Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
03-25-2010, 02:01 AM   #1
Inactive Account




Join Date: Dec 2007
Location: Tokyo
Posts: 16
MZ-3 focusing problem

A while back I rescued a MZ-3 from my office where it was going to be thrown away and its been sitting around at home begging to be used.

Yesterday I finally got round to sticking a couple of CR2s and a roll of neopan 1600 into it and put my FA35 on the front. I quickly noticed that the autofocus and manual focus were at completely different positions, suggesting that something is wrong. In particular, the manual focus point is at a far shorter distance than autofocus.

Any ideas what could be going on? (yes, I have adjusted the diopter to suit my eyes!)

Without developing the film is there anyway of knowing whether its the AF or MF which is faulty?

My suspicion is that the AF is ok, but the optical path to the viewfinder is for some reason incorrect. I did briefly remove the focusing screen and couldn't see any kind of shim underneath and I'm wondering if that's the reason?

I'll know more when my first roll is developed but they may all be blurred.

Oliver

03-25-2010, 02:17 AM   #2
Veteran Member
wlachan's Avatar

Join Date: Sep 2006
Location: Canada
Photos: Albums
Posts: 2,626
There are 5 possibilities I can think of:
1) The AF module underneath the mirror box is out-of-alignment
2) The main or sub-mirror is out-of-alignment
3) The focus screen shim is missing
4) The focus screen clip was pushed too hard and force the whole frame out-of-alignment
5) The mirror box assembly was removed but not assembled properly.

IMHO, 1 & 5 are mostly unlikely. To see if manual focus was accurate, just stick a piece of semi-transparent plastic or paper on the film plane and focus using a 4-10x loupe, then reconfirm the focus through the viewfinder.
03-25-2010, 02:42 AM   #3
Inactive Account




Join Date: Dec 2007
Location: Tokyo
Posts: 16
Original Poster
Thanks Alan, given that the camera is immaculate condition (I hardly think that its been used) it does all seem v strange.

Given that its my understanding that there should be a shim under the focus screen, and I can't see one I'm hoping that this is the cause as I could try and fix it with some carefully cut paper (I'm assuming that original parts will be hard to come by).

However, if its 1,2 or 5 on your list then its going to be a job for a trained specialist.

PS thanks for the tip about checking manual focus, I don't have a loupe but I may have a magnifying glass lying around somewhere.

Oliver
03-25-2010, 02:47 AM   #4
Veteran Member
wlachan's Avatar

Join Date: Sep 2006
Location: Canada
Photos: Albums
Posts: 2,626
Since you are in Japan, why not just send it to Pentax? There is a good chance they might be able to help you. According to the parts manual, the shims came with different thickness. There is no way for us to determine the exact thickness I think.

03-25-2010, 07:39 AM   #5
Senior Member
SquintyEyes's Avatar

Join Date: Aug 2008
Location: Toronto, Canada
Photos: Gallery
Posts: 100
If you have ground glass (I've heard that if you lightly sand a CD case it works similarly), you can place that where the film sits with the back open. Set the camera on tripod and manually focus until you get a sharp image on the ground glass. Then compare that focusing distance to your MF & AF value.

Or even simpler, you can use a different camera that you know focuses accurately, set a tripod, use that camera to focus and mark down the focusing distance. Then put the same lens on the MZ3 and place it on the tripod, you should be able to tell whether MF or AF is more accurate.
03-25-2010, 09:24 AM   #6
Pentaxian
titrisol's Avatar

Join Date: Dec 2007
Location: In the most populated state... state of denial
Photos: Gallery | Albums
Posts: 1,094
QuoteOriginally posted by SquintyEyes Quote
If you have ground glass (I've heard that if you lightly sand a CD case it works similarly), you can place that where the film sits with the back open. Set the camera on tripod and manually focus until you get a sharp image on the ground glass. Then compare that focusing distance to your MF & AF value.

Or even simpler, you can use a different camera that you know focuses accurately, set a tripod, use that camera to focus and mark down the focusing distance. Then put the same lens on the MZ3 and place it on the tripod, you should be able to tell whether MF or AF is more accurate.
Magic scotch tape on a piece of transparency is a simple replacement for ground glass
03-30-2010, 10:48 PM   #7
Site Supporter
knyghtfall's Avatar

Join Date: Jun 2007
Location: Singapore
Photos: Gallery
Posts: 348
QuoteOriginally posted by oliver Quote

Yesterday I finally got round to sticking a couple of CR2s and a roll of neopan 1600 into it and put my FA35 on the front. I quickly noticed that the autofocus and manual focus were at completely different positions, suggesting that something is wrong. In particular, the manual focus point is at a far shorter distance than autofocus.

Any ideas what could be going on? (yes, I have adjusted the diopter to suit my eyes!)
Just curious, how did you adjust the diopter to suit your eyes without using autofocus, or if you suspect the autofocus was faulty? usually i adjust the diopter using AF, i.e. using the camera to focus and adjusting the diopter until the image appears sharp in the viewfinder.

Can also try flipping the focusing screen over - if its placed upside down, the MF will be affected.
03-30-2010, 11:22 PM   #8
Veteran Member




Join Date: Sep 2006
Photos: Gallery
Posts: 5,713
QuoteOriginally posted by knyghtfall Quote
Just curious, how did you adjust the diopter to suit your eyes without using autofocus, or if you suspect the autofocus was faulty? usually i adjust the diopter using AF, i.e. using the camera to focus and adjusting the diopter until the image appears sharp in the viewfinder.

Can also try flipping the focusing screen over - if its placed upside down, the MF will be affected.
Every owners manual I've read seems to have a different idea how to set them.
My method is I leave the lens or body cap on so it's dark in the viewfinder. I then adjust it so that the viewfinder display is sharp. I then of course confirm it with any lens. It shouldn't mater if it's AF or MF, since you do have a focus indicator light in the viewfinder.
It works for me

Reply

Bookmarks
  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Tags - Make this thread easier to find by adding keywords to it!
af, autofocus, focus, mz-3, reason, roll
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
K10D focusing problem sqjaw Pentax DSLR Discussion 6 09-05-2010 12:32 PM
Pentax LX focusing problem oscar_s Pentax Film SLR Discussion 14 01-20-2010 07:14 AM
K200D focusing problem emr Pentax DSLR Discussion 5 10-05-2009 01:35 PM
K10 Focusing Problem hillerby Pentax DSLR Discussion 3 08-30-2009 01:44 PM
Focusing problem canyontraveler Pentax DSLR Discussion 7 07-01-2009 10:30 PM



All times are GMT -7. The time now is 09:54 AM. | See also: NikonForums.com, part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
register
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]
Top