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Ikonnikov

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About Ikonnikov

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    Star Forming

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    West Yorkshire
  1. Should be a great scope, ready in time for (nearly) the start of the next imaging season.
  2. I bought my Altair 10" second hand for half the retail price so wasn't quite so worried about drilling holes etc (although I did watch the instructional video about 20 times before doing the Moonlite decoupling mod!). It would have been a different story if it was my (bought from new) Tak Epsilon though... On the plus side for the GSO-based scopes (including TS and Altair Astro derivatives) the optics are excellent and the quality of the tube construction is sound. The Moonlite flange is rock solid (which highlights the stupidity of GSO in not including this for a couple of extra bucks worth of aluminium in the original design) and the scope holds its collimation well after being lugged in and out of the house. After indoor collimation the scope was essentially seeing limited and I've taken test images with FWHM under 2 arcseconds (which I didn't think my Yorkshire skies were capable of!). And even taking into account purchasing a decent rack and pinion focuser (~£300-500) and the Moonlite decoupling flange (~£125) you're still looking at only around half the price for the equivalent aperture CFF scope. Also (somewhat putting the cat amongst the pigeons once more) see this CN thread on the CFF RC250... https://www.cloudynights.com/topic/577046-cff-250mm-10-rc-arrived/ Paul
  3. The focuser screws on to the back of the primary mirror cell in some of the GSO RC scopes, presumably as a cost/weight saving measure. Agreed it's dumb since colllimating the primary changes the tilt of the focuser unless you install an extra focuser tilting ring (in addition to having the weight of the imaging train hanging off the primary cell which still isn't fixed by instaling the tilt ring). The moonlite mod involves drilling holes in the back of the aluminium rear scope casing to bolt a new threaded attachment to it so that the focuser etc hangs off this and not the mirror cell. Sounds drastic but I'm no craftsman and I managed it fine by following youtube video (once I sourced the obscure imperial drill bit required!). I'm pretty sure the 10" and up enclosed and truss tube designs had this problem but some of the newer TT scopes explicitly state they've been redesigned to incoporate this modification (I think the Teleskop Service 12" TT one mentions this but not sure about their 10"). Old discussion of this problem here for example Paul
  4. I have the altair 10" carbon fibre non truss tube version with upgraded focuser and it's just over 18kg with ccd attached, just light enough for my avalon linear mount to handle ok. For all but the lightest imaging train I'd strongly recommend getting a version where the telescope rear thread is not attached to the primary mirror (I bought a Moonlite kit for this but i think some vesions come with this modification already made) plus upgrading the stock crayford focuser (Im using a TS rack and pinion). Paul
  5. 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
  6. 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.
  7. 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).
  8. 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
  9. 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
  10. 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
  11. Crescent Nebula

    Very nice, I assume this is with the APM 107?
  12. 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
  13. 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!
  14. 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
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