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    SGL 2017 SP


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About Relpet

  • Rank
    Star Forming
  • Birthday 03/06/39

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  • Interests
    Astronomy, films, history books, French Resistance, sitting in the sun pondering the ineffable mysteries of life.
  • Location
    South-west France
  1. Canon DSLR vs Nikon DSLR

    More great advice for anyone on a budget. Many thanks.
  2. Canon DSLR vs Nikon DSLR

    Thanks a million to you and Mike for this advice. Have just checked ebay and found one compatible with the Nikon model at a very affordable price. SGL members, you win again!
  3. Canon DSLR vs Nikon DSLR

    Yes, I have to shoot in manual as none of the auto features will work unless a Nikon lens is attached, as far as I have been able to discover anyway. That's an interesting point about the sensor, though. I may have been pointing the remote in a vague direction rather than a specific direction before so I'll get up close and personal next time. There are astro-modified Canons coming on to the second-hand market all the time in UK so that may be the best way for me to go rather than spend more time trying - and probably failing - to get a result from the Nikon. I'm also intrigued by the Revolution Imager (made in California, I believe) advertised in this month's Sky at Night magazine. This seems to tick so many boxes for a novice, feedback on that would be really valuable. Subject for a new topic maybe.
  4. Canon DSLR vs Nikon DSLR

