The new (old) Pentax SMC 10.5mm XL arrived

[AlexB67]

A nice present came through the post today gave me something to look at over lunch. Who knows, I may even get a brief first light with it this evening, forecast looks promising.  Feels, looks very nice, solid and pretty weighty, it may not be new, but certainly looks it and came with original paper work and all. I think this will be an often used work horse in my collection. It wont impress the FOV freaks, but will give me a decent 65 degrees of quality optics I think.

Only criticism so far, for a rather premium eyepiece, you'd think pentax could supply a bit more than a see through transparent box of the thinnest plastic, but who cares, once it goes in a case and if the views are good as I hope, I'll rapidly forget about that.

 Screens as supplied in the mail by the seller, so I was too lazy to do my own.

[emadmoussa]

Congrats! Looks like pure glass!

[John]

It looks very similar to the Pentax XW's. Definitely a class optic.

Amazingly, Pentax have never promoted their eyepieces for astro use - they were designed for their spotting scopes I believe. 

Also the XW and XL designs have been around for years but it's taken all that time and Tele Vue expertise to match them with the Delos range.

I assume the top section twists up and down like the XW's do ?. I found, as a non-glasses wearer, that I needed the top section in the uppermost position to get the right eye positioning. Too close to the eye lens and you can get blackouts / kidney beaning which can be worrying until you find the right position.

[AlexB67]

The top is fully adjustable, even a little section in the instructions suggesting how to set it for glasses and non-glasses wearers, but only quickly skimmed the paper work, I'll digest that info later.

[John]

The top is fully adjustable, even a little section in the instructions suggesting how to set it for glasses and non-glasses wearers, but only quickly skimmed the paper work, I'll digest that info later.

Like many blokes I did not bother to read the instructions - until I saw the kidney beaning

The instructions advice was spot on though. 

[AlexB67]

Like many blokes I did not bother to read the instructions - until I saw the kidney beaning

The instructions advice was spot on though. 

I am actually the type that does tend to read manuals, does that make me a girl ? Last time I checked I did not put any nail varnish on before going out observing mind you :0)

[John]

I am actually the type that does tend to read manuals, does that make me a girl ? Last time I checked I did not put any nail varnish on before going out observing mind you :0)

Makes you sensible (the manuals not the nail varnish !)

[alan potts]

Looks a very nice eyepiece, I am just using the 7mm XW but it seems to attract clouds. Many congratulations Alex.

Alan

[Qualia]

Ay, that certainly look like a cracking bit of glass there, Alex. I can't wait to hear your opinions on the eyepiece

[AlexB67]

Hi Qualia,

I only had  40 minute test run yesterday with the Heritage 130p. I had hoped for a longer session with the 10 inch but it clouded over, from that brief test I can say so far that.

1. optically razor sharp in an f/5 scope
2. excellent transmission, star colours were  amazing in the 5 inch Dob
3. huge adjustability on the eye cup
4. very immersive and easy to see the edge of the field stop

Only one negative so far, 

This eyepiece  has a very small sweet spot where you see a clear field of view, kidney beaning and blackouts galore to begin with. After playing with the twist cup and making sure my head position is centred very precisely it got better through the session, that said, this is the hardest eyepiece I have every used. I had a similar problem with the 6mm UWA when I got it initially but I got used to it, now I never have a problem with that eyepiece. Hopefully with the pentax it is just a case of adapting and getting used to finding that sweet spot too, fine tune and adjust the eyecup and eye position. I don't think this is an eyepiece  you can easiy switch between non glasses and glasses wearers.  Seems to me you have to get the adjustment just right for it to work, even for non glasses wearers I  suspect some will need to adjust it to their personal liking. 

All in all, I will need to use it more to get to know it better, I can't wait for a first light in the bigger Dob.  At some level in that 40 minutes I got to appreciate that high quality glass though. Lunar views were just amazing last night, but conditions seemed to be very good anyway for lunar viewing, so perhaps I was flattered by the eyepiece and a combination in sky conditions, but the sharp images in the 5 inch Dob of the moon were the best I have ever seen to date I think.

