Sony 50mm 1.4 focus issue

[tracyselena]

I just got a brand new sony 50mm 1.4 lens and when I use it on my Sony Alpha 350 the auto focus is way out. I lock the focus on a specific spot but when I look at the photo that particular spot is very soft. Is there something I'm doing wrong or should I send it back to sony?

[hoffy]

HI,

What camera are you using? Are you testing on a tripod? If you are trying at F1.4, you need to remember that the Depth of Field is paper thin, especially shooting anything close. If you have not tested on a tripod and you are shooting in single focussing mode, it could simply be you slightly moving. I would ensure that I test this fully on a tripod before making any rash decisions.

BUT, that being said, I have heard of people having issues with the 50 F1.4, but that was quite a long time ago. Unless you have already done so, test with a tripod on a fixed subject. If this doesn't help, yes, by all means, take it back.

[tracyselena]

I wasn't sure if I was doing something wrong and if it was from a slight movement as I haven't been using a tripod. It's a sony alpha 350 so I was also wondering considering it's one of the lower end models that was the issue too.

[hoffy]

The reason I ask about the camera was to see if you had the ability to do focus micro adjustments. I don't think the A350 has it. That being said, being an A350 or an A700 (I will leave out the 850 and 900 as they have the micro adjustments), it should behave any differently.

Have you tested other lenses on the same camera?

[tracyselena]

Kit lenses are all I have and they focus fine so i'm wondering if the camera is calibrated to suit kit lenses rather than any other type.

[hoffy]

OK, still test the 50mm on a static object (with a tripod is obviously the best way).

That being said, I just checked the DPreview article on the lens and they had the same issue:

http://www.dpreview.com/lensreviews/..._m15/page4.asp

If you do find that this is the case with your lens (again, test as well as you can. A lot of shops have a tendancy to fob off customers, so the more evidence you have the better of you are), by all means, take the lens back for calibration/repair.

[tracyselena]

Thanks. I was reading that article last night so that's why I didn't know if it was me or the lens. I might call up the sony service centre if I'm still having issues.

[RaoulIsidro]

Try this test. (making sure all AF is working, etc)
Get a long barcode that is printed on the side of a box of cereal, soap, or carton.
Set the box 1 meter away and the surface at a 45 degree angle from the camera.
Focus on the middle of the bar code. (the longer the barcode, the better)
The image result should have the centre of the barcode as sharpest becoming blurred on the edges.
Tell us how you go with this.

[Boo53]

I wasn't sure if I was doing something wrong and if it was from a slight movement as I haven't been using a tripod. It's a sony alpha 350 so I was also wondering considering it's one of the lower end models that was the issue too.

I don't have the 1.4, just the 50 f1.8, on an a300 & a550 and have no problems. Also have a Tokina 11-16 f2.8 used on both bodies and perfectly happy with that as well, so the cameras ok

[hoffy]

Try this test. (making sure all AF is working, etc)
Get a long barcode that is printed on the side of a box of cereal, soap, or carton.
Set the box 1 meter away and the surface at a 45 degree angle from the camera.
Focus on the middle of the bar code. (the longer the barcode, the better)
The image result should have the centre of the barcode as sharpest becoming blurred on the edges.
Tell us how you go with this.

The other option that I find a lot more reliable then the just the 45 deg test is the moire pattern test (I would tend to do both to get a real idea of what is happening).

use a pattern such as those found here:

http://www.komar.org/faq/camera/auto-focus-test/

Setup the camera, on a tripod, dead straight on to your computer monitor and focus on the pattern (the second pattern works best for me). Let the camera auto focus and choose its point (if it happens all a bit too easily, make it go wildly out of focus and then let it pick it up).

When the focus is spot on, you will get a whole bunch of different circles all through the image. It will look really quite weird. If the pattern looks a bit fuzzy, manually focus to see how you go (with the A350, you don't have live view, but even looking through the view finder, you will see the patterns change quite a bit). Take plenty of shots, retest the AF and see how you go. This way, you can see if the camera is focussing straight on and you can eliminate true back or front focus.

Once you have done this test, THEN do the 45 deg test. This will check to see exactly what point the focus is set on the camera. I am not familiar with the A350 focus points, but on my A700, the middle point is supposed to be a rectangle. If the focus point is to one side of the square, this will cause focus to be out at 45 deg, but focus may be OK straight on (if that makes sense)

Cheers

[bigdazzler]

my 50 1.4 is bang on too.

[Keith]

mine too, love it to bits, sharp as
hope you get it worked out, cos its a great lens.

[arthurking83]

post one of the images you have Tracey.

make sure all exif info is intact tho(very important).

post it at 1024pixels size for better analysis.

before we lay blame upon the equipment, which may end up being expensive or nuisance to sort out, the cheaper alternative is to work through all the environmental variables first.. user errors, subject movement, etc...