Rolleiflex Hy6...One of the last medium format cameras in production

[GG12]

Suspect the screen mounting might beoff,but the film plane is likely located just fine.

 

[ic-racer]

It is easy to put the screen in upside down, I have done it. Not all the screens have "TOP" molded in the plastic. Although this makes it so far off it is usually pretty obvious what is going on.

 

[Pieter12]

Shot a roll of film in the Hy6 today. I sure hope I'm doing something wrong because I am not impressed. I shot a target about 8 feet away wide open and, looking at the film, it appears to be focusing at a point about 8" closer to the camera than the target I focused on. The same was true of of other frames. I already have the offset at +30 and it only goes up to +33. Setting the offset more positive makes the lens focus further away which means moving the lens elements closer to the film plane. It was too bright to shoot 400 speed film outdoors wide open, but I'm guessing it won't focus at infinity given it has a hard stop at infinity focus. The autofocus seems quite consistent, so I don't think it was getting confused. The main target was black lines on a white background lit with a softbox at a 45 degree angle, but other targets yielded the same result.

I will do another test to confirm the results and maybe use filters and slower film to do some outdoor shots wide open at infinity.

This would be a lot easier if I could leave the back off and simply do the frosted tape stretched over the film plane trick.

Basically, these results seem to say that the lens is too far forward (the same as saying the focusing screen and film plane are too far away from the lens).

Anyone else ever have issues like this?

This is a focus test I did with the camera a while ago. This is a contact scan, the 40mm looks softer than it is because the image was enlarged to match the others. Note that the focus screen should be matte, fresnel side up. That side should be clearly marked "OBEN" along the edge.

 

[Dave Krueger]

It is easy to put the screen in upside down, I have done it. Not all the screens have "TOP" molded in the plastic. Although this makes it so far off it is usually pretty obvious what is going on.

I checked to make sure the glossy side of the screen was facing up, but I did not remove the screen to look at the other side. In any case, if the screen were upside down, the lens would have to be moved more rearward to achieve focus, thereby resulting in a film image where the objects in focus would be further away than the target, not closer. I will, however, check it again.

I think the term focal plane or focus plane, is confusing. A lens has a plane of focus on both sides of the lens. As you shorten the distance on one, you increase the distance of the other. That's why I autofocused with the offset set to -30, then re-autofocused with the offset set to +30, and watched the way the focusing ring turned on the lens. Upon refocusing with the positive offset, the focusing ring turns in the direction of infinity focus (moving the lens elements closer to the film and screen).

Basically, all the offset does is add a correction to whatever the default "in-focus" position would be. If the offset is negative, it moves the lens further from the film plane by a small amount. If the offset is positive, it moves the lens closer to the film plane be a small amount. But, my negatives show that the lens, even with an offset of +30, is still focusing at a point closer than the target. Maybe if would focus correctly with an offset of +40, but offsets don't go that high. Also, it seems like the lens has a hard mechanical stop at infinity focus, so it's possible that a positive offset wouldn't work at infinity (probably not a big deal with a very small offset value).

And, to be clear, with the offset set to +30 on my Hy6, the split image in the viewfinder indicates "in focus" after the camera executes an autofocus. If I reset the offset down to zero, the split image in the finder will not show the image to be in focus after the autofocus occurs. In other words, if I manually focus strictly using the viewfinder image and ignore the arrows, it will not necessarily be in focus on the film plane. I suspect that autofocus can, in many circumstances, be more precise than focusing manually (ignoring the arrows) even using the pop-up magnifier.

 

[Dave Krueger]

This is a focus test I did with the camera a while ago. This is a contact scan, the 40mm looks softer than it is because the image was enlarged to match the others. Note that the focus screen should be matte, fresnel side up. That side should be clearly marked "OBEN" along the edge.

View attachment 257369

This paragraph from the manual seems to conflict that, but I will check it again. I would hope they wouldn't put the screen in upside down from the factory, but I would be very happy if it were that simple.

 

[ic-racer]

If the offset is negative, it moves the lens further from the film plane by a small amount.

This shifts the image plane (rear of camera) toward the front. Closer to the camera body and rear of lens.

https://www.photrio.com/forum/threa...eras-in-production.177790/page-7#post-2333078

 

[ic-racer]

The fresnel is on top and mat surface toward the mirror. Make sure you push the front of the fame down so it snaps in to place.

