How to determine Mamiya 7 diopter correction?

Hey all, new here.

I apologize if this has likely been asked 1000 times, but I can't seem to find a good answer online. I just received a Mamiya 7 today. Everything looks wonderful and operates beautifully, and the focusing patch is great, but the red light meter reading and shutter speed readings within the viewfinder are incredibly blurry. I understand there are diopters that Mamiya made, but as someone who doesn’t wear glasses, I’m having the hardest time determining which one I need. What’s the best way to do this?

I tried to see what adjustment I made on a digital camera, and the most I could determine was that I turned it all the way to the negative side and that got it in focus for me.

Any insight would be extremely helpful. Thanks so much!

You would need to go to an optician so they can determine the correlation needed.

ic-racer said:

You would need to go to an optician so they can determine the correlation needed.

Click to expand...

Forgive my ignorance, as I’ve never needed to go to one, but do I just walk in with the camera and ask them to help me figure this out?

If you have perfect vision, everything should be sharp in the Mamiya 6/7 viewfinder, both the rangefinder patch and the shutter speed display.

If the rangefinder patch and the over all view is sharp, but the shutter display is blurry. then that may indicate something wrong inside the viewfinder system.

If everything is blurry, check to see if a correction lens (diopter) has been installed on the eyepiece, the correction lenses are rectangular and snap into the viewfinder . Check the manual for a diagram showing what it looks like with and without this installed.

For someone with perfect vision, a diopter of 0 is what is typically used to make everything in the viewfinder focus at infinity. A dipoter of +1 means that everything in the viewfinder should appear at 1m. A lot of people preferred something between infinity to 1m. With they Mamiya 6/7, you use a diopter that is equivalent to your prescription. (Note: not all cameras are this way, on Hasselblads, the the eyepiece objective is built into the correction diopter ie: you replace the front lens instead of adding a lens, so a 0 dipoter eyepeice would be different)

itsdoable said:

If you have perfect vision, everything should be sharp in the Mamiya 6/7 viewfinder, both the rangefinder patch and the shutter speed display.

If the rangefinder patch and the over all view is sharp, but the shutter display is blurry. then that may indicate something wrong inside the viewfinder system.

If everything is blurry, check to see if a correction lens (diopter) has been installed on the eyepiece, the correction lenses are rectangular and snap into the viewfinder . Check the manual for a diagram showing what it looks like with and without this installed.

For someone with perfect vision, a diopter of 0 is what is typically used to make everything in the viewfinder focus at infinity. A dipoter of +1 means that everything in the viewfinder should appear at 1m. A lot of people preferred something between infinity to 1m. With they Mamiya 6/7, you use a diopter that is equivalent to your prescription. (Note: not all cameras are this way, on Hasselblads, the the eyepiece objective is built into the correction diopter ie: you replace the front lens instead of adding a lens, so a 0 dipoter eyepeice would be different)

Click to expand...

Hmm. Okay. Would the fact that I have to turn my digital cameras all the way to the negative have any correlation?

I went to the drug store and tried on those cheap readers and noticed that anything + just makes it worse.

Christopher_Ray said:

Hey all, new here.

I apologize if this has likely been asked 1000 times, but I can't seem to find a good answer online. I just received a Mamiya 7 today. Everything looks wonderful and operates beautifully, and the focusing patch is great, but the red light meter reading and shutter speed readings within the viewfinder are incredibly blurry. I understand there are diopters that Mamiya made, but as someone who doesn’t wear glasses, I’m having the hardest time determining which one I need. What’s the best way to do this?

I tried to see what adjustment I made on a digital camera, and the most I could determine was that I turned it all the way to the negative side and that got it in focus for me.

Any insight would be extremely helpful. Thanks so much!

Click to expand...

By the way …

itsdoable said:

For someone with perfect vision, a diopter of 0 is what is typically used to make everything in the viewfinder focus at infinity. A dipoter of +1 means that everything in the viewfinder should appear at 1m.

Click to expand...

Aren't diopter ratings used to represent additive correction, instead of simply indicating the final focal length? In other words, +1 correction on this Mamiya is not the same as +1 on another camera, and not the same as an absolute 1 diopter (1m) focal length.

This is why I always found the advice of simply going to a doctor confusing. I have never been to an optometrist, but I can clearly see that the stock finders on my Nikons and Leicas have different focal lengths. One of them needs -0.5 more than the other to match my vision. My C330s stock finder is razor sharp without a correction, while the Hasselblad needs -1. Basically you need to know the focal length of the stock finder (not easy to find!), and then do the math. What I do instead is I try different eyepieces between 0 and -1.5 in 0.5 increments and pick the sharpest.

When I dial +1 on the Hasselblad chimney finder, everything gets extremely blurry, yet I my vision at 1m distance is perfect.

