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90 Mak eyepiece


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Hi, I have a Celestron Omni Plossl 32mm eyepiece which is pretty good, but was wondering if it could be improved (budget £75). Also have a 12mm BST which I'm not that impressed with in the Mak (works well in my refractor) again any recommendations for an upgrade (9-12mm considered) similar budget? 

Edited by Marc1964
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There isn't really much at that price and it also depends on what you need it for.

At £54 you have the Baader Classic Ortho 10mm. Narrow fov but very sharp. Moving up to £91 there's the Nirvana 10mm; twice the fov of the ortho and still sharp.

At 32mm, most eyepieces are similar and there's not much benefit from changing.

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The long f/ratio of your Maksutov means you can pretty much use any eyepiece you want.

Chances are likely that there is nothing wrong with the 12mm BST, but that it is merely the magnification that is exceeding the quality of the scope's optics, or the seeing conditions

due to the relative high magnification.

Your refractor probably has a shorter focal length so the same 12mm yields a lower power in that scope.

That the eyepiece works well in the refractor says there is nothing wrong with the eyepiece, the issue is with the magnification it yields in the Maksutov.

There may be NO eyepiece at 12mm that will yield a good quality image in the Maksutov all the time.


Assuming there is nothing wrong with the Maksutov's optics, then the issue is collimation, cooling, or sky conditions.  

Have you checked its collimation?  Have you let the scope cool down outside for an hour before using it at such a high power?

If your scope is an f/15, a 12mm eyepiece will be pushing the limits of the scope (collimation, cooling, optical quality) or seeing conditions.

If your scope is f/12, it is still a high power, but not at the limit.

Here is a way to look at it:

magnification of 3.6 to 10x/inch of aperture is low power. Usable all of the time.

magnification of 10-20x/inch of aperture is medium power.  Usable most of the time.

magnification of 20-30x/inch of aperture is high power.  Usable sometimes, but not all or even most the time.

magnification of 30-50x/inch of aperture is ultra high power.  Usable a very small % of the time.


Are there higher quality 12-13mm eyepieces?  Yes.  But if 12mm doesn't yield a good image quality, a 9mm will be worse.

Now, assuming proper collimation, a cooled scope, and excellent seeing, a 12-13mm should work fine.  A 13mm Nirvana would work fine, but might not be in your range.

Have you considered an Omni Plössl in 12mm?  It would have a slightly smaller field than the BST, and a little less eye relief, but you might find it adequate.

I don't think it will really improve the image quality, though, because I don't think the problem is the eyepiece.


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@Don PensackMany thanks for the thoughtful response, appreciated.

I think the collimation of the Mak is fine, but will check. Not entirely certain that it can be collimated easily (old blue Skywatcher Skymax 90). 

I hadn't considered that at 12mm I may be pushing the limit of the scope. It is F13.8 (I think) so I should rethink my choices. 

Given this, I don't have any eyepiece between my 32mm and the 12 mm, so given your comments, I should look at something between 15 - 18mm.

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Another vote for the Baader Classic Orthos here - the 18mm is very sharp, flat, contrasty and has comfortable eye relief (compared to the shorter FL orthos).  I use it a lot for slightly higher magnification in my SW Mak 127 (gives 83x) for DSO's once found with either a Baader Hyperion 24mm or 40mm Celestron Plossl.  Gives fantastic views in the Mak on Targets like the Ring Nebula, M42 and the brighter Messier galaxies. Generally I pair it with a Neodymium filter. 

Works well too with the 2.25 Barlow that goes with the Hyperion Zoom to give 8mm equivalent (188x in the Mak). 

Edited by SuburbanMak
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It’s a little beyond your budget (~£90), but I find a 16mm Nirvana eyepiece works well in my 102Mak. As it’s 82degrees you get virtually the view of a 32mm plossl, but I’ve found the optics to be a big improvement and you get more magnification which helps on some objects.

I found 10mm is around the highest power I can routinely use/ and for that I use a pretty old school Meade 4000, but works well for me. 

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The Nexstar 4SE, focal length 1325mm.

A couple of others have mentioned the Baader Classic Orthos. I’ve only got the 32mm, which I believe is actually a plossl not an ortho. It’s a decent eyepiece but how much of a difference you’d see compared to your Omni I’m not sure. The range comes in 32mm, 18mm, 10mm and 6mm; which isn’t as thorough as some sets but I think it assumes use of a Barlow to get the intermediate sizes.

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For the low power end, you have to also consider the MAK90 internal construction
limits the potential field of view to around one degree (a bit more!). So, any 32mm
Plossl (with apparent field of 50 deg), giving approx 40x, is "about right" (the limit). 

Alternatively you could go for a slightly higher magnification with a wider angle
angle eyepiece such as the (70deg) Antares 24mm. But, swings & roundabouts. 😁

If available, still a nice eyepiece series, if you prefer a slightly wider field format.

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I have the Orion Mak90 and I keep the sbony 22mm aspheric in it, a 25mm plossl is also fine. The Celestron Xcel is significantly better than the plossls. Mine does not do well at high magnification, probably need a sturdier mount. 

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1 hour ago, Marc1964 said:

@Macavitythe Antarez look like very good value for money at £50. Certainly cheaper than other wide fov eyepieces. Not heard anything about them, I assume that they are a step up from equivalent Omni Plossl? 

Not sure if they are equivalent to anything. lol. They are rather OLDER than many eyepieces used today.
They may NOT actually be available? There are rather few 1.25" eyepieces with 70 deg AfoV. There are
comments on "Antares W70"  (qv) here on SGL. There was once(?) a Review Article on Cloudy Nights? 🤔

They worked rather well, were nicely constructed... and seem (unusually) to have come down in price!

Edited by Macavity
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