Sharpness - Mamiya C330

"Peter Chant" wrote:
Jim Hemenway wrote:

This was highlighted when on a recent film there was one
exceptionally sharp print.
Peter:

Do you wear glasses, especially bifocals?

Yes, but not bi-focals.

Perhaps you're old enough to have prespyopia... the inability of the eye
to focus sharply on nearby objects, resulting from loss of elasticity of
the crystalline lens with advancing age.


I hope not I'm thirty five so I consider myself just leaving my late
teens...

You've got about 5 years before your ability to focus begins to go. (I was
quite shocked at 41 or so (a long time ago now) to be told I had "rogan",
the Japanese for prespyopia, since "ro" means "elderly" and "gan" means
"eyes".) It's a real pain. Someone let me play with a Hasselblad 500C/M with
a digital back on it the other day, and I couldn't focus the thing. Yuck.

FWIW, Mamiya makes nice lenses. With the 55/2.8 and 110/2.8 for the Mamiya
645, I found that I could maybe persuade myself that there was some slight
degradation in sharpness at f/2.8 and f/22, but that (in the plane of focus,
of course) they are lovely sharp from f/4.0 to f/16 when shooting Provia
100F. I suppose there might be some slight problems in the corners, but I
never noticed.

David J. Littleboy
Tokyo, Japan

Hi Peter:

Actually it's a solid prism made by Mamiyaflex.

Had I thought more about my response, then I would have added that I
find the chimney finder with its adjustable lens even better for my 65
year old eyes. It also has a CDS light meter inside which is luckily
exactly one stop off, so is easily compensated for.

Jim, "I shouldn't have ended that sentence with a preposition" Hemenway

P.S. My prespyopia began at around age forty.




Peter Chant wrote:

Jim Hemenway wrote:


This was highlighted when on a recent film there was one
exceptionally sharp print.


Peter:

Do you wear glasses, especially bifocals?


Yes, but not bi-focals.


Perhaps you're old enough to have prespyopia... the inability of the eye
to focus sharply on nearby objects, resulting from loss of elasticity of
the crystalline lens with advancing age.



I hope not I'm thirty five so I consider myself just leaving my late
teens...


If one of the twelve frames was sharp then prespyopia may be the cause,
and I think that if that's the case then all you need is a minus lens in
your waist level finder.



I get around the problem by using a prism on my 220F.



The porroprism I assume. I've never had a problem on my 35mm cameras,
including notably my Pentax MZ-5n which I usually use as manual focus and
has no focusing aids on the screen (ie split prism, microprism) - though it
does have dioptre adjustment.

I can see that putting a rather large -ve lens on top the waiste level
finder gives you a problem, either it does not fold - or you need somewhere
to put the lens you have folded it.

Shot several days ago with the C220F:

http://www.half-fast.com/CapeAnn-C220F-12282006/



Jim Hemenway wrote:

Hi Peter:

Actually it's a solid prism made by Mamiyaflex.

Had I thought more about my response, then I would have added that I
find the chimney finder with its adjustable lens even better for my 65
year old eyes. It also has a CDS light meter inside which is luckily
exactly one stop off, so is easily compensated for.

Jim, "I shouldn't have ended that sentence with a preposition" Hemenway

P.S. My prespyopia began at around age forty.




Peter Chant wrote:

Jim Hemenway wrote:


This was highlighted when on a recent film there was one
exceptionally sharp print.


Peter:

Do you wear glasses, especially bifocals?



Yes, but not bi-focals.


Perhaps you're old enough to have prespyopia... the inability of the eye
to focus sharply on nearby objects, resulting from loss of elasticity of
the crystalline lens with advancing age.



I hope not I'm thirty five so I consider myself just leaving my late
teens...


If one of the twelve frames was sharp then prespyopia may be the cause,
and I think that if that's the case then all you need is a minus lens in
your waist level finder.



I get around the problem by using a prism on my 220F.



The porroprism I assume. I've never had a problem on my 35mm cameras,
including notably my Pentax MZ-5n which I usually use as manual focus and
has no focusing aids on the screen (ie split prism, microprism) -
though it
does have dioptre adjustment.
I can see that putting a rather large -ve lens on top the waiste level
finder gives you a problem, either it does not fold - or you need
somewhere
to put the lens you have folded it.

On Fri, 05 Jan 2007 00:56:21 +0000, Peter Chant wrote:

Chaps,

I've got a Mamiya C330f which I am mostly very pleased with. However, I
have noticed that a number of images - though reasonable were not as sharp
as I was expecting. This was highlighted when on a recent film there was
one exceptionally sharp print. Does this sound to you like I need to get
someone to look at the focusing screen / mirror alignment?

I almost exclusively handhold (I can hear the protests now) but zooming in
on the negs / scans does not indicate any symptoms of shake.

I suppose another option is to buy another body off of ebay (bodies on their
own seem to go for much less than lens + body) and see how that is, perhaps
having a go myself on the least good camera.

I doubt if your sharpness problem is equipment related, since it doesn't
occur on every image. My guess would be it's something you are or are not
doing. I'll pose some questions to further your investigation.

Do you need glasses? Bifocals?

