Stargazers Lounge Uses Cookies

Like most websites, SGL uses cookies in order to deliver a secure, personalised service, to provide social media functions and to analyse our traffic. Continued use of SGL indicates your acceptance of our cookie policy.

Welcome to Stargazers Lounge

Register now to gain access to all of our features. Once registered and logged in, you will be able to contribute to this site by submitting your own content or replying to existing content. You'll be able to customise your profile, receive reputation points as a reward for submitting content, while also communicating with other members via your own private inbox, plus much more! This message will be removed once you have signed in.

Blogs

Featured Entries

Our community blogs

    • 2
      entries
    • 0
      comments
    • 2338
      views

    Recent Entries

    Concurrently with the dome assembly, I am cobbling together the potential contents.

     

    Initially, I intend to install my HEQ5+250mm f/4.8 Newtonian on a tripod.

     

    Have tested mount operations successfully indoors with indilib on a RaspberryPi, remotely connected to KStars.

     

    I think indilib (http://www.indilib.org) is brilliant from many points of view.

     

    Also working remotely with RPi/indlib are:

    • Xagyl filter wheel,
    • Atik CCDs (314E, 460EX),
    • DIY focuser drive,
    • GPS module (USB connected).

    The electric focuser drive uses one of those ubiquitous steppers, controlled by an Arduino nano. This is bolted and belt-connected to a Crayford focuser.
    Works well but is an ugly piece of engineering :embarassed: . Think I'll try to make a better package.
     
    All of that is ready to go if I can just get the dome installed without neglecting too much the remaining work on the house :grin: .
     
    I also have some morale-raising works-in-progress:
    • Have bread-boarded an indiduini meteostation; and am really pleased with the result. I have now to design a robust and rainproof container
    • Have ordered the bits for an all-sky camera (RPi NOIR); following the helpful examples set by several SGL members.
    • Have designed and prototyped automation for the dome. This integrates with KStars/INDI and comprises separate Arduino processors with DC motors for dome rotation and shutter control. The shutter-controller is wirelessly (RF24) linked to the indilib, dome driver. Pleasingly it all works on a test-bed. The challenge I now face is to mount it robustly and (fingers-crossed) aesthetically in the (as yet not assembled) dome. I feel I will be paying for the sheet-metal work. :rolleyes:
    • Have designed a pier for my EQ8 mount. Again, to resist corrosion, this has to be of marine-grade (316) stainless-steel. While I intend to weld the thing together I feel it wise to have the bits laser-cut. I am however unsure about where I can get the material.


    This forum, in particular, has given me the inspiration and the nerve to attempt this project. I admire what people have done and am very grateful that they are willing, so generously, to share their experiences.

  1.  

    Hi does anyone have a PDF or CAD file file for the above it must be anti clockwise as it is going on the top plate i have a setting circle already but it has both scales on clockwise and anticlock wise and this can cause some confusion at night under red light, this is the setting circle i have at present as you can see their are two scales on it, and now I realise after 12 months it can be confusing.

     


    post-31880-0-19275800-1406997623_thumb.j

     

     


    Source: Setting circle 8" Skywatcher dobson Anticlockwise

  2. Before I carry on with my 6 SE experiences I just want to thank all of you for reading my ramblings and for your comments and PMs. It is very much appreciated. I finally have some "me" time to continue the story.

     

    The first thing I did when I got my box of goodies home was to unpack everything. A cup of tea came next.

     

    My initial impressions were of a solidly built bit of kit. Without going industrial strength the tripod is sturdy. It is light(ish), but setting it up with legs fully extended and giving it a good "shove" showed that it didn't wobble perceptibly. Granted, the mount may induce more movement but the platform it'll sit on seems good.

     

    The C6 OTA is just stunning. This is my first SCT but I have owned a Mak before (ETX 90) and these physically short catadioptrics, I think, look lovely. The C6 doesn't have the anodised finish the ETX did but the orange paint job looks great. The whole tube has a good weight and a quick twiddle of the focusser felt solid and smooth.

     

    Next out of the box was the mount. Again, a good weighty but not too heavy feel. It's difficult to describe objectively but to me it feels "about right". Slotting the C6 into the dovetail on the mount was easy and I was already feeling comfortable with having gone for the C6 and not the 8" OTA as the weight of everything was manageable. I wouldn't have wanted it to be any heavier, especially as this is, to me, a grab and go set up.