 

[Dave Krueger]

I will run another roll and do enough shots to exhibit the change in focus with the offset at positive and negative values and using just the screen (without the arrows or autofocus) to focus. I will also check the focusing screen orientation just to be sure. My flat bed scanner scans negatives, so I will even figure out how to do that if need be.

 

[Dave Krueger]

This shifts the image plane (rear of camera) toward the front. Closer to the camera body and rear of lens.

https://www.photrio.com/forum/threa...eras-in-production.177790/page-7#post-2333078

I doubt we're ever going to agree on this. If the lens focuses closer to infinity when I adjust the offset more positive, it has to be moving the lens toward the film plane. In any case, my next set of film tests should verify or refute what I'm saying.

By the way, this camera has firmware version v3.30. Is that you have? It would be a shame to argue about this and find that the problem is due to a firmware bug.

 

[ic-racer]

All motion is relative. As the lens moves forward, away from the camera body, the focal plane (in the back of the camera) follows and moves closer to the camera body.

You have to convince yourself one way or the other with the tests. That is the best way to do it.

 

[Pieter12]

I stand corrected. It is the glossy side up.

 

[Dave Krueger]

I have another bit of info. I am focusing on a target that is 12 feet (3.6 m) away. The camera Status II screen lists "focus" and 'target". After focusing, they are the same. When I set the offset to +30, it says 5.1. After changing it to -30, it says 3.5. That seems to suggest that the camera is focusing closer as the offset goes negative. Assuming the units are in meters, the 3.5 value is a lot closer to reality than the 5.1 value. At offset 0, it reads 3.9. It indicates the "target" value in real time without actually activating autofocus button, but the "focus" value only updates after autofocus activation.

This is so cool. I really want to love this camera.

At one point today it displayed a message that said autofocus fail, but it went away. I also noticed one other thing. I have the camera focus mode set to manual and then use the little elongated button at focus mode panel to activate autofocus. When I turn the focusing ring on the camera manually (with no autofocusing active), it sometime gets to a point where it turns a little harder. That "harder" spot is not always at the same distance and sometime it's not there. Anyone else experience that?

 

[Dave Krueger]

I stand corrected. It is the glossy side up.

I should be okay then. Being an old shaky guy, I'm hesitant to remove it if I don't have to.

 

[AgX]

Note that the focus screen should be matte, fresnel side up.

Matte and fresnel surfaces are on opposing sides. Unless sandwhiched together.

 

[ic-racer]

Here is a diagram of how the focus offset behaves on my camera (small upward arrow is film plane).

 

[Dave Krueger]

Here is a diagram of how the focus offset behaves on my camera:
View attachment 257382

Okay, here is how I'm interpreting your diagram for a given subject distance where a perfect camera and zero offset results in perfect focus on a sensor perfectly positioned.

If the sensor plane is too far forward, the -30 offset moves the lens further forward to compensate. If the sensor plane is too far rearward, the +30 offset moves the lens further rearward to compensate. In both cases the subject distance is the same, but the sensor position changed, so the lens was moved in the same direction by the same amount to compensate. The movement of the lens is accomplished by effectively changing the angle of the focus ring slightly.

If the sensor plane is constant (as the film is in my camera), moving the lens further forward is the same as focusing closer and moving the lens further rearward is the same as focusing further away. Which is what I've been describing. With a zero offset, by camera focuses too close. Setting the offset to +30, moves the lens further rearward by moving the focus in the direction of infinity. The film plane hasn't moved, so this improves the focus. The problem is that the focus is so far off on my camera, that the improvement isn't quite enough.

In my case, instead of the sensor being in the wrong place, I believe the lens elements are too far forward, so compensation is accomplished by moving the lens slightly more rearwards during autofocus (positive offset). This is supported by the fact that when I manually focus the lens (using the screen only) on a target 3.6 m away, the distance info from the lens says the focus is set at 5.0 m. The distance value from the lens doesn't change with the offset. It's hard coded into the lens based on the position of the focusing ring. But, a 5 m focusing distance puts the lens elements slightly closer to the film, just like the +30 offset does for autofocus.

So, I guess we're explaining the same thing from two different points of view.

In any case, with the offset set at +30, the focus was still slightly too close, But, since it goes up to +33, there's a possibility that the extra 3 points might just be enough to bring it in the last few inches. I plan to test that...

