Out of focus images. Camera or lens?

rockyhorror1297 · 03-19-2022, 10:12 AM - **1 Like**

Hello I recently scanned my negatives and discovered that I missed focus on almost every frame. Now I’m not a professional photographer but I don’t miss focus that often. I have a Pentax KM that I recently got a new prism for and I was using a 50mm 1.7 lens. Now I had another roll that I used my 28mm lens and the photos turned out fine. However, I stopped the aperture down quite a bit since we were outside in the sunlight so my focus was pretty dead on. My question is would this be an issue with the lens or the camera? Is it possible that the person who replaced the prism accidentally messed with the focusing screen? Or is that very unlikely? Does my lens need cleaned? When I was looking through the viewfinder everything seemed to be in sharp focus. Thank you!

Jonathan Mac · 03-19-2022, 10:26 AM

It sounds to me like the focus on the screen is not an accurate reflection of what's on the film plane, and that would mean that the screen is out of position: either not properly installed or it needs to be shimmed.

I'm not sure how you'd go about doing that on a film camera. I've done it on digital but that's easy to adjust-test-adjust-test.

**Bob 256** · 03-19-2022, 02:02 PM

There's only one way to find out and that's to do some tests. Shoot some shots with the same lens using a good resolution target. You didn't mention if focusing was autofocus or manual, but use the same method in these test shots.Then try swapping out the lens and get some shots with the alternate lens. Use a range of apertures with each lens. If both sets come out less than sharp, then you know it's the camera rather than the lens. This will also allow you to get the best OVF focus when doing these shots (use a magnifier if available), and it should also let you provide a rock solid support so camera vibration won't be a factor.

If these all turn out good, then it may have been too low a shutter speed or camera shaking which accounted for your unsharp photos, meaning that you need to do something to provide more stability for your camera (or shoot at a substantially higher shutter speed). You can expect less than sharp photos if you used your lens wide open as well. Lenses perform better stopped down (and you kind of alluded to this in your question). That could account for the difference seen when you switched lenses.

**TwoUptons** · 03-19-2022, 05:16 PM - **1 Like**

I had a Nikon F3 that missed focus due to a mirror problem.
If you got a new prism, I wonder if something wasn't aligned or shimmed right when it went back together...

If you have a Pentax digital camera (or a mirrorless with an adapter), you can check the lens pretty easily, but usually if it looks in focus, it should be in focus...
If you do this, look where the lens distance scale is focused... it should be about right at all distances (infinity for very distant objects, 4 m for things 4 m away, etc)

To diagnose what's happening with the KM, focus your 50mm lens as close as it will go. Now measure the distance from the film plane to the thing in focus -- it should match the distance scale on the lens.
Now do the same thing for infinity (or at least "down the street").

When my Nikon was acting up, the distances on the lens didn't match at all what I was seeing in the viewfinder... so if I focused the lens down to 1 m or so, things 1.5 m or so away were in focus in the viewfinder...
When I got the film back, it was focused on the things 1 m away, because nothing was wrong with the lens... the camera viewfinder was just wrong...

You can do the measuring part without film in the camera, but you would obviously need to shoot a few frames to tell for sure...

Finally, if all this comes out right where it should be, what are your eyes like? If you wear glasses, you may need a diopter eyepiece to focus the KM. It doesn't have the adjustable diopter like modern DSLRs do...

-Eric

**Kerrowdown** · 03-20-2022, 01:18 AM

Welcome to the forum, hope you get your issues resolved promptly.

rockyhorror1297 · 03-20-2022, 05:26 PM

Thank you for the all the replies! I’ll try out the methods you’ve told me about, I think I’m leaning towards it being an issue with the camera since I noticed right after I got the prism replaced. Below are two pictures shot with the same camera, but the picture of the lady was shot with a 28mm f2.8 lens and I can’t remember exactly but I believe the aperture was set at f16 the picture of the man is with my 50mm lens I believe at f1.7 or close to that

rockyhorror1297 · 03-20-2022, 05:29 PM

Here are the photos

Attached Images

rockyhorror1297 · 03-26-2022, 10:34 AM

Hello everyone! I took the KM to a camera shop and they said everything looks totally fine but I have noticed that the pressure plate seems to have a little more play and doesn’t seem quite as stable as my other Pentaxes. I’ve heard that can throw off focus on images. Any thoughts?

Jonathan Mac · 04-15-2022, 06:24 AM

Originally posted by rockyhorror1297

Hello everyone! I took the KM to a camera shop and they said everything looks totally fine but I have noticed that the pressure plate seems to have a little more play and doesn’t seem quite as stable as my other Pentaxes. I’ve heard that can throw off focus on images. Any thoughts?

In theory the pressure plate could only affect focus if what it rests on has been altered or if it's too loose to apply the necessary pressure on the film. Basically anything that would cause it to be further forward or back than it should be.

I would say, unless your manual focus skills really are way off, that your camera shop has missed something.

