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Brainstorm

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Posts posted by Brainstorm

  1. You say 6" Orion EQ mount - if the problem is you cannot get the EQ to track then I would say you have to work it out before you do anything.

    "Work it out" in what sense?

    I have the Orion Accutrack SVD, I set the scope in the centre of the mount to point to Polaris, set the Accutrack to "N" for northern hemisphere, RA at 55.7º, fresh battery, no matter what speed I set it to, objects disappear out of the eyepiece at the same rate. What else do I need to "work out"?

  2. Hey guys,

    I currently have a couple of scopes (a 10" Skywatcher Dob, and a 6" Orion EQ mount). Neither of which are any good for taking photos. At best I can get a 1" exposure on the dob, and never been able to get the tracking to work properly on the Orion, so all of my photos are taken at a really high ISO to get any depth, but naturally that brings much unwanted noise into the picture.

    What I'm looking for is something that I can use decent exposure times with, and portable. I don't want a huge behemoth with guidescopes, laptops and cables everywhere, since I am always mobile. I never use the scope at home.

    I'm not expecting hubble quality images, but I am looking for something better than I have. I don't have fortunes to spend, so I will have to sell all my current gear to help fund this.

    Any suggestions?

  3. Some focusers allow you to unscrew and remove the eyepiece holder entirely, revealing a T-thread, allowing you to then screw the T-ring directly to the focuser. Don't know about the Orion but worth checking...

    Ironically, the dob sports this, but the Orion / EQ doesn't.

    I found an adaptor without the extra tubing on ebay. So I'll wait until that arrives and see how I get on there

  4. Hi Brainstorm,

    Have you tried imaging since fixing the RA drive? The stars are very faint compared to Venus, and if you took your images without tracking working then they probably won't show up. But try stretching the levels in the images you took to see if anything is there. Note that a 2x barlow will make the stars 4x (I think) fainter too.

    Thanks Lewis, this would certainly explain the problem. I wonder if the manufactured non-barlowed adaptors are the same length as a barlowed adaptor minus the lens, or if they have been shortened to compensate for the focussing issue?

    If not, can anyone can reccommend a good (short) T-adaptor that will overcome the focusing issue? there seems to be a lot of unnecessary tubing on the Celestron one I have.

    You'll only see the brightest stars through the viewfinder, so I'd suggest trying with one of these first. Also, get/make yourself a bahtinov mask, it's very difficult to get accurate focus otherwise.
    Definitely looking at getting a bahtinov mask now too. I looked on ebay, but they seem scope-specific, and none appear to be available for the Orion Skyview Deluxe 6". If anyone knows where I can obtain one for this scope I would love to know.
  5. When you put the camera into the scope, are you focusing it as well? Have you tried altering the focus point?

    I'm using venus as the focusing point, as it's the only thing the camera will see. Then moving the scope round to a rough area of where I want to take a photo (I have to guess as I can't see anything in either live view or the viewfinder)..

    What camera/scope/adapters are you using?
    I'm using a Celestron Barlow T-adaptor - 1 1/4" Model #93640 with Canon T-Ring

    I've also tried removing the magnifier which makes the adaptor into a barlow, but then the focuser won't go in far enough to obtain focus.

  6. I tried my hand at astrophotography last week, but unfortunately it seems an impossible task. I have a camera adaptor but it only seems to 'see' two bright objects; The moon and Venus (even these are quite rough quality). Even when I point the camera in the general direction of the stars and leave the shutter open for 30 seconds or more, it just takes a black photo - If I lay the camera on the floor pointing up with a standard lens and use the same settings (800 ISO etc..), it takes thousands of stars. Yet nothing through the telescope.

    I'm using an Orion Accutrack SVD Precision motor drive, but this does not seem to track anything (no matter the speed setting), and yes it is polar aligned, with a fresh battery.

    I have absolutely no idea what I'm doing wrong.

  7. Hi guys,

    I have been getting into astrophotography. Admittedly, I only have a basic setup, but I can never get anything in crystal clear focus through the telescope. There's nothing wrong with my camera (Canon 7D), as it takes crystal clear images through any normal lens.