     

    The mount fits into place on the tripod platform really well. There is a centre locating pin and then it's just a matter of rotating the whole assembly until the mount aligns with the fixing bolts in the tripod platform. The platform is cut away in three places which means you can keep a firm grip on the base of the mount as you put it in place. The three sprung captive bolts in the platform find their homes in the base of the mount easily enough with a bit of to and fro wiggling of the mount on the platform. It's all flat and with the OTA pointing down on the mount as it should be at this stage, all very stable. I tighten the three platform to mount bolts a little at a time with frequent jiggles left and right of the mount to ensure everything is square when finally nipped up. Once all in place and tightened, the whole set up feels very solid to me. Certainly moreso than expected. I'm pleased so far.

     

    I knew the mount was going to eat batteries and I'd not managed to get any AAs on the way home so raided our household stash to get up and running. My first objective was simply to mount and align the finder which is of the red dot variety. I've not used a red dot before so was curious to see what it was like.

     

    This is where the first down occurred. I manually swung the OTA to roughly horizontal (you can do this, there is no need to use the Alt drive until aligning) and used the Az drive (you cannot move the mount in Az manually though) to roughly point at a mobile phone mast about a mile away. I'd not done any setup of the goto handset yet, I just switched the mount on and used the up / down and left / right buttons to move the 'scope around. I popped in the star diagonal and standard 25mm eyepiece and centered the top of the mast in the eyepiece. This took a bit of patience while I sighted down the tube and tree / rooftop hopped through the eyepiece to find the mast and work up to the top of it. The 25mm eyepiece gives a magnification of 60x with a field of view of 0.83 degrees-ish (assuming an apparent field of view of the kit eyepiece of 50 degrees here as Googling hasn't turned up a detailed specification) so this took a bit of patience!

     

    The finder bracket was already screwed to the back of the C6 and the red dot finder slides on. Just tighten a couple of philips machine screws to clamp it in place. There are two wheels on the finder to align it - a little like rifle sight adjusters if ever you've used that kind of thing. Sadly, the range of adjustment was not enough to alight the red dot with the aerial mast top I'd centred in the eyepiece. I assumed I'd fitted the finder incorrectly so much removal and refitting followed but still no joy. In the end I decided I'd have to shim the back of the finder mount as even on maximum adjustment the finder was pointing too "high" (i.e. away from the 'scope). My concern was that to do this I'd need to loosen the two screws holding the finder bracket in place and I was worried doing so might disturb something in the C6 tube. I didn't want to assume the threads for these screws were captive no matter how reasonable an assumption that may be. I rigged some shims between the finder and its mount to enable alignment but it was not pretty and certainly not a long term solution.

     

    For a bit of kit costing this much I was very disappointed. The finder, red dot or otherwise, is a critical bit of the setup and I can understand those less handy or ready to give a tweak a go really being put off by this. I did some Googling and found this is a common problem. Or if not common, I didn't have to look too hard to find similar tales of impossible to align finders.

     

    I dropped the shop a line and they could not have dealt with the situation any better. Their recommendation was to shim the back of the finder mount with strips of thin card or plastic, much as I had initially thought of doing. I checked with them it was OK to loosen the finder mount screws and that I'd not be invalidating any warranty by doing so. While the suspicion was the finder mount, without any hesitation the shop arranged for a new finder (without mount) to be sent to me and it arrived within a matter of days. Sadly this didn't fix the problem but at least I'm comfortable with the situation and had the OK from the shop regarding the more permanent solution of shimming the mount. I still think this is poor quality control from Celestron's (manufacturer's) point of view but I wasn't going to let it spoil my fun.

     

    Still being daylight but itching to test the C6 I pointed the 'scope at the bird feeders in the back garden. I'd asked when I bought it if they knew how close it would focus but they didn't. While not being an ideal spotting 'scope I thought it'd be worth a try. I was most impressed when, after much winding of the focus knob (and hoping I'd hit a stop before anything unscrewed completely!) the feeders only some 7 metres away came into focus. Way too high a magnification at 60x to be of practical use but something to bear in mind for when I get that 32mm or 40mm eyepiece! I'm feeling a little happier now so definitely on the way back up.

