Pentax 645NII Focusing nightmare

Wolfeye · 11-23-2015, 09:12 AM

I recently acquired a used 645NII and have had trouble focusing it. The issue really crops up when using a manual-focus 75mm 2.8 lens at f2.8 which is already very shallow in DOF. The AF indicator light comes on, indicating focus, but when I get the images developed they are not in focus. I'm guessing the camera is junk because it's too expensive to fix this, unless my technique can be improved. I did notice the AF indicator light was very difficult to get steadily lit.

Suggestions and commiserations appreciated.

See attached shot as an example.

Last edited by Wolfeye; 06-21-2016 at 06:44 AM.

**bobbotron** · 11-23-2015, 09:29 AM

You could just manually focus it and ignore the focus confirmation. I have an original 645, it focuses great manually, the viewfinder is quite bright.

Wolfeye · 11-23-2015, 10:07 AM

Originally posted by bobbotron

You could just manually focus it and ignore the focus confirmation. I have an original 645, it focuses great manually, the viewfinder is quite bright.

Aye, but the stupid 645NII comes with a cheap focusing screen. No split image nor microprism. It's hard as hell to focus using just ground glass, at least at my age and vision. I'd replace the screen but don't want to lay out another hundred bucks unless I have to.

AquaDome · 11-23-2015, 10:21 AM

Send it to me. I will give it a firm talking-to and we will see how it goes from there.

The original 645 has a split-image screen. You could pick up an original 645 body for less than the cost of an auto-focus lens.

Beattie Intenscreens are only available for the original 645. There was a split-image screen offered for the 645n & nII, but I have never come across one. The screen from the original 645 does not transfer to the 645n - believe me, I tried.

stevebrot · 11-23-2015, 11:40 AM

Originally posted by Wolfeye

Aye, but the stupid 645NII comes with a cheap focusing screen. No split image nor microprism. It's hard as hell to focus using just ground glass, at least at my age and vision. I'd replace the screen but don't want to lay out another hundred bucks unless I have to.

The camera definitely not very intelligent, but I have used the ground glass and with the 75/2.8 you should be able to attain acceptable focus.

Before declaring the camera as junk, I would consider some examination of technique. On the example photo, the details at center of frame appear to be in focus. I would have to examine the negative to be sure, but it appears the AF focus confirmation is not off by much. At 1 meter and f/2.8 your DOF is only about 4 cm. That would be enough to explain much of the softness in the frame with the remainder being due to the lens being wide open and/or a little camera motion (ambient light ghosting @ 1/60s) in this flash shot.

Another consideration might be the quality of the scan. How do you do your scans?

Steve

**bobbotron** · 11-23-2015, 12:12 PM

Originally posted by AquaDome

Send it to me. I will give it a firm talking-to and we will see how it goes from there.

I could also provide this service.

I would also punish it with 40 days of landscape photography.

Wolfeye · 11-23-2015, 12:13 PM

Originally posted by AquaDome

Send it to me. I will give it a firm talking-to and we will see how it goes from there.

The original 645 has a split-image screen. You could pick up an original 645 body for less than the cost of an auto-focus lens.

Beattie Intenscreens are only available for the original 645. There was a split-image screen offered for the 645n & nII, but I have never come across one. The screen from the original 645 does not transfer to the 645n - believe me, I tried.

I have the original 645 too, thanks for the info. I might have tried that. The 645NII purchase was a whim, desire for mirror lockup. I will shoot a roll of B&W tonight and be very careful with the focusing, see if that helps. Otherwise I will try and get a new screen. I've only seen them from Japanese hoarders.

