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  1. #1
    Join Date
    Apr 2007
    Posts
    5

    my A100 won't focus when less than 40cm from the subject, what should I do\buy?

    I like taking close-up pictures of for example flowers but for some reason my A100 is way worse than my cheap cybershot t5 when it comes to this, because it just won't focus!
    I have to bring it like 40 cms away before it can focus (even on manual focus) and that's really annoying.
    What is it that's causing this?
    I'm using the kit 18-70mm lens, would it be solved by buying a lens <18mm or does that have nothing to do with this?

    Thanks
    /Nib

  2. #2
    Join Date
    Jul 2004
    Posts
    4,173
    From the review on this site:
    The minimum distance to your subject will depend on what lens you're using. For the 18-70 kit lens it's 38 cm. If you want to get even closer than you may be interested in the F2.8, 50 mm macro lens ($480), which drops the minimum distance to 20 cm.

  3. #3
    Join Date
    Apr 2007
    Posts
    5
    so the only way to know the focus distance is to read reviews? there's no number in the spec that tells it?

  4. #4
    Join Date
    Feb 2006
    Location
    Des Plaines, IL
    Posts
    9,554

    Lightbulb 28mm lensing ... decreased MFD

    With just a lens:
    • Minolta AF 28 f/2.8, which will get you down to 30 cm (11-inches) (here's your proof)
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    • Minolta AF 50mm f/1.7 will only get to 45cm ~18-inches.
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    I believe the addition of Macro Tubes to the lens might help in decreasing the minimum focus distance, but having never used them, myself ... I cannot be that sure of this side-effect. I know it sure wipes out infinity focus at the other end.

    Adding a teleconverter (T/C) only adds to the minimum focus distance, so that really isn't an option. Some lens are desgined for even closer operation.

    Super wide angle lens offer some serious close-up. too. The TAMRON SP AF11-18mm f/4.5-5.6 will get you within 25 cm (9.8-inches).
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    Shot at 18mm - f/5.6

    I suppose you can use the depth of field (higher f-stops) to try and exagerate this minimum, but that reduces your light significantly. f/8 would be your start point, and that's two full f-stops down from f/4.

    Anyway, good luck ... and please keep us informed of your results.

    BTW: Each and every lens has the minimum focusing distance on it ... because it is THAT important. If not, you can dial the focusing ring on the lens down and see it for yourself.
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    Last edited by DonSchap; 04-30-2007 at 12:00 PM.
    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

  5. #5
    Join Date
    Jul 2005
    Posts
    6,590
    Nice confusing posts again that do nothing for the original poster .

    I guess you want to get closer to have the subject appear larger in your photo.

    As you can try with your 18-70mm lens, putting it at 18mm shows the subject far away, putting it at 70mm brings it closer.

    If you want to get the subject bigger into an image, you can do 2(3) things:
    1. Tele lenses bring things closer without YOU having to get closer to the subject.

    2. Macro lenses allow for closer focussing, allowing smalelr subjects to appear larger in the photo.

    (3). Extension tubes will allow your current lens to focus closer, but your lens will lose the ability to focus a bit further away when using the tubes.

    When you are on a tight budget (my guess is you are), look at the following 2 lenses:
    Sigma 70-300 F4-5.6 APO DG Macro, it will serve as a nice affordable tele zoom (~220 USD), and offers a nice 1:2 macro ability.
    Sigma 50mm f2.8 DG Macro. 1:1 macro, very sharp, for very low price (~250 USD).
    Canon EOS 350D, Tamron SP AF 90mm F/2.8 macro, Sigma 18-50mm F2.8 DC EX, Canon EF 70-200mm f/4 L USM, Tokina AT-X124 Pro 12-24mm F4, Soligor 1.7x C/D4 DG Teleconvertor, Manfrotto 724B tripod, Canon Powershot S30

  6. #6
    Join Date
    Jul 2005
    Posts
    6,590
    Nice confusing posts again that do nothing for the original poster .