     

    Completely out of keeping with the first evening of new 'scope ownership the skies were clear that night too! Being early August at the time, I wasn't going to see much in the way of dark skies. Even in winter, being suburban, our back garden suffers from plenty of light pollution and the horizon is poor to three sides. A big reason for wanting kit I could move to darker sites easily. However, I thought a quick test alignment and goto practice was worthwhile so I headed outside to set everything up. My plan was to just look at a couple of my favourite "easy" objects like Epsilon Lyrae and 30 and 31 Cygni.

     

    I carefully levelled the tripod using the supplied (very basic but seems to be adequate) bubble level. Fitting the mount and 'scope (which I'd left on the mount) to the tripod was as straightforward as it had been indoors earlier. I fired up (well, switched on, it was no more dramatic that that I'm afraid) the mount. Initial set up of the goto handset involves entering location and time and date. This was all fairly straightforward as I'd got my lat / long from the phone GPS and just had to remember to enter the date in MM/DD/YYYY format. The time zone is possibly a little confusing in the handset UI as you need to (for the UK) enter GMT and then in the next "screen" select Daylight Savings for BST.

     

    Next up is alignment and I just stuck with the default of SkyAlign where you point the 'scope at three "bright objects" in the sky. Now, to me, bright is a relative term but from our back garden in twilight I felt there was little danger of selecting anything not quite bright enough. The horizon is very poor in our back garden so I couldn't select objects more than about 100 degrees apart. Not ideal but I hoped it'd be good enough. I'd made sure everything else - time, location and levelling - was as accurate as possible. I can't remember which stars I used in the end but I suspect they were Arcturus, Deneb and Vega, or maybe Altair. Either way, I worked through the process and the handset guides you through it well. But on trying to goto the first object I was after, which was back to the first alignment star I'd used, the 'scope shot off in what seemed a totally random direction. Not what I'd expected at all. I tried alignment again but not even close. Disappointment again.

     

    At this point all I wanted to do was look at something as I was running out of time. I manually slewed to Eplsilon Lyrae and hand guided. Even with just the 25mm eyepeice, while I could not separate the doubles of each component, I could make out elongation in each. Not bad. I popped in the 2x barlow and all four stars popped out at me. Optically, I was very pleased with the C6. The 9mm eyepiece split the close doubles even better. I should also say I found the red dot finder really easy to use and still do. Perfectly adequate before fine centering using the 25mm eyepiece.

     

    A day of highs and lows. I'm glad it finished on a high. I was very very impressed with what views I did get. The finder issues could be dealt with although I was unimpressed at the need for hardware tweaks. The goto issues I was pretty sure I could sort with practice and were probably due to my lack of familiarity with the system. I did wonder whether the AA batteries were man enough for the job though, I had read they get used up very quickly. Overall I was on the slightly happy side of neutral but taking encouragement from the excellent views I'd had so far.

     

    I'm going to wrap this post up here. It's gone on a little longer than planned! Next time I'll share what I've done and learned to make this what I now believe the best 'scope I could have chosen given what I was looking for. Thanks for reading :)

  3. goose35
    Latest Entry

    Hello All

     

    Been a while since I last went out, due to cloud and timing of the clear nights, all ways when im on morning shift.
    During this time I’ve done a system swap from my Olympus E-510 to a Canon EOS1100D. got same kit off the bay, 2 zooms and a flash gun.
    Now have to get the old stuff sold.

     

    Saturday 12 September

     

    Got a few hours in last night, Visual only with the 150p on the EQ 3-2, with new motor upgrade.

    • M39 open cluster
    • The perseus double cluster
    • M103 open cluster


    All were stunning especially the double cluster. It amazing how rich Casseopia and perseus region is.

     

    On each of these I gave first light to my new EOS 1100D.
    I was most impressed, I was getting 2 min tracked subs on the mount. I also gave first light to the Baader MPCC mk 3 which was excellent.
    I didn’t do any calibrating frames as I was only giving a few exposures to see how long I could get on the mount and I was expecting clouds.

     

    Im looking forward to giving the whole imaging setup a good run now after those results. I think the target has to be the double cluster.

     

    Im on afternoons this coming week and a week off after that so Im also going to get the camera with the 70-300 lens and do some tracked wide shots on the EQ3-2.

