Testing Tammy 17-50 f2.8, can you help?

Started Apr 30, 2010 | Discussions
abhijitsarkar
abhijitsarkar Regular Member • Posts: 235
Testing Tammy 17-50 f2.8, can you help?

Hi,

I got my Tamron 17-50mm f2.8 today. Having heard horror stories about good and bad copies of 3rd party lenses, I made a few shots right out of the box. May I request the geeks here to comment on the lens (not pictures)? The AF seems fast and responsive, I have not tested the VR though.

*While fine tuning the focus during AF mode, I recollected that the manual strongly advised againstit. Did I cause any harm?

Abhi

 abhijitsarkar's gear list:abhijitsarkar's gear list
Nikon D750 Nikon AF-S Nikkor 16-35mm F4G ED VR Nikon AF-S Nikkor 24-120mm f/4G ED VR Nikon AF-S Nikkor 70-200mm f/4G ED VR
Ben Seese Veteran Member • Posts: 3,367
Re: Testing Tammy 17-50 f2.8, can you help?

Three questions, Abhi. Why did you downsize to 1280 before uploading? If you weren't able to make a definitive judgment from the 12mp files, how do you expect us to make better judgment from 1mp files?

2nd, why bother shooting at f/22? Above about f/13, diffraction above will make all lenses look equally terrible. Your thorough testing should really be from f/2.8 to f/5.6, where the image quality can be made or broken.

3rd, why choose such a convoluted 3D subject? You have idea which component the camera attempted to focus on, in order to compare with what it actually focused on. The majority of 'bad copies' are lenses whose focus calibration is off, and this is the opposite of the subject that will demonstrate it.

Finally, your cranking the focus dial while in AF won't hurt once or twice. Doing it every day will eventually cause damage, but you've got nothing to worry about in your first day.

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abhijitsarkar
OP abhijitsarkar Regular Member • Posts: 235
Re: Testing Tammy 17-50 f2.8, can you help?

Ben,

I figured people here are pretty busy and they would not bother commenting if a page takes forever to load. That's the reason for downgrading images.

I found the following good article about lens testing. I will post back after I perform the tests.
http://diglloyd.com/articles/LensAndCameraIssues/BrandNewBlur-Testing.html
--
'A photograph is memory in the raw'

 abhijitsarkar's gear list:abhijitsarkar's gear list
Nikon D750 Nikon AF-S Nikkor 16-35mm F4G ED VR Nikon AF-S Nikkor 24-120mm f/4G ED VR Nikon AF-S Nikkor 70-200mm f/4G ED VR
basic state of ignorance Contributing Member • Posts: 624
Re: Testing Tammy 17-50 f2.8, can you help?

Enjoy your lens if you like the pictures.I would not bother with too much testing if images look good. I just bought the non VR version of this lens and it is great

Ben Seese Veteran Member • Posts: 3,367
Re: Testing Tammy 17-50 f2.8, can you help?

abhijitsarkar wrote:

I figured people here are pretty busy and they would not bother commenting if a page takes forever to load. That's the reason for downgrading images.

You misunderstand the basics of posting images. When a reader opens your post, they've only loaded the really downgraded 480 pixel image. They can click on the image to load slightly less downgraded sizes. But only when they click on the word 'Original' above the image do they have to wait for full image to download.

And on top of that, most of your readers are on broadband, so a 4mb original image should take between 5 and 15 seconds to download. If I've intentionally clicked to download an image, I'll wait it out.

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hotiwal Regular Member • Posts: 220
Re: Testing Tammy 17-50 f2.8, can you help?

Nice pictures. Love the 'Copyright' touch.

Sam

stuntmonkey
stuntmonkey Senior Member • Posts: 2,727
Re: Testing Tammy 17-50 f2.8, can you help?

abhijitsarkar wrote:

For what its worth, if you can't see the difference that F22 is making on your picture, then it's not likely you will see if you have a good copy of a lens or not. Don't take this to mean that you are not good enough to evaluate your lens, but it does mean that whatever deficiency there is in the equipment, it is not going to hold you back at this point.

FWIW, except for going past F11, which is a technique issue, there is nothing particularly wrong about your pictures.

abhijitsarkar
OP abhijitsarkar Regular Member • Posts: 235
Re: Testing Tammy 17-50 f2.8, can you help?

hotiwal wrote:

Nice pictures. Love the 'Copyright' touch.

The 'copyright' is unintentional (for these pictures). It is configured in Picasa for any pictures I generate for Web. I would have removed it if I had seen before.

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'A photograph is memory in the raw'

 abhijitsarkar's gear list:abhijitsarkar's gear list
Nikon D750 Nikon AF-S Nikkor 16-35mm F4G ED VR Nikon AF-S Nikkor 24-120mm f/4G ED VR Nikon AF-S Nikkor 70-200mm f/4G ED VR
Steve82 Senior Member • Posts: 2,906
Re: Testing Tammy 17-50 f2.8, can you help?

No one can make any judgments from your image because it is impossible to tell what point you were focusing on. If you are worried about front/back focus (and the available evidence suggests that you should be), then do an internet search for one of the focusing charts and the instructions for how to check for front/back focus. You should do the tests at f2.8....any smaller aperture will tend to mask focusing issues because of the increased depth of field.

The instructions are really easy to follow and the results are easy to interpret. A friend of mine did the test and contacted Tamron to have his lens fixed (back focus issues). Tamron adjusted the focus of his lens and he has been happy with it ever since.

abhijitsarkar
OP abhijitsarkar Regular Member • Posts: 235
Brick Wall Test images
 abhijitsarkar's gear list:abhijitsarkar's gear list
Nikon D750 Nikon AF-S Nikkor 16-35mm F4G ED VR Nikon AF-S Nikkor 24-120mm f/4G ED VR Nikon AF-S Nikkor 70-200mm f/4G ED VR
Ben Seese Veteran Member • Posts: 3,367
Re: Brick Wall Test images

abhijitsarkar wrote:

Posting back with Brick Wall Test images. I noticed some Fisheye distortion wide open but not sure if it's enough to return the lens. Any other comments?

Repeating myself from three weeks ago: Nothing can be evaluated from such tiny sized images. If you care to get any real feedback, please do post these full-resolution images to an Album here at DPR (free Flickr accounts don't allow sharing full-res). Believe me, nobody is going to complain about the download times.

Also, you're confusing your terms above... The curvature of straight lines (what you're calling fisheye distortion) happens at wide angle . Wide open is when you use the widest aperture value your lens allows (f/2.8 in your case). And the distortion you are seeing at wide angle is completely normal for lenses like this.

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seob Regular Member • Posts: 439
Re: Brick Wall Test images

abhijitsarkar wrote:

Posting back with Brick Wall Test images. I noticed some Fisheye distortion wide open but not sure if it's enough to return the lens. Any other comments?

Only if you plan on shooting brick walls all the time

abhijitsarkar
OP abhijitsarkar Regular Member • Posts: 235
Full sized images uploaded to my gallery

Ben Seese wrote:
Nothing can be evaluated from such tiny sized images.

I did not realize that Flickr downsized the images. When I uploaded them, they were full sized.
I have now uploaded them to my gallery.

Also, you're confusing your terms above...

Yes, I was technically incorrect. Thanks for pointing it out.

 abhijitsarkar's gear list:abhijitsarkar's gear list
Nikon D750 Nikon AF-S Nikkor 16-35mm F4G ED VR Nikon AF-S Nikkor 24-120mm f/4G ED VR Nikon AF-S Nikkor 70-200mm f/4G ED VR
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