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rickwayne

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About rickwayne

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    Madison, Wisconsin, USA
  1. Crop factor by itself is, as previous commenters have noted, not the issue. But it does imply that, for a given image circle, images from a smaller portion of it will be enlarged to the viewing size (print, monitor, portion of a webpage, whatever). So the viewer ends up essentially looking more closely at the same angular-size star trails. If you blow up an APS-C image to the same viewing size as a full-frame one for the same optical train (e.g. the Horsehead is 2cm high on each image) the star trails will look exactly the same. This is true regardless of the size of the pixels on the sensor. To exaggerate, a trail might cross 10 px on a fine-grained sensor's image and only 3 on a coarse-grained one. But if the final results are portrayed so the objects are the same size, the star trails will be too.
  2. rickwayne

    First Horse.....

    I should show you my favorite "not quite the Horsehead" shot -- dunno if I can get it posted from my phone. The batteries in the iOptron SkyTracker failed sometime during this exposure. "Warp factor seven, Mr. Sulu!"
  3. rickwayne

    ZWO cool power supply

    I, um found a couple of 12V wall-warts from discarded telephones. Cut the cable off one and wired it to the 12V battery I use in the field (after checking polarity on the barrel connector four or five times) and left the other one intact so I can use it when I've mains power available.
  4. rickwayne

    M31 with a Modified Canon 600D

    The rule of thumb is to expose each sub so that it's showing the histogram peak (most numerous pixel value, aka background) at about the 1/3 mark. Start with 30 seconds, try a few doubling from there (1 minute, 2 minutes, etc.) As far as the number...ALL THE SUBS! SHOOT ALL THE SUBS! Seriously, in light pollution that's your best shot. Take as many as you can stand. More is better, up to a point of diminishing returns, especially if you find yourself having to do shorter subs. At 30 seconds, several dozen at least. Aim for an hour or more of total integration time, and see where you stand. Can't wait to see your results! I love Andromeda, a newb like me can get some half-decent images, while an expert can still strive for a better one.
  5. rickwayne

    M33 Triangulum

    Man, I hear you about the amp glow on the 183. Just got mine, was only able to shoot a few subs. Looked at the result in KStars FITS viewer and almost fell off the porch. Who's been setting off fireworks next to the Horsehead Nebula?!! Really nice Triangulum, here.
  6. rickwayne

    Camera Recommendation

    Hey KevS, It's good too to match potential cameras with your optics and the seeing that's common in your area. This informative page has a good calculator for getting the best out of your optical and pixel resolution: Astronomy Tools CCD Suitability. Hallingskies, having just purchased my very first CMOS (ASI 183MM) I'm all ready to argue...and I totally would if I'd gotten any good images out of it yet! Although I crazily went right off into the deep end, from DSLR to a mono camera and narrowband, so who's going to listen to a lunatic like that anyway. The point about needing a computer in the field is well taken. Though some of us just use a few ounces of Raspberry Pi. PS: No no no no Charic, you keep the camera when you buy the airplane! Then you can sell aerial photos and make back all the money you spent in the shop! (Heck, maybe your mechanic will take photos in trade for maintenance. And I am the Tsar of All The Russias.)
  7. rickwayne

    Why on earth would I buy a DSLR for astrophotography?

    Y'know, sensor size is not in itself an advantage. You want to match your desired FOV to the sensor size, yes, but angular pixel size is also in play. I deliberately chose a smaller sensor for my first dedicated astro camera precisely so that smaller objects would more nearly fill the frame, while the smaller pixels helped address the undersampling that my DSLR rig gives me. Smaller-pixel sensors are often noisier than bigger-pixel ones, true, but between today's sensors and stacking, that's a lot less of a problem than it used to be.
  8. rickwayne

