Create Photography Retreat
I am so excited to be presenting at the Create Photography Retreat again in 2020. It is being held in beautiful Greenville South Carolina October 15-17 when all of the fall colors will be breathtaking. Come join me and others from the Master Photography Podcast network in interactive, hands-on sessions and make some serious progress towards mastering your photography. Check out the Retreat using this link and when you buy youget 10% the cost of your ticket. I would love to see you there!
Autofocus Is A Best Effort Game
There are a lot of listeners who have let me know that they would like less time spent talking about things I have already covered in previous episodes and just get to the new content. I do have quite a few episodes very closely related to this topic that I will call out through this episode and will do my best to limit covering the same topic. Here it goes.
Autofocus is a “best effort” game. Your camera is going to do the very best it can to work with the lens attached to it to find focus. It is not exact. You are asking a chip to make a decision on when things are in focus and there is no chip that is going to get that right 100% of the time. It is going to give it the best effort it can and there are massive amounts of expensive R&D being done by camera and lens manufacturers to improve the performance of autofocus. Sony has made insane steps forward with their Eye autofocus technology built into their mirrorless cameras that has the others playing catchup, but it still a best effort game and will not get it right 100% of the time.
There are things you can do as a photographer to increase the chance that the chip is going to nail autofocus. I am going to offer some suggestions on what you can do to make that happen in this episode. Just remember, it is still chance and not 100%. You can do everything right, follow every technique I am going to talk about, have the very latest technology, and you will still have photos where autofocus failed.
Giving Autofocus the Best Possible Chance
Having told you that autofocus is not perfect and isn’t likely to ever be perfect, I also want to tell you that most misses on focus are not because autofocus didn’t do it’s job. I want to give you a checklist of sorts to go through so that you can give that autofocus system on your camera the very best possible chance to get the focus right. The first few are a you thing, doesn’t cost you anything but your time but are really important to providing the best possible environment for that autofocus to work well. Then there are some equipment things we have to talk about as well.
Focus Miss – Shutter Speed
I have seen it in my own photos and in the photos I have critiqued on a very consistent basis where they are soft and lack sharpness because the shutter speed wasn’t fast enough. It is pretty obvious when the shutter speed is way too slow, we all know what that looks like where there the subject is sort of streaking across the scene and leaving a trail behind them. Sometimes it is done on purpose and used in a creative way like getting car lights to streak across a night scene.
It isn’t as obvious when the shutter speed is almost fast enough but just not quite fast enough. It makes the photo look like the focus was a little off. This usually happens when there is a lack of light. Those times in the day where you don’t have harsh light like during the golden hours and blue hours of the day. Or maybe shooting sports indoors where to your eyes it may look like there is enough light but the reality is that there isn’t enough light in the room and your are in a serious battle to get that shutter as slow as you possibly can.
I am going to give you a general rule here as a quick way to check yourself as you are shooting to make sure your shutter speed is high enough. I am going to try and make it memorable by calling it the 2×4 rule. Hopefully you can remember this by thinking of the 2×4 pieces of wood used so commonly when building things. For subjects that are not moving you shouldn’t use a shutter speed any slower than 2x your focal length. For subjects that are moving you shouldn’t use a shutter speed any slower than 4x your focal length. 2x and 4x. 2×4.
For example, let’s say you are shooting at 50mm. Nothing magical about 50mm, just a very common focal length and it makes the math easier. If the subject of your photo is not moving, you multiple 50×2 and you shouldn’t shoot any slower than 1/100 for a shutter speed. If your subject is moving, you shouldn’t go any slower than 50×4 or 1/200 for shutter speed. Doesn’t guarantee the shutter speed will be fast enough, and there can be other things that may mean you can actually go slower than these numbers and come out with tack sharp photos. I suggest this 2×4 method as a general rule for you to think about as you are in the field and your are making that decision of being able to slow down the shutter because you don’t have enough light.
Focus Miss – Aperture Too Low or Too High
The aperture can also mean your photos don’t end up with the tack sharp focus you are looking for. In some cases you can go too open on the aperture (too low on the number), and you need to be careful about this if you have a “fast” lens, but most photographers don’t think about being too stopped down (too high a number) being an issue and that is very possible.
Let’s start on the too open side of things. With full frame cameras and lenses capable of apertures of 1.8, 1.4, or 1.2 it is not very hard to make the depth of field so narrow that you can get one eye in focus and not the other. Or the camera may focus on an eyelash instead of the pupil of the eye and it means neither eye ends up in focus. We are very forgiving of focus problems in a photo as long as the eye is in sharp focus. To avoid this problem you really need to understand the equipment you are using and how your aperture setting combined with the distance from your subject affects the depth of field.
