Focusing problem

[Manfred M]

I do have a question: are the camera sensors ever known to fail?
Bruce

It depends on what you mean by "fail". A camera sensor that "fails" generally means it is "dead", i.e. non-functional. I have a lens that has had the autofocus electronics and focus motor fail in that manner and it had to be returned to the manufacturer for repairs.

The other view of "fail" is when we try to use it outside of the parameters it is designed to work under. There are two distinct issues here:

1. If the subject not well illuminated or does not have enough contrast, the autofocus mechanism cannot lock focus. Here we are trying to get the camera to work outside of what it was designed to do, and we will not get a focused result.

2. Issues resolving the focus point - we have a number (one or more) points in the viewfinder that the camera uses as focus points. If these are not chosen correctly, the camera may focus on the wrong points and even though it is working properly, it will not be what the end user wanted. I find this is more of an issue when shooting with a long lens at a narrow depth of field. I suspect closeups of flowers would have the same issue.

[Digital]

Posted is a pic that my friend could not find anything in sharp focus.

[Manfred M]

Posted is a pic that my friend could not find anything in sharp focus.

The metadata says the shot was taken at 1/5th of a second and at f/25. Camera shake is a likely culprit (even with a tripod, unless properly executed, mirror slap and other motion can still be an issue) and at such a small aperture, diffraction will cause softening too.

[Digital]

The metadata says the shot was taken at 1/5th of a second and at f/25. Camera shake is a likely culprit (even with a tripod, unless properly executed, mirror slap and other motion can still be an issue) and at such a small aperture, diffraction will cause softening too.

Manfred, I think you are on to something. I am posted another pic my friend sent me.

Bruce

[Stagecoach]

Bruce,

This ones

Exposure Time = 1/8"
F Number = F29
Manual Focus

Not sure why he would have chosen f29 in Aperture priority for this very well lit scene at the cost of the slow speed ?

These results do not seem too surprising to me with these settings.

[drjuice]

Hi, Digital,

I don't see whether you tried Blue Boy's suggestion to check the position of your diopter. So, for people who don't know what this is about, below is a little bit about diopters.

To start, when I first started learning about diopters, I went back to see whether my previous cameras had one. Whew! They didn't! So, at least I hadn't missed using a camera feature because of ignorance!

Diopters turn out to be hugely significant if you wear actual glasses or, if you lose the contact in your "shooting" eye while you're out on a photo shoot. The diopter sits between the rear glass in the viewfinder and the other elements that are used to view the shot before you push the button. The easy way to tell whether you have one is to look at the exploded picture in your user's manual. It will normally be adjusted using the knurled surface on the side of the viewfinder housing. For the process I describe below, it's generally useful to put your camera on your tripod so that everything remains steady while you're learning.

If you wear actual glasses, for this part of the process, remove your glasses. If you wear contacts and want to see how this works, you can leave the contact in your shooting eye, but remember about this for when you lose that contact.

To see what the diopter does, after you've set up a picture where you can have both shallow and deep depths of field in your picture, even if it's just a fence or a couple of kitchen pots, put one fingernail on the knurled surface. Then, while you're looking through the viewfinder, move the knurled surface up and down several and watch how the image goes in and out of focus. This will be particularly obvious if you normally wear actual glasses. The short version of what it does is that it allows a consistent focus (unless you accidentally move the diopter) in the viewfinder WITHOUT affecting the focus of the lens (because sometimes we want different effects on the picture we're taking). Remember, you're NOT focusing the lens, you're focusing the image you see in the viewfinder!

After I found a setting that I was comfortable with, I made two small marks with orangey nail polish (to color coordinate with the orange letter alpha on my Sony Alpha700). One of the small marks is on an indention in the knurled surface and the other is on the viewfinder housing. Matching them gets them back to having them perfectly focus. And, when I take my first picture of the day, I check to be sure they're perfectly matched (before I take my glasses off). ;~)

The I decided it would be good to have my eye ophthamologist check the way I'd set my diopter when I went for my annual visit. He had a device to check it (sorry I don't remember the name of the device) and said that I'd hit the setting exactly right for my distance vision glasses. And, it turns out to work just fine for looking at closeup things as well. Then, he wanted to know what the orange marks were for!

When I am shooting, I can just raise my eyebrows and my glasses drop slightly so that I'm looking over the tops and directly through the viewfinder including the diopter.

If you think your picture is in focus because of your diopter setting, and the diopter is set properly, you should be able to use your camera on autofocus or to use the viewfinder to decide what the proper focus is.

If your diopter is improperly set, YRAHLTV (your results are highly likely to vary) and your resulting images are likely to be out of focus because you think where you've focused is correct and it won't be. It's like walking around without your glasses on!

Hope this helps.

virginia

[Digital]

Grahame, and Virginia: I appreciate your comments, and I believe that we are getting close to resolve what went wrong.
Why he was shooting with the aperture so stopped down is a question I have. He could have used f11 or f16 and got the same results. As Manfred (and Grahame) suggested with that slow of a shutter speed mirror slap could be an issue.
On Virginia's point I also have no idea why he was using manual focus in the first place, and if Virginia is correct about his diopter being off it would definitely throw off his ability to correctly focus.
It is "appearing" to me that there maybe several operator errors at play here.
He is gone for the afternoon. When he returns I will attempt to get more details out of him.

Bruce

[PhotomanJohn]

I think there may be some misunderstanding about function of the diopter adjustment. It is used to correct one's vision so that the image on the camera's focusing screen is in "focus" which is independent of whether the subject is properly focused by the camera's lens on to the focusing screen / sensor. Changing the diopter adjustment won't make an out of focus image on the focusing screen appear to be in sharp focus. The best it can do is clearly represent the image on the focusing screen. Assume that the diopter adjustment is not correctly adjusted for one's eye, the camera will still be in proper focus as long as one makes the image in the viewfinder as clear as possible, whether totally sharp or not.

I hopes this helps.

John

[Stagecoach]

John,

I would agree with your comment on the diopter adjustment as even if it is not correctly set for your own vision as long as you adjust lens focus to give the 'sharpest/most defined' of the represented image in the viewfinder that's all that matters.

[Digital]

I maybe incorrect; however it appears that what John, and Grahame are relating contradicts what Virginia stated in her last paragraph.
Someone enlighten me.

Bruce

[Manfred M]

Diopters aside, the other serious constraint that your friend is working with is the seriously awful focusing screen that most amateur DSLRs are equipped with. The pre-autofocus camera had focusing screens that made it quite obvious (even when not wearing glasses or contacts) when the scene snapped into focus; sadly, these features have been supplanted by all of the things that clutter the viewfinder. The camera manufacturers assume that with an autofocus camera, you will use this feature.

The pro bodies do have an autofocus indicator built in, so at least that helps when trying to manually focus.

I suspect that your friend is trying to shoot at those extremely small apertures because he is having trouble manually focusing his camera and is hoping to compensate by going for maximum DoF.

[Digital]

Manfred, you brought up a good point.

Bruce