    I guess you want to get closer to have the subject appear larger in your photo.

    As you can try with your 18-70mm lens, putting it at 18mm shows the subject far away, putting it at 70mm brings it closer.

    If you want to get the subject bigger into an image, you can do 2(3) things:
    1. Tele lenses bring things closer without YOU having to get closer to the subject.

    2. Macro lenses allow for closer focussing, allowing smalelr subjects to appear larger in the photo.

    (3). Extension tubes will allow your current lens to focus closer, but your lens will lose the ability to focus a bit further away when using the tubes.

    When you are on a tight budget (my guess is you are), look at the following 2 lenses:
    Sigma 70-300 F4-5.6 APO DG Macro, it will serve as a nice affordable tele zoom (~220 USD), and offers a nice 1:2 macro ability.
    Sigma 50mm f2.8 DG Macro. 1:1 macro, very sharp, for very low price (~250 USD).
    Canon EOS 350D, Tamron SP AF 90mm F/2.8 macro, Sigma 18-50mm F2.8 DC EX, Canon EF 70-200mm f/4 L USM, Tokina AT-X124 Pro 12-24mm F4, Soligor 1.7x C/D4 DG Teleconvertor, Manfrotto 724B tripod, Canon Powershot S30

  7. #7
    Join Date
    Sep 2006
    Location
    Porto - Portugal
    Posts
    46

    Thumbs up

    Lovely fotos and they do explain very well indeed, and let me thank you for your hard work first of all because you are not only explaining but also showing us very good examples of it.
    Sony A100 + DT18-70mm + Sigma 70-300mm with 1,4 Conversor.

  8. #8
    Join Date
    Dec 2006
    Location
    Toronto
    Posts
    155
    You will probably have to step back and use the zoom lens. The ones you have now can't focus that close. It's funny - a cheap p&s has better macro (5 or 10 cm, not 30-50cm ) capability than dSLRs in general.
    Best of Both worlds:
    dSLR: Sony a100 dSLR w/ kit lens (18-70mm)
    Minolta Lens Collection: 28-80mm xi, 70-210mm
    Point and Shoot: Sony DSC-T11

    My photo portfolio

    My Flickr

  9. #9
    Join Date
    Apr 2007
    Posts
    5
    DonSchap:
    Ah thanks for that, that's a really good post.
    My kit lens does not include that min focus distance on it tho but I see now that some of the internet stores does provide that information

    ColdRain:
    Thanks for those tips, especially that 50mm one seems to have an incredible 19 cm min focus distance which should be enough
    http://www.tecno.co.uk/Store/s45381/...Id=2143&comp=n

    cgl88: heh yeah I never really appriciated how close up I can use my Cybershot t5 until I bought a dSLR camera for trice as much cost :P

  10. #10
    Join Date
    Dec 2006
    Location
    Toronto
    Posts
    155
    Quote Originally Posted by Niber View Post
    DonSchap:
    Ah thanks for that, that's a really good post.
    My kit lens does not include that min focus distance on it tho but I see now that some of the internet stores does provide that information

    ColdRain:
    Thanks for those tips, especially that 50mm one seems to have an incredible 19 cm min focus distance which should be enough
    http://www.tecno.co.uk/Store/s45381/...Id=2143&comp=n

    cgl88: heh yeah I never really appriciated how close up I can use my Cybershot t5 until I bought a dSLR camera for trice as much cost :P
    LOL. Don't retire the t5. Use both! I really like the benefits of the dSLR and of the p&s. Besides, the t5 doesn't add too much weight to your camera luggage
    Best of Both worlds:
    dSLR: Sony a100 dSLR w/ kit lens (18-70mm)
    Minolta Lens Collection: 28-80mm xi, 70-210mm
    Point and Shoot: Sony DSC-T11

    My photo portfolio

    My Flickr

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