Camera store is not an optometrist. If your eyes need correction, an optometrist can determine the correction needed.
If you have never been to see an optometrist, you may find it fascinating. They have a machine with essentially all the camera eyepiece diopters on a rotating wheel. They ask you to view a chart and YOU tell them which lens gives best vision.

The camera already has a negative lens to make the viewfinder appear to be about the same distance as the chart the optometrist uses. So the lens the optometrist suggests is usually the correct one.

Above would be for a simple case of myopia since you indicated you eye is too powerful (" I turned it all the way to the negative side.."). However, you may als have presbyopia or a combination. Possibly astigmatism (barrel lens) too.

itsdoable said:

If you have perfect vision, everything should be sharp in the Mamiya 6/7 viewfinder, both the rangefinder patch and the shutter speed display.

If the rangefinder patch and the over all view is sharp, but the shutter display is blurry. then that may indicate something wrong inside the viewfinder system.

If everything is blurry, check to see if a correction lens (diopter) has been installed on the eyepiece, the correction lenses are rectangular and snap into the viewfinder . Check the manual for a diagram showing what it looks like with and without this installed.

For someone with perfect vision, a diopter of 0 is what is typically used to make everything in the viewfinder focus at infinity. A dipoter of +1 means that everything in the viewfinder should appear at 1m. A lot of people preferred something between infinity to 1m. With they Mamiya 6/7, you use a diopter that is equivalent to your prescription. (Note: not all cameras are this way, on Hasselblads, the the eyepiece objective is built into the correction diopter ie: you replace the front lens instead of adding a lens, so a 0 dipoter eyepeice would be different)

Click to expand...

I hope that you did not overlook the bolded comment. I believe this is the path to pursue.

Christopher_Ray said:

Hmm. Okay. Would the fact that I have to turn my digital cameras all the way to the negative have any correlation?

I went to the drug store and tried on those cheap readers and noticed that anything + just makes it worse.

Click to expand...

Needing a negative diopter implies you are near sighted. Typically, people are comfortable with a -1 ~0 diopter. If you need more than that, perhaps you should visit your optometrist for a checkup.

(I should clarify/correct that a -1 diopter on a viewfinder mean the image should appear to focus at 1m, a +1 diopter lens is one that has a 1m focal length, so if you place it infront of your eye, it should make eveyrhing focus beyond infinity - negative diopters for nearsightedness, positive diopters for farsightedness)

A diopters are use primarily for eye perscritons, and are, by itself is as follows.

-2 diopter = concave lens with a 0.5m focal length
-1 diopter = convcave lens with a 1m focal length
-1/2 diopter = concave lens with a 2m focal length
0 diopter = flat glass
1/2 dipoter = 2m convex lens
1 diopter = 1m convex lens
2 diopter = 0.5m convex lens

They are used to correct your vision.

If your perspiration requires a -2 diopter lens (nearsightedness), then placing a 0.5m concave lens in front of your eyepiece will make eveyrthing look good, which is the way the Mamiya 7 dipoters work.

Hasselblad eye correction accessories replace the lens that is already there. The wasit level finder has a convex lens with a focal length of 6cm, becasue the focus screen is 6cm below the lens, so to view it as if it was at infinity, you need a .... 6cm lens. That lens is labelled 0 diopter for that system. if you want a -2 diopter lens for that waste level finder, you need a convex lens that has a focal length of 5.36cm - which would make the focus screen appear to be 0.5m away. And this lens would be labelled -2 diopter for this system. And to make it more confusing, the lenses on the 45 and 90 prism are different, because the distance from the eyepiece to the screen is different on those prisms. But the idea is that, if your optometrists says you need a -2 dipoter eyeglass correction, you can just buy the Hasselblad part that is labelled -2 diopter for that system, and it should match.

Christopher_Ray said:

Hmm. Okay. Would the fact that I have to turn my digital cameras all the way to the negative have any correlation?

I went to the drug store and tried on those cheap readers and noticed that anything + just makes it worse.

Click to expand...

Drug store reading glasses are all +ve. You have determined that you need -ve.
Can you see everything in the Mamiya7 with your eyeglasses?
If so, you need to find a suitable Mamiya diopter with the appropriate -ve value.

Do you have significant cylindrical correction (astigmatism) which you can read from your optical prescription? If so, choosing a diopter (which have zero cylindrical correction) will be a little more complicated.

Your eyeglass prescription will be a guide. But I have the same problem as you and I have found by trial and error that slightly different values are better in different cameras (Nikon SLR, Mamiya7, Leica M6). If you're between values, weaker is better than stronger in my opinion (and depending on your age, your need for strong -ve will likely reduce a bit as time passes.)