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11-03-2009, 11:09 PM   #1
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Pentax 67 soft and inaccurate!!!!

I have a pentax67 with a pentaprism and a 90mm.
Lately, I've been noticing that it is really, really soft. I'm not sure if it all of a sudden got sof ton me or if it needs calibration, but it's just not performing well at all. here are a couple images from the last roll of 220 portra400nc through it that are ridiculously soft and fit what i'm trying to explain.

pardon the fairly sloppy/hardly colorbalanced scans.
in the first, the focus was supposed to be on the socks. the second, on the part of the sidewalk where that guy is. and the third, right on the street sign.
http://img.photobucket.com/albums/v604/brenford/downtownsaturday005.jpg
http://img.photobucket.com/albums/v604/brenford/downtownsaturday006.jpg
http://img.photobucket.com/albums/v604/brenford/downtownsaturday018.jpg

on top of this, i've noticed that the accuracy of the finder is HORRIBLY inaccurate and what i see through the prism is about a centimeter if not more less than what is on the negative. my prism sits on almost loosely and if you press it hard enough it will wobble. maybe that has something to do with it, maybe not, but im really getting sick of things creeping into my images when trying to shoot landscapes or really ANYTHING that i want to have a decently clean composition. Any idea where this is coming from, or is every 67 this horribly inaccurate? and if you look at the second image, the left side of the frame was supposed to cut at maybe the "a" or closer in on that big "sign" but its all the way outside of that as it shows.

also, im using an epson 4490 refurb, but i've switched scanners and im still getting the same problem.

Any help or suggestions would be greatly appreciated.
Thanks in advance,
Kohlton

11-03-2009, 11:36 PM   #2
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It might be pretty hard to tell what's wrong when you have so much stuff in the interim that could be the problem. I would first start by listing where things can be going wrong and eliminating or substituting each one of those steps. E.g.

Scanning: if scanning could be an issue, check your film with a light box and loupe. Better if you have reversal film.

Back/Front focus: Shoot a focus test chart at the closest focus distance and see if screen position needs calibration. Shoot landscape/infinity and shallow aperture.


Lens: bump to a lens could've cause misalignment, check for other issues (fungus, haze, etc). If possible, try swapping the lens. Borrow somebody's lens for one shot.


Film transport: I don't have a 67 so I don't know what it looks like inside the film compartment, but in a lot of MF cams, if the pressure plate is not taught, it could cause the film to float and cause softness. This can be especially problematic with bodies that take both 120 and 220 (like my Pentacon Six).

Good luck!
11-04-2009, 12:24 AM   #3
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I shot 6X7's for years, and never had any screen/film plane alignment problems,

Which pentaprism do you have, because the older view finders did not show 100% of the image area, maybe a little more than 90%, if i remember correctly?

Porta 400 film is a very soft contrast film, I never used it, even for portraits. I would never use it for general photography.

220 film is thinner than 120, perhaps the pressure plate on the film door needs to be adjusted.

Which 90mm do you have?

Scanning, most times is the culprit when you are unhappy with contrast, color and general IQ.

REMEMBER - Nailing focus on a 67 takes a lot of practice...its not easy. Get a newer Pentax screen or aftermarket version.

and I assume this is not a diopter problem

Last edited by ramair455; 11-04-2009 at 12:29 AM.
11-04-2009, 12:35 AM   #4
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A few things... The pentaprism finders of all the 67's show only 90% of the image. If you need 100%, use either the rigid magnifying hood or the folding waist level finder.

If the prism is wobbly, replace the foam seals. When these get old and compress or deteriorate, the prism does not fit snugly.

Check the pressure plate to make sure it is in the proper position. it needs to be set for either 120 or 220.

11-04-2009, 07:09 AM   #5
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You haven't mentioned what kind of post processing you do or not. My scans all look soft. I have all features turned of when I scan then I sharpen them in the graphics editor. Also, these look handheld. What is your shutter speed? You're not going to get the sharpest shot handheld with too slow or a borderline shutter speed. And are you laying the negatives on the glass of the scanner? Most need them to be spaced off the surface.

Perform some mirror lockup tests on a tripod. And if you want to reduce camera shake even more for a test, do a long exposure like a minute. And if that 90mm is the leaf shutter 90mm then you can take a vibration free shot with that by using only the leaf shutter. The instructions are in the manual.

And to answer one of your questions: No, every 67 is not that horribly inaccurate.
11-04-2009, 04:07 PM   #6
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although ive had pressure plate problems in the past, i always make sure to properly set it for 120 or 220 when i shoot either.
also, with more though, i've realized that sometimes i move the camera so it centered on my subject, and focus with that little circle to help me, then pan to wherever i plan to keep the camera to shoot. this could cause some misfocusing, such as the sock one, couldn't it?

there's a definite possibility that it could've along the way gotten misaligned, but ill shoot another roll and make sure that's not the case before i take it in.

the prism i have, although im not really sure of the exact model, just says pentax across the front of it, and really doesnt show much else. i think taking that off and looking through the focusing screen maybe before shooting something--if set up on a tripod, which i may have to start doing--will help me with my problem. i don't want to have to treat this like a largeformat camera, but to get theprecision im after, im starting to feel like it might have to happen.

i have the smc 90mm, is there another model or make of it? im sure there is...i just cant remember....

what is a "diopter problem"?

as i stated, these are not post processed at all, and i know i can use usm on them, etc. they are handheld, most at probably 125th or 1/250th. and i do believe i am scanning properly and i use the epson film holders.

thanks so much, im starting to think this is more of a user error...
11-04-2009, 05:13 PM   #7
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I think you should -

Use a tripod - just to eliminate any possible camera shake
Change to 120 & change film type (Reala), a much snappier film
Focus on the ground glass - don't focus and recompose

-then post some new results
11-04-2009, 08:43 PM   #8
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I just thought of something. He mentioned a loose prism. I once put in a new focusing screen in my 67. There were these tiny, super thin washers under those front guide pins. There were two per pin in my case.