11-23-2015, 09:12 AM	#1
Wolfeye Veteran Member Join Date: Jul 2013 Photos: Albums Posts: 782	Pentax 645NII Focusing nightmare I recently acquired a used 645NII and have had trouble focusing it. The issue really crops up when using a manual-focus 75mm 2.8 lens at f2.8 which is already very shallow in DOF. The AF indicator light comes on, indicating focus, but when I get the images developed they are not in focus. I'm guessing the camera is junk because it's too expensive to fix this, unless my technique can be improved. I did notice the AF indicator light was very difficult to get steadily lit. Suggestions and commiserations appreciated. See attached shot as an example. Last edited by Wolfeye; 06-21-2016 at 06:44 AM.

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11-23-2015, 09:29 AM	#2
bobbotron Site Supporter Join Date: Jan 2015 Location: Ottawa, ON Photos: Gallery Posts: 3,349	You could just manually focus it and ignore the focus confirmation. I have an original 645, it focuses great manually, the viewfinder is quite bright.

11-23-2015, 10:07 AM	#3
Wolfeye Veteran Member Join Date: Jul 2013 Photos: Albums Posts: 782 Original Poster	Originally posted by bobbotron You could just manually focus it and ignore the focus confirmation. I have an original 645, it focuses great manually, the viewfinder is quite bright. Aye, but the stupid 645NII comes with a cheap focusing screen. No split image nor microprism. It's hard as hell to focus using just ground glass, at least at my age and vision. I'd replace the screen but don't want to lay out another hundred bucks unless I have to.

11-23-2015, 10:21 AM	#4
AquaDome Veteran Member Join Date: Jan 2014 Location: New Carlisle, IN Photos: Gallery \| Albums Posts: 1,475	Send it to me. I will give it a firm talking-to and we will see how it goes from there. The original 645 has a split-image screen. You could pick up an original 645 body for less than the cost of an auto-focus lens. Beattie Intenscreens are only available for the original 645. There was a split-image screen offered for the 645n & nII, but I have never come across one. The screen from the original 645 does not transfer to the 645n - believe me, I tried.

11-23-2015, 11:40 AM	#5
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	Originally posted by Wolfeye Aye, but the stupid 645NII comes with a cheap focusing screen. No split image nor microprism. It's hard as hell to focus using just ground glass, at least at my age and vision. I'd replace the screen but don't want to lay out another hundred bucks unless I have to. The camera definitely not very intelligent, but I have used the ground glass and with the 75/2.8 you should be able to attain acceptable focus. Before declaring the camera as junk, I would consider some examination of technique. On the example photo, the details at center of frame appear to be in focus. I would have to examine the negative to be sure, but it appears the AF focus confirmation is not off by much. At 1 meter and f/2.8 your DOF is only about 4 cm. That would be enough to explain much of the softness in the frame with the remainder being due to the lens being wide open and/or a little camera motion (ambient light ghosting @ 1/60s) in this flash shot. Another consideration might be the quality of the scan. How do you do your scans? Steve

11-23-2015, 12:12 PM	#6
bobbotron Site Supporter Join Date: Jan 2015 Location: Ottawa, ON Photos: Gallery Posts: 3,349	Originally posted by AquaDome Send it to me. I will give it a firm talking-to and we will see how it goes from there. I could also provide this service. I would also punish it with 40 days of landscape photography.

11-23-2015, 12:13 PM	#7
Wolfeye Veteran Member Join Date: Jul 2013 Photos: Albums Posts: 782 Original Poster	Originally posted by AquaDome Send it to me. I will give it a firm talking-to and we will see how it goes from there. The original 645 has a split-image screen. You could pick up an original 645 body for less than the cost of an auto-focus lens. Beattie Intenscreens are only available for the original 645. There was a split-image screen offered for the 645n & nII, but I have never come across one. The screen from the original 645 does not transfer to the 645n - believe me, I tried. I have the original 645 too, thanks for the info. I might have tried that. The 645NII purchase was a whim, desire for mirror lockup. I will shoot a roll of B&W tonight and be very careful with the focusing, see if that helps. Otherwise I will try and get a new screen. I've only seen them from Japanese hoarders.