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JohnBarlow

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Everything posted by JohnBarlow

  1.   no need to get snarky, just sayin   Nikon only went with achros on the higher dioptr range Ref http://www.mir.com.my/rb/photography/hardwares/classics/nikonf2/macro/index3a.htm   and Zeiss Proxars  for Hasselblad were all single element I believe   Nizo (Schneiders) were the same
  2.   To be achromatic they must have two elements at least. The stretch factor is the ratio of the rear to the front focal lengths. By keeping the ratio fixed and reducing the front and rear focal lengths the spacing between afocal and 2m focal length of the compound lens can be made to be about 1-2 mm. This works for 6mm sensors pretty good within a zoom range of 10x.    Using them with 35mm lenses opens the door to softness and CA
  3.     Close up lens' below 1.0 diotr do not require to be achromatic as there is no CA to correct
  4. You should also search FOTGA on ebay, optical glass and they go up to 82mm
  5. Is this the known slacken the screws? mod Does it show softer focus at F2?
  6. I will bite   1 Not all scopes are soft. If soft, the reasons are due to poor/cheap design or damage/mis-alignment. Schneider scopes can project 65mm at 50metre at F2.   2 Scopes are made to work in front, middle or back of taking lens dependent on design. Scopes are intrinsically negative dioptr devices (like WA adapter) thus need a positive lens to form an image on the sensor   3 This is irrelevant. Anyone can design & make a focussing variable dioptr attachment range 0-2 dioptr. (0 means afocal ). If you make one to fit mine I will buy it from you   4 A spheric lens causes a spot light to focus to a spot, whereas a scope will focus to a line. If the scope has a flat face for rear group it will bounce around internally produces more lines whose colour depends on the coating.
  7. Real Viz reTimer or ReelSmart Motion Blur    --- its what animators use to remove judder
  8. Sometimes you have to perform a deep search for dioptr 0.5   If you are quick you can nab this B+W ebay # 251193694906
  9. I am curious to know the outcome of your plight.   It looks to me like the scope has been shortened (the distance between the front and rear groups has been reduced), to get close focussing. Since the MFD for this scope is 5ft, I cannot envisage another reason.
  10. Based on that article and factoring the 2x optical stretch, it appears like only 960 horizontal is recorded
  11. Cool,   I was flicking through the filmography and thinking to myself - this looks a lot like my DVD collection ;) 
  12. How do you morph from a Burnet to a Sean ;)
  13. Ok, I understand that built in post unstretch function, but if it is recording native 1080p 4:3 it must be 1440 horizontal actual pixels right?
  14. When talking about shooting with 4:3 and a 2x, the recorded horizontal resolution can be only 1440 pixels right?
  15. Mixing footage from ana and spherical is quite common in the movies   A recent example has to be the latest Batman movie, where you can see shots with oval and spherical iris reflections which give the game away somewhat.   I suppose the reason for this is that some DPs (except JJ Abrams) do not like the squishing effect when doing focus pulls    
  16. Hello all,   Like to say hello as I am a new member here.   My first post is explained in the title. I have seen some suggestions that shooting 4:3 is best for 2.66:1 with a 2x Ana, because it does not waste pixels, compared with shooting 16:9 which 'wastes' a third of the horizontal for 2.35:1     I am puzzled by this since 1080p 4:3 format would be 1440 horizontal pixels, which is 480 less than 1920.   Seems like no matter which way, expect some losses.  
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