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Old May 25, 2006, 7:42 AM   #1
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Hi Guys,
I am new in this forum..................please welcome me............... Thank you.
As an enthusiast and not a pro member, I hope anyone can advise me between those two above model zoom lens, which is a better one to buy? I already have Tokina 12-24mm for wide lens and 18-70mm Nikon plus a 50mm/f1.8 Nikon Prime lens. I am now would like to spend for a moderate tele zoom lens. price different about 2/3 for Tokina compare to 18-200 VR nikon. speaking of images sharpness and contrast, is Nikon better than the Tokina? anyone can advise me?Thank you

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Shakyhands


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Old May 25, 2006, 1:16 PM   #2
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If you're looking at consumer grade lenses, I would stick with Nikon. If you're looking higher end, pro level the difference is less apparent. The Nikon 18-200 is wideley accepted as the best lens in the superzoom class, and VR is a great feature to have that the Tokina does not. In reality, if you get the 18-200, that would be the only lens you'd need, as it would make the others redundant.

In all honesty, though, I doubt the casual photographer would notice the difference in an image made withpro glass vs consumer grade glass, especially at normal print/viewing sizes.
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Old May 26, 2006, 12:05 AM   #3
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rjseeney,

I agreed that Nikon have more wider focal and also has VR which is benefit to have it.
I am now saving some dollars to buy one near soon - thank you.

and I have a question regarding result test I did on same subject with same camera but different lenses ( both @ same 24mm focal length ISO 400)
Lens #1 on program mode: 320/f 9.0 - result sharp and bright
Lens #2 on program mode : 350/f 10.0 - result sharp and brighter than with Lens#1
by logic , the images taken with lens#1 should be brighter becoz of slower and wider apperture than the one taken with Lens#2. Please advise me - is it true or not, that one deliver more light into the CCD sensor is showing a better quality of lens? If yes, then on above case, the lens#2 must be a better optical lens than the other?

thank you
Rgds,Shakyhands
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Old May 26, 2006, 3:48 AM   #4
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You don't say what the lenses are, but you lose light on every glass/air surface even with multi-coating. So, if one lens has 12 groups and the other 6 groups, it can make quite a difference. The aperture is a geometric measure and does not tell you how much light is transmitted through the lens, just the ratio of the effective diameter to the focal length.

Keith.
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Old May 26, 2006, 8:18 AM   #5
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well I forgot to mention it........the lens#1 was Nikon 18-70mm/3.5-4.5G ED and Lens#2 was Tokina 12-24mm/F4 ( both test shots was taken with D200 Nikon ) on bright morning time at my backyard.
The think that I could not understand was, why the picture result shot with Tokina lens shutter speed at 350/ f10 looks more brighter than the one shot at 320/f9.0 with Nikon Lens??
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Old May 26, 2006, 11:09 AM   #6
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When you refer to "brightness", I assume you are refering to exposure. Exposure is a relationship between aperature, shutter speed and ISO. Just using a larger aperature will not necessarily result in a "brighter" image. When comparing lenses you need to use the exact same settings. Without seeing the images, I really can't give you an explanation to your results. As was mentioned, alot goes into lens performance.
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Old May 26, 2006, 8:11 PM   #7
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that is my point, at my best knowledge, as the Exposure RULES, if the ISO set at same setting say ISO400 & we use same set-up with the very same camera, than a wider aperture or a slower shutter or both will definitely makes the result image on that shot less darken than one was shot with faster shutter speed or smaller aperture.

in my study case on comparing two lens as my earlier threads posted above, the result the other way around against the Exposure RULES.

Then I jump to my own conclusion, maybe the answer to this fact is that the LENS#2 were better in passing the light onto the D200 CCD sensor( other word is Lens#2 is better optical than lens#1) which is what my original issue on this talking..." If the fact that lens#2(Tokina) that can deliver a brighter result image (less dark) even the exposure setting shown opposite as ours exposure rule than this lens must have a better glasses.

I hope I had addressed my question clearly now, thank you to anyone can correcting my conclusion on my Test Case above.

I wish I can show the pictures to you guys, but some how those test images were gone, maybe I forgot to locked when I do deleted my card.
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Old May 26, 2006, 9:08 PM   #8
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Typically lens quality is not found in exposure. Again, exposure is more a result of aperature/ISO/shutter speed relationship, or in other words the camera's metering ability/and or photographers ability to set exposure properly. Quality of glass is found in areas such as sharpness, aberration, barrel distortion, pincushion etc. One of the problems in your test was the shots were done outdoors, not in controlled lighting. Conditions can change very quickly and even changing positions or focal points can affect exposure. To compare lenses accurately, the shots need to have the exact same focal point and lighting which can only be achieved in a controlled situation, ie. a studio type setup.
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Old May 26, 2006, 11:22 PM   #9
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I am appreciated your explanation rjseeney, well you are right, we can not make sure the available light in outdoor shots, can be change at any time, even while I am doing the exchange lenses on my camera before taken another shots.

I will try another test with a lighting can be controlled.
thanks to rjseeney and keith1200rs to discuss this matter, its helps.


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Old May 27, 2006, 12:28 AM   #10
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My theory is blown now you have said what the lenses are. One thought is whether apertures on cameras are really accurate (except maybe wide open). When we used separate exposure meters they had to be. Also, lenses only had a few elements. Now with TTL metering everywhere and up to 16 elements in a lens, I wonder if they are accurate anymore. Also, maybe some manufacturers take account of the glass/air light loss when marking apertures, others may not.

Only guessing though.

Keith.

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I will try another test with a lighting can be controlled.
thanks to rjseeney and keith1200rs to discuss this matter, its helps.

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