Recent content by dave100

  1. D

    A question on optics and light ratios for astro photography.

    Sorry jescordphoto, I didn't see the second part of your reply, there are two replies from you. The reason I was asking the question is that although the Sigma 24 f 1.4 is a better lens for astro if stopped down a touch, I was toying with the idea of using the other lens because of its shorter...
  2. D

    A question on optics and light ratios for astro photography.

    Thanks for your reply jescordphoto. I am aware of the factors that you have kindly pointed out. I have shot astro with both of these lenses and am aware of the aberrations of both, but that was not the question I asked. Thanks for pointing out that the 500 rule I am using is outdated, can you...
  3. D

    A question on optics and light ratios for astro photography.

    I have probably answered my own question. I have done a rough and ready comparison in daylight by putting a 10 stop filter on the lenses, pointing them at a white sheet and shooting both in turn at the speed and aperture settings in my first post and then comparing the frames on the histogram...
  4. D

    A question on optics and light ratios for astro photography.

    My knowledge of optics and light transmission are not adequate enough to solve this problem so am asking for help from a more knowledgeable photographer. Which is going to give me the best light gathering given the same ISO setting. 1 A 17mm f 2.8 lens set at shutter speed 30 secs (500 rule) (...
  5. D

    Problem keeping tool menu settings on 5D Mk3

    Thanks for replying. Yes took some images, selected auto rotate PC only and images played back full size in vertical (portrait) mode. Turn the camera off and on again and playback is smaller vertical mode. Check setting in menu and back to auto rotate camera and pc. The same thing happens with...
  6. D

    "Approaching Train..." (7 Line Connecting Flushing, Queens To NYC).

    Great composition. Good job on the processing. The only problem I have with the image is the two ladies are the main focus of the image instead of the approaching train. Cover them with your finger and see what I mean. Still a great image though.
  7. D

    Problem keeping tool menu settings on 5D Mk3

    I want to set autorotate to only PC setting. I know how to carry out the action but when I power down the camera on next switch on the menu setting has reverted to the default? setting of Camera and PC. Any advice most welcome.
Top