    I have tried taking photos of the moon, since I can see this through the 'live view' mode on the camera's display. When I use the zoom function in live view mode, it doesn't matter how long I spend on focussing, it just seems impossible to get any decent clarity (this is before actuating the shutter). I can't understand why.

    Also taking photos of the moon should be easy as you only need very short shutter times, so effectively the moon could be photographed through a Dobsonian. However, I have used my Orion scope on an EQ mount with RA tracking, but with no better results.

    Maybe someone here could shed some light on the subject.

  8. I got one of these kits for Christmas, I've not assembled it yet. I do have the British instructions, but again, no illustrations.

    I did however find a German blog which had pictures of the build but no instructions

    Do you happen to have the URL of this site to hand? It would certainly help somewhat.

    I'll let you know how my build goes...

  9. Just found this thread after posting here:

    http://stargazerslounge.com/astro-lounge/161123-sgl-calenders-book.html

    I just got the free Sky at Night one, and most of the photos aren't great (better than I could do, but nothing compared to the quality of photos I've seen posted here).

    Anyway, that sparked off my interest to get myself a decent calendar (I missed last year's batch being a newcomer here), so I thought I'd look on here. But alas, it seems I've missed out again. So I'm now wondering if anyone knows of any other companies that are selling astronomy calendars?

  10. Indeed, I'm after a calendar too.. I missed out last year. I only found out about the calendars over half way through the year, although there was no discount (couldn't justify paying for a full priced calendar with only a few months left to go).

    However, I wouldn't mind one this year, so I'm expressing my interest early to make sure I get full use of it

  11. A fan on the back is a good idea - if the scope was s/h then the old one may have been taken off before sale. It'll draw in cool air and the scope will come down to temperature quicker. Half an hour to an hour and it should start to show good views, maybe quicker with a fan.

    How would I attach the battery to the fan? I know I can solder a 9V battery clip to the wire from an old PC case fan, but the battery would just be hanging there, then there's the issue of finding the right screw threads to fit the bores in the scope. Or are there specific fans designed for telescopes?

    This isn't really a can of worms - just standard operating procedure with a dob - there's all sorts of mods you can do to improve things e.g. dew heater on secondary, Wixey angle guage, AZ setting circle, levelling feet, right angle finder, counterweight for larger eye pieces, Telrad finder, low profile focuser, bobs knobs for collimation, etc, you can make it as technical as you like :)
    Do you know of any good websites or books for beginners like myself who clearly need to learn more about dobs?
  12. A grating with 100 to 150 lines per inch is normally called a "Ronchi" grating.

    You can achieve similar results with a fine mesh - something like a tea strainer, fine fly mesh etc.

    While the mirror is cooling down towards ambient it tends to change its shape and is not as optically accurate as is it will be at a steady temperature....

    I have a tea strainer, do I put this over the empty eyepiece focuser, or do I have the eyepiece attached, if so which size eyepiece is optimal?

    Secondly, what would I be looking for, and how would I know what I see is a problem or normal? Do you know of any illustrations available online? Or any books that might help with this?

    Sorry for all the questions, this is all new to me.

  13. A fine piece of mesh or a Ronchi grating.....

    Held over the focuser while focusing on a bright star...

    This will immediately show if there are issues with your optics/ scope - it also shows thermal currents associated with cooling down.

    A good investment, well worth having in the box.

    HTH

    I just looked on ebay for a "Ronchi grating", but it returned zero results. What is it, what do I do with it, where do I get one, and what exactly am I looking for once it is attached to my telescope? :)

    I'm not sure what sort of 'fine mesh' to buy either, there seems to be a lot of different types of 'fine mesh' on ebay, from gardening resources to fishing nets. Or do I get this specifically from dedicated astronomy shops?

    I'm still stumped about this 'cooling' issue too, can't find what it is exactly, or how to deal with it.

    Seems I've opened a large can of worms by buying a bigger scope.. ;)

  14. Thanks for all your replies. I drove out to the Scottish Borders to ensure absolutely no light pollution, and the telescope is 'bang on' collimation.

