Focus Issue D7100 with Sigma 50mm Art Lens

New user here with a question:

I've had some luck shooting full body shots with my d7100 and sigma 50mm Art lens on a single individual but running into trouble with a second person tucked under shoulder of first. In short, my issue is keeping both in focus. Here are my settings:

M Mode
AF-S
Wide setting 51 point ( have tried all)
Aperture 1.4
ISO 100
Shutter varies

I assumed my aperture at 1.4 was the problem but after changing to 5.6 I see no difference in the focus of second person. Here are two images

I should also note: My focus point was on clothing in both shots.

Thanks in advance for assistance!

In looking at your shots nothing looks to me to be in sharp focus in either of them. Based on the fact I have a D7100 and a Sigma 50mm f/1.4 DG of my own I have a few questions: 1. Are you shooting JPG or RAW? If you're shooting JPG have you adjusted the Sharpness setting in the Picture Control menu? If you're shooting RAW have you done any post processing on those shots? I'm also wondering if you've tested that lens for front/back focus because I'd be willing to bet you dollars to donuts, that's the over-riding issue here. I have two Sigma Art series lenses and both of them needed Auto-focus fine tuning before they were shooting at their full potential. That camera/lens combo should be putting out shots that are superbly crisp; and those shots in your post aren't even close to what I would expect from that combination.
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Take the lens off and check to make sure the aperture moves easily and is not stuck, it would stay at 1.4 all the time no matter what you camera says if it is. I had that problem with my Sigma 50mm (non-art)

Thanks Paul,

I'm shooting both jpeg and raw. I uploaded the jpeg. Both camera and lens are new. I have not calibrated (nor know how) the lens at all.

rscoleman said:

Thanks Paul,

I'm shooting both jpeg and raw. I uploaded the jpeg. Both camera and lens are new. I have not calibrated (nor know how) the lens at all.

Click to expand...

I suggest you go into the Picture Control menu and adjust the Sharpness setting first; this will help sharpen your JPG's but it won't help with front/back focus (more on that in a second):
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To check for front/back focus you're going to need a tripod, a target and some good lighting. Follow these instructions: How to Use the AF-Fine Tune Function. That article will explain how to setup the test and determine if you have a front/back focus issue or not. Another free method is the Dot Tune Method (link goes to Youtube vid) or you can drop dime on software such as Reikan FoCal which will semi-automate the process. Your Sigma 50mm f/1.4 will also accept the Sigma USB dock.

In short, though, testing and calibrating your lenses simply HAS to be done, in my opinion. Based on your previous post, I think your Sigma should be giving you way better overall IQ than what you are apparently getting at this point.
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