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Ken82

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About Ken82

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  1. I’ve had a look online and found a fsq 106ED - fsq 106N comparison and description. So Judging by this image I’m guessing takahashi wouldn’t publish this if it wasn’t an exceptional apochromatic? maybe someone can explain the images ?? Im assuming the focus points for RGB are closer than 0.5mm?! Takahashi company, top-of-the-range manufacturer, has although decided to use ED glasses as well. Stopping the use of Fluorite, mainly for environmental reasons, didn't mean that optical performances have declined. The most obvious example is the FSQ-106ED, that can be judged by the curves of chromatic correction. The result is outstanding : the new ED formula does even better than its Fluorite ancestor ! Moreover, the correction was widened apart from the visible spectrum to adapt to the new demand of the numerical imaging.
  2. Is this the elephant in the room I hope not and for a scope that has been on the market for some time and proven its pedigree I would say it’s perfectly corrected. Just a look around for images shows excellent star colour and the scope itself is marketed as “this is the telescope most imaging refractors want to be” Plus the near perfect correction I appear to have with my fsq 85 would suggest this 106 example is poor. I came across some tests in my research and on this example the focus position between blue and red is almost perfect The intrafocal Ronchi test using a 10 lines/mm grating - very straight lines throughout the colors, the red lines being a little tighter together. Red has just a trace longer focus (at 656nm about 0,01mm longer than at 532nm) maybe I can even do a ronchi test myself. Or even a zygo test ? Not sure what that is really, anyone know ? One of the responders on cloudy nights posted a cropped image showing the small star colour. Again beautiful uniform star colour with no purple That's not normal at all. I also have an FSQ106ED and the stars are perfect. I’ve not used it visually but perhaps a straight through test with a well corrected eyepiece like a televue would be a good test.
  3. Yea it’s been returned to takahashi Europe for some testing. Initial tests suggested the scope was a good example but to be fair I’m not sure what sort of test they would do first??? I’m assuming a collimation and field flatness test would be completed ??? But perhaps not a colour correction/chromatic aberration test ? Now It’s going for a shack Hartmann test which I’m sure will show the different focus points for RGB. Although the disappointing thing is they will not tell me the results of the test maybe they will share the results with @FLO I’m not sure of anything right now. Maybe I’ll have to ply Steve and Grants drinks at the next SGL Star party to reveal the results On a serious note I’m not bothered about the results all I want is a normal uniform star colour in my images which I get with my FSQ 85 and this camera.
  4. Thanks Andrew, interestingly I know the author of this excellent work from speaking to him about a TOA 130 some years ago. (Don’t worry the toa has magnificent Colour correction ) I did ask him back in late May what he thought of my images and the star colour. He did say he thought the “lenses were not well aligned in a rotary sense and that I’d require support from optique interlinten or Tak Japan. I’ve had a similar response from most other experienced astrophotographers and optics specialists I’ve contacted. Spacing of elements, radius errors and misalignment are other common responses I’ve had. I think I’ve sent my images to Just about everyone in the optics world it’s good to acquire knowledge!
  5. I’ve got to agree stub! The general consensus seems to be these chromatic aberration artefacts can be removed somewhat with software. But then what’s the point in spending 5/6k on a “4 element super apochromatic telescope” ? Im quite sure this is a bad example that has slipped through the net. Certainty the colour correction on my FSQ 85 seems perfect to me. I don’t think there is any doubt now that what I am seeing is lateral chromatic aberration and I think my research has been comprehensive and compelling. In a way it’s good to learn about these photographic aberrations but I wish I had learnt another way !
  6. I just say a big thanks Ray as your detailed comparison and video really helped me make this choice. one thing that I did notice is that although the chroma website details you must orientate the filter with the arrow pointing towards the objective. My 50mm unmounted filters didn’t have an arrow so I was a little concerned at first. I was told that the orientation didn’t matter for most telescopes with these filters anymore. However I was reading a few had a halo issue on cloudy nights with the wrong orientation. so to be clear I mounted my filters with the bottom of the writing Pointing towards the objective/nebula. ken
  7. Ken82

    ASI 6200

    Time to eat some humble pie I was getting a halo 120 pixels across using baader RGB, HA and OIii filters. I also got a larger halo 160 pixels across using an IDAS d1/D2. when I switched to chroma the halo was gone so the camera doesn’t cause the small halos. Great camera I need another one now If you already have baader filters the halo is very small so nothing to worry about.
  8. Only problem is how do I now explain to my wife the filters have all doubled in price
  9. When they say no halos they mean it! I was sceptical at first as I thought it may have been the camera producing my small halos with baader and Idas filters. But I tried out a chroma oiii tonight and wow awesome ! delighted, get me a full set of narrowbands and LRGB I’ll update more tomorrow after work. but here is an image of my halos with the baader and and IDAS filters - baader filters with halo 120pixels across and IDAS D2 and D1 160 pixels across. chroma zero halo
  10. Yea I used the same filters/camera on my fsq 85. I don’t use the L filter only an IDAS D2 for luminance so haven’t measured the focus point. I’d imaging it would be where green is so between my R and B focus points. I agree it is horrendous!
  11. I think Ryzen are the leaders at the moment when it comes to cores! im still using an i7 9750h with 32gb ram. It deals with my 61mp camera just fine. I’d seriously recommend an m.2 nvme ssd As these are much faster than standard ssd’s! A good test if you have pixinsight is the benchmark text -
  12. I’m not using the reducer kirkster501, all images are at native F5. I now have it on very good authority from a leading optics engineer that there is likely a spacing or radius error/s with the scope.
  13. Yea thanks for the responses all. Regarding different software and correction/adjustment of focal lengths in RGB the point is if the telescope was truly apochromatic i wouldn't have to mess around with this. Differences between the RGB focus points in my FSQ 85 (0.07mm) and my FSQ 106 (0.51mm) is a massive 629% increase. The FSQ 106 isnt focusing RGB at the same point. These focus points have also been measured on multiple nights over the course of months.
  14. Yea thanks David, this is really what I was expecting. A nice uniform star colour even on the small stars in the image. Very similar to what my fsq 85 produces with this camera.
  15. Thanks for that, what your describing is likely atmospheric defraction as you have mentioned this happens occasionally. Although with my images as I've previously described I've never been able to take an image without the purple fringing. Every picture i've taken with this scope from months of data has a clear purple fringe. Even images taken at or near zenith have a clear problem M106, M101, M63 and NGC 5907. This should limit atmospheric issues. Also my FSQ 85 performed as expected with uniform star colour when tested so this all unequivocally points towards an achromatic aberration problem.
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