     

    steve

  4. crashtestdummy
    Latest Entry

    I've mentioned a few times that I've recently bought a road bike and have started riding a lot more and I though since I've not got anything astronomical to discuss I would do this instead :)

     

    I bought a nice giant defy 0 bike on the cycle to work scheme and spent an extra £200 swapping the brakes, chainset and front mech so it now has a full ultegra groupset.it's perfectly geared for an unfit ex smoker like me with a 50/34 chainset and 11-32 casette and I can get up most hills despite my heart rate touching 190bpm on the long/steep ones.I added a garmin edge 1000 to my ride just over a month ago and have been logging my rides on strava.one particular hill I cycle I have dropped 3 minutes off it in 2 months so the fitness is coming.
    It's all building up to one event-a 73 mile sportive in october-the wiggle south downs ride.I was originally planning on riding the 42 mile version (there's 3-42/73/100) but my friend graham talked me into the 73.so I talked him into riding it too!!!I've analysed the route and there's one section that could cause problems-a closed road climb up butser hill.this is pretty steep with a 0.3 mile section of 10-18.5% and it's narrow and dirty most if the time.I was pretty sure I could do all the rest of it ok but wasn't sure about this as it was as steep but longer than another climb called crooked walk lane that I had failed on.training needed doing so I've worked my way through the steep roads of portsdown hill near where I live and last week I nailed the dreaded crooked walk lane so I was happy with training.anyway I went out Sunday with a route loaded into my garmin that took me from my house, through some gentle hills and quieter roads and out to another longish hill called old winchester hill.managed this pretty ok and down the other side in preperation to try the butser climb on my sportive route.before the ride I had put both these climbs on the route just to recce them and walk if needed but finding my way at the top of butser hill punching the air with lungs slapping my rib cage the mystic had gone a bit.I'm now looking forward to the event even more now I know I can do the hardest bit and can't wait to do the 100 mile version next year.
    In fact next year has big plans.I want to do at least 5 or 6 of the wiggle 100 milers and the Hampshire hilly hundred too and also cycle round the isle of wight.I was close to trying the Isle of wight recently but I'm not sure I'm ready yet so want to leave it a bit.
    I'm already dreaming of a trip to France to do some hills like alp d'huez or mont ventoux or le lacets de montvernier but think I'm a way off that yet.
    Still happy in my new hobby though.

     

    Anyone on strava let me know your name and I will add you :)

     

    Clear skies Rich

  5. Hi all,

     

    So a quick blog today, just to keep things ticking over, and to keep track of my ideas etc – more for me to look back on more than anything else!

     

    Foot is a lot better now – I am getting around ok, and have even started a new fitness ‘regime’!! I have lost 6lbs in one week, by cutting out crisps and flapjacks, and doing 20 minutes of high interval training each morning! Go me!!

     

    I’m still scopeless, and will be until at least Autumn I think. Had my hours knocked down at work from 5 days to 4 days. We can still cope on the reduced income, but it means my scope will be delayed slightly!

     

    I’m not too upset about the lack of OTA right now. Nights are still short, and the weather isn’t exactly brilliant either. It will give me time to finally settle on what I actually want to set – newt or frac!! Its either a 130p-ds or ST102. Both have their pros and cons, and I can’t guess the amount of reviews etc I have read on both scopes!!

     

    In the meantime, I have decided to set myself up with a widefield DSLR rig. Budget is key here! I already have the mount (EQ3-2), DSLR with fast and wide lens, and a means to mount it on the EQ. I just need a polar scope and a motor kit. I am keeping my eyes peeled for them to come up on ABS, AB or on SGL (remember key word – Budget!!). The mount is still due its MOT, which hopefully I will carry out later this month. I want to have it all together for my trip to Pembrokeshire in mid August.

     

    With this set up I am hoping to get my first astrophoto’s of the Milky Way, and perhaps some of the larger constellations. From what I’ve been told here on SGL, 2-4 minute subs should be achievable if PA is good, and LP is not too bad. I will update this blog as each stage is completed, and hopefully with my first photos as well, however they turn out!!

     

    I have been doing a lot of reading up both on SGL, and the wider t’interweb about DSLR widefield, and it’s something I can get into fairly easily, and with minimal outlay. As a keen landscape shooter, I am hoping I can use my current skills to create some pleasing images. We shall see - this blog could well turn into a ‘How To Take AP With No Money’ blog!!

     

    Well, that’s all for this entry – thanks for reading, and sorry it a bit dull this time!! Next entry I am hoping to blog about my mount MOT, along with photos!! Ooooo!!!!

