is also 27mm. To calculate the real FOV  divide 27/1500 ( FL)  x 57.3=  ~1.03 degrees.  So the maximum field of view possible would be 1 degree with an apparent Field Of View of  60 degrees.   Any other eyepiece with a field stop diameter  larger than 27mm would cause vignetting."

The Hyperion 24mm would show a 1.056 deg. TFOV if this were possible, but apparently anything beyond 1.03 degrees will be masked out. The difference at that magnification (0.025 deg. x 62.5 mag.) is about 1.5 deg. of AFOV, so you will get something like 64.5 rather than 66 degrees.

I don't know how precise those numbers are, how abrupt the transitions, and how noticeable that 1.5 degree difference is. In any case, I am now after an XCel LX 25mm, with 60 deg. AFOV, which almost maximizes, without exceeding, my scope's capabilities, at a nicer price than the Hyperion and (I guess) with better performance on faster tubes which may be coming.

[Qualia]

On a personal note, I never really got on with my Hyperion in either the f/5 or f/10 and with regards to quality of image, I regarded the X-Cel LX a better EP. With that in mind, I imagine the BST would be almost on par.

It is probably already known, but to determine approximately the widest possible field of view your telescope can provide, if it has 1.25" focuser, divide 1,750 by the scope's focal length of the scope in millimeters. For example, if your scope has a focal length of 1,250mm, the widest possible true field of view in degrees is about 1.4°.

When evaluating the eyepieces, all you have to do is multiply the focal length of the eyepiece by its apparent field of view (AFOV) and compare that with your number given previously. For example, a 1.25" 32mm TVP with a 50° AFOV yields 32x50 =1,600 which is reasonably close to our rough guide of 1,750 above. Another way of working this out is to divide the AFOV by the magnification that given EP offers in your scope, and this will yield the 'true' field of view. For example, 50º / 39mag = 1.28º.

Depending on budget and time you will give yourself to save or look out for one on the secondhand market etc, you can't really go wrong with a Tele Vue Panoptic 24mm and this eyepiece will remain with you if you ever change to a faster scope. Other then that, I'd go for the Tele Vue Plossl which will be superb optically and will have a fit and finish equal to that of the Pan. The only reason it is cheaper than the Panoptic is because its apparent field is in the 50° range versus the 68° of the Panoptic, and the lesser magnification of the 32mm will provide a brighter sky background, which is aesthetically speaking not as pretty and might make it a tad more tricky to locate those ellusive faint fuzzies.

[part timer]

I have owned and used both of these on my f8 newtwnian, my 90mm skywatcher maksutov and my f5 achromat.

No contest at all.

Get the Televue, Image quality is better in every way, eyepiece is smaller and of a different league in terms of build quality.

It is just a better eyepiece.

[jgroub]

I know this thread is a year and a half old, and you most assuredly have bought whatever you decided on long ago, but I feel the need to throw my two cents in here for anyone like me, who is reading this thread for general knowledge in the future.  

Don't buy either.  

Sure, both are nice EPs, and you're never going to go wrong buying a TeleVue.  

But with an f/12 focal length, ANY 32mm Plossl is going to look good through this scope.  You don't have to spend the extra money on the TV, when any old Meade, Celestron, or GSO Plossl will do just fine at less than half the price.  The very long focal length makes these "lesser" EPs perform like champs.  That's what I did.  I bought a 32mm Meade 4000 Super Plossl, and the views are, ahem, stellar.  

And the best part is that you can take the money you saved and buy a second EP!  Win-win!