Tamron SP 90mm micro

[giddygoat]

Hi, so the aperture does change...do you have any idea why? Isn't it suppose to be constant?


majere2sg : Does it matter how long ago this thread was started? And I'm certain which lens I touched at wich shop, the test was done on aperture priority...why doubt me?

If you enjoy mocking at others, pse don't, coz there's a lot of people here like me looking for answers here.

hi, take it easy. i'm sure majere meant no harm.
anyway, i remembered my friend's nikkor 105mm also did the same thing and so did a quick google search. check out this link:

http://www.photo.net/bboard/q-and-a-fetch-msg?msg_id=002Sp6

hope it helps.

kenneth

 

[nolongerloner]

Kenneth, so grateful to you for taking the pain of finding the link. Appreciate it.

Regards,
Dickenson

 

[majere2sg]

Hi, so the aperture does change...do you have any idea why? Isn't it suppose to be constant?


majere2sg : Does it matter how long ago this thread was started? And I'm certain which lens I touched at wich shop, the test was done on aperture priority...why doubt me?

If you enjoy mocking at others, pse don't, coz there's a lot of people here like me looking for answers here.

Sorry if I have offended you but I just tried with both aperture and manual mode, with AF, the aperture stays at F2.8, not sure why yours changes..

 

[giddygoat]

Kenneth, so grateful to you for taking the pain of finding the link. Appreciate it.

Regards,
Dickenson

no problem. i was curious too

 

[giddygoat]

Sorry if I have offended you but I just tried with both aperture and manual mode, with AF, the aperture stays at F2.8, not sure why yours changes..

noticed that you were using a canon cam. that may be why. the excerpt below is taken from a article linked to the page i posted above.

"On thing that Canon hasn't learned how to do is display the effective aperture in the body's LCD. In the Nikon system, you set aperture on the lens. Suppose you want a lot of depth of field so you set f/32. You know that f/32 on a 60mm lens is not going to be super high quality because of diffraction (the lens is starting to act like a pinhole camera; pinhole cameras are not sharp). But you think it is worth it. Then you start to focus close. Out to 1:1. If you had your copy of the Kodak Professional Photoguide with you, you'd realize that the lens was now functioning at f/64 for both exposure and diffraction purposes. So your picture would be two f-stops underexposed and incredibly unsharp.

[If you are confused about the underexposure part, think about the fact that as the lens gets farther away from the body, it is casting a larger and larger circle of light. The fixed 24x36mm frame is intercepting a smaller and smaller fraction of that light, hence the loss of effective aperture for exposure purposes. If you are confused about the diffraction sharpness loss, I refer you to all the physics textbooks that I read and didn't understand at MIT.]

Anyway, if you didn't have your Kodak guide and were using a Canon EOS body or a Nikon F4, you'd be screwed. If you were metering through the lens, you might get proper exposure, but you'd never enlarge to 8x10 without embarrassment. [Ansel Adams took a lot of great pictures at f/64 and smaller. But he was using long lenses so the actual opening of the aperture was pretty good sized. And he was using an 8x10 view camera so he didn't have to enlarge very much.] "

 

[nolongerloner]

Sorry if I have offended you but I just tried with both aperture and manual mode, with AF, the aperture stays at F2.8, not sure why yours changes..

No worries majere2sg. I guess the difference is like what giidygoat has found out. This lens for Canon and Nikon mount somehow differs.

Giddygoat, once again, you enlighten me. Thanks!

Dickenson

 

[giddygoat]

no problem.
one thing though, i think the lens is the same regardless of mount but the difference is due to the camera bodies.
well, another CSer also PMed me and he/she is also apparently interested in getting the lens (for minolta mount though). maybe one of you should start an MO. unfortunately, i can't join in as i'm kinda low on cash now.
cheers.

 

[nolongerloner]

mmm...I just bought a Sigma 105mm. During testing, it can maintain at f/2.8. Have yet to test it out though. My first try at macro :embrass:

Sorry, guess I saw this thread a little too late....if not I'll definately take up your suggestion of having a M.O on this. :cry:

 

[plsoong]

QUICK, gg go organise MO for Tamron 90mm Macro SP :devil:




:bsmilie:

 

[giddygoat]

QUICK, gg go organise MO for Tamron 90mm Macro SP :devil:




:bsmilie:

which part of "no money" don't you understand. :bsmilie:
anyway, let's not OT, it's irritating.

 

[Kho King]

A said: Aperture won't change, constant at f2.8

b said: I swear the aperture CHANGED!

Actually, both are right. Reason?
1. Phsycially the lens is maintaining its aperture at f2.8. It won't change. However, in real world, when u focus from infinity to 1:1, there are some light lost due to the 1:1 magnification. Thus, the actual effective aperture (light going into the camera) is less as compare to when using the lens as a normal (non-macro/closeup) lens. Some camera makers display the effective aperture (the light), some just display the aperture that a lens is being used.

For Nikon camera, it will display the effective aperture. Eg. using a 90macro lens and focus to 1:2 or 1:1 at f2.8, the camera will show f5.6 instead of f2.8 because of the light lost due to high magnification.

Hope this clarify something.

 

[ahsiang]

i used the len (1:1) on F80, can't open to f2.8 when the focus distance is small but at big focus distance - it's ok.

for FM2N, no problem, 'cos all manual.....kekeke

this len (1:1) is worth more than 560 you paid for. no horse run for nature & portrait shots. sharp & clear.

 

[chrisang]

Hi All,

I have about 20 of these lenses which I bought in bulk for resale at my website, planned end this year. Based solely on visual conditions, I have categorised them into 3 - Excellent, Good, Fair. They are all without mounting but I managed to buy 3 Nikon Adpatall 2 mounts from ebay at about $25 each 3 months back.

If you are keen, drop me an email and make your offer. I will be reasonable since we are in the same community. I will also give a 3-day warranty to ensure you are satisfied with what you got or full refund. Cheers