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  1. #1
    Join Date
    Mar 2006
    Location
    Sheffield
    Posts
    18

    Have I got this right?

    I am currently using a Canon S2 IS (5 megapixels). I mainly shoot subjects needing as much magnification as possible, like garden birds, sailing boats, windsurfers etc where it's not possible to get physically close.

    Using a 1.54 Raynox convertor, I have an effective focal length of 665mm, so I can usually get close enough to the subject, but I often find I could do with more resolution.

    If I bought a Canon 350D, I would get 33% more horizontal resolution (3456 v 2592). However, the longest EF IS lens I can afford is 300mm (I need IS as my subjects don't lend themselves to using a tripod). This has an effective focal length of 480mm, which is around 30% less than I have now.

    Am I right in thinking the gain in pixels would be offset by the reduction in focal length?

    If I upgrade to an S3 IS, I only get 9% more pixels in each direction, which hardly seems worth it.

    Can anyone suggest another way of getting more detail? My budget is around 1000, which probably equates to around $1000 in the US.

    Thanks for any suggestions.

  2. #2
    Join Date
    Feb 2006
    Location
    Des Plaines, IL
    Posts
    9,560

    Lightbulb Consider a T/C on the lens

    If you decide to go the dSLR route... consider buying a teleconverter for your lens. Things to consider though:

    1. The 1.4x T/C will drop off one full-f/-stop of light, right off the bat
    2. The 2x T/C will drop off 2 full f/-stops of light, right off the bat
    3. If you use a 300mm f/4-5.6 with a 1.4X T/C, you will probably have Autofocus at 300mm, if you do NOT use a polarizer (The polarizer will cause sever enough light loss to have exceeded the f/8 AF-threshold).
    4. If you use a 300mm f/4-5.6 with a 2X T/C, you will probably lose Autofocus at 200mm-300mm, because your 'light loss' due to the 2x T/C will have exceeded the f/8 AF-threshold... even if you do not use a polarizer.


    If you can get an f/2.8 lens... you can add a Kenko 3x T/C to it and probably not suffer loss of AF. Unfortunately, a fixed telephoto 200mm f/2.8 lens start around $650.

    A telephoto 300mm f/2.8 is at upwards of $1000.

    Neither of these lenses has 'Image stabilzation', so a tripod or some kind of stabilizing mount seem absolutley mandatory.

    As you can see, there is no great way to do this.

    My personal recommendation of the cheapest and best (using decent glass) approach... is the get the following:

    1. Canon EF 70-300mm f/4-5.6 IS USM ($559 @ B&H)
    2. TAmROn SP 1.4x Teleconverter ($179,95 @ B&H)


    and go from there. What you get is an image stabilized 1.4x (T/C) + 1.6x (Camera's DCF) + 70~300mm from the lens. You can still autofocus... and have an effective 210~600mm (35mm equivalent) zoom.

    Stay away from the 2x T/C... as while it may look attractive, but it will just slay your autofocus capability at the high end, where you will really need it.
    Last edited by DonSchap; 07-23-2006 at 09:19 AM.
    Don Schap - BFA, Digital Photography
    A Photographer Is Forever
    Look, I did not create the optical laws of the Universe ... I simply learned to deal with them.
    Remember: It is usually the GLASS, not the camera (except for moving to Full Frame), that gives you the most improvement in your photography.

    flickr & Sdi

  3. #3
    Join Date
    Mar 2006
    Location
    Sheffield
    Posts
    18
    Thanks very much, that's a really helpful reply

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