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Thread: is it normal for tamron 90mm?

  1. #1

    Default is it normal for tamron 90mm?

    i just got tamrom 90mm 2.8 macro not long ago... i have a problem is that i can't get 2.8 when i do close focus... i only get 2.8 at minimum focus... but when i get closer focus it seem that my aperture getting smaller.. is it normal?

  2. #2

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    Quote Originally Posted by WatWatz
    i just got tamrom 90mm 2.8 macro not long ago... i have a problem is that i can't get 2.8 when i do close focus... i only get 2.8 at minimum focus... but when i get closer focus it seem that my aperture getting smaller.. is it normal?
    Yes it's normal for macro lenses, f2.8 is only when you focus to infinity

  3. #3

    Default Re: is it normal for tamron 90mm?

    Won't go into scientific explanations.

    Take a black disc, say front opening is 20mm. This is the aperture (f/2.8)

    Put it on a long, telescopic blackened tube. Put the tube over one eye. Aperture end is furthest away from you.

    When you bring the aperture close to your eye, a lot more light gets in (infinity focus - the lens looks short, right?).

    When you extend the aperture far far away, a lot less light gets in ... like the FAR end of a dark tunnel (min close focusing distance-lens becomes long long).

    Hope this helps some.

    Cheers!

  4. #4

    Default Re: is it normal for tamron 90mm?

    thx u all... iv no worried since its normal... thx u again

  5. #5
    Member iguanavon's Avatar
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    Default Re: is it normal for tamron 90mm?

    Quote Originally Posted by WatWatz View Post
    thx u all... iv no worried since its normal... thx u again
    Actually, The aperture should remain at F2.8 no matter how close is your focusing. I've a Tamron 90mm macro and I've just tested it out. I can maintain F2.8 no matter focusing at min. distance or at infinite range.

    There's 1 possibility which is that you're using Shutter spreed priority, Program mode or Auto mode

  6. #6

    Default Re: is it normal for tamron 90mm?

    What you say is actually correct.

    The aperture, being a physical dimension 'Never' changes.

    Only the AMOUNT of light that reaches the sensor//film plan DOES.

    I'm afraid I have no idea what you speak of in your second sentence and/or paragraph, though. My Bad.
    Last edited by Dream Merchant; 9th April 2011 at 03:27 AM.

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    Member iguanavon's Avatar
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    Quote Originally Posted by Dream Merchant
    What you say is actually correct.

    The aperture, being a physical dimension 'Never' changes.

    Only the AMOUNT of light that reaches the sensor//film plan DOES.

    I'm afraid I have no idea what you speak of in your second sentence and/or paragraph, though. My Bad.
    Erm... For my 2nd paragraph, what I wanted to say was that in S, P or Auto mode, the aperture will automatically change according to the amount of light available. So the issue that TS is facing might be caused by what I've mentioned.

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    Default Re: is it normal for tamron 90mm?

    Quote Originally Posted by iguanavon View Post
    Actually, The aperture should remain at F2.8 no matter how close is your focusing. I've a Tamron 90mm macro and I've just tested it out. I can maintain F2.8 no matter focusing at min. distance or at infinite range.

    There's 1 possibility which is that you're using Shutter spreed priority, Program mode or Auto mode
    I think it depends on what mount of the tamron you are looking at. IIRC, nikon bodies will show the change in effective aperture. My canon doesn't.

  9. #9

    Default Re: is it normal for tamron 90mm?

    im using D90.. always on full manual mode

  10. #10

    Default Re: is it normal for tamron 90mm?

    I just got the tamron 90mm as well and the aperture does not remain at 2.8. For those that own this lens, what is the "normal" F when you use it for macro? I find myself using F22 and above yet the DOF is still shallow, is this normal? Thanks...

  11. #11

    Default Re: is it normal for tamron 90mm?

    Quote Originally Posted by sept19th View Post
    I just got the tamron 90mm as well and the aperture does not remain at 2.8. For those that own this lens, what is the "normal" F when you use it for macro? I find myself using F22 and above yet the DOF is still shallow, is this normal? Thanks...
    Yes it is normal to have very shallow DOF even at high f numbers, so try to fit the insect into the plane of focus if you want the whole insect sharp. Also, try not to shoot at above f16, it will cause diffraction, which will lower your image quality.

  12. #12
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    Default Re: is it normal for tamron 90mm?

    Quote Originally Posted by WatWatz View Post
    im using D90.. always on full manual mode
    Quote Originally Posted by sept19th View Post
    I just got the tamron 90mm as well and the aperture does not remain at 2.8. For those that own this lens, what is the "normal" F when you use it for macro? I find myself using F22 and above yet the DOF is still shallow, is this normal? Thanks...
    Hmm... Can know what mode are you shooting with? I'm using A33 and I shoot mostly in Manual mode, but I don't experience the aperature problem that both of you are facing.

