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Posts: 1
Registered: ‎01-09-2020

Sigma/80D Focus Problem?? (Long)

New to forum, first post:

 

I have been shooting with my 80D for a couple of years but lately I have been submitting to Shutterstock.  You're probably aware of their requirments for technical excellence and it sort of smarts to get photos rejected.  On the postive side it forces you to become a better photographer or at least better technician. 

 

Lately I have been getting photos rejected for "Main subject not in focus" reasons.  I try hard to hold sharp focus with proper settings and camera technique but I still get rejections from time to time.  I don't always agree with them but lately I've become concerned that maybe my photos are really not as sharp as they could be.  It's become an obsession as now I'm pixel peeping to the extreme.  I recently purchased a Sigma 18-35 f1.8 Art series lens with the intent of getting photos just a tad sharper than my Canon collection.  I'm aware of this lens' reputation for missing focus sometimes but it still is considered a sharp performer.  Still, I'm not completely satisfied that I'm getting tack sharp photos from the Sigma hooked to my 80D.

 

Attached is a test photo I took today.  It shows green moss growing on the fascia of an old barn.  I took the photo handheld at 1/100, f3.5, ISO 100, zoomed to 35mm.  I was just few feet from the moss and used single spot AF, Live View, and a 2 sec. timer shutter release.  I used the taught camera strap technique to stablize the camera since there is no IS in the Sigma.

 

I was expecting the moss zoomed in at 1:1 to be super tack sharp with individual strands well defined but it looks more dithered and smudged than I would like.  The photo was taken RAW then processed and sharpened in DPP.  The red square is the approximate single shot AF square indicated in DPP.

 

Please give me your opinion regarding sharpness.  I think I could have increased the shutter speed a little by boosting the ISO but 1/100 should be sufficient to dampen camera shake at 35 mm for an APS-C setup.  Also f3.5 should have enough DOF.  I have not calibrated the Sigma on the dock it came with but since I was shooting Live View it should not be an issue.

 

Zoomed in at 1:1 do you feel this is the sharpest performance I can expect from this lens/camera combination?  Do you think I can improve on the settings to get a sharper photo?

 

Apologies for the long post.  Thanks for your help.

 

 

Sigma Art 18-35 Focus Test.JPG

VIP
Posts: 8,870
Registered: ‎08-13-2015

Re: Sigma/80D Focus Problem?? (Long)

Where is your point of focus in this shot?  Depending upon where you focused and aperture setting, this photo may be normal.

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"I don't rent software. I use Photoshop CS6, ACR 9.8 and Lightroom 6.8 ."
Respected Contributor
Posts: 1,427
Registered: ‎11-19-2017

Re: Sigma/80D Focus Problem?? (Long)

[ Edited ]

Greetings,

While we do see considerable detail in the shot, AF point "the moss", it's clear that at f3.5 DOF drops off quickly in the background.  Bright overcast can be tricky.  No shadows, but can also give photos a washed out appearance.  

 

Your shutter speed was fine, I would have taken more than one shot for comparison and you could have bumped the aperture up safely without a hit in graininess or noise.

 

I have a few Sigma lenses and the dock.  I was lucky and neither needed front or back focus adjustment.  I think you need to take some additional shot before concluding there is an "adjustment needed" issue with the lens.    

 

Overcast sky, my trip to Russia was in late fall.  80% of my pictures have a drab overcast background.  It was raining in this one, so I got some clouds at least.  Nice contrast with the building facade, but blah sky.  Take some more photos for comparison. 

 

Red Square.jpg  

~Rick
Bay Area - CA
~6D2 ~Many Lenses ~DxO PhotoLab Elite ~Windows10 Pro ~EVGA RTX 2080 FTW3 Ultra ~Pixima Pro-100
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VIP
Posts: 11,902
Registered: ‎12-07-2012

Re: Sigma/80D Focus Problem?? (Long)

"Please give me your opinion regarding sharpness."

 

The Siggy is a great lens.  It is super sharp but I too have seen reports of it missing focus at times.  That is probably what yours did.  I don't see any thing grossly wrong with your settings maybe not exactly what I would have chose but OK.

 

I will tell you from decades of product photo experience for a large company, you never take one shot of something that is important.  I have seen photographers take 500+ shots of a red rose and a team of people examining each for the best one.  Now I am not suggesting you take 500+ shots but 10 or so would be reasonable. There are just too many variables.  Maybe the wind blew or changed direction or whatever.

Next, you should always bracket your shots.  Change your settings for additional shots. Now do I still do this? Every time?   For high important shots I do for snapshots I don't.

 

If you are concerned if you have a quality copy of the Siggy, you need to use a good tripod and a fixed unmovable subject.  Run through all apertures and again several shots of each not just one.

 

While on the subject, turn down the contrast and brightness on your computer monitor.  Most folks have both set way too high.

You are shooting Raw format and using Photoshop? Raw is not effected by sharpness settings in the camera. You do that in post among all the others. The camera is there to just capture the data, not any adjustments.

EOS 1DX and 1D Mk IV and several lenses!
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