    • 1
      entry
    • 3
      comments
    • 2776
      views

    Recent Entries

    Hi all relatively new to Astronomy I have a StarBlast 80mm from Orion without the Syn scan hand controller!!
    Has anyone had any luck using Stellarium to drive the scope without the $420 hand controller??? :laugh:

    • 0
      entries
    • 0
      comments
    • 1097
      views

    No blog entries yet

  6. So the last week was kind and I managed another couple of sessions under the stars.
    The lack of dark nights has made this a labor of love indeed.

     

    I have gathered 5 hours for each Ha pane so I have managed one of my bonus goals.

     

    Total integration time so far is 17 Hours:
    blogentry-11689-0-90188000-1434153606_th

     

    I may not add any more data to this until the darker skies return :sad:

     

    Project status
    Stage 1 - Complete
    Stage 2 - Complete
    Stage 3 - Skipped
    Stage 4 - 0% Complete
    Stage 5 - Complete

    • 1
      entry
    • 0
      comments
    • 661
      views

    No blog entries yet

    • 1
      entry
    • 1
      comment
    • 2523
      views

    Recent Entries

    Hi guys , I have just purchased this telescope and it's the first one I have had. I know nothing about astronomy only I wanted to buy one to attach my Slr to it to get some good photos. I have seen the moon close up but I am having problems seeing any stars as when you look through the viewfinder nothing appears to be in line through the scope . There is no red dot finder for alignment and probably don't really know what I am suppose to be doing . I have tried reading the set up guide and have put in the location coordinates but am struggling to find 2 stars for alignment as I cannot see anything through the telescope . Please help , thanks

  7. I originally wrote this one back in May last year and since it is time of the year relevant it make sense to post now. This one has a slightly nostalgic tinge to the usual mix of pop culture references and dubious facts wrapped around a vaguely astronomical theme.

     

    As we enjoy the longer days and the slightly warmer winter weather that here in the British Isles we optimistically call summer, it inevitably signals the end of what many would consider the astronomical observing season. Living so far north on our home world means we are fast approaching that period in our orbit when we don’t experience astronomical darkness and our view of many deep sky objects is denied to us. Oh, I know you can still spot the planets and in particular Saturn becomes visible at a less unsociable hour but many people choose to pack away their telescopes for the summer. Instead we spend our money on holidays in the sun, tasty bedding plants for slugs to consume and the obligatory barbeque whenever the temperature hits the high teens and Sol puts in a brief appearance. The other thing we do of course is look back on the winter recently passed and wonder (as we did last year) why we've invested many hundreds if not thousands of pounds on equipment that we've only managed to use a handful of times in the previous six months.

     

    The weather must surely be the most common frustration amongst the UK’s astronomy enthusiasts. Nothing seems to guarantee cloud like a once in a lifetime solar eclipse or a particularly spectacular meteor shower. Oddly enough given our national preoccupation with the weather it also seems to be the one thing we fail to consider when deciding that astronomy is the hobby for us. Much like we all remember long, golden summers from our youth we also only seem to recall winters being crammed full of cold and frosty clear nights. The reality of course is that for most of the year our seasons are a constantly disappointing temperature variation on a dreary grey theme of cloud and drizzle. Yet in the UK we have an uncanny optimism about the weather that flies in the face of all observable evidence and a lifetime of experience. Every year we imagine that this time we’ll have textbook seasons; a gently warming spring giving way to a glorious summer of warmth and activity before easing into a colourful autumn and a cold winter of frost and snow. For a nation that is so cynical about many things our unreasoned optimism about the weather is difficult to understand. Yet the evidence is everywhere from the sales of convertible cars to the popularity of golf. Let’s face it the only reason they recently put a roof on Wimbledon wasn't because of the weather stopping play but because the tennis was being overshadowed by what was fast becoming Cliff Richard’s annual London gig when it did inevitably rain.

