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Gtech

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About Gtech

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    Nebula

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    Hampshire UK
  1. I was getting similar (purple) Halos with a 2" Baader uhc-s filter but not with a 2" Baader Neodymium Moon & Skyglow filter.
  2. Forgot to mention, you can use these for panned timelapse photography, just set the Polarie level (as a turntable) on a tripod and choose one of 4 racking rates and timelapse away!
  3. The Vixen Polarie was what gave me the Astro bug. I bought one last year as I wanted something ultra portable (I do a lot of off grid motorcycle touring). This little beauty together with a belatedly purchased Polrascope fit inside my tank bag along with my Fuji X-E1 and a few primes. Running off a USB power pack, this thing will go all night and it works exceptionally well with wide angle lenses (Fuji XF-14).
  4. For pro use I use 1 series, 5D2 etc, but for astro I looked long and hard at options and went for a modified 1100D. The 600D has higher read noise, too many small pixels and its heavier, although you'll get a tilt screen You'll be using 400-1600 iso most of the time and the bigger pixels of the 1100D will serve your 200p better. More smaller pixels will not gain any real IQ advantage under UK skies. The 1100D and 450D are the jewels in the Canon crown for budget astrophotography.
  5. The average levels and SD values are in ADU. RON is in e.
  6. Sorry to drag up an old(ish) topic but I've also been keen to understand the characteriscs of the X-Pro 1 and X-E1 cameras. So I thought I'd share my findings. My analysis started as an exercise in determining the optimum exposure for metered sky glow in the field. I've since gathered a sizeable number of darks, flats and bias' to help determine what ISO/Expsoure settings would yield the best return for X-Trans astrophotography. I adopted Craigs Starks well documented method for determining the following and used DCRAW 9.19 for RAF > TIFF conversion (since most proprietary Raw converters Adobe, C1 Silkypix do voodoo to the raws). All analysis and calcs were done with AstroArt5 and Excel : First off, I noticed that the X-Tran sensor had similar ISO gain to my 5D2 and was much lower than the 1100D. Saturation was marginally higher than the 5D2. Calcualted dynamic range was also marginally better at lower ISOs. Read noise was also better than the 5D2. So far so good! There's no prizes for noticing that Fuji have applied some (Canonesqe magic) or black point dark current reference intensity scaling to long exposures, since the average levels decrease over time. The conclusion I draw from the data is that ISO800 is the sweet spot for these two models while working with 2, 3 or 4 min exposure times. The X-Trans sensor captures almost as much IR out of the box as my modded 1100D. While its 16MP - 4.8um pixel size and 15.6 x 23.6mm format yeilds a favourable 1"/pixel on my MN190 with a slightly wider FOV than a 1100D. I guess the only real drawback is the lack of a Fuji SDK that could offer up future BYE or APT functionality for the X-E1. Unlikely, although I've just sourced a wireless intervalometer (Phottix Aion) that will offer a big step forward in remote control which I will couple with an Eye-fi card for snapshot focussing. I'm now looking forward to some clear nights and some field trials.....
  7. Very nice....The QHY8L seems very capable (jn the right hands) over the modded dSLR. I must start saving! I'd be interested to know the differences in exposure times (sky background ADU as reference) between the two cameras. I assume no darks needed from the QHY8L?
  8. Superb, I'm itching to try my EF500 out (still waiting for a plate from FLO) as the extra stop (over my 190MN) in light would allow more shadow detail to play with in terms of less thermal noise off the 1100D. I analysed a few dozen darks off my modded 1100D and was surpised how much the background and Std Dev dropped when you halve the exposure time.
  9. Thanks for your kind comments. I also see a magneta cast. I'm finding thay when I edit an image for the first time, I tend to overcook it. I guess one's keen to get results. I then go back a few hours (or days later) and retry with a more natural colour palette. Here's a re-worked version......
  10. Taken just before the moon rose on Friday night from my urbanish garden... SW 190MN on NEQ6 Mount, taken with a modified Canon 1100D - ISO 800, 20 x 180s + 18 darks. Processed in AstroArt5 with tonal contrast adjustments and resizing in CS6. The question I'm now asking (myself) is whether its time to invest in a dedicated CCD. The 1100D sensor was hovering between 10-14c for most of the subs and with almost as many dark frames, I'm now wondering if this is the best I hope to achieve with a dSLR.
  11. 4 hours of subs tonight and not a hiccup, its lookimg like it might have been the USB lead afterall. I made sure it was lashed down with a velcro strap and and a rubber band. The new saddle is sweet!
  12. ADM arrived (but no plate yet) and fitted.....what a nice hefty saddle. Pity the clamp nuts aren't captive. Now to sort out the DEC drift problem..... Ah yes the Geoptik CW bar, looks good, but a Moonlight is my next priority, then a stepper focusses, then a.........My, the list is never ending. Wish I had a Llathe / Mill though, spent my first 10 years earning a living as a Toolmaker/Engineer, 90% of this stuff I could make and save a fortune! Oh well, that what happens when you leave your hands on engineering roots behind for greener managerial pastures.
  13. Strange, I loop back the USB cable and attach with a velcro wrap to the Lodestar body. Up to now most of my subs have been north side of the Meridian, last night, when it happened, I was working on M33 and the scope was South side....I marginally change the RA balance to compensate but kept the DEC as-is (slightly camera heavy). I also noticed that it was down to -1c, lowest temp I've worked to date.....coincidence? Whilst posting this Fedex delivered the ADM saddle so I may pull the DEC axis apart later today before fitting.
  14. Set up last night and merrily started imaging. After about two hours I started to get almost repeatable DEC drift (12-15arcsec) every 40 secs whilst PHD was OAG. I switched to guiding with AstroArt and the same thing happened. Each time I reselected the drifted star in AstroArt, the DEC drift would be almost identical (amount, time and duration) but in the opposite direction. I decided to shutdown the whole rig and stat again. I then spent 3 hours trying to resolve and gave up at 2:00am as my subs had eggy stars. This is the first session where I've seen such a repeatable drift. Nothing has changed parameter-wise and I've manged 6 hour session without issue Polar alignment was good, scope balance was good. Looking at the logs in both PHD and AstroArt, the 40 sec interval drift doesnt correspond with any drive component. I also checked battery voltage and there was no issue. Weird this one... Your thoughts appreciated before a pull the mount apart again!
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