Pentax 67ii front focus - easy to fix?
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I hope you really like that lens-as in you never plan to use any others-because if you modify the body no other lens will work.
Yes, it's an slr. The focus on focusing screen and film must match, regardless of lens.
Work the problem the other way...it is an SLR camera, so if the image from the 130/f2 lens when in focus on the ground glass screen does not come out focused on the film plain neither would an original Pentax lens. In other words, not a camera problem if the modern lenses work.
My $0.02 worth.
My $0.02 worth.
Last edited:
MattKing
Moderator
So a test is in order.
At our old place, I had a fence that was perfect for focus testing! Sadly, not so much where we are living now.
There are too many variables to say it's due to focusing screen.
These issues can come from quite a few different sources and it will depend on how much is the focus plane out. Test with a target that can show you exact focus plane should be able to provide more detail.
1. Focusing screen height probably never changed since it left factory unless someone tried adjusting it. It can be adjusted.
2. Mirror angle could be out of 45 degree angle
3. Film type or thickness or curling properties could also impact it in some way
4. Above #3 in conjunction with pressure plate could cause some issues. #3 and #4 are not likely as they would cause backfocus unless something is really bent out of shape.
5. Body lenght/focal flange distance out of tolerance
6. The lens itself could have some aberrations that could affect the ability to focus and potentially change the plane of focus.
7. Most viewfinders have magnification of only 3-4x times. That means if you manage to hit focus to the best ability of your vision, you're only actually seeing the negative magnified 3-4 times. So if used without tripod or any other movements or focusing error, it will be miss-focused to some extent if the depth of field is shallower than the result of all of these factors. 130mm f2 lens might produce plus/minus 1-1.5 cm of reasonably focused DOF. If that lens is extremely sharp and contrasty, it will already look bad if focus is missed only by a small amount. If your lens is Schneider Cinelux 130mm f2, it's a contrasty lens and will look bad with smaller focusing error.
For example, in my experience, Hasselblad 110mm f2 and 150mm f2.8 are easier to focus precisely for me than 150mm and 180mm lenses as it somehow shows more contrast and are better in focus differentiation.
Some wide open lenses like projection lenses can have different aberrations and it can be hard to achieve critical focusing.
For focusing calibration it's recommended to use 30-60x magnification microscope directly on the focusing screen as that's the only way to examine focus at more relevant magnification.
It's often seen that people focus at 3-4x magnification but inspect at 30-40x magnification. That kind of pixel (grain) peeping only makes sense if the image is critically focused.
Here's one of the links for focusing targets with some explanations. You can use Siemens star or some other pattern that's easily visible for manual focusing.
www.pointsinfocus.com
These issues can come from quite a few different sources and it will depend on how much is the focus plane out. Test with a target that can show you exact focus plane should be able to provide more detail.
1. Focusing screen height probably never changed since it left factory unless someone tried adjusting it. It can be adjusted.
2. Mirror angle could be out of 45 degree angle
3. Film type or thickness or curling properties could also impact it in some way
4. Above #3 in conjunction with pressure plate could cause some issues. #3 and #4 are not likely as they would cause backfocus unless something is really bent out of shape.
5. Body lenght/focal flange distance out of tolerance
6. The lens itself could have some aberrations that could affect the ability to focus and potentially change the plane of focus.
7. Most viewfinders have magnification of only 3-4x times. That means if you manage to hit focus to the best ability of your vision, you're only actually seeing the negative magnified 3-4 times. So if used without tripod or any other movements or focusing error, it will be miss-focused to some extent if the depth of field is shallower than the result of all of these factors. 130mm f2 lens might produce plus/minus 1-1.5 cm of reasonably focused DOF. If that lens is extremely sharp and contrasty, it will already look bad if focus is missed only by a small amount. If your lens is Schneider Cinelux 130mm f2, it's a contrasty lens and will look bad with smaller focusing error.
For example, in my experience, Hasselblad 110mm f2 and 150mm f2.8 are easier to focus precisely for me than 150mm and 180mm lenses as it somehow shows more contrast and are better in focus differentiation.
Some wide open lenses like projection lenses can have different aberrations and it can be hard to achieve critical focusing.
For focusing calibration it's recommended to use 30-60x magnification microscope directly on the focusing screen as that's the only way to examine focus at more relevant magnification.
It's often seen that people focus at 3-4x magnification but inspect at 30-40x magnification. That kind of pixel (grain) peeping only makes sense if the image is critically focused.
Here's one of the links for focusing targets with some explanations. You can use Siemens star or some other pattern that's easily visible for manual focusing.
DIY Autofocus Calibration Target • Points in Focus Photography
As much as I swore off AF testing and calibrating, I’m back at it again. This time I’ve decided to forgo the sheet paper targets and build a target
www.pointsinfocus.com
Possibly so. I had a similar issue with a Mamiya 6 and the 150mm lens but not with the 50mm or 75mm. I sent the camera and 150mm lens to Mamiya in Munich for adjustment, and when it came back, the issue was resolved for all lenses with this body. From that ,I conclude it was a body-only problem, which showed with the 150mm lens the most, but maybe it was a lens-only problem?
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