     

    It is no wonder then that there comes a time for every astronomer when they seriously consider selling their equipment to fund a new hobby that doesn't involve a dependency on our unpredictable weather. Arguably the most famous example of this is Brian May who clearly got so fed up with his PHD taking so long to complete due to cloud and rain that he learned to play the guitar and became a rock star instead. There’s a good chance you too may harbour thoughts of musicianship being a more entertaining way to spend hundreds of pounds on equipment. Maybe you can picture yourself at family birthday parties standing on your garage roof playing a Hendrix style version of ‘happy birthday’ on a Stratocaster with a full Marshall stack turned up to 11. The reality of course with this being the UK is it will obviously be raining on any given birthday, particularly if some sort of outdoor activity is planned so fortunately for your neighbours that scenario is unlikely to happen. Not only will the weather put a dent in your rock star dreams but you’ll also quickly discover that your coordination isn't what it was when you were a teenager and more crucially you don’t have the uncounted hours of free time that you actually need to learn how to play a guitar with any degree of competency. Sure when you first buy that old six string you may very well play until your fingers bled but you’ll realise that you should really have learned to play in the summer of ’69 not when you are rapidly approaching that age.

     

    If it’s not music then you may decide that you've always wanted to make things out of wood and your sky at night magazine will be replaced by the screwfix catalogue with its many pages of power tools, laser measuring devices and power tools with integrated laser measuring devices. Your shed/observatory will be transformed into your workshop. The pier will now be home to a vice. The desk where your computer and books once resided will now be decorated with an array of saws and chisels and the walls where your moon posters were once pinned will now be covered in arterial spray because those saws and chisels are really, really sharp.

     

    Once you return from casualty you’ll probably decide that you need a nice, relaxing hobby that doesn’t involve sharp implements or ear splitting, vacuum tube powered amplifiers. Thinking about it you will recall those relaxing evenings spent under lovely, crisp, clear skies that you used to enjoy last winter and wonder why you ever decided to get rid of your telescope. Once you’ve reset your password on stargazers lounge and read a few postings you’ll whip out your credit card and spend a ridiculous amount of money on some new astronomy equipment. You will then spend the next few days filled with the kind of excitement you recall from a childhood Christmas when you were expecting to receive a shiny new bike. And much like that Christmas of long ago you will find the day your parcel of astro kit arrives it is pouring with rain.

    • 2
      entries
    • 2
      comments
    • 2473
      views

    Recent Entries

    blogentry-44755-0-53194500-1432634083_th

     

    Hi Everyone,

     

    Thank you for the warm welcome. As you can guess I'm new to this. I have just purchased a Kronos 3T- 65 telescope for very little money. I purchased it so my daughter could gaze at the skies at night as she has a few issues going out during the day. The telescope is in great condition but there is two items missing from the telescope. The Barlow lens is missing and a sleeve extender. At the moment I only have the eye piece. I have looked all over the net trying to find the company who makes these telescopes. They look very similar to the TAL Alcor. I was wandering is there any alternative Barlow lenses, sleeves and accessories I can purchase for the telescope. I did not want to purchase a bigger scope as I have not got the room for one. Any information would be fantastic.

     

    Regards Anthony

    • 1
      entry
    • 5
      comments
    • 2817
      views

    Recent Entries

    I am told that a beam of light gets bent by the gravitational pull of our planet.

    If so, the same beam of light will get bent every time it passes close to a celestial object.

    As the beam of light travels through our galaxy and out into the universe, I imagine that it must constantly get bent by millions of objects.

    As the beam of light gets further from its origin and towards the edge of the universe, I imagine that it must get bent more towards the concentrated matter of the universe and might therefore end up travelling in a complete circle.

    If so, anyone outside of the circle would not be able to see the light.

    Hence our universe would be a black hole ?.

    Can anyone progress this theory, or shoot it down in flames ?.

    Bert B.

    • 1
      entry
    • 4
      comments
    • 2278
      views

    Recent Entries

    Investigate911
    Latest Entry

    Hello, I am relativley new to astrophotography , and I have a question. I'm using a n 8 inch Shmidt Cassegrain Celestron Telescope, with a 2x Barlow and a webcam. I tried removing the lens from the webcam exposing the chip, however it completly ruined the image, I would just get a big blur of light and shadow, so I put the lens back into the webcam, and butt the camrea up to the eyepiece with a special jig. I am using a Logitech C920 webcam. I notice people with webcams getting these pics of Jupiter and they are large images of jupiter , everytime I shoot video of jupiter to use with Registax , my image is so tiny ! I Was wondering if there is anything I can do to enlarge the image without distorting it to much . Thank yall

  8. It's a question that comes up regularly, but what is the difference between a Barlow and a telecentric amplifier (TA), otherwise known as a Powermate, ES Focal Extender. Meade Telextender, Bresser SA Barlow, etc? A telecentric amplifier does give a 2x magnification, just like a Barlow but that's where the similarity ends.

