Used Sony DT35MM difficulty focusing

[james9120]

Purchased a used lens and while the lens is in great condition, I started testing it today and noticed the auto focus is a bit off. I was shooting at F1.8, ISO 100 and letting the camera do the rest and most of my pictures came out blurry. I'm sure it's most likely user error. The only thing that slightly worries me is when I was removing the hood, I accidentally twisted the lens zoom adjustment while the camera was on and focused. Oops.

Here are some examples of my blurry photos.

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drive.google.com

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drive.google.com

But then again it might very well just be user error because the lens is very capable of pictures like this:

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drive.google.com

Let me know what you think, thanks

 

[tbcass]

What focus points are you using? This lens has shallow DOF at f1.8 so using a single AF point over the area you want in focus gives best results. If you use wide area focus or even a group of multiple points it becomes a crap shoot.

--
Tom
Look at the picture, not the pixels

 

[lehill]

Purchased a used lens and while the lens is in great condition, I started testing it today and noticed the auto focus is a bit off. I was shooting at F1.8, ISO 100 and letting the camera do the rest and most of my pictures came out blurry. I'm sure it's most likely user error. The only thing that slightly worries me is when I was removing the hood, I accidentally twisted the lens zoom adjustment while the camera was on and focused. Oops.

I downloaded the RAW file, if I'm reading EXIFGUI correctly you were in Wide Area AF mode and letting the camera pick any ol' focus point it wants to.

Switch to any single AF point you want and use it to tell the camera what you want to be in focus. You'll have a lot more success.

--
Lance H

 

[james9120]

Purchased a used lens and while the lens is in great condition, I started testing it today and noticed the auto focus is a bit off. I was shooting at F1.8, ISO 100 and letting the camera do the rest and most of my pictures came out blurry. I'm sure it's most likely user error. The only thing that slightly worries me is when I was removing the hood, I accidentally twisted the lens zoom adjustment while the camera was on and focused. Oops.

I downloaded the RAW file, if I'm reading EXIFGUI correctly you were in Wide Area AF mode and letting the camera pick any ol' focus point it wants to.

Switch to any single AF point you want and use it to tell the camera what you want to be in focus. You'll have a lot more success.

 

[lehill]

Purchased a used lens and while the lens is in great condition, I started testing it today and noticed the auto focus is a bit off. I was shooting at F1.8, ISO 100 and letting the camera do the rest and most of my pictures came out blurry. I'm sure it's most likely user error. The only thing that slightly worries me is when I was removing the hood, I accidentally twisted the lens zoom adjustment while the camera was on and focused. Oops.

I downloaded the RAW file, if I'm reading EXIFGUI correctly you were in Wide Area AF mode and letting the camera pick any ol' focus point it wants to.

Switch to any single AF point you want and use it to tell the camera what you want to be in focus. You'll have a lot more success.

 

[james9120]

Purchased a used lens and while the lens is in great condition, I started testing it today and noticed the auto focus is a bit off. I was shooting at F1.8, ISO 100 and letting the camera do the rest and most of my pictures came out blurry. I'm sure it's most likely user error. The only thing that slightly worries me is when I was removing the hood, I accidentally twisted the lens zoom adjustment while the camera was on and focused. Oops.

I downloaded the RAW file, if I'm reading EXIFGUI correctly you were in Wide Area AF mode and letting the camera pick any ol' focus point it wants to.

Switch to any single AF point you want and use it to tell the camera what you want to be in focus. You'll have a lot more success.

 

[Jeadm]

Focusing mode and metering mode are independent of each other.

I recommend Gary Friedman's fine collection of e-books to learn and get the most out of your Sony gear, they're specifically tailored to Sony cameras and your model in particular.

 

[tbcass]

Thank you, I can't multi quote or I'd quote both messages here. Would you suggest using local (multi) or spot for an area? I think spot is just focused directly in the center so not sure if that would work out.

Use spot. The spot can be moved about if you desire or you can use single focus, half press to lock focus and recompose. The choice is yours. What camera are you using?

And wouldn't using spot mess up my exposure setting by just adjusting for what's in the center? Please correct me if I'm wrong, learning everyday!

No, exposure is not determined by the spot focusing point. It's determined by the image sensor.

 

[tbcass]

Is it efficient to use the spot focus and then pan the camera to the angle I want, while holding down the shutter button half way?

I find doing it that way works for me for single focus. It won't work for continuous focus..

Example would be to center my car, hold the AF button so it focuses, then pan the camera slightly (on a tripod) to suit the angle I want?

That should work.

 

[james9120]

Thank you, I can't multi quote or I'd quote both messages here. Would you suggest using local (multi) or spot for an area? I think spot is just focused directly in the center so not sure if that would work out.

Use spot. The spot can be moved about if you desire or you can use single focus, half press to lock focus and recompose. The choice is yours. What camera are you using?

And wouldn't using spot mess up my exposure setting by just adjusting for what's in the center? Please correct me if I'm wrong, learning everyday!

No, exposure is not determined by the spot focusing point. It's determined by the image sensor.

 

[james9120]

Focusing mode and metering mode are independent of each other.

I recommend Gary Friedman's fine collection of e-books to learn and get the most out of your Sony gear, they're specifically tailored to Sony cameras and your model in particular.

Are you referring to this book?

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friedmanarchives.com

 

[Jeadm]

Yes, if you have the A300 or A350, that's the one.

