is my lens front focusing?

[lewys]

i got the sigma 70-200 a few weeks ago but took it back as it was front focusing by 20 something mm. i have just got a new one and i think it has the same problem but not as bad.

i only noticed on this lens when i took a pic and focused on the eye (see link). it just looked really soft/blurry


i managed to take a few before it got dark today so here they are.
here


in the paper pic i focused on the word ' suspects'
in the pebble shot i focused on the twig in with the pebbles
in the two flower shots in the first one i focused on the stem leaf behind the flower and in the second i focused on the actual flower
on the light shot i focused on the top of the light





it seems like this lens is also front focusing like the last sigma 70-200 i took back for it.
i bought a tamron 28-75 a few weeks ago and took that back due to front focusing and when i tried a sigma 20something-70 in the store it didnt seem to sharp around the eyes when i took a portrait of my girlfriend so i didnt bother buying it.

my nikon 50 1.8 and my tamron 90mm dont seem to be front focusing (if they are it is by hardly anything and i cant really notice it) and i really cant tell if my tamron 10-24mm is as its hard for me to see on a wide angle

could it be that there is a problem with my d90? i dont have another body to try so i cant really test.

if it is my body would it be wise to trade in my d90 for a second hand d300 body or is the d90 better? i dont use the video function on the d90 much

 

[KmH]

Wow! You have really crummy luck with consumer electronics, because it looks like you need to get your keyboard shift key fixed too. :lmao:

 

[lewys]

no need to be an ass. just looking to get my question answered.

 

[KmH]

No need to be that lazy, or convey such a low level of respect for others either, by taking short cuts that reduce the readability and credibility of your written communications. Just pointing out the obvious.

 

[lewys]

did you have an answer to my question?

 

[Derrel]

I think the smaller, more-detailed images show that the focus is pretty close to acceptable. Seriously, 20mm is within the tolerances of modern manufacturing I think, and honestly, that error could be your fault. The AF brackets on a camera--how wide an area do you think they ACTUALLY cover? I mean, literally, how many millimeters across and up and down do you suppose the central AF bracket of your camera spans with the lens set to 70,85,100,135,150,180,and 200mm at say, 10 feet. You are not aiming a LASER at a target; instead you are aiming a camera and lens combination, with an AF system that has to span "some amount of physical space" in order to come up with a focusing target. The brackets themselves are also typically ***not*** exactly indicative of the AF system's actual, real-world, focal-length based viewpoint. The AF brackets in the viewfinder and guidelines, but some parallax between the brackets and the AF system's targeting zone is perfectly normal. Again--it's not a laser...the AF area is "an area".

I think some reading at Thom Hogan's web site will turn up some articles on autofocus systems and autofocusing methods that will give you a more realistic appreciation of what your camera is doing.

d

 

[Garbz]

How about getting your camera checked. It sounds like it is front focusing.

And It's not being an arse, it's just good advice. You simply seem childish when you can't use basic grammar. This may work on WoW forums but you're on a forum here full of middle aged professionals, many of whom don't respond well to people who can't even type their question properly. Expect to be called out if you type like a 15 year old on a mobile phone, also expect to get more constructive responses if you act like an adult.

 

[Bitter Jeweler]

ifyouwanttobetakenseriously

 

[table1349]

abcdefghijklmnopqrstuvwxyz is not a word, just a Sesame Street song.

It is however a good place to start with the English language. From there capitalization, spelling and punctuation will all follow allowing for effective communication with the written language.

If you would like to confirm your suspicions might I suggest that you use this test. Nikon D70 Focus Chart It is far more accurate than the swag method.

 

[OrionsByte]

Are you performing those tests using a tripod? 20mm could just be variations from hand-holding the camera.

 

[mc_hudd]

And It's not being an arse, it's just good advice. You simply seem childish when you can't use basic grammar. This may work on WoW forums but you're on a forum here full of middle aged professionals, many of whom don't respond well to people who can't even type their question properly. Expect to be called out if you type like a 15 year old on a mobile phone, also expect to get more constructive responses if you act like an adult.

I kind of agree with you, however, it seems that KmH has a problem just keeping their mouth shut. Did their post really help the OP? Why did they even waste their time typing out their reply?! Seriously! "...middle aged professionals..." Do you really think KmH's comment was "professional"? Seemed a little immature to me.

Just my 2 cents!

 

[Kerbouchard]

Sigma is notorious for quality control issues. The only way, IMO, you should buy a 70-200 2.8 from Sigma would be to go to an actual store and sit there and try them until you find one that focuses well with your body.

In any case, since you didn't do that, the easiest way to check to see if you are actually front focusing is to put your camera on a tripod, use a remote, and take one shot using the regular focus and taking another shot in live view. They autofocus differently. If the contrast detect from the Live View gives acceptable results but regular autofocus does not, then yes, you have an issue.

 

[Bitter Jeweler]

I kind of agree with you, however, it seems that KmH has a problem just keeping their mouth shut. Did their post really help the OP? Why did they even waste their time typing out their reply?! Seriously! "...middle aged professionals..." Do you really think KmH's comment was "professional"? Seemed a little immature to me.

Just my 2 cents!

We all have a problem keeping our mouths shut, it seems.

Oh well.

:meh:

 

[mc_hudd]

I kind of agree with you, however, it seems that KmH has a problem just keeping their mouth shut. Did their post really help the OP? Why did they even waste their time typing out their reply?! Seriously! "...middle aged professionals..." Do you really think KmH's comment was "professional"? Seemed a little immature to me.

Just my 2 cents!

We all have a problem keeping our mouths shut, it seems.

Oh well.

:meh:

Apparently.