Do you use the pop-up magnifier when focusing? You should. All the time,
every time.

Is your focusing screen, mirror and focusing lens clean or loose, etc?
Do you use filters? If you do, the filter needs to be on the focusing
lens when you focus. A filter with 2 air/glass surfaces changes the
optical path which can affect the focus point.

Are any of the "unsharp" pictures shot with the lens wide open or fully
stopped down? This can affect apparent image sharpness due to lens
aberrations, which mostly disappear after stopping down 2 stops, or image
diffusion, which begin to occur as you approach the higher f-stop numbers.
Try to use a moderate f-stop range from at least 2 stops down to 2 stop up
from minimum aperture.

Lastly, here's a quick test you can do to check if focus is out due to
problems in the camera. Mount the camera on a tripod facing a blank wall,
level the camera so it is parallel to the wall, place a focusing target of
sufficient size that it fills the viewfinder entirely. I use a page of a
newspaper, which is mostly fine print. Make sure it's absolutely flat to
the wall. No sags or bulges. Evenly illuminate the target either with
natural or artificial light. A large north facing window opposite the
wall, behind the camera will work. You just want the light even and
diffuse. With no film in the camera, open the back and tape a piece of
fine ground glass over the film gate. Make sure the textured side is at
the film plane and pointed toward the lens. If you don't have any ground
glass, substitute any smooth media that will hold the image. Rear screen
projection material is good. In a pinch, I've used a smooth piece of
heavy waxed paper.

Now, with the taking lens wide open, focus on the center of the
focusing target as you normally do. And use the focusing magnifier.
Remove the focusing hood and place it over the film gate to make it easier
to view the projected image. Is it sharp or out? Now, refocus on the film
gate image making it as sharp as you can. Examine the image focused on
the normal viewing screen. Is it in focus? In both cases, if everything
is working properly, the images should have been in focus for both
procedures.

Repeat the test with the taking lens stopped down to a mid-f-stop, f8 is
good. Compare the results.

Now, without changing the set up, make a test carefully focusing in
the normal manner using medium speed b&w film shooting wide open, stopped
down mid-way, and stopped down all the way. That chromogenic b&w film
that can be processed in color chemistry is fine. You just want to check
if things are in focus on film when they are in the viewfinder. Don't make
prints. Examine the film directly with at least an 8X loupe. If images
are out, take your camera and lens to a tech and have it checked it out.

I know that the Mamiya TLR lenses give excellent results having owned a
C-220 and a couple of lenses years ago, that I shot with professionally --
glamour, advertising, editorial, PR, etc. Never received any complaints
from any ADs or editors about "soft" or out of focus images, unless, of
course, they were suppose to be. ;-) The lens(es) you're using are the
black barrel type? Right? Not the chrome ones?

Stef

my other C330 works just fine...not this one....i use 2.8 i churh for
natual lght....one camer blurrr other sharp as can be

but my other C330 works fine at 2.8..this one don't.............

PRO SHOW_SS wrote:
my other C330 works just fine...not this one....i use 2.8 i churh for
natual lght....one camer blurrr other sharp as can be

Then you need to have the spacers changed for the viewing screen. These
heavy cameras are prone to having the top lens of the pair of lenses
knocked backwards when the camera is dropped (it nearly always lands on
the top lens - you can tell from the filter ring being bent on a lot of
these lenses). This reduces the distance from the top lens to the
focussing screen and also the angle so spacers need to be put on the
focussing screen to get it to agree with the focus on the film.

RolandRB wrote:
PRO SHOW_SS wrote:
my other C330 works just fine...not this one....i use 2.8 i churh for
natual lght....one camer blurrr other sharp as can be

Then you need to have the spacers changed for the viewing screen. These
heavy cameras are prone to having the top lens of the pair of lenses
knocked backwards when the camera is dropped (it nearly always lands on
the top lens - you can tell from the filter ring being bent on a lot of
these lenses). This reduces the distance from the top lens to the
focussing screen and also the angle so spacers need to be put on the
focussing screen to get it to agree with the focus on the film.

Just to expand on that, it is not the lens itself that gets shortened
by an impact (it will just get the filter ring dented) but rather it is
the lens housing that gets knocked back. You will be able to see this
if you look carefully at the affected camera because at infinity the
edge that makes contact with the camera body will touch the housing at
the top before the bottom of the lens housing does. To my way of
thinking, this is a design fault as this is way too easily damaged
considering the rest of the camera is so heavy and prone to being
dropped. Nearly all these camera have added spacer washers and strips
to move the focussing screen up so as to compensate. I think they are
great cameras (I have a few) but you have got to be aware of this
weakness with them and to be on the lookout for a problem with it.

RolandRB wrote:

dropped. Nearly all these camera have added spacer washers and strips
to move the focussing screen up so as to compensate. I think they are
great cameras (I have a few) but you have got to be aware of this
weakness with them and to be on the lookout for a problem with it.

I think they are screws on the C330f?

--
http://www.petezilla.co.uk

Jim Hemenway wrote:

Shot several days ago with the C220F:

http://www.half-fast.com/CapeAnn-C220F-12282006/

Nice, need to get out and take some myself!

Where is Cape Ann?

Pete