    The eyepieces I used are the Orion Plossl's (25mm & 9mm) that I got with the 6" Orion, and I also have a Japanese Meade 6.4mm Plossl (which was totally useless).

    I'm not sure what the 'cooldown' issues people are referring to? Could it be that the mirrors may have gathered condensation after being in a warm car? And if that is the case, how long does it take to de-condensate them?

    On the bottom of the scope under the primary mirror, it appears there's a space which would possibly fit a computer case fan.. Would it help if I fitted one and attached a 9v battery?

    Also, if there is a 'problem' with my telescope, what could it be? There's not much to go wrong with these things, surely? I mean the mirrors are immaculate and well collimated. I would have presumed that's all there is to it...

    Where can I find more info on 'cooldown', and how to deal with it?

  15. After reading a few posts regarding upgrades, it has often been recommended to upgrade by about 4" a time for the best 'wow' factor. However, my new Skywatcher 10" Dob doesn't seem any improvement over my Orion 6" EQ.

    In fact, Peiades looked 'dimmer' in the 10" dob, Andromeda about the same (an oval fuzz), Jupiter was useless, I may as well been looking at a white ball (absolutely no 'stripe' definition, compared what can be seen through the Orion scope). Ironically, Orion was about the only object that showed up better in the Dob. Although I couldn't find any other nebulosity or galaxies in the sky with the Dob (I tried looking for the Horsehead Nebula, but nothing).

    I'm not disappointed, just surprised that a 10" telescope (much bigger than the little 6" Orion), is not bringing in any better results.

  16. A friend of mine had the same problem. Except his camera was an advanced Nikon! Using a 6 inch F:10 telescope and the camera attached to the photo-adapter, he could NOT see anything through the viewfinder.

    What exactly is an "advanced Nikon", and why would it differ from my Canon 7D?

    Do you mean "advanced" as in modified for astrophotography?

    But trying to focus with the viewfinder is really not going to get you very far, anyway. The best way to focus such a setup is to look at something during the daytime that is a long ways away, and then don't change anything until you have a chance to try the setup under the stars.

    A couple of problems with this method, I don't do any astronomy from home, I always drive out to dark sky areas, away from light pollution. This would mean sitting with my setup in the middle of nowhere for hours on end waiting for the stars to become visible.

    Secondly, due to my camera being a professional model, it has a magnesium body and is a lot heavier than the entry level DSLRs, the problem being that over time, the focus tube sinks into the telescope under the weight. Maybe I'd be better off buying a lightweight entry level DSLR, such as a 450D or something.

  17. I got my T-ring through the post and thought tonight would be a great night to try it out. Managed to get Andromeda galaxy in sight, so I put the T ring adaptor on and attached it to the camera. I tried in Live view; nothing.. I tried looking through the viewfinder; still nothing. Just pure black, the sort of thing you'd expect to see if the lens cap had been left on (it hadn't)... How am I supposed to focus on a plain black field of view?

  18. I just took a look at my EQ2 tripod (and rest assured, one of my extension leg's locking bolt is about to break off soon too) and as getting a new tripod seems price ineffective, I would suggest choosing the tripod legs' hight you use the most and just glue or bolt them down hard - or the broken one at least. Seems rather agricultural, I know, but better than just scrapping the thing, anyway :D or of course, a large enough hose clamp might work well, should you get an appropriate diameter

    There's a couple of issues with this method,

    (1) due to the nature of a newtonian, the eyepiece sometimes ends up in such a position that you need to adjust the legs height to compensate.

    (2) It will not load into the car extended.

    I think the route of a large "wingspade" hose clamp is the most feasible.

    Since this appears to be a common fault, I'm wondering if Skywatcher have changed their design to solve this.

  19. Try a Jubilee clip or a U-bolt (used to bolt TV aerials on) in place. Not very pretty, but a quick, cheap and efficient fix.

    It's a fairly common problem with these brackets I'm afraid - has happened to me in the past.

    Brilliant idea! I'm wondering if there's such thing as a jubilee clip with a 'wingnut' tightener. Just so I don't have to carry a flat head screwdriver around with me. Thanks again though.. at least there's a light at the end of the tunnel :D

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