Originally posted by 6BQ5 Lots of people say the C-AF performance in the K-1 is weak. I think I have two specific performance issues I can bring up from my own experience shooting this year's Walk-A-Thon at my kid's elementary school.
1) Lag - slow shutter activation. The K-1 with a D-FA 24-70mm can acquire focus and track subjects decently well. It's the speed of the shutter firing that makes images soft. The kids who ran toward me leaned forward. Their chests were ahead of their feet. In all the images I captured their feet were very sharp but their chests and their faces were soft. Yes, I used SEL9. Yes, I set the focus position point correctly. Yes, I used a very high shutter speed in TAv mode (1/2000). We have to remember that the camera stops focusing when the mirror goes up and the shutter starts to cycle. It's during that time the subject moves forward and is now slightly out of focus. Focus is perfect-perfect for still subjects and even when panning.
Wish : I wish the mirror could go up faster. I wish the shutter could cycle faster.
Yup the K-1 has some Lag but you can change some settings and reduce this.
I started my chronicles with the focusing lag issue with this post:
Forum Pos 74 in K1 Autofocust
I found settings that work pretty well and some other considerations to take and listed them in this post:
Post 111 in K1 Autofocus
At best I could get about 40% accuracy with moving subjects and a tight DOF. The issue wasn't the Lag for me anymore, but the K1's autofocus algorithm. It uses a hunting style with catch-in-focus to fire it when you set it to Focus-Priority. This hunting style can cause some complications. I am sure that with a fast focusing motor in a good lens you might go much higher than my 40%.
Originally posted by 6BQ5 2) SEL9 seems to pick the furthest subject in its selection area. Given two people side by side with one person standing 3 feet back the K-1 seems to focus on the further back person. It's like the camera wants to focus closer to infinity instead of minimum. I thought Nikon had an option in their menus to let the photographer decide the priority. Where is this in Pextax? Am I missing something very fundamental somewhere?
Wish : Give priority to focusing to closer subjects instead of more distant subjects.
The best suggestion I have for this is to use a single focus point. Make sure your camera is set to allow you to select which focus point to use and set it up that way. But if you are going this way, it is a good idea to map out your actual location of your focus spots. Just so that you know where they really are.
In the end here are things that will help with action shots in the Z-axis with the K-1:
1) Increase your DOF a bit more than what you would think. (Sucks, I know!) In my case I used a DOF calculator for a while just to get a feel for how large it really is, since you cannot properly evaluate it on the back screen.
2) Fine tune your lenses. I used the Dot-Tune method
3) Planning - take your time and decide where the shot is going to be and set up for this. (Pre-focus to that area) In sports, this is where knowing the game and where it is going to go, helps a lot!
4) Practice with your lens to find the range where your lens is the most dead on target. Some lenses have a small throw for a large focus range, this can cause some hunting before the lens lands on the spot, using the K-1 algorithm. Lenses have a sweet spot when it comes to this and it is important to know this for the K-1. The K-1 brings these flaws out in shining colors!
There is quite a bit of woo-woo out there, it is going to be up to you to dial in your style with the K-1 when it comes to Z-axis action. It isn't the best action camera available, not even close. Many professional photographers have commented on this when they reviewed the camera. In some cases they skim over this topic and in others they shine a beaming light on it, but it is a common issue listed in most reviews. But with practice: you could get your action accuracy up there; as long as you manage the DOF well, and plan your shots, you should be able to hit 20-40% consistently. If you know your subject well and know where they will be, as well as get that subject when they are at the slowest in their Z-axis travel, you might even get up to 60% accuracy.
Contrasting lines are important for the focus system in the K-1 so lower light situations will have an affect on the accuracy as well. In a forest situation my accuracy fell to 10% with a moving target on a path. My subject didn't have well defined lines in the dim light and it played havoc on the focus system.
If you are planning on doing a lot more Z-Axis action, consider a second camera. 2351HD expressed his experience in this post:
Post 113 in K1 Autofocus
Quote: "You buy a system for what you need it for, so when its great for somebody else if may not be the case for you, but thats fine too." by 2351HD
At the moment I don't do too much Z-axis action. If I suspect there is going to be some, then I bring the Nikon D3000 along (its small) with the K-1 for all the scenic shots. If I do have a greater need for action; I might get a D500, since I have access to existing Nikon glass.
Good Luck!