dsjtecserv

Lives in United States Northern, VA, United States
Works as a Technical Director
Joined on Jan 21, 2005

dsjtecserv's recent activity

  • We need to be careful how we state such generalizations, since this statement is either true or not true depending on what conditions you assume. If everything (f-number, focal length, focus ...
  • As Gerry pointed out, changing your position is not equivalent to changing the focal length. When you change position you affect not only the framing but also the perspective -- the relative size ...
  • Yes, subject movement presents a challenge for focus stacking! I have used it for macro as well as for landscape shots with a near to far focus goal. However, the problem I described in my post ...
  • You ran into a fundamental problem with focus stacking when edges of near objects are superimposed next to a significantly more distant background. For a certain area surrounding the edge of the ...
  • The information provided for the image does not indicate what aperture was used, so there is no reason to assume it was a large one. The stars themselves are not blurred; they are about as sharp ...
  • Tom is probably right that the above picture was likely taken with a tracking mount to allow for a long enough exposure to record very faint stars and colors. However, useful non-trailed Milky Way ...
  • The rule of the thumb for the maximum exposure time without noticeable start trails is to divide 500 by the effective focal length of the lens. So in your example of a 30 mm focal length on a 1.5 ...
  • 300 mm; the Nikon crop factor is 1.5. The field of view would be the same, but the images may or may not be equivalent in other ways, depending on other factors. Note that the same would also be ...
  • See friendly edit above, to avoid perpetuating the misunderstanding that the sensor itself results in greater depth of field. If all of the above-noted factors are held the same, then a lens of a ...
  • In addition to the effect that Mark pointed out, it matters what parts of the sky are included in the scene. If the camera is pointed more or less north, the stars revolving around, but close to, ...
  • My first thought was also that this could be a fogbow . Compared to a rainbow, fogbow colors are weak or non-existent; they can appear to be a white ring. If the sun itself was very diffused then ...
  • Replied in don't think so
    Thanks, Michael. That's well stated; no doubt better than I did. The point that I tend to emphasize in all of this is that the parameters that affect depth of field are under the control of the ...
  • Replied in don't think so
    Um, well...do the math. When all other conditions are held constant (focal length, f-number, focus distance, print size and viewing conditions), a larger sensor will product greater, not shallower, ...
  • Replied in right
    Yep, but as you point out below, the results do depend on exactly how each of the factors play out. My point is that it can go either way, or somewhere in between, depending on the nature of the ...
  • Because stitching can be the equivalent of using a larger format camera, depth of field will tend to be greater , when other factors are held constant. This is because, as with single shot images ...
  • Replied in right
    Actually a stitched panorama does not necessarily decrease depth of field. In fact, for most applications it will result in increased depth of field, when compared with a single frame print of the ...
  • I haven't used either method but they sound like automated versions of what I was talking about. Sounds like a good approach. Dave
  • Let's clarify something! In your first post when you said working from left to right, etc, that implied that you were moving or panning the camera to shoot different things, like a panorama, to be ...
  • Let me second and endorse this suggestion. Bracketing is both cheaper and lighter than ND grads, and if you can only use a screw-on type, you might as well not bother. With a set of bracketed ...
  • The basic answer is yes -- any picture taken from the same position contains the same perspective relationships among objects -- the relative position and size of the objects. The focal length ...
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