    A Barlow is a negative doublet (Smyth lens) that causes the exiting light rays to diverge and hence deliver the image amplification. If you move the EP further from the Barlow the magnification increases, whilst taking the Barlow nose-piece off and screwing it onto the EP will [generally] give 1.6x magnification, assuming we're talking a 2x Barlow.

    In the FE/Powermate/TE/SA Barlow (the latter isn't a Barlow, which is a confusion) the negative doublet is followed by a positive doublet that turns the exiting rays back to parallel - ie, telecentric. Because the rays are parallel, the distance between the EP and the amplifier elements is [broadly] irrelevant as the image amplification was done internally, between the TA lens elements.

    In practice, this still means that the effective focal ratio of the scope is doubled - It's a common misconception that the EP focal length is halved - but unlike a Barlow, the eye relief of the EP in use is unaffected. In other words, you insert an ES FE in the scope and the EP behaves exactly as it did before and the scope has effectively doubled in focal length.

    The down side is that double the number of lens elements costs more, but whereas a Barlow (which has other uses because of what it does) tends to feel like a second-best-to-an-additional EP, the ES FE simply feels like you have an extra EP. In visual terms, it's a less intrusive and more transparent solution and a more transparent device.

    So the Barlow is second best? Well no, not all of the time.

    For the reason why, you only really have to look at Televue Naglers and the clones thereof. They weren't the first (contrary to popular forum lore, but they're certainly the most successful) to use the idea, but what Unc Al realized was that whilst it was easy(ish) to create a wide field EP, the difficulty was in creating them at shorter focal lengths with an eye relief usable by humans AND with a well corrected field of view, especially in fast scopes like large Newts.

    Essentially, what he did was create longer focal length wide field EPs and then fit them with a Smyth (Barlow) element in the nose. Thus, you got an EP that acted as a shorter effective focal length, but had greater eye relief than it would have without the Smyth element. Very cool. In fact, this is the source of the reason why Naglers (and there derivatives) are renowned as well corrected in fast scopes. The Smyth element does increase eye relief, but as per a Barlow, it effectively increases the focal length and therefore focal ratio of the scope. As we know, a slower scope is less prone to aberrations, but in this case, it's the EP that is effectively delivering it. Your Nagler is better corrected, because it effects a better correct scope.

    So, this is also what your Barlow can do. A 20mm EP in a Barlow (and TA) will give a better corrected view than a 10mm EP, all other things being equal. This is handy, especially if you like your Orthos and Plossls which tend to have ever shorter eye relief with decreasing focal length. A Barlow can be partnered with a longer FL EP to give an effective shorter FL EP, without the need to glue your eyeball to the EP it emulates.

    Whereas a TA uses up it's focal length in the focal path, a Barlow does the opposite and pushes the focal point outward - It adds optical path length. How is this handy? Well if you have a binoviewer that uses up 110mm+ of focal path, the scope (refractors in particular) may not have enough space available to rack the focuser inward to compensate. A Barlow, or at lest the doublet element from the nose of it, screwed into the Binoviewer is enough to push the focal point outward and get you that focus point back.

    That's just one example. The important point is that whilst a TA is, as long as it has room to work, a generally superior device, there are times when a Barlow has qualities all of it's own. A good example of both will be a one off purchase and both will deserve space in your EP case. Buy right first time and you may find they remain a constant, whilst your prized EPs come and go.....

    Russell

    • 1
      entry
    • 3
      comments
    • 2416
      views

    Recent Entries

    I would propose the material currently missing from our universe was all there at the Big Bang moment but over the billions of years much has radiated off into the void. Every star,pulsar,quasar and black hole radiate out, from birth, their contents over time. Some of the material would be retained but much would be lost especially at the outer fringe of the universe where there is nothing to stop it from leaving the universe entirely.

    As an additional thought, is it possible that the expansion of the universe is caused by the pressure of all the radiation flowing out from every body onto every other body. I remember the ECHO satellite being pushed out of its orbit by sunlight.

    Any reader will soon determine that I am a rank amateur despite my 77 years.

    • 1
      entry
    • 3
      comments
    • 2573
      views

    Recent Entries

    IenAABQDVmk32Xq
    Latest Entry

    Hi. I have a Star-watcher 200P scope on a EQ5 Mount. Is it easy to upgrade it using a SynScan Go-To Upgrade kit for standard EQ5? If so please could you give me some tips to help?

