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My Sony DSC-H1 has a tube with 58mm threads for mounting converter lenses and/or filters. Among the lenses available from manufacturer itself are a 0.7x wide converter, an 1.7x tele converter, and a macro converter (don't remember the scale right now).

The camera settings menu has an entry for specifying any of those converters. What will be the consequences?

I can think of three things: different ranges for focus hunting (no point in looking beyond ∞) and different scale for manual focus display, different ranges for the built-in zoom (no point in going to full tele with a wide converter and vice versa), and different motion shake compensation (a wide converter will warrant less optical correction for the same amount of angular displacement of the camera, a tele converter will warrant more).

I am pretty sure that the first two are implemented (and they actually limit what you can do) but would the third be likely?

The user manual makes no mention whatsoever about why one should try specifying the right kind of converter. It does mention that zoom/focus ranges get constrained. But that does not sound like being overly useful.

EDIT: Movement of the lenses stays safely behind the tubus threadings for all unmodified settings, so I doubt that mechanical safety is an issue here. The usual EXIF data is not impacted with either unannounced or announced converter lens (and doesn't tell the focusing distance, but the focus length stays the same) but the Sony MakerNotes entries might contain some info. Too bad that exiftool does not manage to decipher it.

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  • \$\begingroup\$ my first thought was different lens correction profile... \$\endgroup\$
    – osullic
    Commented Oct 1, 2018 at 22:59
  • \$\begingroup\$ "It does mention that zoom/focus ranges get constrained. But that does not sound like being overly useful." That is very useful. It's what you described a couple of paragraphs earlier: different ranges for focusing and zooming. \$\endgroup\$
    – Michael C
    Commented Oct 2, 2018 at 2:35

2 Answers 2

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  • The tube mounts the converter in front of a moving lens element, not on the lens directly. Some conversion lenses contain protruding rear elements. Zoom and focus movements must be limited to prevent damage to the lens and converter.

  • With wide-angle converters, zoom range may be restricted to prevent the inside of the converter from being visible in the corners.

  • Changing the setting may cause different Exif metadata to be saved with the images.

  • The built-in lens may also behave differently with different converters because they have different optics. Such changes include those you mention:

    • different distance scales
    • different motion compensation algorithms
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    \$\begingroup\$ I should have mentioned that the tube is "standard" and also used for mounting filters. The motion range of zoom/focus does not reach the converter lens (well, at least not the third-party wide-angle converter I use) and stays several mm behind the threading, so I would be surprised if any of the available lenses would be in mechanical danger. \$\endgroup\$
    – user78040
    Commented Oct 1, 2018 at 22:00
  • \$\begingroup\$ Accepting this as answer because it's more relevant than the higher-rated other answer to the camera I am asking about. Thanks! \$\endgroup\$
    – user78040
    Commented Oct 3, 2018 at 20:51
  • \$\begingroup\$ there's no hurry to accept an answer if you dont feel your Q is fully addressed \$\endgroup\$
    – xiota
    Commented Oct 3, 2018 at 21:31
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Another reason a camera might want this information would be in order to use correct profiling for any software corrections of lens distortions. This would almost certainly be the case for any recent fixed lens camera, but possibly not for one this old (for lack of available processing power). It would be difficult to say for sure, since this camera doesn't appear to produce any type of RAW file to compare to JPEG output. The answer applies generally to the question as asked, though.

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  • \$\begingroup\$ I don't think the sensor resolution of this camera would make lens distortion correction feasible. If it did, I'd expect the camera to keep chromatic aberration better in check though of course the sensors are not monochromatic and thus have to account for a lighting-dependent aberration distribution rather than a single value. \$\endgroup\$
    – user78040
    Commented Oct 1, 2018 at 23:08
  • \$\begingroup\$ Distortion correction is feasible at that resolution - I was doing it to smaller images than that in 2001 as part of stitching panoramas with panotools. :) Transverse CA correction does benefit from more resolution, and I wouldn't expect that camera to be doing it even if it was correcting distortion. Ultimately, though, it's a question of whether the hardware could do that much number crunching in a short enough time, and I would guess not. \$\endgroup\$
    – junkyardsparkle
    Commented Oct 2, 2018 at 0:18

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