Picked me up some new glass last week :)

05/06/2007 03:26:03 AM · #1

Well last week i bought myself a replacement for the 18-55mm kit lens. I got a Tamron 17-50mm/2.8. For the money i'm pretty happy with it. Ive taken a few test shots that i'm happy with but i'm finding that a few shots where i used auto-focus on the subject (mostly my family) when zoomed in i found that the background was far sharper than them, when i know i was focusing on them. Is this normal for this lens or is it a defect. Or is it neither of those and it is infact my fault lol. Some of the closer shots i've done i find are pretty sharp, but when we get a little further away they seem to be a smidge oof. I haven't done many tests but at 17mm a photo of my family will have the effect of them being a little oof and the background being far sharper. Ill see if i can find an example of this. Any thoughts?

edit: after looking through more shots, i find that there not extremely sharp, I heard good things about this lens both from outside reviews and those of some of you guys here. Is there a good test i could do to really test the sharpness of this lens. I want to be sure that its not something im doing wrong thats making these pictures come out a little out of focus before i consider taking it back or something.

Message edited by author 2007-05-06 03:29:52.

05/06/2007 04:09:06 PM · #2

really? nothing? :(

Canon EF-S 15-85mm f/3.5-5.6 IS USM

05/06/2007 04:12:55 PM · #3

Well if it's a problem with the focusing, that's relatively easy to test for. You can go here for a nice, easy test to see if it's working properly. As far as sharpness goes, I'm not sure how to test for that. Maybe someone else on here with the same lens can post a 100% crop of an original image taken with that lens? Another option is to go over to photozone and read the review on that lens. The also have some unedited originals to look through. Good luck!

TJinGuy

Nikon Coolpix 2100

05/06/2007 04:18:27 PM · #4

Go outside where there is a lot of light and set the aperture to something like f/11 or f/16. Make sure your camera is set to focus on the center and take a picture of a tree or something. Then blow up the shots and see how they look. That will tell you how sharp the lens is and maybe how well it focuses. Then do some shots at f/2.8 of the same things and see how they look. They will be softer than the f/8+ shots but they should be in focus.

Feel free to post up some 100% crops.

Sting11165

Canon EOS-20D

Tamron SP AF 17-50mm f/2.8 Di II LD Aspherical (IF) for Canon

05/06/2007 08:19:33 PM · #5

I also just bought the Tamron 17-50 f/2.8 about a month ago. So far, I haven't noticed any specific problems, although it does seem to be a bit softer than my 50mm F/1.8 II (as is expected). I've never done any tests though. I've heard of a few cases where the 17-50mm 2.8s aren't calibrated correctly.

Would you like to try to take the picture of the same (similar) thing and see if we notice a difference? Maybe the photo.net focus test?

Also, this may be obvious to you, but make sure you use a tripod or a sufficient shutter speed. Usually when I notice a soft photo, if I look at the EXIF data I notice my shutter speed was too slow for the focal length (need 1/(focal len) shutter speed or faster -- remember the focal length is actual focal length * 1.6 with a Rebel XT). For family pics, this could easily happen when taking photos inside.

05/06/2007 08:44:57 PM · #6

Originally posted by Sting11165:

Mmm idk i thought i was using 1/80 but i might have been using 1/60. I should have set it higher but idk why i didn't lol. Still though, shoudn't 1/60 at 50mm be sufficient? Ill do some test shots tomorrow if its sunny.

05/06/2007 09:04:17 PM · #7

Ok heres a few examples of the softness i was talking about, looking at them again there not extremely bad, i think i zoomed in too far before when looking at them.

Kinda softish, both 100% crops:
//i4.photobucket.com/albums/y110/kawana/100CROP.jpg
//i4.photobucket.com/albums/y110/kawana/100crop1.jpg

This one isn't that bad, left is unedited, and right is with a little sharpening. It seems that closeup shots are pretty sharp but further away get soft which im sure is normal. If the pic is too big, mods feel free to switch to a link or something.

//i4.photobucket.com/albums/y110/kawana/beforeandaftersharpen.jpg

Message edited by Manic - please keep images under 500px/30kb or post links or thumbs instead.

Canon EF 24-70mm f/2.8L USM

05/06/2007 09:24:55 PM · #8

Well judging from your posted photos, I think it would be a focus problem. Run that test that I posted on here above. From the last example that you posted, you can see that the unedited version is about right. dSLRs do not do very much in camera sharpening, unless you tell it to. That example you posted is about the level of sharpness I get out of my 28-75 f/2.8. So if the lens itself was bad, it would show in ALL of the shots, not just a few here and there. Like I said, run that focus test and see what you get.

Simms

Canon EOS-5D Mark II

05/06/2007 09:28:21 PM · #9

That shot of the two people looks far too soft, you shouldnt expect that from that lens. Was that at 2.8?

Sony DT 18-70mm f/3.5-5.6 Aspherical ED Zoom Lens for Sony Alpha

05/06/2007 09:39:18 PM · #10

Originally posted by Simms:

That shot of the two people looks far too soft, you shouldnt expect that from that lens. Was that at 2.8?

No the thing is that was at 19mm, 1/60 at f/14, this is why im a little confused. Ill run that focus test though. Im hopeing that perhaps for that shot i was focusing a little more on the background or something which would account for why they might not be as sharp.