 

[TillmanB]

I bought an A37 a while back and when using the kit 18-55mm zoom the focusing seemed ok. I like primes so I bought a Minolta 28mm f2.8 and was disappointed that my memories of that lens from a previous copy I owned didn't match this one, everything came out soft unless stopped down quite a bit. So I sold that and bought the 35mm DT lens since I knew that one was pretty sharp. After taking a bunch of shots of my kids I was still coming up with shots where their faces were soft. I determined it was probably because they moved at the last second and I was using too slow of a shutter speed. I took some more shots being certain to set the camera to faster speeds and spot focus. Still had issues when shoot at wide apertures. I began to notice that focus was sharp, just not where I was focusing. I found a guide online to adjust the calibration of the focus sensors on my camera, and VIOLA! Suddenly things were sharp where I wanted them sharp.

The takeaway here is that I had not noticed a problem with the camera using the kit lens since the slower f3.5 max aperture had enough DOF to hide the issue, but once I used lenses that had shallower DOFs the problem presented itself much more and I initially assumed it was the lens. Now I feel kind of dumb for selling off that 28mm...

 

[james9120]

I bought an A37 a while back and when using the kit 18-55mm zoom the focusing seemed ok. I like primes so I bought a Minolta 28mm f2.8 and was disappointed that my memories of that lens from a previous copy I owned didn't match this one, everything came out soft unless stopped down quite a bit. So I sold that and bought the 35mm DT lens since I knew that one was pretty sharp. After taking a bunch of shots of my kids I was still coming up with shots where their faces were soft. I determined it was probably because they moved at the last second and I was using too slow of a shutter speed. I took some more shots being certain to set the camera to faster speeds and spot focus. Still had issues when shoot at wide apertures. I began to notice that focus was sharp, just not where I was focusing. I found a guide online to adjust the calibration of the focus sensors on my camera, and VIOLA! Suddenly things were sharp where I wanted them sharp.

The takeaway here is that I had not noticed a problem with the camera using the kit lens since the slower f3.5 max aperture had enough DOF to hide the issue, but once I used lenses that had shallower DOFs the problem presented itself much more and I initially assumed it was the lens. Now I feel kind of dumb for selling off that 28mm...

That's the exact issue I'm having. Take this example of my dog i snapped a picture of today.

https://drive.google.com/open?id=0B3yBUOtnRj3TRVQ0cXBjVDdFaWs

The AF was cleared centered with my dogs head, but his head came out soft and shoulders came out sharp. This is with spot auto focus. Do you know the guide that you used? I would like to give it a try.

There's a chance it it might just be me. I took these a few minutes ago.

https://drive.google.com/open?id=0B3yBUOtnRj3TcVRhY0puWGYxUU0

Loading…

drive.google.com

 

[TillmanB]

I bought an A37 a while back and when using the kit 18-55mm zoom the focusing seemed ok. I like primes so I bought a Minolta 28mm f2.8 and was disappointed that my memories of that lens from a previous copy I owned didn't match this one, everything came out soft unless stopped down quite a bit. So I sold that and bought the 35mm DT lens since I knew that one was pretty sharp. After taking a bunch of shots of my kids I was still coming up with shots where their faces were soft. I determined it was probably because they moved at the last second and I was using too slow of a shutter speed. I took some more shots being certain to set the camera to faster speeds and spot focus. Still had issues when shoot at wide apertures. I began to notice that focus was sharp, just not where I was focusing. I found a guide online to adjust the calibration of the focus sensors on my camera, and VIOLA! Suddenly things were sharp where I wanted them sharp.

The takeaway here is that I had not noticed a problem with the camera using the kit lens since the slower f3.5 max aperture had enough DOF to hide the issue, but once I used lenses that had shallower DOFs the problem presented itself much more and I initially assumed it was the lens. Now I feel kind of dumb for selling off that 28mm...

That's the exact issue I'm having. Take this example of my dog i snapped a picture of today.

https://drive.google.com/open?id=0B3yBUOtnRj3TRVQ0cXBjVDdFaWs

The AF was cleared centered with my dogs head, but his head came out soft and shoulders came out sharp. This is with spot auto focus. Do you know the guide that you used? I would like to give it a try.

There's a chance it it might just be me. I took these a few minutes ago.

https://drive.google.com/open?id=0B3yBUOtnRj3TcVRhY0puWGYxUU0

https://drive.google.com/open?id=0B3yBUOtnRj3TVDRwVjZVc1BDcEU

Back focus problems and solution, Sony SLT-a55

My SLT-a55 had severe back focus problems, but Sony gave it a clean bill of health. Here's how I found and solved the problem.

b.kl3in.com

This is what I followed, not sure how closely it relates to the A300 you said you have, but maybe someone else can chime in with some info on that.

I set everything up as precisely as I could, had the camera on a tripod with the lens set to f1.8 (this is important since this offers the shallowest depth of field), the test chart I taped to the lid of my laptop and angled it about 45 degrees and set it on a table about 6-7 feet away. It took some time and fiddling but now my camera focuses exactly where it should across the frame.

To start, I would print out the test chart and try the spot autofocus on it a few times and see if this is your problem. If you focus on the middle of the angled target you'll be able to zoom in when you review the shot and see if it's focusing where you want or if it's a little front or back of the focus point.