Just spent some time this weekend playing with my new D7100. Went out with my 150-500 Sigma and did some shooting. I need to get more into the AF of this camera as I mad e a Bird shot and the focus was on the limb slightly behind. Also made some longer shots at F16 and on a monopod . Most came out soft. Had noticed this somewhat on my D90. Any tips for making these adjustments as the manual is a little vague. I thought it might be my eyesight but stability on the monopod and auto focus should have helped. One last Caveat! I am viewing on LR3.6 in Zoom mode. Could I be getting a wrong sense of what is really clear? Waiting for some good setup tips on the net, but figured I'd ask here. As I am not home, my files are not here so I can Post. Any other thoughts?? JIM
#1. "RE: D 7100 Focus help" In response to Reply # 0
I have tried focus charts, lining up batteries, sw such as focal Web,,, and have decided I don't like any of these options. I've found I go into my yard, set aperture wide open, single point center focus. Setup a tripod 45 degrees to a post on a wooden fence. Focus on the post and shoot. Zoom in on the post and see if it is sharpest in front of, behind, or on the post. Adjust af fine tune until focus is best on the post.
#3. "RE: D 7100 Focus help" In response to Reply # 0
When focusing on moving objects that are small it is best to switch over to spot focus and focus on the EXACT area you intend to focus on! Unless you zoom in to fill up the viewfinder frame, then center-weighted is okay in this instance as well.
Nikon's matrix metering - especially the 51 point area of the D7100, will focus on several areas at the same time. That is, for any given aperture setting, their is a certain depth of field associated with that given aperture setting. Thus, a number of focus points across the frame will light up and set at the same time.
This is no good if you just want a bird within the frame to be set as the actual focus point because areas in front as well as behind the bird are in focus. The depth of field for the aperture set could render parts of the bird to appear softer than intended - especially at apertures of F2.8 and F4! The depth of field is narrow and might not encompass the entire animal within the frame.
This also applies to portraiture shots - focus on the eyes and use either spot metering or center-weighted metering.
The default Matrix metering is best used for non-moving, and very large depth of field shots such as landscapes and architecture, etc.
#4. "RE: D 7100 Focus help" In response to Reply # 0
F16 is probably contributing to softening your shots. Are you sure you need that much depth of field?
Viewing images at 100% (or whatever high magnification you're at) is making them look soft. Note that viewing a D7100 photo at 100% on your monitor at home or zoomed in to 100% on the rear LCD of the camera is equivalent to a five foot wide print viewed from a few feet away. Not very realistic or useful as a means of judging sharpness.
Post links to some of the photos which concern you. It would help to see what you're seeing.
#5. "RE: D 7100 Focus help" In response to Reply # 0 Wed 03-Apr-13 10:12 AM by km6xz
St Petersburg, RU
There are too many unknown variables to judge the technique on the images you are concerned with unless we can see them. AF is complex on modern cameras and we often ignore that when most of the time it guesses correctly what we intended to be in-focus. When it guesses wrong based on our intended focus point, it is not just randomly picking a different target to frustrate us, it is picking one that the camera calculates as being more likely to be the desired target. To have the camera guess correctly more often we do better by intending a focus point that the camera would most logically pick instead of one we want it to pick. We can adjust how we pick focus targets easier than you can re-engineer the software of the AF system. We can make those adjustments easily on the fly by knowing what the camera can see and how it evaluates the targets. If for example we knew the focus sensor was larger in coverage area than the little box that represents the focus point in the view finder, we would be more careful about how much confusing possible focus points fall into the sensor's real detection area. Couple that with the traits of the focus object that are better for the focus sensor to make a decision on. For example we might see a wall, that nicely lit and large compared to the focus sensor cross section area and assume it is a great focus target. It probably isn't however if the wall is uniform in color or devoid of texture. If a fly was flying in the area between the wall and the camera, it would be possible for the camera to see a closer subject as being a more logical and higher quality focus target, and blur the wall in attempts to focus on the fly that was not your target at all. So thinking of what the camera see and what it thinks about the target choices it has within any chosen focus point, goes a long ways to helping the AF do what we intend, by wanting the same criteria as the camera has. What, according to the camera is a good focus target? One that fills the focus point with the same focus plane. One that has texture, instead of featureless or diffused scattered light. One with sharp demarcation between light and dark regions. One with well defined edges One that is well lit
What are bad focus targets? Those with seamless featureless areas. Those with several targets within the same focus sensor area. One which has lower contrast. One that is on varying focal planes.
