Tamron Focus Issues - Maybe - Advice Needed

I have the Tamron 17-50 f/2.8 lens and have been really quite pleased with it. However, today during package opening I noticed a few instances of "out-of-focus" issues, including where the AF meter hit the object, but the area in front of the spot was more in focus. I believe this to be called front-focusing...

Has anybody experienced this with the lens that I have?

It really could be user error due to taking at 2.8 from about 3 feet at 1/60 with flash of a 9 month old. However, I usually have good results. I also had a few issues going across the room at 1/60 of my father.

It could be user error...but I wanted to ask. Are there any good, simple, tests to be done?

Thanks
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Newbie as of Dec 1, 2006
XTi
Tamron f/2.8 17-50

I know how annoying that is, with my sigma 18-50 f/2.8. Although it misfocus more than front focus. I've ruined some family snaps as well.

You can use this focus test chart:
http://www.focustestchart.com/chart.html

Or put 5 books on a table straight up so that each overlaps the other, spaced 5-15 cm (2-6 inches), depending on the min. aperture. Then focus on the middle book in good light (no flash) like 500W halogen bulb or daylight. If it consistently front focuses with every lens, you need to send in your camera for calibration. If it is just your lens, call Tamron to see if the lens has a chip that can be calibrated and send it in.

Good luck!
Imqqmi

MinnesotaHawkeye said:

I have the Tamron 17-50 f/2.8 lens and have been really quite
pleased with it. However, today during package opening I noticed a
few instances of "out-of-focus" issues, including where the AF
meter hit the object, but the area in front of the spot was more in
focus. I believe this to be called front-focusing...

Has anybody experienced this with the lens that I have?

It really could be user error due to taking at 2.8 from about 3
feet at 1/60 with flash of a 9 month old. However, I usually have
good results. I also had a few issues going across the room at
1/60 of my father.

It could be user error...but I wanted to ask. Are there any good,
simple, tests to be done?

Thanks
--
-------------
Newbie as of Dec 1, 2006
XTi
Tamron f/2.8 17-50

Click to expand...

imqqmi said:

http://www.focustestchart.com/chart.html

Click to expand...

Problem with this method is the 45 deg requirement.

imqqmi said:

Or put 5 books on a table straight up so that each overlaps the
other, spaced 5-15 cm (2-6 inches), depending on the min. aperture.
Then focus on the middle book in good light (no flash) like 500W
halogen bulb or daylight.

Click to expand...

Much better. The books can also be replaced with 5 identical 9 V batteries.

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See the colors of my world in:
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to hear about front focusing with the Tamron 17-50 f/2.8 lens, especially when it's on a body like the Canon XTi which has very precise focusing with the center cross sensor for f/2.8 lens (1/3rd DOF).

I had MAJOR focusing problems with the Tamron 28-78 f/2.8 lens. Looks like I need to stay with Canon lenses.

-------------------------------------------
See the colors of my world in:
thw.smugmug.com

Could it be that the 9 month old moved outside of the DOF of your 2.8 fstop?
--
Charter member of Atlanta CSLR Challengers Society
~ Be the kind of person your dog thinks you are. ~

http://www.359degrees.org

I am not saying that there are front focusing issues...I was wondering if this has been a problem with others.

I am in no way ready to say anything negative about the lens..

--
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Newbie as of Dec 1, 2006
XTi
Tamron f/2.8 17-50

It very well could have been...or the child moved...or I moved the camera...or we both moved...

I would say misfocus could be the issue...more likely...

--
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Newbie as of Dec 1, 2006
XTi
Tamron f/2.8 17-50

Tripod and mirror lock up, then test.

Over the holiday I used mine in very low light with mixed focus success. I am certain that I could never have gotten a focus with my EF-S 60 macro. The Tamron hesitated a few times whennin shadows, but overall it appeared to lock on target most of the time. I shot using f/2.8 - f/4, zooming mostly from 24mm - 50mm, but with a few at 17mm. Lighting came from a flash mounted in an umbrella. Many of the shots are in focus, but more than I would expect are slightly out of focus. Those that are not spot on focus are mostly front focused. At this point I am reluctant to blame the lens as I was shooting a moving target and f/2.8 gives really shallow DOF. I was actually amazed that the lens could focus at all considering the extremely low ambient lighting. Also, the XT is not known for its focus ability, which is the one serious sore point that makes me want to upgrade (which will not happen any time soon).

I have used the same lens for portraiture and gotten perfect focusing, but of course with much better ambient light and only at 50 mm. More use is needed to come to any real conclusion about the lenses focusing.

--
-Gene L.
http://ttl-biz.com

I am not convinced that creativity can be taught. However, I do believe that it can be coaxed from its hiding place.

It's funny you brought this up. I was taking pics of my 9 month old yesterday (using the Tamron 17-50 2.8, and I also had a couple of shots where the focus was off. I was shooting at 2.8 in low light. But my son is also pretty active. I took some shots at F4 and those were all spot on. So I think it has do with what the other member mentioned. Leaving the tight DOF area.