I love the PhotoPills app as a really good tool you can have on your phone to help you understand the depth of field. It is a great way to make sure you are using an aperture that is appropriate for your shooting situation to get everybody in focus. For more information check out the Hyperfocal Distance Explained! Episode.
Now for the too stopped down side of things. As you stop down the aperture you expand that depth of field so that more of the photo will be in acceptably sharp focus. However, as you start getting into f/16, f/18, f/22, or higher numbers on your aperture you also have a battle against a horrible thing called diffraction that can make your photos start to look soft again. Diffraction negatively impacts the overall quality of your photos and you really want to avoid that. This may not be an issue most portrait photographers face since they all want to shoot as wide open as they can, but landscape photographers need to be aware of this. It would be better to do focus stacking to get that landscape in sharp focus than to shoot at those really high f-stop numbers.
Focus Miss – High ISO
Yep, the entire exposure triangle can be a problem that makes your images look soft. Dialing up a really high ISO will do that too. You may have been told or even observed that when you shoot at high ISO values there is a lot of noise/grain added to your photos. Most photographers tell you that it is setting the camera at a high ISO that does this, but the reality is that the lack of sufficient light for the photo is really what is doing this. That isn’t what this episode is about so I’ll leave that argument alone for now.
The thing to really take away from this as far as how ISO may impact the focus of your photos is that as the ISO goes up the dynamic range of your sensor goes down. You don’t have to understand what dynamic range is, but the end result is that high ISO makes it harder for the sensor of the camera to depict the edges in the photo, and edges are what make up sharpness.
Not every camera is the same here. Some have the sharpness of the photo pretty significantly impacted by ISO at 1600. Others can go all the way to 6400 or ever higher without it becoming a significant issue. This is where some testing can be done so that you can figure out where you see an impact to the sharpness of your photo when the ISO is higher. Setup a test in a relatively dark room, anything indoors would work, and take photos with the same shutter speed and aperture and just go from ISO 100 to 800 to 1600 to 3200 and then increase the exposure on your computer and see where it is the image is no longer as sharp as you would like.
Focus Miss – Poor Focus Technique
Another very common reason for focus not being tack sharp where you want it is the lack of proper focus technique. Learning how to use the right focus mode, the right focus point, and even how to do a good job of pressing the shutter button is difficult.
For example, learning the difference between the phase detect autofocus points used by the camera in the viewfinder vs the contrast detect focus used in Live view on a DSLR can be overwhelming. For some of you listening, that last sentence sounded like a foreign language to you. If you didn’t fully understand that sentence, then you have to check out two other Photo Taco episodes. One I published back in March of 2015 is called Contrast vs. Phase Detect Autofocus Modes. Another published back in February 2016 is called Focus Points. Both of those episodes should help you with that sentence but you really need to spend some time reading in the manual and experimenting with those focus modes and focus points so that you know exactly how to setup your camera to give you the best chance to nail tack sharp focus in different shooting situations.
Incidentally, I say this a lot on this show and on the Master Photography podcast, but investing the time it takes to truly learn how to use the focus system on your camera is going to do more for improving the quality of your images than buying a new camera. If you don’t know what every focus mode is and when and how to change the focus points in the camera you have, don’t buy a new camera until you have learned that.
Before leaving this idea that focus technique may be the reason your photo lacks sharpness, the other thing to make sure you develop technique for is holding your camera and pressing the shutter button. The shake you have when using the camera can often be the reason a photo lacks sharpness. Think about how it is you are holding the camera and pressing the shutter button and try some things to see if you can improve your ability to hold the camera as steady as possible.
This is tough to to in audio, but let me try to describe how I hold the camera. With my right hand I have my index finger push the shutter button and my thumb is in position to press the buttons on the back of the camera. Neither is really able to do a lot to to keep the camera steady because they are operating the camera. But I use the remaining three fingers to really warp around the camera and squeeze the camera body against the palm of my hand. As I am shooting I put my left hand under the lens, kind of cupping the under part of the lens with my hand. I may take that hand from under the lens to change a ring on the lens to zoom it, but before I press the shutter button I put that left hand under the lens with my thumb pointing to the left of my body so that I can have my elbow add support by making contact with my lower body and make kind of a pseudo tripod.
