Problems with the focus of PENTAX SMC FA 50mm 1:1,7

magic.pill · 05-01-2015, 10:50 AM

Hello everyone.

I own a Pentax K5-II, a FA 50 1,7 Lens and a Tamron 17-50 2.8.

When shooting with the Pentax FA50 I encounter very many unsharp images. It does not always fail, but its too often to accept it. Its very annoying. The Tamron Lens at 50mm works just fine, the FA-50 not. Here are two examples of a shot with FA50. One is sharp another one not, same lens though. It is not even stepped down to 1.7. The shots are at 2.8.

I ask myself if I got a bad copy of this lens or if its just a shitty lens altogether?

Cheers
MP

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**jrpower10** · 05-01-2015, 11:23 AM

My FA 50 1.7 is one of my favorite lenses and works great. The first shot looks like it front-focused. Are you selecting the focus point or letting the camera pick? Try selecting the focus point and see if it improves. Also, you may need to fine tune autofocus in the camera. You can get a test kit, or simply lay a ruler at an angle to the camera and focus on a line. If actual focus is in front of the line the camera indicated in focus, then the combo is definitely front-focusing and you'll need toadjust in the camera menu.

stevebrot · 05-01-2015, 02:27 PM

Are you able to manual focus and get sharp images with the FA 50/1.7? If not, the lens has optical issues.

Steve

Jonathan Mac · 05-01-2015, 03:27 PM

My copy is great, though I'll admit the focus is not as reliably accurate as my DA limited lenses. Having said that, these appear to be taken in bright sunlight so it's hard to imagine any camera's AF system failing in that situation.

Have a look at the link below, print the chart and check the focus with the lens wide open. It may be that it needs some adjustment. You may be able to do that on the camera, depending on the model, or you may need to send camera & lens Pentax to adjust.

http://www.efoto.lt/files/focus21.pdf

05-01-2015, 11:23 AM	#2
jrpower10 Site Supporter Join Date: Sep 2011 Location: Richland, Washington, USA Posts: 935	My FA 50 1.7 is one of my favorite lenses and works great. The first shot looks like it front-focused. Are you selecting the focus point or letting the camera pick? Try selecting the focus point and see if it improves. Also, you may need to fine tune autofocus in the camera. You can get a test kit, or simply lay a ruler at an angle to the camera and focus on a line. If actual focus is in front of the line the camera indicated in focus, then the combo is definitely front-focusing and you'll need toadjust in the camera menu. Last edited by jrpower10; 05-01-2015 at 12:21 PM.

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05-01-2015, 02:27 PM	#3
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	Are you able to manual focus and get sharp images with the FA 50/1.7? If not, the lens has optical issues. Steve

05-01-2015, 03:27 PM	#4
Jonathan Mac Pentaxian Join Date: Apr 2009 Location: Madrid, Spain Posts: 10,902	My copy is great, though I'll admit the focus is not as reliably accurate as my DA limited lenses. Having said that, these appear to be taken in bright sunlight so it's hard to imagine any camera's AF system failing in that situation. Have a look at the link below, print the chart and check the focus with the lens wide open. It may be that it needs some adjustment. You may be able to do that on the camera, depending on the model, or you may need to send camera & lens Pentax to adjust. http://www.efoto.lt/files/focus21.pdf