New to MF - have a few ?'s

[SamHodde]

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!

 

[compur]

Is the DOF shallower on MF because the imaging area is so much larger?

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.

 

[Dave Colangelo]

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.

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.

Is the DOF shallower on MF because the imaging area is so much larger?

Generally no (see other responses)

Is there a trick to focusing I haven't picked up yet?

I would not chalk it up to tricks until you can confirm that the camera is 100% operational.

 

[Ysarex]

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!

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

 

[Ysarex]

Is the DOF shallower on MF because the imaging area is so much larger?

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.

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:

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

 

[480sparky]

Is the DOF shallower on MF because the imaging area is so much larger?

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.

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:

View attachment 134572

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

View attachment 134573

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.

 

[Ysarex]

Is the DOF shallower on MF because the imaging area is so much larger?

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.

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:

View attachment 134572

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

View attachment 134573

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.

Look at the top illustration -- I provided both options.

Joe

 

[Ysarex]

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

 

[compur]

This is not correct. DOF does change with the size of the recording media. ...

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."

 

[SamHodde]

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!

 

[Ysarex]

This is not correct. DOF does change with the size of the recording media. ...

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."

"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

 

[Derrel]

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.

 

[compur]

"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.

No, that's not what it says. Read it again.

Same focal length plus same enlargement = same DOF for different formats.

 

[Ysarex]

"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.

No, that's not what it says. Read it again.

Same focal length plus same enlargement = same DOF for different formats.

And that is saying the very same thing -- that's what "same enlargement" means. "Same enlargement" means you crop out the equivalent area of the larger format and enlarge it to the same degree as the smaller format.

You first said; "DOF is determined by lens focal length and aperture regardless of film format." That's incorrect. Folks who shoot medium format cameras don't process their film and then only make prints enlarged to the same degree as if they had shot 35mm film. They don't take a pair of scissors and cut out 35mm sections from their 120 negs to print from.

Joe

P.S. From the same Wikipedia article: "When the "same picture" is taken in two different format sizes from the same distance at the same f-number with lenses that give the same angle of view, and the final images (e.g., in prints, or on a projection screen or electronic display) are the same size, DOF is, to a first approximation, inversely proportional to format size (Stroebel 1976, 139)."

 

[Derrel]

The idea of the same picture made at the same f-stop but using larger or smaller camera formats explains the practical everyday reality of depth of field. Anybody who has used medium format roll film will tell you there is a need to close the lens down at least two f-stops smaller than what one would use for the same type of clothes in pictures made on a 35 millimeter camera. Anybody who has used an iPhone will tell you that the depth of field is almost incredibly deep at 5 feet at any lens aperture.

As far as Split Image Rangefinder focusing goes this system is very accurate with a skilled operator in a properly calibrated camera, but neither of those two are a given in every situation. Medium format cameras like the Mamiya are great for slow shooting and careful placement of the focus point and the depth of field band. It's not too surprising that your first efforts with the new camera did not produce the kind of fast,easy results you're used to with digital systems. The Mamiya was never intended to be a fast, fluid, carefree camera, but was designed for a very disciplined, practiced type of shooting. As I mentioned earlier, at closer distances, medium format cameras do not deliver the type of depth of field or the fast and easy Focusing that many people are used to with modern digital cameras.