So using this camera thinking, we have a few problems with birds that we humans much help the camera with by providing less ambiguous targets. The birds are often small in the frame, which means something else is also in the frame that is not the target desired. Birds often have soft diffused texture, feathers that have little contrast or detail texture seen at the scale we(the camera) sees it. Either fast moving and small in the frame or sitting still on a perch. Both are tough on AF systems. A perched bird in the wild is often using a thicket or branches as camouflage and their coloring is not by accident similar to the camouflage so there are lots of confusing information the camera focus sensor is trying to evaluate. The twig or branch behind the bird you mentioned could easily have been a more logical focus target than the bird since it has well defined edges, sharp texture elements, more reflective of light, and has portions with linear lines. Was the tree/bush in focus sensor area? Remember the focus sensor area of detection is larger than the area shown by the box in the VF. How to focus when the subject is confusing to the AF system? Try to pick a good target on the same focal plane as the desired subject that is not such a good target. Filling more of the sensor with the edges or high contrast areas of the desired subject. Use manual focus. This last one is not popular but is the only one that assures that what the camera focuses on is the same one you intended in the first place. You can help manual focusing by stopping down so your focus adjustments will not be so critical. You can install a special focusing screen like those from Katz-Eye which make manual focusing a snap like it was in the film all manual focus days....when it was rare to have an out of focus photo.
Regarding AF mode, if the subject is still, like a perched bird, you would probably get better results in AF-S mode and active birds, on the wing or ground feeding you will get better results with AF-C mode. Then select the number of focus points you would like the AF system to evaluate if the subject moves away from a focus point. The fewer the better if the subject's fast movements are constrained to a small area around your chosen focus point that you are attempted to keep centered n the focusing target.
#6. "RE: D 7100 Focus help" In response to Reply # 5
All great information. I think you are hitting what I need to figure out. I will respond later when I am on my computer. I'll also send pics. Very concise info from you all. I will resond later when not on the phone.
#7. "RE: D 7100 Focus help" In response to Reply # 6
Here are three of the shots that I took during testing. The Information you guys have provided give me some direction. I thought that maybe the zoom of the LR program was giving me a false indication Great presentation on using autofocus.
#11. "RE: D 7100 Focus help" In response to Reply # 10
better, but still showing a lot of compression artifacts. do you have the exif data? What pic format and size did you shoot? Raw? JPG Large basic? Compression set to max quality or size?
For the sparrow pic can you turn on focus point to see what point the camera was focusing on? If it is focused on the sparrows eye then it would appear to have some back focusing. This could be corrected by adjusting the lens AF fine tune.
#12. "RE: D 7100 Focus help" In response to Reply # 10
St Petersburg, RU
Are these small crops and originally JPGs? The best reason, among many, reasons to shoot RAW is to preserve the original capture data and be able to make edits and conversions without every changing the original raw file. It appears that you saved these as JPGs which compresses them and tosses out a lot of data, then saved them again which further destroys data by compressing again. By 3 or 4 saves there is no fidelity left and the image is ruined. It is possible to get good JPG compression if the file is only converted once. If you need another size or additional edits, start with a new conversion of the original untouched file so every version of the edited version of an image is a first generation of conversion and saving as a JPG.
