John

The effect on the eye relief depends on the focal length of the barlow lens as well as that of the eyepiece. The "shorty" types of barlows increase eye relief more than longer designs. So a short barlow used with a longer focal length eyepiece gives the maximum eye relief change. I wish I had a neat "sliding scale" type diagram to illustrate this, but I don't

There is something about that orange and dark grey colour scheme that is very attractive in a slightly nostalgic kind of way The age you have estimated may well be right but I believe that I read somewhere (Rod Mollise ?) that the serial numbers are not a precise dating tool. The condition of your example looks really superb though

Personally I prefer not to barlow now. If I did, with the XW's I think I'd be using a Powermate to maintain very fine optical quality in the optical train and to avoid lengthening the already generous eye relief beyond the reach of the adjustable eyecup.

Last year I added the 10 and 7 to the 5 and 3.5 that I already had. I got impatient waiting for used ones so gave FLO my business as their prices are good for the XW's.

Great eyepiece, really great The Astroboot site sells the "bolt cases" in various sizes: http://www.astroboot.co.uk/AstroBoot Probably available elsewhere as well. Interesting piece on the Pentax XL & XW's here - personally I'm not going to strip mine down though ! https://www.astromart.com/reviews/article.asp?article_id=716

What's going onto there Mike ?

I think so - the 2" barrel of the eyepiece will restrict the diameter of the field stop and therefore the AFoV.

It's all very confusing ! Vixen still list a 50mm in the same "skin" as your 30mm but that seems to be called the 50mm NLV rather than NLVW

The 42mm bodywork is in the old LV style. The 30mm seems to be a newer bodywork design. There used to be a 30mm to match the 42mm in looks I seem to recall, and a 50mm too.

Interesting report The only focal reducer that I've used with an SCT was the Celestron F/6.3 one which I used with a C5 and later a C8. It seemed to do a decent job with 1.25" plossl eyepieces up to around 25 mm in focal length. In longer foacl length eyepieces I can recall seeing a blurred and narrower field edge. I didn't try it with 2" eyepieces because I'd read that the vignetting would be worse with the larger format eyepieces. Looking at the one that you have tried out, it looks from the photo that the clear aperture of the reducer optics might be a fair bit smaller than the aperture of the field stop of a 24mm 68 degree AFoV eyepiece ?

Pure class Matt That do you mount it / them on ?

I used to have one of those and had a number of different mount heads on it over a few years. Very stable tripod - same as the EQ6 but with an EQ5/HEQ5 hub. Quite a bit taller than the 1.75" HEQ5 tripod as well.

I ended up keeping a Skytee II over the much more lovely Giro Ercole. Bottom line was that the Skytee II held my big refractor steadier than the Ercole could which I demonstrated to myself over a number of sessions. Sometimes you have to go with your head rather than your heart !

I tend to cherry pick from ranges. Some ranges are pretty consistent across all the focal lengths but most that I've tried have some variation with some "stand out" ones and one (or sometimes more) not quite so good. Pentax XW's are an interesting range because of the variation in optical design. They are not a "scaled design" so the characteristics vary focal length to focal length. None are actually bad eyepieces though, as far as I'm aware. Incidently, not all ranges are par-focal thoughout by any means. The Delos 17.3 and 14 rech focus around 8mm further in than the rest. Ethos eyepieces have a widely varying focal plane range.

Just on the bolt size for the Ercole, I used the standard HEQ5 one (M10 I think) that came with the Uni 28 and it worked fine:

I had the Ercole that I used to have on a Uni 28 tripod but I was intending to put a 130 F/9.2 triplet on it ! One of the 1.75" steel tubed HEQ5 tripods would do the trick though. Not sure a photo tripod would be quite enough unless it was a really good quality one such as the one that Matthew was using here: http://alpha-lyrae.co.uk/2015/05/03/tele-optic-giro-ercole-alt-az-mount-review/

Thats quite a mix but some very nice glass in there. My main 2 sets are not so mixed these days although I do still find it hard to resist picking up an interesting eyepiece bargain now and then which seemed to have formed a 3rd set on their own My "oddball" set comprises (L to R): Vixen NPL 30mm KK Widescan II (branded Fullerscopes) 20mm Orbinar (yes, really !) branded zoom 21.5mm - 7.2mm (really rather good for just over £50 !) HD Ortho (Japanese but non branded) 4mm Sorry about the rubbish pic - taken in a hurry !

Sorry to hear about your dog passing away. I don't make any link between the loss of my sons pet and any celestial event. Pure coincidence as I'm sure your loss was as well.

Down to earth with a bump this morning. I've just had to deal with one of my childrens pets that passed away in the night. From now on Barnard 33 is going to be known as "The Dead Gerbil Nebula" to me commemorate of this event I'll notify the IAU later......

Yes, The Horsehead does seem to be relatively straightforward to image. I could probably get it with my Canon DSLR in my EQ mount with a little guidance from imagers. But it does seem to be a notable challenge for observers. I guess imagers have their "Everests" too ?

It did cross my mind at one point to try my DGM NBP filter (similar to a UHC) but I was so much "in the zone" with the Astronomik HB that I was afraid that I would loose my concentration if I swapped filters. Next time I will give it a try

Thanks Stu. I think my experiences last night will help next time around but the transparency of the sky last night was exceptional for here. Probably the best I've seen in 12 months or more. If we get a cold winter this time around and a few more nights similar, who knows though ? One further indicator that I had that the night was particularly good was that late in the session a quick look at M1. That nebula, which can be rather dull visually, was bright, contrasty and showed structure even with the H-Beta filter in place. Normally I'd observe The Crab filterless or with the DGM NBP filter and David Knisely reckons that M1 is virtually invisible with a 10" using an H Beta so goodness knows what it would have looked like with the NBP !. Apart from this quick foray into Taurus, I spent at least 3 hours exclusively in Orion

Congrats to you Paul - I think the reason that I parted with that filter was frustration with me and my regular skies rather than the filter !

