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parallaxerr

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About parallaxerr

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    Caerleon, UK
  1. Can coma direction help with determining spacing?

    I've just done the very same thing and observed very different results, so I too am now a little dubious. I think I'll stick to the mk1 eyeball for now...the centre of my images are good and it's only a little coma that caught my eye, with which I can play about with spacing. The tilt, if actually there, may be due to sag. The camera is held in place by the short MPCC inserted in the draw tube so I've added a 30mm extension to the front of the MPCC and it now slides into the draw tube much easier and looks to be straight.
  2. Can coma direction help with determining spacing?

    Just measured my spacing with a vernier, looks like I'm bang on the suggested 55mm, I may try a little spacing out. Here's what CCD Inspector has to say about my setup, would welcome comment...I'm seeing curvature and tilt, correct?
  3. Can coma direction help with determining spacing?

    I downloaded a CCD Inspector trial yesterday so will run the image through it tonight. I have tilt adjustment on the moonlite so that's something else to have a look at, but not sure how that works out if you subsequently rotate the focuser.
  4. Can coma direction help with determining spacing?

    Thanks AKB that's a good post. I searched for ages but was obviously using the wrong terminology. Having said that, would you call the effect seen in my image as star elongation? If so, I'm in luck as the link you posted suggests the spacing is too close, which I can address with some delrin spacers, can't adjust inwards.
  5. I am using a Baader MPCC as a flattener with my ST120 refractor and Nikon DSLR. Due to the large chip I have a lovely wide field but notice some coma/flaring towards the edges, pointing towards the centre of the image. Granted this is not a common setup, a cheap achro with known SA and a newtonian coma corrector, but it mostly does a good job, especially in Ha it would seem. Question: Is it possible to work out from the direction of the coma which way I need to adjust the spacing? Here's an example of the coma/flare from top right of image... And full image...
  6. Canon vs Nikon

    Agreed - one of the main reasons I think Canons continue to be recommended over Nikon, the old "star eater" stories are consigned to the history books now but they get dragged up occasionally. I use a Nikon and the read noise is very low. No noticeable difference processing images with or without dark frame subtraction.
  7. What did you get up to imaging wise last night?

    It was clear as a bell here in South Wales too. I tried out my new setup for the first time on the Horsehead & flame. Only 7x600 Ha lights and 3x600 darks, no flats yet. A very quick run through StarTools...
  8. Sneaky Celestron Nexguide update

    Must have had a lot of boxes, 4yrs later......
  9. I'm not sure how common knowledge this is as it happened a while ago, but judging by the research I had to do to find out, I guess it's not! I'm 99% there with my new imaging rig and have just bought the final pieces - a guidescope and autoguider. As I am using a DSLR, I decided I wanted a stand alone guider thus avoiding the hassle of a laptop in the field. The usual candidates came up when searching - Skywatcher synguider, Baader LVI and Celestron Nexguide. Being a Celestron fanboy and not having the funds to splash on the highly rated Baader, I settled on the Nexguide. However, a little research threw up a lot of bad reports on sensor sensitivity, failed guiding attempts & hot pixel tracking which was enough to put me off until I dug a little deeper. No doubt a lot of the bad experiences are due to user error but I noticed a lot of the posts were dated back around, or shortly after the initial product release date. What late came to light was that in 2012/13... CLESTRON updated the Nexguide...and didn't tell anyone!!! The chip was changed from a Sony CCD to an Aptiva CMOS with smaller pixels and more importantly, sub-pixel guiding software was added instead of peak-sensitivity. I initially came acorss the information on a CN thread where one particular user owns both pre and post-mod versions, claiming the newer one to be much better. Subsequently I contacted Harrison telescopes and Ed was kind enough to open up a box to check the manual for sensor specs. Sure enough, the manual says V2.0 on the front and the sensor spec was Aptiva, however, the outer retail box still has the SONY specs and the part number hasn't changed? So there you go, now you know. Just thought I'd share this incase anyone's been put off by early reports. Also, for me, the new chip was the difference in bringing the pixel scale closer to that of the imaging scope for better guiding...in theory. CN thread: https://www.cloudynights.com/topic/448573-standalone-autoguider-question/
  10. SOLD, thanks Kaliska
  11. Nikon Astro-mod in UK?

    Yep, they do. £350 for a 3 week turn around. They don't do an astro specific mod, i.e 700nm shortpass, they do full spectrum which is no problem with a UV/IR block filter.
  12. Reduced to £60 inc. P&P. Gotta go, got no use for it now.
  13. Nikon Astro-mod in UK?

    Hi Luter, I'll drop you a pm
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