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Ikonnikov

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About Ikonnikov

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    Star Forming

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    West Yorkshire
  1. Not a refractor owner (yet) but in the 80mm category I would go for the Esprit 80 too (with the FLO bench test), money permitting. Plus the matching flattener if you have a larger chip. Paul
  2. Reducer Myth: Some data.

    My understanding is: The image for a given extended object that is projected on the camera chip by a telescope is the same brightness at the same focal ratio regardless of aperture, but the size of the projected image increases as aperture increases (keeping focal ratio constant) so there are more total photons for the object. You can take advantage of the extra size/photons of the projected image from a larger scope by using a finer image scale to try to gain more detail compared with a smaller scope (if you use the same camera as with the smaller scope the image from the larger scope will be the same brightness but contain finer detail, seeing permitting). If instead you used a similar image scale to that achieved with the smaller scope (by switching to a camera with appropriately larger pixels and corresponding chip area) you would get a brighter image with the same resolution as that obtained from the smaller scope. For point sources then brightness increases with aperture regardless of image scale.
  3. Reducer Myth: Some data.

    Assuming the same camera was used for both imaged then photons per pixel are less in the TOA image due to the fact that the increase in aperture is too small to compensate for the difference in focal length (and corresponding image scale).
  4. Intro to CMOS vs CCD

    Being able to use shorter exposures with CMOS does seem to allow some pretty tight images to be produced, there's been some very detailed narrowband Astrobin images of the day taken with these cameras on longer focal length scopes recently. I guess even though the sub lengths used are typically 2-5 minutes (which is far longer than anything that can be called lucky imaging) it still allows you to be a lot more fussy about which ones you throw out compared to with 20 or 30 min CCD subs. The small pixels and high sensitivity also allow for some pretty high sampling rates without too much noise. IMHO, CCD probably still has the edge for lower resolution widefield imaging (especially with the mono chip sizes available) but there isn't much in it. Paul
  5. KAF8300: RBI real life experiences?

    My understanding is that it only becomes noticeable on the KAF-8300 chip with extreme cooling (well below -30 C) and even then is very slight. I think some of the bigger full-frame CCDs get it quite badly so NIR preflash is pretty much essential (along with dithering) but I don't think most people bother using it on the 8300 (I would think it probably introduces more noise than is lost by the effect of deeper cooling). Paul
  6. Show us your one sub images!

    With the state of the weather and speed at which I'm gathering data for this image, a single sub pic seems like a good idea... 30 min Ha (with the E130D and G3-16200 CCD), bias subtraction, defect map, a light stretch and some curves. Some random squiggly bits that normally get sigma clipped out are still lurking in there. Paul
  7. Crescent Nebula

    Very nice, I assume this is with the APM 107?
  8. Atik 490ex mono

    Hi Rodd I had one for a while, it just has power and a USB connector (for the camera interface only) if I remember correctly so the FW would need its own cable(s). The camera its self was good, nice QE and quite low noise although shallow well depth and tiny pixels. Cooling was not overly powerful but -10 Celcius is all that's needed to kill the dark current. I found the ICX694 chip in my subsequent SX camera slightly cleaner than the ICX814 in the 490EX but then it does have slightly larger/fewer pixels. Paul
  9. Flaming Star + Tadpoles in Hydrogen Alpha

    Thanks Sara! Not decided whether to do some oiii or lrgb to go with it but at this rate it's going to be a decision for next winter!
  10. Flaming Star + Tadpoles in Hydrogen Alpha

    No worries, enthusiasm is good! Looking at the two side by side makes me think I might need to bring my black point in a bit more... An excellent attempt for your first NB/Ha image! I have used some star reduction on my image in PI (and a strong dose of deconvolution) so this goes some way to explaining the reduced size/prominence of the stars in addition to the 3nm filter. If you can get your guiding good enough it would definitely be beneficial to up your sub length to 20 min or more with your KAF8300 chip (similar noise levels to the 16200 in my camera). Shouldn't be too hard at this kind of image scale as long as you're confident of getting a good polar alignment. Only other thing is focus (can be a pain with Ha), looks like it could be a tiny bit out (although that could just be the guiding issues increasing the star sizes slightly)? Paul
  11. Imaged with the usual gear (Tak E130D, G3-16200 and chroma Ha 3nm, PI for processing) over four nights but still only 9x30 min due to Yorkshire cloud. A mixture of average and very ropey seeing and a bit of moon thrown in on a few of the subs so not quite so crisp as some of my previous attempts with this kit. Not sure I've rung all I can out of this with the processing but was getting to the point where I found it hard not to blow out the brighter regions of nebula (including the tadpoles). Have avoided the (dreaded?) HDR wavelets so far but might be tempted to blend some into this version (especially if I can get the noise down with some more subs). As ever C and C's welcome! Paul
  12. Borg 55fl

    I do like my E130D although it's been quite a trial to get the collimation, spacing and camera orthogonality right with a bigger chipped CCD, and once you factor in the Tak rings & finder, a decent losmandy plate and cat's-eye tools it's looking closer to £3k... Paul
  13. IC1805, a Bi-colour Heart

    Thanks Graham and Adriano. I've had a quick go at reducing the blue halos with SCNR and clonestamp but I think a complete reprocess and some more/better OIII subs are probably in order to get on top of them.
  14. IC1805, a Bi-colour Heart

    Thanks for the encouraging comments folks, looks like I'm going to have to tackle those halos with processing then (would be interesting to see how much some decent sky transparency would reduce them but it doesn't look like the weather's going to play nice any time soon!). Paul
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