As I have looked through my pictures, I notice that at 2.8, unless I have my daughter "holding" still (at months that is an oximoron), especially when I am inside of 30mm, I can have some focus issues.

If I up at 3.5 or higher, I don't notice them as much.

--
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Newbie as of Dec 1, 2006
XTi
Tamron f/2.8 17-50

--
Charter member of Atlanta CSLR Challengers Society
~ Be the kind of person your dog thinks you are. ~

http://www.359degrees.org

Gene L. said:

The Tamron hesitated a few times whennin shadows,
but overall it appeared to lock on target most of the time.

Click to expand...

That's not a good sign. The Canon 350D may not have very accurate focus but it's definitely fast with any Canon USM lens. I had the 35 f/2 which faced the same problem. Doesn't sound promising at all.

-------------------------------------------
See the colors of my world in:
thw.smugmug.com

I have used 400 for most all of my indoor shots.

--
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Newbie as of Dec 1, 2006
XTi
Tamron f/2.8 17-50

I was up late last night looking through all of the pictures I took of Christmas. At a smaller size (i.e. "fit to window") the sharpness looks pretty good, but when you look at them 1:1, many many times the focus was not so great.

I looked a the DOFMaster site and using my normal 30-50mm settings, even at f/4 from around 6-8 feet, the DOF is not very large, something in the 1 foot range and if you are using f/2.8, it is closer to 4"...

That said, I don't feel like I got a good lock on some of the pictures, even though ZoomBrowser shows the lock point right on my daughter's nose.

One other thought I had is, when using the flash indoors, does it really matter if I have it at 1/60 or 1/100 or faster? I wonder if the focus would be much different at a higher shutter speed over 1/60.

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Newbie as of Dec 1, 2006
XTi
Tamron f/2.8 17-50

MinnesotaHawkeye said:

I was up late last night looking through all of the pictures I took
of Christmas. At a smaller size (i.e. "fit to window") the
sharpness looks pretty good, but when you look at them 1:1, many
many times the focus was not so great.

I looked a the DOFMaster site and using my normal 30-50mm settings,
even at f/4 from around 6-8 feet, the DOF is not very large,
something in the 1 foot range and if you are using f/2.8, it is
closer to 4"...

That said, I don't feel like I got a good lock on some of the
pictures, even though ZoomBrowser shows the lock point right on my
daughter's nose.

Click to expand...

Maybe that's one of the problems with shallow dofs like that, focusing on the nose is still about 1" (2.5 cm) from the eyes. Rather focus on the eyes and recompose (slightly).

MinnesotaHawkeye said:

One other thought I had is, when using the flash indoors, does it
really matter if I have it at 1/60 or 1/100 or faster? I wonder if
the focus would be much different at a higher shutter speed over
1/60.

Click to expand...

If the flash overpowers the ambient light, shutterspeed does not really matter. But there won't be much of a difference at 1/60 or 1/200 if none of the 'natural' light comes through.

thw said:

thw said:

The Tamron hesitated a few times whennin shadows,
but overall it appeared to lock on target most of the time.

Click to expand...

That's not a good sign. The Canon 350D may not have very accurate
focus but it's definitely fast with any Canon USM lens. I had the
35 f/2 which faced the same problem. Doesn't sound promising at all.

-------------------------------------------
See the colors of my world in:
thw.smugmug.com
-------------------------------------------

Click to expand...

The Tamron focus is not quite as fast as my 85 f/1.8 or EF-S 60 macro, but it isn't far behind either. If I had been using my EF-S 60 macro, then it would have been a longish wait while the thing went from min to max focal length and it certainly would not achieve any focus lock (the 60 macro really needs a focus limiter). The room lighting was very dim, just one small light bulb for a good-sized room and lots of shadows. I am quite amazed that the lens could focus at all.

When focusing in very low light, the Tamron tends to take a big step quickly and then a few small steps a bit slower. Since I was hand holding the camera, it is probable that it almost achieved focus and then had to move some more to compensate for my unsteady hand, hence the hesitation while it decided that the focus point had moved. I have no idea how much this is affected by the lens -Vs- the camera, but focusing is definitely different between my different lenses, and the EF-S 60 macro with its USM is definitely my worst lens in low light.

--
-Gene L.
http://ttl-biz.com

I am not convinced that creativity can be taught. However, I do believe that it can be coaxed from its hiding place.

I have the f3.5 in the same lens. Purchased roughly two years ago. When researching I came across many articles discussing the fact that these lenses tended to focus short, in other words, in front of the subject. I knew that it would not be as fast as a Canon lens, but reportedly this was a problem observed with some sample of the lenses and was persistent. It was noted that if this problem did not crop up early on, then likely the lens was fine.

Mine happens to not have this problem. But I thought I would mention my research anyway.

Gene L. said:

hand, hence the hesitation while it decided that the focus point
had moved. I have no idea how much this is affected by the lens
-Vs- the camera, but focusing is definitely different between my
different lenses, and the EF-S 60 macro with its USM is definitely
my worst lens in low light.

Click to expand...

Well, the EFS 60 is a Macro lens and all Macro lenses hunt in low light.

-------------------------------------------
See the colors of my world in:
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