focus issues Mamiya c330

bhaning · Sep 8, 2021

I was gifted a Mamiya c330 kit by a relative. It seems to be in good working order except my percentage of in focus photos is low. I replaced the foam seals in the back door and the foam under the focusing screen when I received it. The problem is most of my photos are out of focus. The photos were hand held, but I think I kept the shutter speeds up. I have not shot another roll on a tripod to confirm the focus problem is not due to camera shake, but I doubt it. I can shoot a test roll on a tripod I guess. If that is still unfocused should I send it off for a CLA? I used the same 80mm lens on my c220 and the photos were mostly in focus.

pbromaghin · Sep 8, 2021

It sounds like the work may have left the distance to the focusing screen a wee bit more or less than the film plane. When this happened to my C33, it ruined a lot of pretty important family shots. My tests showed that the difference was only 1mm. The repair manual (available online) shows both how to determine this and how to fix it. I found it a fascinating read and sent it right off to a repair man. However, you have already done most of the needed work once and proven yourself mechanically sophisticated enough to fix it without having all the microscopic screws spew all over your floor.

grahamp · Sep 9, 2021

What screen is in the C330? There are some designed for particular aperture lenses and special use. It's probably the standard microprism or split image, but worth checking.
What focus aid are you using? The original C330 WLF flip up finder magnifier does not always come level, and may not suit your vision anyway - you have to be able to focus the edge of the focus aid on the screen. As I get older I realize that my vision is not constant and some cameras really bring that out 8-(

Then there are the camera issues. If the camera has been dropped, the lens panel may not be parallel to the film plane. The focus screen could be been wrongly reassembled. If you have another lens, check that the issue is consistent to rule out a lens pair issue. If you can try the lens on another camera body you can confirm the lens is good.

My approach is to start with the simplest and least invasive possibility first, verifying as I go. Assume nothing!

grat · Sep 9, 2021

Don't forget the lenses usually have shims in them as well. If someone has had the lens apart, the shims might have gotten lost or rearranged.

bhaning · Sep 9, 2021

Thanks for the suggestions. The screen on the c330 seems to be a regular screen with split center. I had not considered it was my changing eyesight. I struggle a little with trying to use the flip up magnifier and my bifocals. I think I may have better luck focusing with just looking for the focus to snap instead of checking carefully with the magnifier. The magnifier does seem to be properly aligned. I have the prism and waist level finders, so I may try focusing with each and see which works better for nailing the focus. I can also compare the 55mm and the 80mm to see if it is related to which lens I'm using. I'll do the same test shots with my c220 to see if happens on the other camera. I guess there is no short cut to ruling out all the possible causes for my lack of focus. I'll shoot a couple test rolls and process them this weekend.

xtolsniffer · Sep 9, 2021

An easier way to check focus is opening the back and putting a pices of ground glass at the film plane. You can then compare film plane to viewfinder.

gone · Sep 9, 2021

What xtolsniffer said. Set it on a tripod, put the lens on B, lay a piece of gg on the film rails, focus on something 50-100 feet away, and compare what you see on the back w/ what is on the top. You'll undoubtedly need to re shim the top focus screen after replacing the foam as you mentioned. It's an easy calibration though. If you don't have a loupe to ck the focus an SLR lens will work.

bhaning · Sep 9, 2021

Thanks for the advice for checking with ground glass. Will the ground glass from a 4x5 camera work to test the c330?

pbromaghin · Sep 9, 2021

bhaning said:
Thanks for the advice for checking with ground glass. Will the ground glass from a 4x5 camera work to test the c330?

No , it won't. It is too big. The film plane is about 1/4 inch closer than the parts of the camera that the glass would rest on. You would need a glass cut to fit on the film guides.

Auer · Sep 9, 2021

Wax paper works in a pinch as ground glass substitute.

mshchem · Sep 9, 2021

Auer said:
Wax paper works in a pinch as ground glass substitute.

+1

mshchem · Sep 9, 2021

Flat waxed paper

reddesert · Sep 9, 2021

You can cut a piece of clear plastic (like from a CD case) and put scotch tape or waxed paper, etc to make an improvised ground glass. For focus testing, you could also cut a frame of opaque plastic with a hole and stretch scotch tape or wax paper over the hole. It's also not hard to grind your own ground glass with some glass from a picture frame and 600 grit silicon carbide, but that's a little more involved.

Compare 1. the focus at the film rails with the GG, 2. the focus at the screen, and 3. the focusing scale. Hopefully, 2 of the 3 will agree.

markjwyatt · Sep 9, 2021

I took my C330f, and put a ground glass on the film guides on the sides of the opening to the lens. Just eye balling it focus looks good (I have had no problem with focus). This ground glass came from an old 6x9.5 cm plate holder focusing hood. I did have to remove the film spool to avoid interference.

I was worried about the rollers. I placed a precision ground metal surface on the rollers- inside the film guide surfaces, and slid the ground metal component (think of it as a coating die lip) outwards thinking the roller may be at the same height as the film guide ground surface. In fact, the precision ground metal part stopped at the edge of the guide indicating the rollers are a little below the ground plane of the film guide. The four metal surfaces (including the red dot, etc.) outside the film guide are higher, and the glass needs to be narrow enough to fit inside them, which mine does.

Not sure if this works for other models (I do have a C220f and a C2, but have not looked).
EDIT: Got curious- C2 and C220f are configured the same (C220f slight difference on the outer rails, but it makes no difference for this purpose).

bhaning · Sep 12, 2021

I finally found the glass, glass cutter and 600 grit. I'll make the ground glass today and check the focusing screen vs the film plane.

Don_ih · Sep 12, 2021

Make sure to check the focus with the aperture wide open. It may also be more illuminating to focus on something close, since it will give you good separation between the object in focus and the out of focus background.
I always have trouble finding my glass cutter, also - and I think I have three of them...

bhaning · Sep 12, 2021

Ok, I made the ground glass and checked the focus on the screen vs the ground glass film plane. The focus is correct on both. I checked all three lenses(55mm, 80mm, 180mm) all
focus fine on the screen and ground glass, and focus fine near and at infinity. I also tried the prism finder vs the waist level finder and they both focused the same as the ground glass. So I think my hand holding technique needs to improve. I'm going to try a roll on a tripod with cable release to see if they are in focus. I'll give an update after my test roll.

pbromaghin · Sep 13, 2021

It's either good news or bad news!

Jojje · Sep 13, 2021

Photograph a tape measure with full aperture at an angle, say 30 degrees (with a tripod of course), focusing on a near distance (3ft) and mark the point where you focused. From the negative you should see if the focus is too far away or near.

bernard_L · Sep 13, 2021

Auer said:
Wax paper works in a pinch as ground glass substitute.

Planeity?

Auer · Sep 13, 2021

bernard_L said:
Planeity?

Planitude.

bernard_L · Sep 14, 2021

Auer said:
Planitude.

Neither. Regardless, the meaning was conveyed: a ground glass is a (much) better solution than wax or tracing paper.

Auer · Sep 14, 2021

bernard_L said:
Neither. Regardless, the meaning was conveyed: a ground glass is a (much) better solution than wax or tracing paper.
View attachment 285342

Most excellent if not in a pinch my dude.

grat · Sep 15, 2021

Translucent scotch tape (not the clear stuff).

focus issues Mamiya c330

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