Message edited by author 2007-05-06 21:40:10.

kiwinick

Sony DSLR-A550

05/06/2007 09:59:06 PM · #11

agood test for any lens is to photograph a double broadsheet newspaper
tape a duble sheet to a garage door or flat wall with camera on tripd fill the frame and shoot a test set of apatures

05/06/2007 10:14:32 PM · #12

would a dirty sensor effect the sharpness at all? I really need to clean mine lol :P

05/06/2007 10:37:13 PM · #13

Originally posted by kawana:

Try shooting something at f/8 and put the camera on a tripod. If that still ends up soft, I would put my money on a focus issue. If that's the case, attempt to manual focus it and see if that helps.

05/06/2007 11:12:56 PM · #14

Originally posted by SamDoe1:

Originally posted by kawana:
No the thing is that was at 19mm, 1/60 at f/14, this is why im a little confused. Ill run that focus test though. Im hopeing that perhaps for that shot i was focusing a little more on the background or something which would account for why they might not be as sharp.

Try shooting something at f/8 and put the camera on a tripod. If that still ends up soft, I would put my money on a focus issue. If that's the case, attempt to manual focus it and see if that helps.

Ok ill try that, if it does need to be calibrated is that something that would be covered in my warrenty, or no?

Canon EF-S 15-85mm f/3.5-5.6 IS USM

05/06/2007 11:17:44 PM · #15

thinking back i remember accidently trying to manually focus when it was on auto, i didn't turn it very far at all though like 3mm then i realized that it was still on auto. Could this have messed up the auto-focusing at all?

TJinGuy

Nikon Coolpix 2100

05/07/2007 12:20:31 AM · #16

I have turned the focus ring on my 28-75mm while AF is engaged but it is difficult. It has never hurt it.

05/07/2007 12:39:33 AM · #17

I doubt you hurt the AF mechanism, but just forget that you ever attempted that.... If it is a problem with the focus calibration, Tamron should have that covered under the warranty. Test it out and give them a call if it's bad.

Tamron SP AF 17-50mm f/2.8 Di II LD Aspherical (IF) for Canon

05/08/2007 02:40:01 PM · #18

Ok i did that little focus test and this is what i got, i hope i did it right but it doesn't seem to be even on all sides.\
I drew arrows where i think its focusing more, seems the right 2 and left 3 are about evenly out of focus. This was shot at f/2.8.

//i4.photobucket.com/albums/y110/kawana/calibrationtest.jpg

fyi its grainy cuz i accidently shot at iso 800, that shouldn't effect the test though right?

edit: I hope i didn't read the test wrong, is there a certain distance i should be shooting at or no? all i did was set the paper at 45deg. and shot while zoomed in

Message edited by Manic - please keep images under 500px/30kb or post links or thumbs instead.

Sting11165

Canon EOS-20D

05/08/2007 03:12:01 PM · #19

I haven't run the focus test on mine yet (but I will). Yours looks like it is backfocusing a bit, but I expect that is within the standard tolerance for autofocus. I doubt that would cause the problem you noted in your pictures. To find out for sure, take a bunch of test shots like that (making sure to lose focus both in front and behind the test focus) and see if you consistently see a problem either way.

In your images, yes, they are definitely soft, but I can't rule out camera shake if you took them at 1/60s (and with the large depth of field with aperture like f/14, even if you have a focus problem it may not show up in that image). I've had blurry pictures at 1/60s if I have 'jabbed' the shutter release or was moving around too much. And sometimes the camera chooses the wrong thing to focus on.

Like the SamDoe said, stick the camera on a tripod (or any stationary object) at f/8 and use a remote release or timed release. That will tell you for sure if it isn't focusing right.

And yes, if it isn't focusing right, send it to Tamron. They'll fix it under the warranty.

Tamron SP AF 17-50mm f/2.8 Di II LD Aspherical (IF) for Canon

05/08/2007 03:56:50 PM · #20

Uh.. i cant remember if i got some warrenty paper or not.. Say i lost it, is there any way to still get this fixed under warrenty if i need to? Ive never had to get anything fixed with a warrenty so im not sure how this works. I got the camera on the trip so im thinking that if i did get a peice of paper stateing i had some warrenty, it probably is lost somewhere in california lol

Sting11165

Canon EOS-20D

05/08/2007 04:14:51 PM · #21

Originally posted by kawana:

Do you have the warranty for the lens? (I'm assuming we are talking about the lens here for your focusing problem but yes, it could be the camera too)

You may need the warranty paper and you may need the receipt. Many companies (like Canon) refuse to repair anything unless you have a receipt (from what I have heard, I have yet to try to repair anything underwarranty). But, if you are in NZ, and you bought the camera in the USA, you may not have warranty coverage in NZ.

Either way, if you decide it is needed, then look up the support info and give them a call to see if they will do it under warranty.

05/08/2007 05:34:04 PM · #22

I do have the receipt from when i bought it, that might have been the only paper he gave me, i forget.

05/08/2007 06:44:17 PM · #23

Here, i just took this picture, it seems that the outside edge is nice and sharp whereas the middle is blurry. I dunno if maybe i was a little too close but it did the auto-focusing just fine.//i4.photobucket.com/albums/y110/kawana/Untitled-1.jpg

Message edited by author 2007-05-08 18:44:29.

05/08/2007 07:37:27 PM · #24

Originally posted by kawana:

Here, i just took this picture, it seems that the outside edge is nice and sharp whereas the middle is blurry.

That's cause the object is more or less a sphere... If you look in the middle, you can see some of the little brown parts that are focus. So it's not the the outside of the image is sharper than the middle, it's that the DOF is too shallow to capture the whole thing in focus. What were the settings?