mu43 vs APS-C aperture

[pcovers]

The supposed equivalence is based on the premise that you want to photograph an area that is identical in size with the same
View attachment 511486

This question has been responded to in many wordy ways on many forums, this table explains it it the most straightforward fashion with a perfect set of examples.

Thank you!

 

[Krandall]

To expand a bit on what Adam just said, DoF is determined by Focal Length, aperture, and distance from camera to subject. Change any of those three things and your DoF changes.

A lot of sites don't always explicitly state WHY the DoF changes when you go to a micro-4/3rds sensor camera from a full frame camera or an APS sensor camera. It isn't the sensor size at all. Instead because the crop factor changes your field of view changes. Therefore to get the same magnification (how your subject fills the frame) when you switch crop factor is that you have to change either the focal length being used or the distance to your subject. THOSE are actually what change the DoF, not the sensor.

If you took an Olympus OM film camera with an old OM lens mounted on it, put it on a tripod, took your photo, then removed the OM camera and instead placing an OM-D camera behind that same lens not changing the distance (tripod stays put) nor changing the aperture of that lens, the resulting photo would have identical DoF as the film camera. What would look different about the shots is the OM-D version would have a much smaller field of views (if your film shot was a head & shoulders shot, your OM-D shot would now be a lips & nose shot ). In the real world, with the OM-D you would need to move the tripod back further to frame the shot the same or leave the tripod put and switch to a wider focal length.

Really good explanation!

 

[EarthQuake]

To expand a bit on what Adam just said, DoF is determined by Focal Length, aperture, and distance from camera to subject. Change any of those three things and your DoF changes.

A lot of sites don't always explicitly state WHY the DoF changes when you go to a micro-4/3rds sensor camera from a full frame camera or an APS sensor camera. It isn't the sensor size at all. Instead because the crop factor changes your field of view changes. Therefore to get the same magnification (how your subject fills the frame) when you switch crop factor is that you have to change either the focal length being used or the distance to your subject. THOSE are actually what change the DoF, not the sensor.

If you took an Olympus OM film camera with an old OM lens mounted on it, put it on a tripod, took your photo, then removed the OM camera and instead placing an OM-D camera behind that same lens not changing the distance (tripod stays put) nor changing the aperture of that lens, the resulting photo would have identical DoF as the film camera. What would look different about the shots is the OM-D version would have a much smaller field of views (if your film shot was a head & shoulders shot, your OM-D shot would now be a lips & nose shot ). In the real world, with the OM-D you would need to move the tripod back further to frame the shot the same or leave the tripod put and switch to a wider focal length.

This may seem correct, but in reality it is not because it ignores the role of magnification in determining DOF.

Firstly I will say that, if you do the above experiment, the light will come into the lens at exactly the same way, and project the image onto the sensor in exactly the same way; the sensor does not physically change any attribute of the lens. However, this is not the only factor that determines DOF.

Assuming that we print or view the two photographs at the same size, the M43 shot will be magnified 2x more, the circles of confusion will be significantly larger, and the image will have half the DOF as a result. You can plug these values into any DOF calculator to verify:

50/2 on 35mm camera at 5 feet:
DOF :0.35 feet

50/2 on 43 camera at 5 feet:
DOF: 0.18 feet

If we move the 43 camera to normalize the framing, the shot will now have 2x larger DOF than the 35mm camera (the perspective will change as well):

50/2 on 43 camera at 10 feet:
DOF: 0.72 feet

The only way that two shots from the same distance and same lens with difference sensors would have the same DOF is if you printed/viewed them at sizes proportional to the sensor area. For instance, print the 35mm shot at 36x24 inches and the 43 shot at 17.3x13 inches, and you would have two images with exactly the same DOF.

 

[Costas_Gr]

Except moderator nobody other gave a clear answer to the question: if we have to shoot a subject 10 feet from the camera with lens 25 mm at MFT and 50mm at foule frame, what will be the aperture at each one camera so as to be all in focu?. That is the interesting for users more than the reason.

 

[DanS]

if we have to shoot a subject 10 feet from the camera with lens 25 mm at MFT and 50mm at foule frame, what will be the aperture at each one camera so as to be all in focu?. That is the interesting for users more than the reason.

No one is giving answers, because many many calculators exist!
Bokeh simulator & depth of field calculator

 

[pcovers]

Except moderator nobody other gave a clear answer to the question: if we have to shoot a subject 10 feet from the camera with lens 25 mm at MFT and 50mm at foule frame, what will be the aperture at each one camera so as to be all in focu?. That is the interesting for users more than the reason.

There may be some variables missing to fully answer your question. If your focus distance is set at 10 feet, then everything will be in focus 10' feet away, no matter what lens, camera, or aperture you use. What will be different is how far that focus will extend in front of and beyond that 10 feet. When you say "so that all in focus" you may have to explain what you mean.