    Simple is...OK, I guess

    I was exhausted and so almost didn't shoot the eclipse at all. When I decided to, I did it as simply as possible, and napped through much of it. Still, some images resulted! These are all with a Pentax K-5iis at 200 ISO, through a Stellarvue SV70t. 1/640th, 10, 10, and 1 second, respectively.
  9. Without any kind of tracker (e.g. with an alt/az mount), the rule of thumb is no longer than 500 / focal-length for full-frame cameras, and maybe 300 / focal-length for APS-C to avoid objectionable star trails. Before everyone jumps on me, these are GUIDELINES, and your tolerance for trailed stars in your images may be more or less than this. And of course it depends on declination, too, Polaris will be pretty tight at most exposures :-). For example, if you're shooting APS-C with a 300mm lens without a tracker, you can't expose more than 1 second without trailing. Which means you're going to have to run a pretty high ISO, and then shoot gonzillions of sub-exposures and stack them to get rid of all the ugly noise. You'll also have to adjust where you're pointing periodically. That need not be every frame, stacking programs like Deep Sky Stacker and even Photoshop can align images that are displaced and rotated. But if nothing else, your target is going to eventually move right out of frame. I'd never even heard of the Nano before your post -- thanks! It claims a weight limit of "< 5kg", which is hard to believe; my $1000 equatorial mount claims 12kg, and most astrophotographers use only half of their mount's rated weight. Still, it might work! The challenge with Orion is getting enough photons to bring out the nebulosity without totally blowing out the Trapezium area, which is quite bright. (To say nothing of the stars themselves!) I have gotten reasonable results with as few as 10 149" ISO 400 exposures through a f/4.6 telescope (https://rickwayne.zenfolio.com/astrophotos/ea84bfd37); in really dark skies, I got not-too-bad with just half a dozen two-minute ISO 800 ones (https://rickwayne.zenfolio.com/astrophotos/eba9bb032). With the Nano, I'd go with a higher ISO and much shorter exposure, maybe even 30 seconds to start with, and take a LOAD of frames, stack them, see what you get. And welcome!
  10. rickwayne

    How to get into imaging?

    Note that you can indeed mount a DSLR to an astro mount, all you need is the requisite mounting plate -- usually either a "Vixen" or "Losmandy" dovetail bar, depending on what the Mount of Your Dreams has. I spent $40 on a Vixen dovetail and a couple of 1/4"-20 bolts, and was able to slot my DSLR right on in.
  11. I'm an all-DSO guy myself, so here's the advice from the Other Side. +1 on going spendy on the mount first off. Since DSOs require extended exposure times, you simply cannot get around the need for a stable mount. The finest optics on a wobbly mount will disappoint. OK optics on a great mount will amaze. The classic advice for DSOs, found in books like MEPC and The Deep-Sky Imaging Primer, is to go with a wide-field, fast refractor of around 80mm. That obviates many issues while delivering good results. Astro imaging and processing is much harder than it seems, and when you start you do well to eliminate as many knee-knockers as possible. Classic error is to go for too much aperture (and thus too much focal length) and get frustrated with inability to get anything decent out of it.
  12. rickwayne

    M42 single frame first effort

    I like that you didn't blow out the Trapezium. M42, like M31, is easy for a beginner to image but challenging for an expert.
  13. You are primarily interested in lunar and planetary imaging, right? If you just did that because the software was in front of you, well, there's a whole 'nother world out there. But if that's your goal, us deep-sky guys will shut up and shuffle away quietly.
  14. I align with my guide camera and scope (ASI120, Orion 50mm) and that works pretty well. I'm using KStars and Ekos, which are free. I am fortunate enough to have a pretty decent polar scope in my mount, but after I rough it in with the scope I use the Ekos PA routine. You shoot three images at varying RA, it analyzes the cone error, then displays a live view with a vector. You click on a suitable star and it sticks the base of the vector there; the other end has a little alignment reticle (looks like a lollipop). Twiddle the mount until the star is licking the lollipop, and you're laughing. Usually gets me within a couple minutes of arc on the first try. I think the nadir for me was when, hours into a session that burnt 50 minutes just getting the stupid target into the camera's view (!!!), I had the scope fall out of the saddle and hit the ground. Talk about discouraged, I wanted to gnaw through all my cables in frustration. But then was treated to miracles and wonder when I processed the data from that trip. It gets better.
  15. rickwayne

    Hello from southwest Texas!

    Here is a WAY better edit of the Lagoon/Trifid data. Apologies if I already posted this, but I don't see it here. Not so much the fuchsia... >;-}
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