Focus issues with sigma lens

Stache · 10-31-2019, 09:23 AM

I have a sigma 70-200mm f2.8 EX APO and when I use the focus adjustment system I got lots of front focus. I adjusted it down as far as It will go on the fine adjustments but it seams to still front focus. I thought I was fallowing the instructions pretty well. I had the aperture set to 2.8 the zoom to 200. I'm pretty sure I was about 1.8m away from the card when focusing. Will the distance mater that much or is it common to have this problem? Thank you.
Stache

Vasyl · 10-31-2019, 09:54 AM

Originally posted by Stache

I have a sigma 70-200mm f2.8 EX APO and when I use the focus adjustment system I got lots of front focus. I adjusted it down as far as It will go on the fine adjustments but it seams to still front focus. I thought I was fallowing the instructions pretty well. I had the aperture set to 2.8 the zoom to 200. I'm pretty sure I was about 1.8m away from the card when focusing. Will the distance mater that much or is it common to have this problem? Thank you.
Stache

Not sure if I understood your question. Yes, the distance matters. I tend to believe you are familiar with DOF as a term. This parameter is very narrow for large apertures (1.4, 2, 2.8), so if you missed with the distance, you are in trouble. You have to be exact and precise with the distance (that is what rulers are for).

Stache · 10-31-2019, 09:58 AM

Originally posted by Vasyl

Not sure if I understood your question. Yes, the distance matters. I tend to believe you are familiar with DOF as a term. This parameter is very narrow for large apertures (1.4, 2, 2.8), so if you missed with the distance, you are in trouble. You have to be exact and precise with the distance (that is what rulers are for).

I'll have to double check my distance. Thought I was right on. I'll see what happens. Thanks

**Kobie** · 10-31-2019, 05:55 PM - **1 Like**

This may help
How to optimize focusing accuracy with large-aperture lenses / Beautiful Photo-life | RICOH IMAGING

10-31-2019, 09:23 AM	#1
Stache New Member Join Date: Oct 2019 Photos: Albums Posts: 18	Focus issues with sigma lens I have a sigma 70-200mm f2.8 EX APO and when I use the focus adjustment system I got lots of front focus. I adjusted it down as far as It will go on the fine adjustments but it seams to still front focus. I thought I was fallowing the instructions pretty well. I had the aperture set to 2.8 the zoom to 200. I'm pretty sure I was about 1.8m away from the card when focusing. Will the distance mater that much or is it common to have this problem? Thank you. Stache

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
sigma 35mm 1.4 focus issues	hadi	Pentax SLR Lens Discussion	16	07-23-2018 03:21 PM
Pentax KS2 kit lens (18-50) focus and shooting issues towards 50mm	PhiH	Troubleshooting and Beginner Help	4	05-13-2018 10:16 AM
Manual focus lenses with infinity focus issues - anyone else encountering them?	kiwi_jono	Pentax SLR Lens Discussion	8	10-18-2017 01:19 PM
Focus, Focus, Focus (or the usefulness of focus charts)	GoremanX	Pentax DSLR Discussion	31	12-21-2014 11:49 AM
Sigma 70-200 focus issues, worth sending to Sigma?	nobbsie	Pentax SLR Lens Discussion	4	11-17-2008 03:06 PM

10-31-2019, 09:54 AM	#2
Vasyl Veteran Member Join Date: Aug 2010 Photos: Gallery Posts: 648	Originally posted by Stache I have a sigma 70-200mm f2.8 EX APO and when I use the focus adjustment system I got lots of front focus. I adjusted it down as far as It will go on the fine adjustments but it seams to still front focus. I thought I was fallowing the instructions pretty well. I had the aperture set to 2.8 the zoom to 200. I'm pretty sure I was about 1.8m away from the card when focusing. Will the distance mater that much or is it common to have this problem? Thank you. Stache Not sure if I understood your question. Yes, the distance matters. I tend to believe you are familiar with DOF as a term. This parameter is very narrow for large apertures (1.4, 2, 2.8), so if you missed with the distance, you are in trouble. You have to be exact and precise with the distance (that is what rulers are for).

10-31-2019, 09:58 AM	#3
Stache New Member Join Date: Oct 2019 Photos: Albums Posts: 18 Original Poster	Originally posted by Vasyl Not sure if I understood your question. Yes, the distance matters. I tend to believe you are familiar with DOF as a term. This parameter is very narrow for large apertures (1.4, 2, 2.8), so if you missed with the distance, you are in trouble. You have to be exact and precise with the distance (that is what rulers are for). I'll have to double check my distance. Thought I was right on. I'll see what happens. Thanks

10-31-2019, 05:55 PM - 1 Like	#4
Kobie Site Supporter Join Date: Oct 2014 Location: Bowmanville Photos: Albums Posts: 1,211	This may help How to optimize focusing accuracy with large-aperture lenses / Beautiful Photo-life \| RICOH IMAGING