03-19-2022, 10:12 AM - 1 Like	#1
rockyhorror1297 New Member Join Date: Mar 2022 Posts: 21	Out of focus images. Camera or lens? Hello I recently scanned my negatives and discovered that I missed focus on almost every frame. Now I’m not a professional photographer but I don’t miss focus that often. I have a Pentax KM that I recently got a new prism for and I was using a 50mm 1.7 lens. Now I had another roll that I used my 28mm lens and the photos turned out fine. However, I stopped the aperture down quite a bit since we were outside in the sunlight so my focus was pretty dead on. My question is would this be an issue with the lens or the camera? Is it possible that the person who replaced the prism accidentally messed with the focusing screen? Or is that very unlikely? Does my lens need cleaned? When I was looking through the viewfinder everything seemed to be in sharp focus. Thank you!

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03-19-2022, 10:26 AM	#2
Jonathan Mac Pentaxian Join Date: Apr 2009 Location: Madrid, Spain Posts: 10,911	It sounds to me like the focus on the screen is not an accurate reflection of what's on the film plane, and that would mean that the screen is out of position: either not properly installed or it needs to be shimmed. I'm not sure how you'd go about doing that on a film camera. I've done it on digital but that's easy to adjust-test-adjust-test.

03-19-2022, 02:02 PM	#3
Bob 256 Site Supporter Join Date: Jun 2008 Location: Idaho Photos: Gallery Posts: 2,378	There's only one way to find out and that's to do some tests. Shoot some shots with the same lens using a good resolution target. You didn't mention if focusing was autofocus or manual, but use the same method in these test shots.Then try swapping out the lens and get some shots with the alternate lens. Use a range of apertures with each lens. If both sets come out less than sharp, then you know it's the camera rather than the lens. This will also allow you to get the best OVF focus when doing these shots (use a magnifier if available), and it should also let you provide a rock solid support so camera vibration won't be a factor. If these all turn out good, then it may have been too low a shutter speed or camera shaking which accounted for your unsharp photos, meaning that you need to do something to provide more stability for your camera (or shoot at a substantially higher shutter speed). You can expect less than sharp photos if you used your lens wide open as well. Lenses perform better stopped down (and you kind of alluded to this in your question). That could account for the difference seen when you switched lenses.

03-19-2022, 05:16 PM - 1 Like	#4
TwoUptons Loyal Site Supporter Join Date: Nov 2015 Photos: Albums Posts: 4,225	I had a Nikon F3 that missed focus due to a mirror problem. If you got a new prism, I wonder if something wasn't aligned or shimmed right when it went back together... If you have a Pentax digital camera (or a mirrorless with an adapter), you can check the lens pretty easily, but usually if it looks in focus, it should be in focus... If you do this, look where the lens distance scale is focused... it should be about right at all distances (infinity for very distant objects, 4 m for things 4 m away, etc) To diagnose what's happening with the KM, focus your 50mm lens as close as it will go. Now measure the distance from the film plane to the thing in focus -- it should match the distance scale on the lens. Now do the same thing for infinity (or at least "down the street"). When my Nikon was acting up, the distances on the lens didn't match at all what I was seeing in the viewfinder... so if I focused the lens down to 1 m or so, things 1.5 m or so away were in focus in the viewfinder... When I got the film back, it was focused on the things 1 m away, because nothing was wrong with the lens... the camera viewfinder was just wrong... You can do the measuring part without film in the camera, but you would obviously need to shoot a few frames to tell for sure... Finally, if all this comes out right where it should be, what are your eyes like? If you wear glasses, you may need a diopter eyepiece to focus the KM. It doesn't have the adjustable diopter like modern DSLRs do... -Eric

03-20-2022, 01:18 AM	#5
Kerrowdown PEG Moderator Join Date: Aug 2008 Location: Highlands of Scotland... "Hold Infinity in the palm of your hand" - William Blake Photos: Gallery Posts: 57,863	Welcome to the forum, hope you get your issues resolved promptly.

03-20-2022, 05:26 PM	#6
rockyhorror1297 New Member Join Date: Mar 2022 Posts: 21 Original Poster	Thank you for the all the replies! I’ll try out the methods you’ve told me about, I think I’m leaning towards it being an issue with the camera since I noticed right after I got the prism replaced. Below are two pictures shot with the same camera, but the picture of the lady was shot with a 28mm f2.8 lens and I can’t remember exactly but I believe the aperture was set at f16 the picture of the man is with my 50mm lens I believe at f1.7 or close to that

03-20-2022, 05:29 PM	#7
rockyhorror1297 New Member Join Date: Mar 2022 Posts: 21 Original Poster	Here are the photos Attached Images

03-26-2022, 10:34 AM	#8
rockyhorror1297 New Member Join Date: Mar 2022 Posts: 21 Original Poster	Hello everyone! I took the KM to a camera shop and they said everything looks totally fine but I have noticed that the pressure plate seems to have a little more play and doesn’t seem quite as stable as my other Pentaxes. I’ve heard that can throw off focus on images. Any thoughts?

04-15-2022, 06:24 AM	#9
Jonathan Mac Pentaxian Join Date: Apr 2009 Location: Madrid, Spain Posts: 10,911	Originally posted by rockyhorror1297 Hello everyone! I took the KM to a camera shop and they said everything looks totally fine but I have noticed that the pressure plate seems to have a little more play and doesn’t seem quite as stable as my other Pentaxes. I’ve heard that can throw off focus on images. Any thoughts? In theory the pressure plate could only affect focus if what it rests on has been altered or if it's too loose to apply the necessary pressure on the film. Basically anything that would cause it to be further forward or back than it should be. I would say, unless your manual focus skills really are way off, that your camera shop has missed something.