I can already say, unless I can't live with the back outs and/or kidney beaning this is an absolute  keeper.

[YKSE]

Nice short sesstion, Alex, hope you get along with it and can fully enjoy it's potential.

[NGC 1502]

I am actually the type that does tend to read manuals, does that make me a girl ? Last time I checked I did not put any nail varnish on before going out observing mind you :0)

Well actually you know, we only have your word for it that you're NOT a girl 

Seriously, enjoy that fine eyepiece, Ed.

[alan potts]

Alex.

Nice report

It would be very nice if you could build on it as the conditions allow, it is always nice to read about fairly rare eyepieces, it's not one that everyone has, sort of wish I had one.

Alan

[John]

Nice report Alex 

Quite a few of the more exotic eyepieces that I've owned have taken "some getting used to", it's not just the XL. So keep at it !

[AlexB67]

Thanks John, I am not too discouraged by the hard to use bit, for the first 15 minutes It was a bit of a fight and a struggle, but by the end it was getting noticeably better. the pinpoint stars are a site to behold, the little bit of less than perfect sharpness I could see in the pentax at f/5 in the Heritage was just that last few percent, without actually measuring it, but of course the scope is only to blame for that, it only looks like a little coma to me.    Having had a taste for what besides a little coma is essentially a razor sharp field with super transmission, that does not want to make give up easily.  I think it is a question of getting the eyecup just the right height, but also keeping your eye dead centre above the view on axis. I think it is in the latter category where I have never experienced an eyepiece so sensitive. I believe what I am suffering from is a combination of all of the following: lateral and axial misalignment and fighting a little bit of both to supress them.

All that discussed and explained nicely here http://www.handprint.com/ASTRO/ae3.html#dimensions   in a subsection titled eye misalignment  

[Qualia]

Thanks for the review, Alex and don't worry about the eye position for now. I figure with any new tool, it takes a while to get used to them. I recall folk having a similar issue with the Delos eyepieces until they practiced a little with the eye-relief sliding thing. It might be an idea to raise the eyecup to maximum and work from there. When the weather allows be nice to hear your opinion on different objects, say a glob, galaxy, Moon and Jupiter.

[AlexB67]

Qualia

Part 2: Jupiter observing using in the 10 inch Dob.

First of all blackouts and kidney beans, I had no problem whatsoever with it, not even once with a blackouts or eye positioning. Now I suspect the larger exit pupil may be helping or whatever it was, perhaps I got the adjustment right and/or found the sweet spot    , I was not even sitting but bending down a bit to look at Jupiter, it was as comfortable to use as any of my other eyepieces.   (Focuser slop on the heritage 130p causing alignment issues under the weight perhaps upsetting things too ?, to be investigated at a later date )

During the test, as well as the pentax, I also used the 8mm BST, switching back and forth between them.

Really really impressive views with the pentax. Great detail, contrast  and colours on the bands showing up under what were a bit foggy skies, but nevertheless quite still and clear around Jupiter.

Against the BST, where it mainly wins is off axis, no prolate or oblate planet shape pretty much all the way to the edge  , this allows for much longer viewing to tease out the details while Jupiter drifts across the view, a very nice luxury to have.  Whilst the magnification with the pentax is on the low side for planetary observing,  there was as much detail to be seen as with the 8mm BST, in fact I preferred the views in the pentax. On axis the 8mm BST actually does do very well against it, but as soon as you get about a third a way off axis the pentax really comes into its own whilst retaining the details on the bands ( I tried in the process to account as best a I can for atmospheric variations over the sessions with each to try and not bias my opinion ). 

I am stoked with this eyepiece  , It may have cost me twice as much as a BST, and a little bit more,  but this is well in proportion with off axis improvement for what you get when viewing a planet like Jupiter in a f4.7 Dob. 

With the slight fog and moon I did not test anything else. More to come though, globulars, open clusters, galaxies.

[John]

It's all sounding very good Alex