    • 2
      entries
    • 10
      comments
    • 2580
      views

    Recent Entries

    AaronLPK
    Latest Entry

    Hi, i just bought a skywatcher explorer 200p and yesterday when i went out side to have a look, i would look through and see a bright circle with the front spikes in.

    what do i do to fix this???

    • 0
      entries
    • 0
      comments
    • 362
      views

    No blog entries yet

  9. It's been quite a few months now since I've been out for any serious sessions with the Telescope. However the bad habit of smoking does get me outside on a regular basis where naked eye observing was regularly taking place during those months.

    My latest purchase is a GoPro Hero 4 Silver. Working in IT and having a love of gadgets the camera has opened up a lot of opportunities which also include using it for a bit of Astro Photography.

    I only purchased the camera a few days ago and the forecast was goof for some clear skies during the evening. Leaving the GoPro in its waterproof housing the camera was mounted onto a Gorillapod and just sat on the decking outside my back door. The light in my back garden was very poor in not being able to see very much of what was around on the floor. I set the camera to take 30 second exposures constantly where over the 2 hours it recorded 240 images.

    When I started viewing the images I was absolutely amazed as to how much detail it had picked up in my garden as well as picking up the movement of the sky. The amount of stars captured was also quite a surprise.

    A well worth purchase where I hope to produce a lot more images similar to these but in some better locations.

    http://youtu.be/19RiC0DMoX4

  10. blogentry-38966-0-35827800-1423083299_th

    Ok, so the photo isn't a classic but to me it's a masterpiece :-) ...the first time I have ever seen Jupiter through a telescope let alone been able to photograph it. Pretty awesome to be honest considering I've managed to take a photo of a planet over 550million km away and whilst I don't think it'll win any prizes it has made me a happy man!

    • 1
      entry
    • 0
      comments
    • 2118
      views

    Recent Entries

    29/01/2015 - 30/01/2015 New toy day - laser alignment tool. I thought the 130SLT was working pretty well until I checked the collimation: way out. There should be a warning that your new scope will be off focus until a laser alignment tool is used and the collimation corrected. So that done I got the scope outside only to have the batteries die. Then I found that my 12V PSU is the wrong polarity. So I got the NiMH fast-charged, and of course the skies clouded over 8/8 with some heavy stuff from the west for the rest of the foreseeable.

  11. So the much belated start to 2015, while the real year started 17 days ago but, with the weather in Edinburgh having been on the terrible side of atrocious, the star gazing year only got going last night. For the first night of the year i thought i would do something a little different and i had my first night out at Harperrig Reservoir (Edinburgh). What a place it is; you get a slight red glow to the NW from Edinburgh/Edinburgh Airport and the lights of one house but, for the darker sites that I've been too and to be fair it's not many, it's the best.

    Normally I'm a city centre amateur astronomer; sometimes when i get out to a darker site my mind does get a little blown away. I'm used to Orion slowly rising over the houses to my left not being sat there fully out in all its glory. I'm used to star hopping with a limited number of visible stars and using "Turn Left at Orion", so when i can see so much i often forget what to look for and just end up gawping up at the night sky and not using the scope. I suppose my normal plan is to just look out of the window and if its not cloudy get the scope out, not very scientific but it can be fun. Last night i went out with a plan, Comet Lovejoy was the prime target, Jupiter and then as many Messier/NGC items i could throw in and this was the haul;

    Comet Lovejoy (It was like a star with a fuzzy nebula around it, but don't worry others confirmed that it was the comet)

    Jupiter (all four moons and some great detail and colour on the planet itself)

    NGC1981

    M42(M43)

    NGC1662

    Pleiades

    NGC2169 (The 37 Cluster)

    NGC2175

    NGC2129

    M35

    M36

    M37

    M38 (Starfish)

    M1

    M31 (Andromeda)

    M33

    NGC752-C28

    NGc2244-C50

    NGC2264 (Cone Nebula)

    It was getting cold, -4 when i got in the car and i'd forgotten my flask of tea so enough was enough and my first night of 2015 was over.

  12. Happy days V0.11 is finally available - see post http://stargazerslounge.com/topic/234260-lodestar-live-v011-beta/

    Looking forward to seeing how people get on with the new display processing controls!