why is my focus ring not working?

wfooshee · Apr 2, 2021

You still haven't told us how close you're trying to get to the subject, and that is the MAJOR question everyone has. Most lenses have a minimum focus distance, where nothing inside that distance can be placed in focus. That distance changes with the zoom setting.

It's perfectly normal for a zoom lens to be able to focus on something close at the 24mm setting, but be unable to focus that close at the 70mm setting. It's also perfectly normal for some zoom lenses to not hold focus as you change the focal length; technically, that makes it a vari-focal lens, not a zoom lens, but the actual use makes no difference. ( "true" xoom does not change the focus distance as the focal length is changed, but many current lenses do, as that makes them less expensive.)

SquarePeg · Apr 2, 2021

This is my last post in this thread unless you can provide straight answers to the following questions.

1 - can you use manual focus to focus on something far away?
2 - exactly how physically close are you from the subject (in feet/inches or meters) when you are having issues manually focusing?

snowbear · Apr 2, 2021

SquarePeg said:
OP you haven't really answered any of our questions - you keep posting the same info/statements. Can you manually focus on something far away?

SquarePeg said:
This is my last post in this thread unless you can provide straight answers to the following questions.

1 - can you use manual focus to focus on something far away?
2 - exactly how physically close are you from the subject (in feet/inches or meters) when you are having issues manually focusing?

Maybe it's time to just lock the thread if the questions are not actually answered.

ph0toe · Apr 2, 2021

I know a lot of what was said here was reiterated

Dropbox - IMG_0662.mp4 - Simplify your life

but to answer ya'll questions , when you say manually focus, I imagine stationary and it not continiously tracking. in that case yes i am able to manually focus. i noticed when i move closer it wont focus, so i can understand what you mean by there being a focus distance for every lens. when i move oh so slightly away i can focus and i get the sounded beep. however, the image is STILL NOT as crisp as i would like it, and that might be something to do with my ameatur skills, or something else

in terms of inches/feet i dont know how to measure that off the top but if you review the video, you'll see how close/far i am away from subject (bag hanging off the door knob) . i know thats not really helpful but it is the best i can show. fyi my room is around 12 x 11inches so from one end to another give or take.

weepete · Apr 2, 2021

read up on depth of field.

ph0toe · Apr 3, 2021

I did. aperture affects dof.since mine could only go as far down to 4.0, i wont get a shallow dof to say a 2.8. but it should focus on subject and blur background a bit as opposed to say a f/11. what am i missing here?

SquarePeg · Apr 3, 2021

ph0toe said:
the image is STILL NOT as crisp as i would like it, and that might be something to do with my ameatur skills, or something else

This is likely due to your settings and/or shooting stance if you are hand holding or due to lens vibration if you are on a tripod and didn't turn off VR. Too slow shutter speed or too high ISO can reduce sharpness. Post a photo along with your settings so we can take a look and try to help.

weepete · Apr 3, 2021

The closer you are to a subject the thinner your DOF is, at minimum focus distance your DOF will be very thin even with a small aperture. That means you can't hold focus over a large area and you need to refocus the lens. That's just optics.

At a focal length of 105mm and an aperture of f4, when you are 0.7m away from your subject your DOF will be 0.01m (10mm). You'll need to keep your shutter speed up as well, so use at least 1/100th of a second, 1/200th would be better to eliminate camera shake. You won't be able to hold focus over a large area.

My advice is to get an actual subject, buy a cheap action figure off ebay or use a flower or something and try that.

ph0toe · Apr 6, 2021

Dropbox - IMG_0662.mp4 - Simplify your life

thank you for your patience

wfooshee · Apr 7, 2021

That's definitely not too close for the lens, nor are you zooming to the point of pixelating the image in Live View, both of which are what we were thinking might be happening. It's also suspicious to me that when you touched the shutter button to display your exposure setting in the top LCD screen, the lens did not focus, and you hadn't switched from AF to MF yet, nor had you turned on Live View. It should have focused at that point.

The number "1" that you pointed out indicates that the lens is focused at 1 meter, which is much closer than the subject. A later glimpse of that window after you'd half-pressed the shutter button but before you switched to manual focus shows the distance scale in the same position, meaning the lens did not focus. That windows indicates the distance to which the lens is focused. On "1" something 1 meter away should be in focus.

Later, when you turned the focus ring it did adjust the distance scale, but it appears nothing changed in Live View. That tells me that something's wrong with the lens. When you manually focus while looking through the viewfinder instead of Live View, does it focus, or is it the same behavior? Is this your only lens? If you have another lens, does it exhibit this behavior, or does it work correctly?

weepete · Apr 7, 2021

Yup, looks like the the lens is bust. That turn of the focus ring should have thrown it way out of focus and then back in, it seems like you are seeing no change. It may be that BBF has been enabled, and that could explain why AF doesn't work with a half depress of the shutter, but everything else in your video is pointing to a lens with a broken focusing system.