Long Range 'Macro'....Options?

Discussion in 'Nikon' started by mike_halliwell, Jul 27, 2021.

  1. You used lenses proportional to the sensor size. The DOF, at the same relative aperture and FOV, is proportional to the cropping factor. This is shown in your example. The key phrase in my post is "absolute magnification", regardless of the sensor or film size. The subject would be the same size on 4x5 film as 35 mm (e.g., 1:1), although the 4x5 would have a much larger FOV.
  2. But nobody was talking about absolute (in-camera) magnification Ed. The point was to use a shorter focal length - from the same distance - and crop, as opposed to a longer focal length utilising the full-frame area.

    Besides, 'absolute' magnification could be taken to mean from subject size to final viewed image size. In which case the focal length and sensor size definitely alters the depth-of-field for a given relative aperture.
  3. The premise of this thread was to use a longer lens to photograph the same subject at a longer distance. If you apply lenses with different focal lengths to a camera, and adjust your distance so that the subject is the same size on the focal plane, the depth of field is the same (at the same relative aperture). although the perspective changes.

    Shooting from the same distance and cropping the image so that the enlarged print covers the same field of view of the subject preserves the perspective but magnifies the circles of confusion too, hence decreases the apparent depth of field.
    petrochemist and q.g._de_bakker like this.
  4. Although it is not a lens I carry about without some forethought, I have used a Sony 200-600 effectively for closeups in nature (or at least a cultivated nature). Treading through plantings to get close to "the flower" is frowned upon in the Chicago Botanic Garden. Nor is it wise to wade into a lily pond. 600 mm (576) comes to the rescue. While not exactly a fly's eye closeup, it is what I would have done with an ordinary macro lens, only closer than about 8'.

    mike_halliwell and davidspahr like this.
  5. Errr. Did you actually look at my 3 examples above?

    I'm pretty sure that they prove otherwise.

    What you've missed out from the above statement is "using the same focal length lens" and that makes the part -
    "cropping the image so that the enlarged print covers the same field of view of the subject" - nonsensical.
    You need to shorten the focal length to keep the field of view the same while cropping or using a smaller sensor size. Otherwise the field of view cannot possibly stay the same.

    Halving the focal length also halves the physical aperture diameter for a given F-number, which effectively doubles the depth-of-field for the same viewed image size.

    Do the experiment before formulating the theory!

    In your long lens example above, had you cropped from a shorter focal length, you would have seen the depth-of-field extend for the same aperture number.
    Last edited: Aug 4, 2021
  6. I agree that cropping an image has the same effect on DOF as using a longer lens at the same distance and aperture. That said, cropping an image for composition is one thing, but is of little practical use to emulate a longer lens. You lose too many pixels in the process. I return to my original thesis, consistent with the OP's post, that using longer lenses for macro photography is both useful and effective. The working distance is greater for the same FOV, and the amount of background is reduced.

    John Shaw's "Photography in Nature" has an excellent exposition on this subject, and to a lesser extent, Ansel Adam's "The Camera."
    Last edited: Aug 4, 2021
  7. I missed this when it started, but I'd just add another voice to suggest that catadioptric (mirror) lenses sometimes have close focus and in this application the "donut" highlights are usually less obvious.

    Even a relatively poor lens like the Quantaray can produce pleasing results - here hand-held at the lake:
  8. Here are examples to show how cropping, or better yet, using a smaller format (sensor) size helps with jittery subjects like insects. Since they rarely stay still long enough to get a focus-stacking set.

    The subject here was a tiny day-flying moth that's only about 10mm in wingspan. Therefore even 1:1 magnification gets you nowhere near to filling the frame on the DX format, let alone full-frame.

    Example 1, at almost 1:1 camera magnification -
    OK, but severely lacking depth-of-field.

    Example 2. Taken from further away and cropped more severely -
    Despite the lower pixel count, I think this actually looks sharper due to the greater D-o-F.

    The same 105mm lens at f/8 was used for both shots. You might notice that the moths are different though! But they were both of a similar size.

    IME the lack of pixel count isn't too problematic with the likes of Topaz Gigapixel software available. Or simply uprezzing and using the smart sharpen filter in PhotoShop.

    FWIW, even viewing the above thumbnails on my small smartphone screen shows the moths at larger than lifesize.
    Last edited: Aug 5, 2021
    mike_halliwell likes this.
  9. Interesting plane of focus in the 2nd shot..

  10. That could be because I rotated the image to get the moths comparably orientated.

    Or simply because the OOF wingtip was drooped away from the camera. Whatever, I don't see anything strange about it. Not when the DoF is measured in millimetres, or even fractions thereof.:)
    mike_halliwell likes this.

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