The photo of the bird is a good example of a number of better focus targets in the same focal point coverage area. The branch is a better target than the dark low contrast bird. Both were in the same focus sensor coverage area. If these were small crops, the bird was just too small in terms of defining pixel count to dominate the focal point. If his head filled the focal point, the camera would have been more likely to pick the same target as you did. Stan St Petersburg Russia
#13. "RE: D 7100 Focus help" In response to Reply # 12
Yes;,, These were jpgs as LR was not recognizing raw I exported with a smaller size and copied to seperate folder. I than took those same pics from LR (after your comments on compression) and exported again as I believe 1200x 800. But yes jpgs.
#15. "RE: D 7100 Focus help" In response to Reply # 14 Fri 05-Apr-13 03:27 AM by agitater
I see evidence of camera shake, possibly slight downward movement of the camera as the shutter is pressed, and subject movement. There may also be some lens softness at play here too.
The medium shot of the bird on a branch is simply misfocused. The lens was all the way out at 500mm, the image seems to have been cropped (if I understand your previous posts correctly), so the original subject must have been quite small in the viewfinder. There seems to be enough contrast in the subject for a good focus lock, but at the distance I think you were shooting it's probably difficult to get a good focus lock. It seems like the camera locked on the branch rather than the bird. If the subject bird was under a non-cross type AF point, the camera was probably struggling a bit.
There's also just a hint of haze in the shot. Shooting at 500mm through a bit of haze in the air makes for soft looking shots. I think you should consider trying to get much closer to your subject matter.
The Sigma 150-500 is a bit of poor performer at 500mm at f/11. Mind you, center performance at f/11 is about as good as that particular lens can do, although it's not rated very well at that length. The lens has been reviewed a number of times, and most of the reviewers complain of literally hazy looking shots at 500mm. The lens is a winner from 200-400mm, by all accounts, from f/5.6-f/11.
Get much, much closer to your subjects, straighten your horizon, keep your focal length between 200-400mm, increase your shutter speed (something much faster than 1/500th at those focal lengths - at least 1/800s), keep your aperture at f/8 or larger, and I think you'll be much happier with your results.
#16. "RE: D 7100 Focus help" In response to Reply # 15
When using my Sigma150-500m while bird shooting, I have found first that best results are achieved with a solid tripod and a sturdy head. Sweet spot on this lens is F8 therefore, my ISO is in Auto set at 800 with a Max 1600 and no less than 1000 on Aperture. On cloudy days, I push it up to 3200 especially with the D7100. Don't worry about soft corners since you need to catch the object in the center then crop it. The luxury of the 7100 is the 24mp it gives so even if you crop at 100%, you will still have approximately a 12mp image to play with. Now, I know that I will stand corrected by someone on the exact megapixels. All I am trying is to give you an approximation. Lastly, don't forget to shoot bursts on CH and turn your VR off when using a tripod. Good luck and post some more!
#17. "RE: D 7100 Focus help" In response to Reply # 16
<<Lastly, don't forget to shoot bursts on CH and turn your VR off when using a tripod.>>
Or indeed at very high handheld shutter speeds, say x1.5 the focal length shutter speed equivalent. E.g. A shot taken at 300mm should be able to achieve sharp images without VR at 1/450. This is an old lens rule too before the days of optical stabilization. I only know for 2 reasons. Firstly, I was using high shutter speeds (e.g. 1/1200) and getting soft or blurred shots and referred to specialist help on here. Secondly, I was referred to Thom Hogan's excellent explanation of when and when not to use optical stabilization.
#18. "RE: D 7100 Focus help" In response to Reply # 17
Hi All: Wanted to thank each and every one of you for the information you provided in this thread. I printed much and read all. The paper on the D7000 autofocus was a big help. I did try many of the settings and was able to see some of the problems encountered. I consider myself fairly seasoned from the old Nikkormat days, but this newer fandangled stuff blows me away. I am not one to set on auto and just have fun, as the photographer in me won't allow that. My eyes have slightly deteriorated over the years, to quick I might add, but I choose to look for the the technical skills as being the problem. The nice thing about these challenges is that it keeps you sharp. I'll master this beast until a new toy comes out. I do appreciate all your help now and in the future.