 

[Pieter12]

 

[reddesert]

I don't have one of these cameras. But I know it's easy to make sign errors in reasoning about focus. I'd suggest setting up a target that runs obliquely across the field of view, like a picket fence or a yardstick with one side closer than the other. Focus on some landmark in the center. Take images at a range of values of the offset (eg -30, -20, -10, 0, +10, +20, +30) focusing each time. You may want to do that for both AF and manually focused just to be sure (since I don't have one, I don't know if this number is just affecting the AF system). Then develop the film and look for where the point of best focus is and how it moves.

 

[Dave Krueger]

View attachment 257387

Yes. It adjusts the focal plane toward the camera by moving the lens in the same direction (forward), which is accomplished by rotating the focusing ring in the direction of closer focus.

 

[ic-racer]

Did you download the 'extra' manual that explains one way to set the focus offset? In the description he is using a digital back and trial-and-error. In fact the "-" and "+" adjustment is downplayed. Just adjust until it is right. Film will be the same method, it will take longer, because the film has to be processed.
Also, make sure your film back is snug in the keepers.

...
7. inspect your shots at 100%.Visually inspect to see when the focus is improved.This can be done in either Leaf Capture live view, or alternatively, one can take a range of shots to a compact flash card and then inspect them in C1.
8. Once you know where the best general range for your lens, repeat the process using smaller increments to get the precise value, working more precisely (+3, +4, +5) to get the best offset for each lens.
Thats all to it. It takes about an hour or so (the first time) for each lens to learn what the offset is for that lens, but you only have to do it once. Once you get the hang of it, you can get the general offset much faster and then jump to getting the precise setting much sooner.
Typical ranges? A few lenses are at 0 or perhaps +5. Most of my lenses are around +15, and I have heard of some being at +30. Rare to hear of any (-), meaning that the sensor locations are consistently off from the film plane in one direction.

 

[Dave Krueger]

I don't have one of these cameras. But I know it's easy to make sign errors in reasoning about focus. I'd suggest setting up a target that runs obliquely across the field of view, like a picket fence or a yardstick with one side closer than the other. Focus on some landmark in the center. Take images at a range of values of the offset (eg -30, -20, -10, 0, +10, +20, +30) focusing each time. You may want to do that for both AF and manually focused just to be sure (since I don't have one, I don't know if this number is just affecting the AF system). Then develop the film and look for where the point of best focus is and how it moves.

That is exactly what I intend to do. In fact, that list of offsets is identical to what I already wrote down in my list of exposures (among a few others).

 

[Pieter12]

That is exactly what I intend to do. In fact, that list of offsets is identical to what I already wrote down in my list of exposures (among a few others

This works too.

 

[Dave Krueger]

Did you download the 'extra' manual that explains one way to set the focus offset? In the description he is using a digital back and trial-and-error. In fact the "-" and "+" adjustment is downplayed. Just adjust until it is right. Film will be the same method, it will take longer, because the film has to be processed.
Also, make sure your film back is snug in the keepers.

Yeah, film is taking a lot longer, but the first roll I shot was just with the offset adjusted to so that the autofocused image would be in focus on the focusing screen, but on the film the focus was still about 8 inches off at 8 feet. I plan to expand on that tonight with a little better setup and a plan to actually vary the offsets through several values. I happen to have very little 120 film at the moment an it's all expired. A digital back would be very handy right now, but I'll do okay with film.

 

[Dave Krueger]

This works too.

View attachment 257393

That's very similar to what I used when I shot the first roll, but I figured there's a possibility that the angled surface might induce some confusion into the autofocusing algorithm. I've had one of those for years and have used it with 35mm cameras, but I've never tested a camera with it that has offset capabilities. 35mm cameras are generally quite accurate, although not prefect. I've never had one this far off, though. Not even close.

 

[GG12]

Did you download the 'extra' manual that explains one way to set the focus offset? In the description he is using a digital back and trial-and-error. In fact the "-" and "+" adjustment is downplayed. Just adjust until it is right. Film will be the same method, it will take longer, because the film has to be processed.
Also, make sure your film back is snug in the keepers.

Glad someone is looking at it! It was written some time ago, before C1 had a good live view on the digital backs. Not to repeat what was noted above, but this is a critical adjustment largely used for digital backs. It may have relevance for film, but in general, I've not heard of it being used for those as much. Something else seems off here.