Well, I didn't think I'd be making this post but here it is - tonight I have managed to see the Horsehead Nebula, Barnard 33 The sky here tonight is the best and darkest I've experienced for a long, long time. The transparency is excellent although the actual seeing is mediocre in terms of star images, splitting doubles etc. M31 is a direct vision naked eye object and notably extended too. The double clusters in Perseus are clear without any sort of optical aid as is M35 in Gemini and the brighter 3 star clusters in Auriga. I don't know what the naked eye limit at the zenith is - probably close to mag 6 ? This is as good as it gets from my back yard. By 12:30 Orion was well above the rooftops and the streetlights have gone out. Neighbours have gone to bed and there are no lights on in our house or any in the vicinity. It's all "come together" for a change and my 12" dob is definitely the right instrument for these conditions. I've been trying to see the Horsehead Nebula for a few years now. I've got to know the star field around the star Alnitak (lowest of the "belt" stars) well and I've read the advice pages on the target plus reports from those who have seen it many times. All lights off. Laptop screen is dimmed, curtains are closed tight. I spend 20 minutes outside just looking around the sky, getting as fully dark adapted as I can. First stop on the path to the Horsehead is NGC 2024, the Flame Nebula, which is right next door to Alnitak. Good start tonight - the Flame Nebula was not only visible without a filter, but the dark rifts that run through it, like the branches of a tree, were also visible. Even the dazzling Alnitak in the same field of view could not drown out the illuminated lobes of the Flame. Ok, time to add the Astronomik H-Beta filter to the eyepiece of choice for this search, the 24mm Panoptic. Filter in place, I was pleased to see that the Flame Nebula,it's shape and form were still quite visible. Time to push Alnitak and the Flame out of the field of view and to concentrate on the 1 degree of sky that is home to the Horsehead Nebula. There are 3 stars that frame this patch of sky on one side, one of which is bathed in faint nebulosity which this evening was visible with and without the filter. This is NGC 2023, a faint emission and reflection nebula. I had seen this before but not as clearly as it was showing tonight. Another hopeful sign. Now the big challenge. I knew that the key to seeing the Horsehead Nebula was to detect the faint glow of the emission nebula IC 434 but in previous attempts this was the fence that I'd fallen at (Horsehead - get it ??!! ). Tonight though, as my eye adjusted to the filtered light across the field of view, the elongated but rather amorphous band of slight cloudiness that is IC 434 gradually became apparent, varying in density here and there, almost not there sometimes but re-confirmed subtly over and over as my eye swept around the field of view. And there it was. A bay, an intrusion, a dark overlay, a piece of IC 434 was missing !. Quite a large piece as well or so it seemed as my eye moved from one side of the field to the other bringing various degrees of averted vision into play. It's been described as a dark thumbprint and I'd concur with that. Not a chesspiece, no snout or ears, but a soft edged, ill defined shark bite chunked out of the side of the nebulosity, leaving the black sky to spill into that cove and the nebulosity of IC 434 to curve around it. One side of where the dark intrusion started was marked with a very faint pair of stars which I believe I've read Swampthing / Steve describe as his indicator of the Horsehead location. I kept observing for 20-30 minutes trying all the tricks I know to keep all stray light from around my eye and the eyepiece. The clarity of what I was seeing ebbed and flowed, possibly after a while because my eye was just trying so hard !. But the more I observed, the more confident I became that I was seeing this long sought target. Ok, it was very indistinct - well I'd thought it would be, especially if I ever managed to see it from my back yard, but I was pretty sure that I was looking at Barnard 33, at last !. I rather reluctantly dragged myself away from the eyepiece and tried a couple of other eyepieces with the H-Beta filter attached - a 30mm plossl (Vixen) and the 17.3mm Delos. Each time I came back to the eyepiece I needed 10-15 minutes to get back "into the zone" again. But the same pattern of vague nebulosity was indeed replicated with the darkened bay pushing into the cloudy edge of IC 434 in the same place, to the same extent and at the same angle, each time. The original 24mm eyepiece seemed to provide the most distinct view but I should really say the least indistinct !. Not a spectacular view at all, just suble variations of dark and slightly darker patches of space peppered with stars. Without the filter the stars brightened but only the Flame and NGC 2023 were visible in terms of nebulosity. IC 434 and the large, dark, thumb shaped indentation were nowhere to be seen. OK. Back inside to warm up (it's cold out there despite the adrenalin flow that the hunt has prompted). Take stock of what has been observed. I turn to one of my favourite web references on deep sky observing - Jeremy Perez and his wonderful "Belt of Venus" website. Here is what Jeremy says about his observations of this target, albeit with a smaller aperture scope than mine (from a darker sky though, I'll bet !): http://www.perezmedia.net/beltofvenus/archives/000379.html Re-reading the above has confirmed 100% for me that, tonight, I have seen the Horsehead Nebula So much of what Jeremy describes chimes with my experiences and my impressions tonight I got into astronomy 40+ years back with the help of Sir Patrick Moore's "The Observers Book of Astronomy" and in that little volume there is a greyscale long exposure image of the Horsehead Nebula which made a big impression on me then and has stuck with me to this day. Quite possibly this is the least impressive target I've seen though a scope in all those years observing but the pleasure that seeing it at last has delivered is very tangible indeed. If you have got this far, thanks for bearing with my rambling descriptions

Your Skywatcher Mak Cass 150 will be doing a pretty good impression of a 120mm apochromat so you are probably not missing much to be honest