 

[DoofClenas]

The way I look at it is:
1. I know there is a visual difference between the same f stop and different sized sensor, but I don't care. I tend not to focus on what others are shooting
2. I know what to expect when I shoot my lenses wide open... and as long as I'm happy with the results or if it's for a project, the client is happy, then all is well.

 

[Costas_Gr]

There may be some variables missing to fully answer your question. If your focus distance is set at 10 feet, then everything will be in focus 10' feet away, no matter what lens, camera, or aperture you use. What will be different is how far that focus will extend in front of and beyond that 10 feet. When you say "so that all in focus" you may have to explain what you mean.

I mean if you want for example to shoot two people sitting on an sofa and we want the two be all in focus, no clean face and blured hands. The interesting for us is if with mft can use bigger aperture so as to keep is lower.

 

[EarthQuake]

I mean if you want for example to shoot two people sitting on an sofa and we want the two be all in focus, no clean face and blured hands. The interesting for us is if with mft can use bigger aperture so as to keep is lower.

For the same AOV and distance to subject, DOF will be twice as wide on M43. So if you need to use F8 on 35mm, you could use F4 on 43, and use two stops lower ISO for the same shutter speed.

 

[tkbslc]

I mean if you want for example to shoot two people sitting on an sofa and we want the two be all in focus, no clean face and blured hands. The interesting for us is if with mft can use bigger aperture so as to keep is lower.

But you have to keep ISO lower on a small sensor because it's more noisy. So it's not really an advantage very often. There probably like a half stop sweet spot where m4/3 is as ISO 3200 and FF is at ISO 12800 and m4/3 has cleaner output, but for most of the time it's a wash.

 

[Costas_Gr]

For the same AOV and distance to subject, DOF will be twice as wide on M43. So if you need to use F8 on 35mm, you could use F4 on 43, and use two stops lower ISO for the same shutter speed.

I agree 100%. This answer I try to take ecause some one which he is interesting to purchase a mft camer, listen about the small pixels and bad ISO management without to know that at most of the difficult situations you can keep ISO under the red line.

But you have to keep ISO lower on a small sensor because it's more noisy. So it's not really an advantage very often. There probably like a half stop sweet spot where m4/3 is as ISO 3200 and FF is at ISO 12800 and m4/3 has cleaner output, but for most of the time it's a wash.

There is an article at other photography site which explain everything with examples. At portrait which all systems have used f1.2, only mft gives clean face all in focus. At FF one eye is in focus and the other blurred. At aps-c little better with the second eye but at the skin you can see less detail than mft.
So at the real life, FF has to use smaller aperture and bigger ISO so as to have the same DOF and light as mft. The same for aps-c.

 

[SojiOkita]

Except moderator nobody other gave a clear answer to the question: if we have to shoot a subject 10 feet from the camera with lens 25 mm at MFT and 50mm at foule frame, what will be the aperture at each one camera so as to be all in focu?. That is the interesting for users more than the reason.

Whatever the camera and the aperture, only one plane will be in focus.

However, there is the area where the image will be "acceptably sharp", and then it begins to be very subjective.
Do you want it to be sharp when pixel peeping? Sharp when printing? The needed aperture will not be the same for both.

As explained abobe, most dof calculators are very optimistic on the values they give.
It's easy to experiment, taking the given "hyperfocal" value, infinity will not be totally sharp.

With the values I do know consider on calculators for an assessment of what is sharp, I get these results, with a subject at 10 ft, focus on the subject:
m43 - 25 mm - f/4.5
24x36 - 50 mm - f/9
In both cases, everything is "acceptably sharp" from 4.8 ft to infinity.

 

[Costas_Gr]

Whatever the camera and the aperture, only one plane will be in focus.

However, there is the area where the image will be "acceptably sharp", and then it begins to be very subjective.
Do you want it to be sharp when pixel peeping? Sharp when printing? The needed aperture will not be the same for both.

As explained abobe, most dof calculators are very optimistic on the values they give.
It's easy to experiment, taking the given "hyperfocal" value, infinity will not be totally sharp.

With the values I do know consider on calculators for an assessment of what is sharp, I get these results, with a subject at 10 ft, focus on the subject:
m43 - 25 mm - f/4.5
24x36 - 50 mm - f/9
In both cases, everything is "acceptably sharp" from 4.8 ft to infinity.

I have find exactly the same aperture at my 12-40 f2.8 pro. When I shoot with f4-5 everything is in focus and real sharp. I shoot often our students when they are drawing. So I am interesting about that.
The aperture and DOF are very important at indoor shooting when you shoot people. Of course a foul frame camera with a good lens hasn't problem at f5.6 -8 and also has better DR but I can't carry it every where as I do with my mft which is all the day with me.
I think EM1 mk2 covers most of us. It isn't easy to be done first camera for a professional photographer but sure will be very useful for them as second.