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About Marky1973

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  1. Marky1973

    Doing my head in with numbers

    Yeah, I have been in touch with Steve at FLO and he says the same thing about the reducer being designed to cover an APS-C sensor, which helps with my decision - slight undersampling, but to a much lesser degree than my old set-up, so I'm going to try and ignore it....
  2. Marky1973

    Doing my head in with numbers

    Hi Dave Yeah, thanks - more numbers! Looking at the filter size calculator on Astronomy Tools, my 1.25" filters should be okay...fingers crossed.....so much to think about, but I think I am close to settling on the 72 and the 1600. Just as long as I don't start looking at other scopes/combinations in the meantime! Cheers Mark
  3. Marky1973

    Doing my head in with numbers

    That would be interesting to know - if the reducer does mean the ED72 could cover the 1600mm sensor, that might have an influence on my decision (or make it even harder) - I have both the ED72 and reducer on order....which is convenient...
  4. Marky1973

    Doing my head in with numbers

    That's part of the reason why the Ts65 is looking attractive as I believe it should be able to cover the 1600 sensor and my DSLR....
  5. Marky1973

    Doing my head in with numbers

    I don't think the reducer/flattener is essential.... obviously you will have to put up with curvature at the edges of your images, which may or may not be a problem depending on your targets and how fussy you are. The point that was made to me was that without knowing the corrected field of the ED72 it is difficult to know if it will be able to cover the whole of the sensor of the 1600....mind you, I struggle with understanding that much, so it's the blind leading the blind! It does look like a lovely scope though....
  6. I've been rebuilding my set-up to widen the field I can image narrowband targets with with an initial plan on the Evostar ED72 and AWO183MM but a recent discussion with Uranium/Rob started me thinking more carefully about resolution and Rayleigh limits.....which means I have gotten myself even more confused as I am not sure the scope/camera is the "best" match and then I stumbled across the TS APO65 which looks to be a serious contender to the ED72 - flat-field, quadruplet, 44mm corrected field and less issues about camera back focus (I think) as it has the flattener built in. I know the early ones had problems with pinched optics and astigmatism in the cold, but I believe that was sorted in the later production. So, I got to looking at the figures for these two scopes.... (I hope I've got this right) - and I included the 0.85 flattener/reducer in the 72 calculations to make it equal Ultimately the under/oversampling on the Rayleigh limits doesn't look "massive" on either scope, but Rob pointed out that we are not sure if the ED72 could cope with the big 1600 chip. I believe the TS65 could with its 44mm corrected field. So, looking at these figures, if I was to stick with the ED72, I should go for the 490EX (expensive!) or, if I went for the TS65, then the 1600mm might be the better bet (just?) The 1600mm/TS65 obviously gives a wider view than the 72/490ex combination, but there isn't a great deal in it I am probably getting too carried away with looking at the numbers but, from this information, I am presuming that either of those two combination would be "okay" and I just need to figure out how much I really want to spend. The 490ex is £1k more than the 1600mm, but I am familiar with CCD imaging and daunted about moving to CMOS and learning all over again....but the 1600mm looks like a nice option with the 65....anyway, not asking anyone to make a decision for me, just making sure that, if I went with either of these options, I wouldn't be creating a set-up that would cause problems down the line. Thanks for reading (if indeed you still are!! ) Mark
  7. Marky1973

    Undersampled images

    To be honest, "Seeing" &"Gloucestershire" are 2 words you don't very often see in sentences!
  8. Marky1973

    Undersampled images

    I did presume issues with blocky stars can be processed out, but I guess that becomes harder the more undersampled the images are. I can't imagine ever having to blow the images up too big, but a little bit of tolerance is always welcome!
  9. As I sit "patiently" awaiting the arrival of my ED72 I am thinking long and hard about the camera I am going to get with it. In discussions with Steve at FLO, the ZWO 183mm (cooled) was mentioned and it it gives a nice FOV, wider than my old combination of the ED80 and Atik 414ex. I developed more of an interest in narrowband and want a larger FOV to capture some of the larger targets, so the 183 was a tempting prospect with 1.18"/pixel to 1.38"/pixel with the reducer (which I am also waiting "patiently" for ) However, once you start looking you see the Zwo1600MM which has a slightly larger FOV and comes in at 1.86"/pixel without the reducer and slightly undersampled with the reducer at 2.19"/pixel. Then there is the comfort of staying with CCD rather than CMOS and the Atik 383l+ which has a similar FOV as the 1600 but I am familiar with the workflow needed for CCD imaging. However, this route is undersampled with and without the reducer at 3.12"/pixel and 2.65"/pixel - but it does sound like a lovely camera. From various searches I have been reading about undersampling and the dangers of blocky stars, but also that this might not be a major issue for a wider field unless imaging at or over 4"/pixel. So, for the sort of imaging that I am looking to do, will it make that much of a difference whether I go for the 183/1600 or the 383L+ (other than price) and is the issue of undersampling not really an issue with a wider field of view? Does the 383 push it a little too far, meaning the 1600 is the best compromise? My old combo of the Atik414ex and ED80 was undersampled at 2.61"/pixel but I never noticed any major issues there, despite the smaller FOV - although that may be down more to my lack of skill that anything else! I know this is probably one of those "which is the best camera for...." posts and there is probably no hard and fast answer, but I'm just interested in people's views on the "danger" of undersampling, or whether it is not worth worrying about when imaging at a wider FOV? I'm not an expert and don't really understand all the ins and outs of selecting cameras, so perhaps might be putting too much stock in simple figures and need some real world arguments from people who actually know what they are talking about.... Cheers Mark
  10. Marky1973

    Why are the planets so low in the sky?

    Jupiter isn't too bad for observing at the moment....just recently discovered, after moving into our newly converted attic....that I can comfortably observe Jupiter through my binoculars, while tucked up in bed....middle-aged heaven....
  11. Marky1973

    weird looking stars

    Did you stack in DSS? If you did you need to switch off Hot Pixel Detection....that can cause those funny looking stars. Although the focus does look a bit out...
  12. Marky1973

    COMPLETED - Skywatcher SCT Focuser £70

    No problem, glad we checked!
  13. Marky1973

    COMPLETED - Skywatcher SCT Focuser £70

    Hi Measured it and it is the standard 2" thread, so if you have a 2"SCT connection on the scope, it should fit nicely! Cheers Mark
  14. Marky1973

    COMPLETED - Skywatcher SCT Focuser £70

    Hi, sorry for the late response. If the Skymax has a standard SCT fixture at the back, it should fit? I can measure the thread width tonight so you can double check. Unless someone else more knowledgeable stumbles in and can answer in the meantime! Cheers Mark

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