    My input is from a very inexperienced user. I have had a Nikon D5100 on long loan from a cousin for a couple of years now. Whenever I have tried to use it for prime focus work with either a Dobsonian, Mak or APO because the camera does not recognise the telescope as a Nikon lens it will not allow me to use certain features on the camera, the most important of which is the infra-red remote. I always have to press the shutter button manually which makes for faster shutter speeds and thus higher ISO ratings than I would like but still with inevitable vibration. More experienced photographers than me have probably found a way around this but a pal with an older Canon has no such problems.
  5. There are probably thousands of newcomers to this pastime who have reason, like me, to be thankful for your piece on collimation. Any time a beginner asks for advice about collimation someone, somewhere - anywhere in the world it seems - refers them to your article. When your site went down there was weeping and wailing and gnashing of teeth so it's so good to see you back and, for me, have the chance to say a big thankyou for the help it gave me. May your return to health last a very long time.
  6. I bought the Seben 8-24 a couple of years ago. It does a reasonable job. If you remove the rubber ring you'll find a thread beneath which you can screw into the T-mount of a DSLR. You won't get fantastic pictures but for showing somone the basic principles you'll get a reasonable picture of the moon through all the zoom range. What I don't like about Seben's marketing is that they offer a gift if you give them a rave review on ebay or Amazon, so don't necessarily trust those reviews. I did post a three-star review once explaining why it wasn't higher but something else I bought from them was too good to mark down and I ended up with a packet of sweets. The attached picture was taken three days ago by eyepiece projection through an 80mm apo refractor, (just for information not for critical response). If, as other posters say, the same product is available under different brand names you might prefer to go that route.
  7. Having recently started using a powered mount I was a bit alarmed a week or two ago when I realised everything was saturated with dew to an extent I'd not experienced before. Being unable to see through the finder was the first clue. So I have to sort out dewstrips but the next step in my long march towards imaging is to link the mount to the laptop to start using a ZWO 120MC. I re-arranged the barn so that the laptop was as close to the door as possible but I would still need to use a USB extension lead to connect the laptop to the camera at the best observing position. I checked before my first attempt that, without the extension, every piece of software on the laptop recognised the camera. In the field, with the extension, zilch. Windows 10, ZWO's own software, Firecapture etc all declared no camera recognised. So, if the mountain won't come to me, the laptop has to go to within 8 feet of the 'scope. I've read previous posts about dew protection but rummaging around the barn, where everything resides that should have been thrown away, I thought I'd try to design something with what I could find rather than recycle a plastic box or whatever. Ingredients found: I x 5-footed chair pedestal (chair long since dumped); 1 x piece of chipboard 4 feet x 2 feet; 1 length of aluminium curtain rail, about 2 metres; 5 x curtain rail supports; 1 piece of copper gas piping, about 15"; 1 x unopened packet of velcro rolls; 1 x part-used roll of double-sided tape; 1 x yoga mat, matt black on each side and purchased last year for a failed project (nothing to do with yoga); 1 x part-used roll of black Duck tape; a few wood screws; a couple of dozen tacks. All this without a trip to the DIY shop. There's no need to bore you with the construction process but the finished article has a quite pleasing appearance. The desk is a convenient height for sitting at and there is space to keep a few EPs free of dew; reference documents up to A4 size and still leave room to operate a mouse. (I don't get on with touch pads. It's an age thing.). Having spent some of ny childhood nights in an Anderson shelter I hasten to add that any resemblance between my dew shelter and Mr Anderson's idesign is entirely coincidental. It will be illuminating (is that the right word?) to see how this works but, in the meantime, I have to order some dew strips. Nothing in the barn yielded anything that might be useful there. Even wartime babies sometimes have to resort to commonsense.
  8. My first 'scope was an 8" Dob. A member here recommended 6mm as about the maximum magnification I could expect while staying in focus. I have a Skywatcher 6mm and a Starguider 5mm, both within your price range. On exceptionally clear nights I can focus the 5mm in the Dob, otherwise the 6mm is max. Both have good eye relief for me. Whatever you buy I hope you find the investment worthwhile but, as Charic says, the seeing conditions make all the difference.
  9. I started a topic a week or so ago about an 80mm TS Photoline apo delivered last Monday. Amazingly we had three and a half clear nights on the trot so I was able to get faster familiarity with it than has been my experience in the past. Clearly the TS was bought for imaging, about which my two-year old grandson knows as much as me. And he's in England so I can't ask him anyway. So, there will be a lot of trial and error. Having unobstructed views across the valley (and no neighbours to accuse me of spying on them) I was able to put the 'scope on a bench and play around with all kinds of stuff I've acquired over the last three years, mostly on the cheap - sometimes the really cheap. This was all bought to have a stab at AP with an 8" Dob, hence the emphasis on cheap. I have the use of a Nikon D5100 DSLR, on what seems like permanent loan from a cousin in Andorra. I didn't have much luck with prime focus using anything from the miscellaneous box. Eyepiece projection, though, revealed some remarkable uses for bits I hadn't touched for many months. Though I have an adjustable 2" extension tube it seems to need to be shorter for use with my 2" GSO Barlow to get focus. Short of taking a hacksaw to the tube I couldn't see a way around that so that's on one side. I had bought an unbranded 1.25" 2 x Barlow simply because it had a T-thread, (I had already bought a similar product from Seben without the thread.). Frankly, I was stunned when this swam into focus. So, that was the first one I would try on the moon. For what it cost it gave a very satisfactory result (to me). The moon filled the flip-out screen from top to bottom compared to the tiny image in prime focus. A 32mm GSO 1.25" EP which I bought through ABS and normally use for preliminary finding also has a thread. So that was next. I think it will do better than the Barlow but while struggling (unsuccessfully) to find the right exposure for Earthshine I forgot about focusing, so that needs to be tried again. Finally, today, I remembered a 7mm to 28mm zoom I had bought from Seben for kids to have fun with on a 4" Newt. That too has a thread. I trained it on the cell 'phone mast on top of a hill four kilometres distant and got focus through the whole zoom range. So that's something to get into lunar action on the next clear night. I'm sorry if this seems rather trivial to some but I thought it might encourage others to explore what they've already got before determining the next step, which in my experience is bound to cost more than they ever dreamed of spending. Powermate next? Gulp!
