Pentax or Vixen?

[Tyke 123]

Any thoughts if anybody what has (or has had) a skymax 127 mak or equivalent and used a Pentax XF 8.5mm or a Vixen SLV 8mm eyepiece. 

These eyepieces will be the usable high power limit for this Mak from what I've read being from the UK and it's rubbish sky's.

I don't expect to be using this eyepiece regularly due to seeing but it would be nice to have one in standby just in case.

So any user's of this set up please give us you're thoughts please.

[Jiggy 67]

Why do you think the UK has rubbish skies compared to any other country??....a bit more LP maybe as a result of our large cities but everywhere has intermittent variations of seeing depending on conditions at the time, regardless of location. I have no experience of a Mak but I can get to x300 mag in my newt under UK skies in reasonable conditions 

Edited May 2, 2021 by Jiggy 67

[Tyke 123]

Sorry ,I should have mentioned that I live among a fairly light polluted area RUBBISH UK skies.

Thanks for the great recommendation of the eyepiece question though....invaluable. 

Edited May 3, 2021 by Tyke 123

[Jiggy 67]

32 minutes ago, Tyke 123 said:

Thanks for the great recommendation of the eyepiece question though....invaluable.

No problem 😉 

Your original post implies you are worried about high power mag due to UK skies and poor seeing. Your 8mm would give you x187 mag. My point is that our skies won’t stop you achieving that so both your choices will be fine. However I have no experience of Maks so another user might disagree. My point was to demonstrate sky quality was that I can comfortably achieve x300 and beyond.

Light pollution is a different issue and has little to do with seeing 

[Stu]

2 hours ago, Tyke 123 said:

Thanks for the great recommendation of the eyepiece question though....invaluable. 

Please can we leave the sarcasm for other places on the web, not on SGL. Thanks.

I’m sure someone will be along soon to give an opinion on these two. I’ve not used the Pentax, but the SLVs are good, sharp eyepieces with generous eye relief.

I echo jiffy’s comment though, that whilst our skies can be rubbish at times, it is not always the case, and higher magnifications are useable when the seeing steadies. This is nothing to do with light pollution; I used x300 in a 4” refractor a few times last year on Mars and the Moon from Bortle 7 skies near London.

You are right though that when the planets are low, using high power doesn’t often work, but x187 should be useable more often than you might think, provided your scope is well cooled and collimated and the skies are steady.

[F15Rules]

Both the Pentax and SLV eyepieces you mention are excellent, both have a very good optics, good contrast and are ergonomically comfortable.

However, the Pentax has a 60 degree field, noticeably wider than the SLV's 50 degrees: since your Mak is a long focus scope (nominally c F11.8) it will already have a narrowish field, so I personally would choose the Pentax 8.5mm.

Also, there are a number of online reviews which claim that the Skywatcher 127mm Maks are actually operating at 118-119mm, ie about half an inch less aperture than claimed by the manufacturer.

If this is correct, this would have the effect of increasing your scopes' focal length bit more (to c F12.8), so all the more reason, to my mind, to take the wider apparent FOV of the Pentax.

Dave

[johninderby]

Perhaps an Opticstar or ES 82° 8.8mm eyepoece if wide angle is important to you.

http://www.opticstar.com/Run/Astronomy/Astro-Accessories-Telescopes-Opticstar.asp?p=0_10_5_1_8_322

[mikeDnight]

I do not believe the UK has "rubbish" skies! Our skies have deteriorated over the last 40 years, of that I'm certain, but we still get excellent seeing and transparency at times. Only a few miles from where I live is a darkish site where ten years ago my friend and I saw M33 with the naked eye. Just a mile away in any direction and you lose that advantage. The point is, there may be sweet spots even close to home, we just need to search them out.

Edited May 3, 2021 by mikeDnight

[Louis D]

I would start with an 8mm BST Starguider for less than half the price of the Pentax XF unless you're trying to tease out low contrast details, at which the XF excels.  Both have about a 60 degree AFOV.  I have all but the 3.2mm Starguider, and the 8mm is probably the best of the bunch.

There is no such thing as an 8mm Vixen SLV.  There's a 6mm and a 9mm.  There used to be a 7mm Vixen LV, but it was not carried over to the NLV or SLV lines.  I have the 9mm Vixen LV, and while it is Pentax XL level optical quality, it views a bit darkly.  Otherwise, it's a great eyepiece if you need long eye relief and can live with a 50 degree AFOV.  Focal lengths below 9mm are all 45 degree AFOV, so be aware of that.  The advertised specs are wrong.

Again, the Vixen SLVs are more than twice the cost of the Starguiders, at least in the US.  If you can find a used LV for under $70, they're worth it in my opinion.

[Don Pensack]

This review should be read by someone contemplating the 8.5mm Pentax XF:

https://www.cloudynights.com/articles/cat/user-reviews/review-of-at-paradigm-8mm-and-pentax-xf-85-mm-r2737

It's a fine eyepiece for everything except the Moon and planets, where internal reflections are an issue.

[DeanCJ]

I have a 127 Mak, and also a large collection of Vixen SLV’s.
I have a 8mm Vixen NPL 50 degree plossl which I find very nice but the eye relief is quite short and at the limit for me personally, I also have an 8mm BST Starguider 60 degree which is a good eyepiece and has much better eye relief. 
I find 8mm really good for the moon and on nights of good seeing I have used it on Saturn with good results. I also have a 7mm Vixen LV which I use mainly for lunar on exceptionally good nights. Skywatcher also do a 7mm 58 degree planetary eyepiece which I found to be a surprisingly good eyepiece. 
I have used 8mm more than I expected and to be honest I think that with 7mm I have probably reached “empty magnification”.
I am a big fan of Vixen eyepieces, and with the Mak I really like the 30mm Vixen NPL, the twist up eye-cup is great for eye placement and helps reduce kidney-beaning, and has a good fov.
I am still very much a beginner and am sure other members will give you better advice than I can.
 

[DeanCJ]

Speaking of internal reflections, @Don Pensack has posted some excellent photos and comments about some kind of retaining ring? inside Vixen SLV eyepieces which has no paint or anodising applied to it, causing strange reflections. General opinion seems to be that this was on early production eyepieces, so if you are considering buying used I would try to buy as new as possible.