haven't had one, did try & buy one from US but at the time the middle man wouldn't post it to me, some CN'ers are fans - though i forget which are the cherries & which were the prunes
Yeah, for some reason there are many folks who don't want to sell their products overseas, . Oh well, they have their reasons, not for me to judge. But there are ways around this too, that have been discussed often here in IIS.
I got a suprising PM the other day. A fellow IIS member has lent me three of his Russell Optics eyepieces for a bit of a fang. Bloody amazing too. Get a load of these focal lengths, all in the 2" format:
65mm Super Plossl XL
72mm Super Plossl
85mm Super Plossl XL
Truely astounding!
These EPs are not that big either, about the same size as my GSO 30mm Superview, and weight wise, 350g, 215g & 285g respectively for the RO's. The GSO being 270g.
The main difference being the material used for the housing, not aluminium but Delrin, a type of black plastic.
A couple of those Eyepieces look similar in design to the Siebert Optics http://www.siebertoptics.com/ - whether they are the same I don't know but I have a 28mm from them and had a few problems with construction fit with my DOB. Not sure about my Refractor though.
I thought I'd write a few notes on my experiences with the Russell Optics eyepieces I've been lent. Again, they are:
65mm Super Plossl XL
72mm Super Plossl
85mm Super Plossl XL
The test scope I used was my Orange Tube C8, and used as a comparison eyepiece my GSO 30mm Superview.
This first use of these eyepieces was under new moon conditions under urban skies from my backyard in Sydney. I'm looking to get to use these EPs at a dark site in the next few days.
I have to say first off that the Delrin material used in the body is brilliant! It's warm to the touch compared to metal body EPs. I didn't like much the experience of exchanging EPs from the RO's to the metal ones! The fit into the 2" diagonal was fine, with the 85mm a little more snug.
Next thing to be noticed is the enourmous eye lens on these buggers. Upto 42mm in diameter with the XL's. The lenses are also noticably multi-coated.
After locating the target object of M8 in the GSO, first into the diagonal was the 65mm. Gosh! The eyerelief is extraordinary! I had to pull my head back from the EP a full inch to be able to see the whole FOV. This only got longer with the others, about 50mm for the 72, and a full 3" to use the 85mm.
The AFOV in the 65mm is larger than with the GSO, but the limiting factor with these EPs is the barrel, this is called vignetting. At 2", the FOV potential of these EPs is crippled. The AFOV is wider, it is the exact same size for each EP, but the FOV does get smaller going up in FL. This also manifests with the last 5 to 10% of the FOV loose light intensity very quickly, resulting in a soft field stop, not a sharp, crisp finish. I actually don't find this objectionable. Expecting to see this, I was not surprised to notice it, and it is not a real issue as one never really focuses on the edge of the FOV when observing.
While the eye relief was unexpected, and took a few moments to get used to it, the 65mm is actually quite comfortable to use. I can't say the same for the others. As the night wore on, I began to find the 65mm much easier to use than the GSO.
There is one draw back to using long FL EPs in urban areas, the background sky glow does get brighter. This made distinguishing the nebulosity of M8 more difficult to make out as contrast is reduced. However, the stars themselves are still nice and crisp. A quick view of Omega Centauri had the GC's image resemble that through binoculars - a fuzzy undefined ball. Concentrating a little on the image did begin to expose resolution detail, but it was faint.
I actually couldn't make out any distortion to the stars across the FOV of all these EPs. My guess, apart from the slow F/ratio of the SCT, is that the vignetting reduces the potential distortion area to outside the visible AFOV. My GSO still displayed a tiny amount of astigmatism in the very last 5% of its FOV.
This first experience was an interesting one. The 65mm is a really easy EP to use. For urban areas, this EP may not be the best choice if trying to see DSOs, but it makes a fine finder EP. The two others, not only do they show a smaller FOV due to vignetting, but the eyerelief on these is ridiculously long.
I'm excited at the prospect of using these at a dark site, particularly the 65mm. I'm hoping to be able to use these also in an even slower Maksutov scope, along side the C8, and maybe a few other EPs too. But that's a few days away if the clouds behave.
The AFOV in the 65mm is larger than with the GSO, but the limiting factor with these EPs is the barrel, this is called vignetting. At 2", the FOV potential of these EPs is crippled. The AFOV is wider, it is the exact same size for each EP, but the FOV does get smaller going up in FL. This also manifests with the last 5 to 10% of the FOV loose light intensity very quickly, resulting in a soft field stop, not a sharp, crisp finish.
This is all clear as mud - you seem to confuse apparent field sometimes with true field. Why not just list the true field in degrees with each eyepiece and /or the field stop diameter and also list the Apparent Field of View for each one in degrees and everyone will work out what you are trying to say .
The True Field of View (TFOV)was the same in all eyepieces. That is, the same amount of sky was seen, no larger or smaller. This is due to the limitation of the 2" barrel. This is what I meant to say when I mention AFOV. The TFOV visible in all of these is essentially the same as that given by a 40mm 68deg eyepiece.
The Apparent Field of View (AFOV) as a result gets smaller as the focal length increases. All of these eyepieces have a field stop of 43mm. The AFOV of the 65mm is approximately 38deg. This gets smaller with the 72mm and smaller again with the 85mm. The AFOV of the 72mm is 34.2deg, and that of the 85mm is only 29deg.
I think you can get a televue 55mm Plossl having an apparent field of a healthy 50 degree and an exit pupil of 5.5mm with a C8 - guaranteed to get that cone into a +40 year old eye. I wouldn't bother with the `drainpipe' eyepieces seeing as they are not giving any greater true field , although they may make sense if you own an F15 Cassegrain or refractor and you want to get the exit pupil size up . The lack of apparent field with those shouldn't bother such owner anyway as they are probably living in the 1950's anyway if they own kit like that
Wow the RO 65mm Plossl is a very nice eyepiece...in my f12 Refractor. Gives amazing views like a finder scope on steroids! All the detail is there...albeit small but it has it's place. Very much like my ES 40mm 68º which maxes out my scope at 1.5º TFOV.
Thanks Alex...one nice eyepiece in the right scope.
A couple of pics....
HOORAY! The 65mm Russell has finally found its true home!
It really needed a scope like yours, Matt, with its slow focal ratio. It was wasted with my scopes. Its AFOV may be a little small, but the image it throws up really is beautiful. And it weighs nothing!
I have no regrets in having initially bought this 65mm eyepiece. It is a special piece and needed to be experienced and enjoyed I still have its 50mm Russell Optics brother. It too uses Pentax glass like your 65mm, Matt. These Pentax lenses are very hard to come by now, even for Russell Optics. Very special pieces these. The 50mm better suits the instruments I have.
By the way, the most beautiful image I've seen through my old orange tube C8 from a dark site was using that 65mm Plossl! Its clarity, and the brightness of the image, the amount of pin-point stars right across the entire FOV, is forever seared into my mind's eye. So much so that I still remember where I was, and the occasion too. I really am very happy to see it finally find its true home.
Oh, and how is that eye relief with that 65mm!!!! Freaking astonishing!
. Oh well, they have their reasons, not for me to judge. But there are ways around this too, that have been discussed often here in IIS.
- you seem to confuse apparent field sometimes with true field. Why not just list the true field in degrees with each eyepiece and /or the field stop diameter and also list the Apparent Field of View for each one in degrees and everyone will work out what you are trying to say .
I still have its 50mm Russell Optics brother. It too uses Pentax glass like your 65mm, Matt. These Pentax lenses are very hard to come by now, even for Russell Optics. Very special pieces these. The 50mm better suits the instruments I have.
Freaking astonishing! 