When I reassemble the the thing, I left one of them off. The prism and WLF fit loose and the focus was off. Is your focusing screen the stock screen? Maybe you have something like that going on.

You can test your focus by setting up a target at a distance from the film plane on your camera that matches a round number on your lens. Say 7, 8 or 10 feet. On a tripod, focus on the target. Look at what the lens says. Should be close.

11-04-2009, 09:57 PM   #9
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surfotog and others mentioned the usual things to look for. The sudden, unexplained onset of the fuzziness makes me think it's the pressure plate setting or a scanning problem.


Two more thoughts:

-- You might need to install/change the viewfinder diopter in the pentaprism to suit your eyesight.
Especially if you use bifocals or reading glasses. A 67 with a 90/2.8 should actually be pretty easy to focus (especially in daylight), if your eyes can easily focus on screen itself. (ramair455 mentioned this briefly)

-- Don't use up a lot of film on focus tests.
A camera shop can test focus accuracy problems more quickly by using a ground glass screen placed on the film plane.
11-05-2009, 12:54 AM   #10
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It is the stock screen, i do believe. what do you think i should do to make sure that's not the case?
tried that focus target and it seemed pretty accurate.

how do i "install/change the viewfinder diopter"?

thanks all!
11-05-2009, 10:38 AM   #11
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QuoteOriginally posted by kohlton Quote
how do i "install/change the viewfinder diopter"?
In the 67(non-II), you have to swap out a lens. Strength depends on your eyesight and whether you are wearing glasses/contact lenses when focusing. See the "read a newspaper at 1 meter" test below.

It's also possible that a previous owner has already installed a corrective lens that doesn't suit your vision. Does the viewfinder become easier to use if the eyepiece frame is removed completely?

From the manual:

DIOPTER ADJUSTMENT AND FOCUSING
For accurate focusing, please check if the
focusing screen can be seen clearly. Should you
need a diopter adjustment, please use a cor-
rection lens (option).

Turn the eyepiece frame counterclockwise and
remove it. Turn the inside ring and replace the
plain glass with a correction lens.
The diopter of the TTL Pentaprism and
Pentaprism is -1D. If you are not able to
read the letters of a news paper 1 m
away, you would better put a correction
lens in the viewfinder eyepiece. -1D
should normally be sufficient for near
sighted people, while the + 1D should be
sufficient for farsighted people
11-05-2009, 09:48 PM   #12
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alright, so i do wear contacts and have an astigmatism. I set my lenses' focus to 1 meter and put down a piece of paper with typing on it on the ground of a room lit decently but an overhead ceiling light. I moved back and forth till it was clearest and i still couldn't read it. I know i have decently bad vision. Do i need to get this different glass?
11-05-2009, 11:41 PM   #13
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Hmmm. . . I'm pretty sure that the test is to read the newspaper directly, without looking through the camera. The idea is that the viewfinder optics create an image of focusing screen 1 meter away from the eyepiece -- if your eyes can't focus on the newspaper, then your eyes can't focus on the viewfinder image.

A corrective lens in the viewfinder (for a presbyopic or far-sighted user) acts like a lens in a pair of reading glasses. If reading glasses help you read a newspaper, a corrective lens of equal power in the viewfinder should help you use the viewfinder.
11-06-2009, 10:37 AM   #14
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yeah, although just because i cannot read a small font from a meter away does not mean i cannot clearly see it and cannot focus a camera on most objects. I just started another roll, and will shoot it how I would've shot it if my camera were fully functioning, but ill keep close watch on exactly where i focus and even try to shoot certain things that require decently precise focusing. I'll even use a tripod.
After this, I'll check back in, let you guys know how it goes, and then see if there's anything that needs to be done.

Also, with the finder being only 90%, does this mean that just looking through the prism you're seeing 90% and taking that off and just looking at the focusing screen you're seeing 100% OR is that 90% of the negative from the focusing screen and even less with the prism attached?

Hey, thanks again Troyz and everyone else who've consistently helped me with my issues!
11-06-2009, 10:58 AM   #15
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QuoteOriginally posted by kohlton Quote
Also, with the finder being only 90%, does this mean that just looking through the prism you're seeing 90% and taking that off and just looking at the focusing screen you're seeing 100% OR is that 90% of the negative from the focusing screen and even less with the prism attached?
You see 100% with the prism off. If you get yourself a waist level finder (also called a folding hood) you'll always see 100% with that and it is more accurate for critical focus because it has a magnifying glass that flips into place. It doesn't cost much and is an option you can put on when doing shots it is good at which is a lot.

The downside for some people is you'll need to meter the scene yourself. The upside is your camera will be lighter and more compact, 100% viewing and easy to focus critically.
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