billyharris72

I was going to chime in that the ST80 will outperform the 70mm (though CA is not something you just get used to - it does reduce contrast and blur the image, and above about x80 the ST80 deteriorates badly). But the Mak suggestion is miles better. Not great for birding or DSOs, but perfectly serviceable with a 32mm Plossl or similar, and a good performer on the Moon and planets, plus sturdy and very portable. I reckon the Skywatcher 72ED would make a nice travel scope but it's a bit over budget (and the Mak will beat it on the Moon and planets). Billy.

I'd be a bit surprised if those outperformed what you already have, at least in terms of edge sharpness (though with that field I'm sure they would give good views). I'd stick with what you have and only look to trade up if they're not up to the job. This is interesting. For me at f5 and f6 the 18mm is the pick of the bunch, with the 12 and 25 pushing it close. I'm not that impressed with them below 9mm (though it's not edge sharpness that bothers me; I just find the image a bit dim and mushy). I wonder if that's a difference in taste or if the quality is a bit variable. Billy.

Thanks for the suggestions SkyGibbon. I was pretty worried about it but I think I just need to slow down, step back and work it out. Not at home for a couple of days but when I get back the first step will be to replace the screws (a couple of them - not the tension ones - are so mangled I couldn't put them back), then check the tension. Maybe also the other bearings - if one of them was damaged I suppose that could account for it. From what I can see the Crayford design is not that complicated, so it ought to be fixable, even for an incompetent bodger like myself. Billy.

Hi Ant. I think it depends on the type of focuser it is. If it's from the 150p then I'm pretty sure it won't do the job, as it is not low profile enough (so the camera won't reach focus). If it's the low profile one from the P-DS range (or similar) then I should think it would work fine. If it is the right one then fantastic - but not to worry if not. Thanks for the offer in any event; it's much appreciated. Billy.

Maximum for me is about 100x, with a 4mm plossl and a Baader semi-apo filter. It works, but I wouldn't call it pretty. Billy.

Hi there. I don't have anything faster than f5 (where they work fine) but the following thread suggests they are good performers in fast scopes. If I were you I'd be reasonably confident and would definitely hold off on buying EPs until I'd tried them. In the end different people have different expectations but if say the omens are good! Billy.

Hi all: I' looking to replace the focuser on my 130pds (I've made a couple of mods in the past that if I'm honest have not worked out that well and would like to get back to the original setup. Has anyone out there upgraded their focuser and found themselves with a spare - let me know if so. Happy to pay any reasonable price - new price from FLO is £106 but they don't seem to be in stock currently. Cheers, Billy.

Hi all: Today I decided to improve my scope (130 P-DS) by fitting a Skywatcher auto focuser (you know, the one that doesn't fit it but does with a bit of fiddling). After a bit of fiddling I managed to dismantle the focuser - this needed a bit of rough treatment as some of the allan bolts were very badly rounded and I did try to move it by tapping a screwdriver in (gently!) with a hammer. In the end it was a hacksaw and flat head screwdriver job. After fitting the autofocuser I put the thing back together only to discover that the focuser now barely gripped the tube - any pressure on it at all and it would just slide back into the focuser. I wasn't able to get at the adjustment screws with the autofocuser attached, as the bracket that attaches it obscures them. In the end I had a go at reassembling the focuser in the original (manual) configfuration. I still have the issue with the tube slipping, but also it seem to catch and "grind", like metal is rubbing against metal. It doesn't feel right at all - it would be barely usable for visual and not at all for AP (it won't support the camera). I guess my question is, does this sound like something that can be readilty fixed (and if so how) or does it sound like I need a new focuser? Thoughts appreciated. Billy.

I think this is a fair point. There's also the issue of scale. The Moon is tiny (smaller than it looks, actually about the size of your pinky nail) so if Neil Armstrong had stood on it he would probably have squashed it flat. Billy. Earth and the moon are like this.

Meant to add - the main limitation of your Canon is probably not the sensor. It's almost impossible to get single frame DSLR shots that are pinpoint sharp at high manifications - the seeing conditions will pretty much rule it out. The idea is to shoot video and use Registax or Autostakkert to produce a sharp image from several thousand frames. If I remember correctly this doesn't work well on a DSLR because when shooting video the camera does not use all the pixels on the camera, but reduces the resolution by taking every nth one. As a result you're effectively shooting with much bigger pixels and lose a lot of resolution (while gaining nothing in light sensitivity as you would with CCD binning). Hope this helps. Billy.

Hi Murray: It's not so much the resolution of the camera in MP that matters as the size of the chip and the size of the pixels. A larger chip will get you a larger field of view, and smaller individual pixels will get you more resolution (provided your scope has enough resolution and seeing conditions will support it). The ASI178 wins on both counts (1/1.8 inch chip will get you a wider field while vs the 1/3 inch chip in the 224, while the 178 has 2.5 micron pixels vs 3.75 for the 224). In terms of the field of view the 178 will always show you more in the field. The pixel scale (0.21 vs 0.33" per pixel) might get you some gains on nights of good seeing, but the UK is not exactly known for this. I think the benefit of the more expensive camera would be the flexibility to frame slightkly wider shots (you can always choose to go narrower by shooting using only part of the sensor). I don't think there are any out and out advantages to the 244, other than price, but it should bag nice (though very narrow field) images. Billy.

Biggest being the operative word for the fainter DSOs. Quality is nice, but for visual observation of galaxies and the like aperture trumps it every time. Clearly both matter, but when deciding where to spend your money there is a trade off to be considered, and the optimum will differ depending on what you like to observe most. It probably also differs from person to person. There's a simple test here - if you can take a partially defocused scope, point it at a DSO with no bright stars visible in the field and get the image pinpoint sharp by focusing on the DSO (test it by moving to a brighter star and verifying that there really is no room for improvement) then quality is going to be your limiting factor. What I've tended to find is that, for an 8 inch scope of standard Chinese manufacture (in my case a Bresser Messier Dob) quality becomes more important for objects with clearly resolvable stars (the Auriga open clusters, for example, or M13; not including planets here as that's pretty obvious). I've yet to find a galaxy (including the bright ones like M81 and M82) where it was as much of a factor, and once we get fainter than that it's aperture all the way. My 2p worth at any rate, but I suspect plenty have a different view. Billy.

I suspect everyone finds work a massive inconvenience - even non astronomers and people with jobs they enjoy (including professional astronomers). Maybe it's supposed to be that way - that's why they call it work! Billy.

I don' think the HEQ5 will struggle with that at all. Total OTA weight, sans accessories, is under 7kg I think. Even with the cameras I should think you'd be fine (though you might want to unmount the Mak for longer exposures). Image scale will be fairly small with that setup (I use the 150mm and it' the same story - I also find the setup doesn't Barlow well for some reason, though that could be my Barlow) but it's certainly workable. I suspect a camera with smaller pixels would be better, but we can only work with what we have. Billy.

x150 seems a pretty good result if you're looking over town. I rarely go above about x133 (9mm) on Jupiter these days, and often less - I always find I end up seeing less if I try to push it past that. Billy.