New to MF - have a few ?'s

Discussion in 'Medium Format & Large Format' started by SamHodde, Feb 6, 2017.

  1. SamHodde

    SamHodde TPF Noob!

    Joined:
    Feb 6, 2017
    Messages:
    2
    Likes Received:
    0
    Can others edit my Photos:
    Photos NOT OK to edit
    Hi All,

    I shot a bit of 35mm a few years ago in college and have since been shooting exclusively digital for work and other things since then. I recently picked up a Mamiya 645 Pro to try my hand at MF film and do something new. I got my first few rolls back from the lab the other day and after looking at my prints I've noticed a few things I wanted to ask other shooters about.

    -I noticed that a lot of my photos were soft or the focus was not where I remember focusing when I made the image. I'm familiar with focusing on a split focusing screen and I remember focusing so that the two halves of the image matched up.
    Is the DOF shallower on MF because the imaging area is so much larger?
    Is there a trick to focusing I haven't picked up yet?

    Let me know if there is any other info I can provide!

    Thanks!


     
  2. compur

    compur No longer a newbie, moving up!

    Joined:
    Mar 6, 2008
    Messages:
    2,972
    Likes Received:
    491
    Location:
    L.A.
    DOF is determined by lens focal length and aperture regardless of film format. However medium format cameras do tend to use longer lenses than 35mm cameras so in that sense you will tend to have shallower DOF with a MF camera but it's not the film format that is causing it. In other words, if focal length and aperture are the same on a 35mm vs MF camera then the DOF will also be the same with both.
     
  3. Dave Colangelo

    Dave Colangelo No longer a newbie, moving up!

    Joined:
    Apr 27, 2016
    Messages:
    292
    Likes Received:
    90
    Can others edit my Photos:
    Photos NOT OK to edit
    Your approach is correct but there could be a host of problems. If you have the version with the removable back make sure that the back is being mounted properly and securely. If the locks are lose or there is something obstructing it it may not be mounting properly. You should also make sure that the plate that holds the negative in place is providing adequate pressure to keep the film taught.

    Make sure that the adjustment on the eye piece (if there is one on the viewer you have) is set correctly.

    Gently make sure the mirror is operating as it should and is in the proper place.


    Generally no (see other responses)

    I would not chalk it up to tricks until you can confirm that the camera is 100% operational.
     
    • Agree Agree x 2
  4. Ysarex

    Ysarex Been spending a lot of time on here!

    Joined:
    Nov 27, 2011
    Messages:
    5,332
    Likes Received:
    2,347
    Location:
    St. Louis
    Can others edit my Photos:
    Photos OK to edit
    Yes, DOF is shallower on MF and yes it is in part due to the larger film size. If you're shooting 120 roll film with f/stops in the 5.6 to 8 range of say head/shoulder portraits focus carefully.

    Joe
     
    • Agree Agree x 2
  5. Ysarex

    Ysarex Been spending a lot of time on here!

    Joined:
    Nov 27, 2011
    Messages:
    5,332
    Likes Received:
    2,347
    Location:
    St. Louis
    Can others edit my Photos:
    Photos OK to edit
    This is not correct. DOF does change with the size of the recording media. To do a proper comparison of DOF between formats you need to use both cameras to take the same photograph. A required variable to calculate DOF is the circle of confusion. The value for the CoC is predicated in part on the size of the film/sensor and so the film size is a factor.

    Joe

    Same focal length and same f/stop on both 35mm and medium format and DOF is different:

    dof_02.jpg

    Same angle of view between both cameras and DOF is again different:

    dof_01.jpg
     
    • Agree Agree x 1
  6. 480sparky

    480sparky Chief Free Electron Relocator Supporting Member

    Joined:
    Mar 8, 2011
    Messages:
    22,546
    Likes Received:
    8,088
    Location:
    Iowa
    Can others edit my Photos:
    Photos NOT OK to edit
    Yeah, things change........ when you change the focal length too! Put in the same FL in both and see what you get. Changing just the recording medium changes exceedingly little.
     
  7. Ysarex

    Ysarex Been spending a lot of time on here!

    Joined:
    Nov 27, 2011
    Messages:
    5,332
    Likes Received:
    2,347
    Location:
    St. Louis
    Can others edit my Photos:
    Photos OK to edit
    Look at the top illustration -- I provided both options.

    Joe
     
  8. Ysarex

    Ysarex Been spending a lot of time on here!

    Joined:
    Nov 27, 2011
    Messages:
    5,332
    Likes Received:
    2,347
    Location:
    St. Louis
    Can others edit my Photos:
    Photos OK to edit
    We go through this here every couple months over and over. Either bleepin bleep Bryan Peterson or Ken Rockwell must be behind it! The size of the film or sensor is a determinant of DOF. It's not the biggest determinant but it does play it's part and that part is essential. You can't calculate the limits of DOF nor the hyperfocal distance for a camera without including a value for CoC. In all of the various formulae used to do those calculations the CoC value is predicated on the size of the film/sensor. Look at the DOFMaster illustrations I posted above and note the CoC change with the film size change.

    Until next time.

    Joe
     
  9. compur

    compur No longer a newbie, moving up!

    Joined:
    Mar 6, 2008
    Messages:
    2,972
    Likes Received:
    491
    Location:
    L.A.
    What I wrote is correct if both formats are given the same enlargement.

    See the section "Same focal length for both formats" here:
    Depth of field - Wikipedia

    "If pictures taken from the same subject distance using the same focal length, are given the same enlargement, both final images will have the same DOF. The pictures from the two formats will differ because of the different angles of view. If the larger format is cropped to the captured area of the smaller format, the final images will have the same angle of view, have been given the same enlargement, and have the same DOF."
     
    Last edited: Feb 7, 2017
  10. SamHodde

    SamHodde TPF Noob!

    Joined:
    Feb 6, 2017
    Messages:
    2
    Likes Received:
    0
    Can others edit my Photos:
    Photos NOT OK to edit
    I didn't mean to spark a large debate, but thank you to everyone for your information and those provided links. I know that I do need to refine my manual film shooting technique a bit, and will also certainly make sure that my camera is in proper working order before the next time I go out and shoot.

    Just wanted to make sure I was on the right path.

    Cheers!
     
  11. Ysarex

    Ysarex Been spending a lot of time on here!

    Joined:
    Nov 27, 2011
    Messages:
    5,332
    Likes Received:
    2,347
    Location:
    St. Louis
    Can others edit my Photos:
    Photos OK to edit
    "If the larger format is cropped to the captured area of the smaller format" -- In other words the same format used. Yep, take the same picture twice with the same camera and you get the same picture. But take the same picture using two different format cameras and you get different DOF because of the different formats used.

    Joe
     
  12. Derrel

    Derrel Mr. Rain Cloud

    Joined:
    Jul 23, 2009
    Messages:
    40,015
    Likes Received:
    15,007
    Location:
    USA
    Can others edit my Photos:
    Photos OK to edit


    In real world uses, yes, medium format cameras have fairly shallow DOF compared to 35mm or APSC type cameras. Especially inside of 30 feet, and on close-in shots, the MF camera will show limited DOF, and will demand very accurate focusing. Larger apertures like f/4 or f/5.6 might not get as much in focus as one might expect, based on experience with smaller-format cameras and the lenses those systems use.
     
    • Agree Agree x 2

Share This Page