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Ben last won the day on July 16

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About Ben

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  • Birthday 09/15/1982

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  1. Hi, many forums and the "pros" once were certain that the star eater issue makes the Sony A7 Series unusable for astrophotography but I always had good results with my Sony A7rII. So I recently went ahead and had it astromodified. The thick IR-Block Filterglas was replaced with a thin Baader substitute that lets IR Light down to the h-alpha line and the sII line through to the sensor with high transmission. The results can be seen in detail on my google drive link here: https://drive.google.com/file/d/1SrdJ7tJbEUwN5KcbXsfpKaesq8KltzmY/view?usp=sharing I could write a lot of thin
  2. This recent Article on philipreeve.net might hold some insights that could help you. https://phillipreeve.net/blog/adapters-manual-lenses-sony-a7-series-guide/ In regard to the length of the adapter the following illustration from the article is most comprehensive why these adapters not only need to make a physical connection of different bayonet standards but must also maintain the proper distance to the projection plane. If the adapter is too long, you lose the ability to focus on a target at infinity and if it is to short, you decrease the close focus ability. Both errors push the
  3. I do not think that bias frames are meant to counter hot / dead pixels. AfaIk they are meant to compensate for artificially added values that are added between exposure and raw file writing by the firmware. Some manufacturers do this to keep the look of the files consistent throughout the ISO ranges by effectively in- and decreasing the blackpoint of the data. But in general DSS can handle many calibration frames for each stack - be it flat, dark or bias. You can configure in what way the sets of calibration frame types are stacked, too(usually you do not want to emphasize rejection here and c
  4. I am glad you are making progress. Short explanation about the different modes in which stacking programs work. Average(DSS), Mean(Photoshop): creates the mathematical mean value which adds all values and divides it by the number of frames. This method yields the best results for reducing noise and even increases accuracy(effective bit depth). But every outlier will influence the final outcome. I think outliers will not influence your result because you have nothing you want to filter out. Median (DSS, Photoshop): creates the statistical mean value which puts all pixel values in an ord
  5. What timde said. bulb exposures is really not the strong suite of the A7rII. Due to the nature of bsi sensors there is more crosstalk noise in the recorded data. I haven't done a lot with dark frames yet but in my experiences they did not help too much with the noise. In more astrophotography related forums I got the advice that dark frames only show a good effect if you take a lot of them and average - so 3 frames might just not cut it. There has however been some cases were the stuck/dead pixel map that the camera generates from time to time when you turn it off - was not properly
  6. Hi, here is a good resource for metabones performance with many lenses: http://briansmith.com/sony-a7rii-canon-ef-smart-adapter-tests/ My recently aquired Canon 300/2.8 L USM 1st gen (no is) works very well with the metabones IVt in green mode on the A7rII. I have yet to test the advanced mode but I intend to write a longer post about this combination. Regards, Ben
  7. Hi, If you want to assess the image quality impact you could just put it on a tablet with a white background in aperture priority and stop down until you see an impact on iq. Just make sure you test different focussing distances and focal lengths. May be it is not visible at all or may be only stopped down to something beyound F16. That at least gives you confidence about the extend of the issue. You could also try to see if pumping between 24 and 70mm moves enough air inside the lens that it might move the spec. Good luck!
  8. The Witch Head Nebula Acquisition details: 110 x 30 sec subs @ ISO1600 f4.5 1 x flat frame Nikon Ai ED IF 300/4.5 lens Sony A7rII Skywatcher - Star Adventurer with counter weight Shot in rural Germany (bortle 6/7) on 29th of December 2016 from 2000h to 2150h I was happy to see some nebula details until I saw the NASA version. Focus was slightly off and I think that is the reason I was not able to bring out better star colors. The lateral chromatic aberrations mixed with the actual star color to form one single and false color disc. I hope you like it despite my errors in the field.
  9. The Pleiades Acquisition details: 140 x 30 sec subs @ ISO1600 f4.5 1 x flat frame Nikon Ai ED IF 300/4.5 lens Sony A7rII Skywatcher - Star Adventurer Shot in star park Eifel @ Vogelsang - Germany (bortle 5) on 30th of December 2016 from 1910h to 2220h
  10. Ben


    This looks very promising. Please post your final result once you manage to pull of a stack from raw files. The 70-200gm with the 2x extender seems to be very good for astro(at least much better than my 170€ Nikon ai 300/4.5 ed if). Did you stop down on top of the implicit 2 stop loss of the 2x extender or is this as wide open as you can go with this combination?
  11. I think you make this feature request sound more trivial than it actually is. I know that it has been done before by ie Nikon, but basically a downsized raw file is no raw file anymore. Resizing breaks the Bayer grid distribution that makes raw files interpretable by raw developers. It would however be nice to have higher bitrate saving options than jpeg.
  12. Ben


    This very picture was acquired with a Nikon D750 and a 50/1.5 piggy backing the same mount(shutter shock was no issue). In my experience the Star adventurer can handle up to the advertised 10 pounds, iirc. But I must add that I use the 1kg counter weight and try to balance my gear in all axis. I made up to 90 second exposures at 500mm that showed no sign of trailing on a really flimsy tripod. Maybe I have a good copy but aside from that you could try: checking the batteries balance each axis mind ground vibrations from streets, or walking near the tripod mind the wind at the spot sandbagging
  13. Ben


    Thank you I used a lent Alta Vanguard (http://www.vanguardworld.us/photo_video_us/alta-pro-263at.html). But I haven't had any troubles getting steady shots with my old aluminum tripod either. I use the timelapse app (which disables IBIS) to capture all sub exposures and during stacking they get a score depending on how many stars were found. It is easy to remove bad frames that way. But it is mostly the first frame or the last that I have to disregard. BTW, I can only recommend staying below firmware 3.3 for now. Sony enabled the low pass spacial filter a.k.a. the star eater algorithm
  14. I installed it from https://sony-pmca.appspot.com/apps via safari on mac os on the a7r2 and it was rather self explanatory. Did you use this browser method or from source? What OS do you run?
  15. Ben


    Details on the shot: This shows part of the Orion constellation, a rather busy part of the northern hemisphere winter night sky. You can see 4 signature nebulas horsehead, running man, orion and the flame nebula. I tried to bring out the fainter interstellar dust lanes but succeeded only in parts due to shooting only from a bortle 6/7 region. I used the A7rII with an adapted Nikon 300/4.5 Ai Ed IF from the late seventies on an equatorial tracking mount (Star Adventurer). The stack, that is the basis of this image, consists of 197 x 30sec exposures and 1 flat frame (a calibration frame
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