  10. Thanks, Stu. The loss was occasioned, really, because of the wonderful behaviour of the astronomical community whose generosity of spirit should be an example to the world. Thinking I was buying from an astronomer I failed to perform a number of blindingly obvious checks. Longs story, nuff said. Thanks for your kind words. I just love what I'm doing and being part of this forum. Best wishes Peter
  11. Just to finish off this report the best of the trial moon shots is attached. Prime focus with a Nikon DSLR produced an image too small to be useful. A GSO 2" Barlow with an extension tube through the star diagonal I couldn't get in focus. Need a different tube length. A 32mm GSO 1.25" EP with a T-thread should have produced the best result but fiddling with exposures trying to capture earthshine I forgot about focus! So in fact the best picture came from a cheap (I mean cheao) Barlow with a Seben extension tube. For the record, that's the picture attached.
  12. One of the lovely things about this scope is that it is small and light so I was able to bench test it today through the barn door to the hills yonder with various bits I've bought over the years. I won't bore you with the catalogue but a 2" extending tube directly into the OTA after removing the diagonal was the eureka moment, my first experience of prime focus! So thanks a million, Louise, for pointing me in the right direction. Clear skies tonight so might even get a trial shot of the moon. Peter
  13. First light The forecast had been saying for the last 48 hours that the sky would clear at ten o'clock tonight. In spite of the fact that at 9 o'clock it was still quite overcast I got the Photoline out on the AVX mount. Blow me down, the forecast was spot on. Balancing was problematic. In RA the counterweight had to be so far up the shaft it started fouling an azimuth knob. Further down and the 'scope was out of balance. Fortunately I had a smaller, compatible Skywatcher weight which solved that problem. Dec balancing could also be tricky. The supplied platform is so short that there is very little leeway at one end once the tube has been moved along the mount. These problems are clearly more to do with the mount than the 'scope but might be worth bearing in mind if anyone else considers a similar pairing. I had intended to run the whole system but, as I knew already that the tracking worked just fine with another tube, when I saw the moon come up I just swung around in manual to align the red dot finder. Once aligned I found the Celestron RDF perfectly satisfactory and probably won't need to change it - not just yet anyway. I tried a number of EPs on the moon and was very pleased with the crispness in all of them. Of particular note was the complete absence of any coloration around the limb in any of the EPs. Then I compared what I was seeing with the Dob. The extra precision of the TS focuser is a real boon. Next to Jupiter. This was a revelation because the four moons were all clear dots. I am used to their being slightly fuzzy. Jupiter itself was very clear. A 5mm Starguider EP was the highest magnification I could get but it was in focus, something I rarely achieved with the Dob. I thought I'd better make the comparison and was quite taken aback to see how good Jupiter looked through the Dob tonight. Only then did I realise that the seeing was probably the best I've enjoyed in about 9 months. The image was larger but almost as clear - almost. Again I can't quite get the focusing at high mag with the Dob and, yes, the collimation is spot on. Finally to Saturn. Much the same result as Jupiter. Experimented with a number of EPs. I was quite impressed with the performance of a 2" GSO Barlow in the Photoline added to a number of EPs. I hadn't used it much before but certainly see the benefit now. By now I was beginning to sense that if I carried on flitting in the dark between the two 'scopes with pockets full of EPs sooner or later I would regret it. As tomorrow is also forecast clear we'll probably have a little star party so a friend can take charge of the Dob and show them the works while I explore the Photoline more fully. I know first light reports are usually more technical and useful to expert observers but I hope there is something helpful, nevertheless, to someone in this attempt. Thanks to everyone for their kind responses.
  14. I did try a variety of extension tubes, Louise, but when the moon is a bit fuller I'll have another go. Daylight bouncing off the flip-out screen makes it hard to see in bright sun anyway. Thanks Peter
  15. Part the second Testing this telescope in daylight was an obvious first step. It's only recently I acquired the AVX mount and have had few chances to test that, never mind the Photoline. So, it's a sunny, if breezy afternoon. What I am about to write will seem old hat to experienced frac users and they may wonder what all the fuss is about. The dovetail slid into the plate like a knife through butter. A couple of turns of the stabilising knobs and the whole set up is firm as a rock. First I trained a 25mm Orbinar flat field 1.25" EP on the church steeple about 400 metres away. The cockerel on the top is a subject I choose for aligning or re-aligning finders. The focuser brought the image into such sharp detail I though I was seeing it for the first time. I then tried a 7mm Skywatcher and had fine focus. The next subject was the view across the valley to the mountains a good 100 miles away. With the Orbinar everything was in sharp detail but the mountains, quite vague in a heat haze, seemed to have colour fringing along the peaks. I thought this was probably the EP and switched to the Skywatcher. It did reduce but when I put the 2" 17mm Nagler in any doubts vanished. The heat shimmer was clearly visible but no colour fringing. I had much the same result with a 2" 38mm ES wide-angle. There are several lines of trees between us and the mountains and the three dimensional effect of shifting focus from one line to the other was something I might find myself doing for fun in future. Bearing in mind that this tube alone was twice the price of my complete 8" Dob I would have expected something a bit special but until you see for yourself it's hard to believe what a difference it can make. The focuser is claimed by the retailer to be a bit good (a 2.5" RnP) and without doubt it's Premier League compared to what I'm used to. My eyes are not only old and tired but afflicted by glaucoma but seeing these images just snap into focus was a new experience. The fine focus know is covered by a plastic cap but I found I hardly needed to use it, the main focus knobs do a superb job. It's also the first time I have used a star diagonal so I have nothing to compare it with but simply being able to rotate it to the most comfortable position was another justification for the expense. Even with the breeze blowing down the valley, and the heaviest EPs in use, the image in the eyepiece was steady as a lighthouse Christer, I think that may have been part of my learning curve. When I first put an EP in today I found the tube wobbled. I had to slide it forwards a bit so that the rear ring would tighten. Even then the forward ring is tight around the tube, the rear one still shows a gap. I was very careful to instal the RDF so that the screw heads would not mark the tube but I will take another look to see if I have it right. I may have to wait a day or two for the next clear night to be able to train this on Saturn and Jupiter so if anyone is still interested I'll post a proper first light. As it is I have found the experience faultless so far - apart from the foam in the case!