    For macro, I shoot mostly at F16 and yes, the DOF is still shallow. Therefore, you need to always think of how to position yourself to the subject. If you want a larger DOF on your photo, you can try focus stacking.

  13. #13

    Default Re: is it normal for tamron 90mm?

    I think Canon camera will read the same f2.8 when mounted with the Canon 100mm f/2.8 L Macro, but the f aperture will change on Nikon cameras. Read from Ken Rockwell website:

    Macro lenses lose light as focused more closely. I'll skip you the real reason, but suffice it to say that as magnification goes up, the light has to be spread further.

    Canon EOS cameras don't show the true f/stop as these lenses are focused more closely. As one focuses to 1:1, one loses about 1 1/2 stops of light, but EOS cameras keep reporting the same f/stop regardless.

    Because of this, you will have to compensate if using an external meter, which is very uncommon today. Most of us use our TTL meters, which work fine.

    On the other hand, Nikon's AF cameras and macro lenses report the actual effective f/stops as one focuses more closely, so they always show the correct reading.
    Last edited by kentwong81; 12th April 2011 at 01:53 PM.
    Kent Wong Photography |Leica Q & Leica M-P 240 | 75 & 28mm Summilux

  14. #14

    Default Re: is it normal for tamron 90mm?

    Quote Originally Posted by kentwong81 View Post
    I think Canon camera will read the same f2.8 when mounted with the Canon 100mm f/2.8 L Macro, but the f aperture will change on Nikon cameras. Read from Ken Rockwell website:

    Macro lenses lose light as focused more closely. I'll skip you the real reason, but suffice it to say that as magnification goes up, the light has to be spread further.

    Canon EOS cameras don't show the true f/stop as these lenses are focused more closely. As one focuses to 1:1, one loses about 1 1/2 stops of light, but EOS cameras keep reporting the same f/stop regardless.

    Because of this, you will have to compensate if using an external meter, which is very uncommon today. Most of us use our TTL meters, which work fine.

    On the other hand, Nikon's AF cameras and macro lenses report the actual effective f/stops as one focuses more closely, so they always show the correct reading.
    i don't know about Ken Rockwell's camera testing techniques....

    neither do i use canon nor nikon. Mr Rockwell is a nikon fanboy, and anyone shooting with canon and knows the limitation will just use ringflashes/ringlights or external flashlights to get the shot.

    what's Ken's beef with Canon? simply because it's not a Nikon.

  15. #15

    Default Re: is it normal for tamron 90mm?

    Quote Originally Posted by kei1309 View Post
    i don't know about Ken Rockwell's camera testing techniques....

    neither do i use canon nor nikon. Mr Rockwell is a nikon fanboy, and anyone shooting with canon and knows the limitation will just use ringflashes/ringlights or external flashlights to get the shot.

    what's Ken's beef with Canon? simply because it's not a Nikon.
    I have a friend using Canon 100mm f2.8 Macro too. When I told him about the changing of apertures for Nikon, he was surprised as it doesn't happen for Canon and it always stay at f2.8. So what Ken Rockwell said might be true.
    Kent Wong Photography |Leica Q & Leica M-P 240 | 75 & 28mm Summilux

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    Quote Originally Posted by kei1309

    i don't know about Ken Rockwell's camera testing techniques....

    neither do i use canon nor nikon. Mr Rockwell is a nikon fanboy, and anyone shooting with canon and knows the limitation will just use ringflashes/ringlights or external flashlights to get the shot.

    what's Ken's beef with Canon? simply because it's not a Nikon.
    I think KRW as ridiculous as he sometimes is also owns and shoots a 5dm2. And he praises the hell out o it.

  17. #17

    Default Re: is it normal for tamron 90mm?

    Rent a Canon 100mm Macro to try out or ask your Canon friends if they a Macro lens to prove KRW wrong in this case.
    Kent Wong Photography |Leica Q & Leica M-P 240 | 75 & 28mm Summilux

  18. #18

    Default Re: is it normal for tamron 90mm?

    Doesn't really matter whether if it's NiCanOlyLeicaNyHasseyHoesemanSinarBlaBlaBla.

    Whether the aperture readout registers as a variable scale or a constant going, your metering will clue you in if there IS a drop of EV when you go from infinity to MFD.

    As far as I can recall, Nikons show that variation, whereas Canon does not. But the truth lies in the metering readouts, all things being constant, so it matters naught what the aperture readout says.

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