Join for FREE
It only takes a minute!
Magnifying the passion for nature. Zeiss Victory Harpia 95. New!

Welcome to BirdForum.
BirdForum is the net's largest birding community, dedicated to wild birds and birding, and is absolutely FREE! You are most welcome to register for an account, which allows you to take part in lively discussions in the forum, post your pictures in the gallery and more.

Reply
 
Thread Tools Rate Thread
Old Friday 1st July 2016, 17:36   #1
Rapala
Registered User
 
Rapala's Avatar

 
Join Date: Jun 2013
Location: Michigan
Posts: 904
Sigma 100-300 f/4 Front Focus

It seems that my copy of a Sigma 100-300 f/4 has some serious focusing issues. After suspecting the lens was front focusing, I printed off a test chart and conducted the test. The test itself was pretty simple, requiring the test chart propped up at about a 45 degree angle and shooting straight at it from a tripod. I aligned the center focus point with the center line on the chart and shot with a 10sec timer to reduce shake. The results I got are much worse than I had expected. The first photo attached shows the chart from about 7ft @ 300mm, 1/2000 f/4 ISO 100. Right about near the number 1 seems to be the perfect focus, showing prominent front focus. The second photo below is from about 12ft away @ 300mm, 1/1600 f/4 ISO 100. This one looks even worse, with focus around the number 2. BTW, both photos have been cropped to the center of each frame.

To show what this equates to in the field, the third photo would have been a nice photo of a young chickadee. The photo is uncropped, so the center focus point was directly on the bird's head. Instead I came away with a detailed photo of the Chickadee's alula and primary feathers. (Okay, maybe I looked up alula ) This is very frustrating since it would have otherwise been a great photo. In this thread I am looking for guidance since I have never had this issue before. I assume that my lens requires micro adjusting to fix this issue, but I am not sure. I also don't know how or where to get it micro adjusted if that is the case. Any help here is much appreciated.
Attached Thumbnails
Click image for larger version

Name:	AFTest7ft.jpg
Views:	58
Size:	226.5 KB
ID:	590442  Click image for larger version

Name:	AFTest12ft.jpg
Views:	55
Size:	212.4 KB
ID:	590443  Click image for larger version

Name:	Chickadee2.jpg
Views:	84
Size:	234.8 KB
ID:	590444  
__________________
A bird doesn't sing because it has an answer, it sings because it has a song. -Maya Angelou
Latest Lifer- Eastern Whip-poor-will
My Gallery
Rapala is offline  
Reply With Quote
Old Friday 1st July 2016, 18:17   #2
Geoff Pain
Rural Member
 
Geoff Pain's Avatar

 
Join Date: Aug 2002
Location: Stackhouse,North Yorkshire
Posts: 2,108
What camera are you using? You can microadjust the lens on some Canon cameras.
__________________
Geoff

http://flickr.com/photos/126691646@N04
Geoff Pain is offline  
Reply With Quote
Old Friday 1st July 2016, 18:25   #3
Rapala
Registered User
 
Rapala's Avatar

 
Join Date: Jun 2013
Location: Michigan
Posts: 904
I am using a Canon T4i. As far as I know, micro adjusting is only available on high-end Canon DSLRs.
__________________
A bird doesn't sing because it has an answer, it sings because it has a song. -Maya Angelou
Latest Lifer- Eastern Whip-poor-will
My Gallery
Rapala is offline  
Reply With Quote
Old Sunday 3rd July 2016, 23:01   #4
Rapala
Registered User
 
Rapala's Avatar

 
Join Date: Jun 2013
Location: Michigan
Posts: 904
Also, how can I tell if it is my lens or camera that needs adjustment? Is it usually one of the two?
__________________
A bird doesn't sing because it has an answer, it sings because it has a song. -Maya Angelou
Latest Lifer- Eastern Whip-poor-will
My Gallery
Rapala is offline  
Reply With Quote
Old Monday 4th July 2016, 14:10   #5
seaspirit
Registered User

 
Join Date: May 2008
Location: Nova Scotia
Posts: 439
Quote:
Originally Posted by Rapala View Post
Also, how can I tell if it is my lens or camera that needs adjustment? Is it usually one of the two?
This is a complex problem as in an ideal world both camera and lens have a certain range that is considered within tolerance. So your lens could be fine on a different body and your body could be fine with another lens, depending on how the tolerances of both combine. This article explains the whole can of worms (and some of the comments show how tricky it can get).
https://www.lensrentals.com/blog/200...d-other-myths/https://www.lensrentals.com/blog/200...d-other-myths/

Only way for you would be to get body and lens tuned to each other by a service station. Not sure if Canon will do this for a non-brand lens or Sigma is able to do this on a Canon body, nor what the costs for this would be. Them the question is how other lenses one owns will behave after the tuning.

One day when we all use mirror-less cameras and AF is done not by a AF-module and straight from the sensor this could be a thing of the past. For now it is just sometimes a major pain "you know where".

Love Sigma (and Tamron) for giving some of their newer lenses AF fine tuning ability in the lens itself. It took me over an hour to set-up my 120-300 for a camera body (values for several different focal length at several different distances had to be determined), but the result could have never been reached with in camera one value/lens AF micro adjustment. Unfortunately your 100-300 f/4 isn't one of those lenses.
seaspirit is offline  
Reply With Quote
Old Friday 8th July 2016, 22:39   #6
Rapala
Registered User
 
Rapala's Avatar

 
Join Date: Jun 2013
Location: Michigan
Posts: 904
Thank you seaspirit.
I will be off to Colorado for the next couple of weeks so I will try to find a camera shop there to calibrate my gear (no such shops exist in the U.P.). Hopefully all goes well.
__________________
A bird doesn't sing because it has an answer, it sings because it has a song. -Maya Angelou
Latest Lifer- Eastern Whip-poor-will
My Gallery
Rapala is offline  
Reply With Quote
Advertisement
Reply


Thread Tools
Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is Off
HTML code is Off

Similar Threads
Thread Thread Starter Forum Replies Last Post
'Dust' Under the front glass - Sigma 17-50 2.8 Creepy Nick Sigma & Other Third Party Lenses 1 Friday 7th August 2015 20:36
Front or Back Focus Ian Hardy Nikon 4 Thursday 11th March 2010 19:07
I can't get it to focus Sigma 105mm 2.8 shooter Macro Photography 3 Friday 15th January 2010 20:06
Sigma 500 f4.5 focus problem with 1.4x paulwinclad Sigma & Other Third Party Lenses 20 Sunday 22nd February 2009 18:23
Sigma 120-300 F2.8 focus issues ? raggetty Nikon 7 Wednesday 18th January 2006 22:46

{googleads}

Fatbirder's Top 1000 Birding Websites

Help support BirdForum

Page generated in 0.14631104 seconds with 18 queries
All times are GMT. The time now is 02:10.