Spend some time working on how you press the shutter button too. It is often called “mashing” the shutter button because there are some who really press that button with so much vigor they really can’t help but make the camera shake. You obviously have to make sure you push it, but the better control you can have to only use the force it takes to press that button and not much more is also a valuable skill to develop. It takes practice.
Focus Miss – Lens Quality
Now we are getting into the equipment side of things. You can have the shutter speed high enough and use great focus settings and technique, and still end up with images that lack the sharpness you see other photographers get because you are using a lens that simply isn’t capable of that sharpness.
I think photographers fall into the trap of jumping to their equipment being the thing holding back the quality of the images too quickly. The “you” stuff I have already gone over is far more likely to be the thing making your photos not have the sharpness they should have rather than it being the lens or the camera you are using. So make sure you spend the time on the “you” stuff first and be sure that isn’t causing the focus issues. Once you are really confident you are there, try renting a higher quality lens and see if that truly makes a difference.
There is a reason those lenses that you got with your camera are inexpensive and were sort of thrown in a kit with your camera. They aren’t high quality lenses and the optics are not as good as lenses that are more expensive. However, I am also a firm believer here that you don’t have to buy the most expensive lens available for your camera to have high quality optics that give you a better chance at tack sharp focus. Third party lenses from manufacturers like Tamron and Sigma make excellent lenses that rival, and some argue surpass, the optical quality of those from Canon, Sony, or Nikon.
Focus Miss – Insufficient Light
If you have listened to Photo Taco or Master Photography Podcast much you know that I am a huge proponent of adding flash to your photography. Photography is the art of capturing light and when there isn’t enough of it the quality of the photos really suffers. Adding artificial light through flash helps improve image quality but it doesn’t help with focus.
Camera manufacturers are always working on this, trying to make it so that cameras can do a better job of focusing in the dark. After all, the bride went to great lengths to get that romantic mood at her reception, she doesn’t want you disrupting that mood by requiring more light.
I bring up the wedding reception example here because it is a perfect way to think about focus in the dark. You may have flashes set up throughout the room so that no matter where you are taking photos the room will temporarily have enough light for you to create incredible images, but that flash only helps when you press the shutter button. Focus happens before that and if it is too dark it is more likely that autofocus will miss completely or be very slow.
This is where autofocus assist options that some flashes have can help for sure, but in the example of the wedding reception you may have to just test to see if there is enough ambient light for the autofocus to work and if there isn’t talk the bride into adding a little bit more constant light.
Focus Miss – Autofocus Out of Tune
If you have the shutter speed high enough, the focus mode and points set appropriate to your shooting situation, excellent technique for holding the camera and pressing the shutter, and high quality lenses and you STILL get images that lack tack sharp focus. You may need to tune the autofocus to the specific lens you are using.
This only applies to DSLR cameras. This is not an issue with mirrorless cameras. I have covered this topic, and a few related topics, in previous episodes. I have an episode called AFMA Explained that I published over two years ago back in April of 2017 where I went over this in more detail. I also have an episode called AFMA Revisited where I refine some things based on what I learned doing the process for a few months.
If you have listened to photography podcasts, watched YouTube videos about photography, or just talk to photographers much, you something like “this lens is so sharp!” It’s true, the quality of the optics in a lens has an impact on the sharpness of your images. It’s also true on a DSLR that you may be able to increase the sharpness of your photos by calibrating the autofocus system with the specific copy of the lens you have.
If you haven’t heard that term before, the copy of the lens you have, it has to do with the amount of variance lens manufacturers allow to be in the optics of the lenses as they make them. The cost it would require for the lenses to be manufactured to have identical optics would be so large none of us could afford it. As a result they have to allow a certain amount of variance in the optics as they build them. The lens you have be EXACTLY the same as the one a friend of yours may have that is the same make and model. If they are high quality lenses they will be closer there than those kit lenses are, but there will be some variance there.
If you calibrate the copy of the lens you have to your camera you can improve the sharpness of your images and this could be the final piece to the puzzle that gives your autofocus the very best chance to do its job. This also means you really have to calibrate your focus with every lens you have.
There are several methods for tuning the autofocus to your lens The method I prefer is called DotTune. You can check out some forum posts created back in 2013 when it looks like this method was first thought of. You can also check out this YouTube video to see how the DotTune process works. I like DotTune the best because it takes very little time and it doesn’t require me to decide between a couple of photos which is the most sharp. Once you learn how to do DotTune it can take as little as 5 minutes to find a good AFMA setting for the copy of the lens you have with your camera.
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