Which has better background blurriness?APSC 50mm vs M43 75mm

I was researching to buy a light combo for doing portraits and I enjoyed using GM1 with Olympus 45mm but I know the bokeh of Sony 50mm is better. The question now is when compared to Oly 75mm, which has more bokeh between these two cameras:

Any M43 camera with Olympus 75mm F1.8

versus

Any Emount APSC with Sony 50mm F1.8

COnsidering the effective aperture calculation for both?

I read that you can compare the background blurriness by dividing the focal length and the aperture.

So the Olympus combo will yield a ratio of ~42 and the Sony combo will yield ~28. That's a lot!

But they are from different systems, so if I will use their effective apperture..

Olympus 75mm will have 21[75/(1.8x2)] and SEL50 will have 18[50/(1.8x1.5)].

Then they are almost the same! WIth the sony combo, I dont need to be much farther to the subject and the body+lens combo is lighter. (Of course, I would be needing a good IBIS body like GX7, EM5, EM1, EPM2 etc and not GM1/GM5)

ageminmo wrote:

I was researching to buy a light combo for doing portraits and I enjoyed using GM1 with Olympus 45mm but I know the bokeh of Sony 50mm is better. The question now is when compared to Oly 75mm, which has more bokeh between these two cameras:

Any M43 camera with Olympus 75mm F1.8

versus

Any Emount APSC with Sony 50mm F1.8

COnsidering the effective aperture calculation for both?

I read that you can compare the background blurriness by dividing the focal length and the aperture.

So the Olympus combo will yield a ratio of ~42 and the Sony combo will yield ~28. That's a lot!

But they are from different systems, so if I will use their effective apperture..

Olympus 75mm will have 21[75/(1.8x2)] and SEL50 will have 18[50/(1.8x1.5)].

Then they are almost the same! WIth the sony combo, I dont need to be much farther to the subject and the body+lens combo is lighter. (Of course, I would be needing a good IBIS body like GX7, EM5, EM1, EPM2 etc and not GM1/GM5)

While I do not dispute your calculations, what about angle of view provided by the focal lengths?  The FF angle of view equivalent of the 75mm is 150mm, while the 50mm is 100mm.  I have not done any calculations, but it seems that the longer focal length does a lot to background blur, even at smaller apertures (e.g. 150mm @ f5.6) ...this is just observation from personal experience, not calculations.

Fetishising Bokeh is one way to go for taking portraits.

The other is to learn about composition.

ageminmo wrote:

I was researching to buy a light combo for doing portraits and I enjoyed using GM1 with Olympus 45mm but I know the bokeh of Sony 50mm is better. The question now is when compared to Oly 75mm, which has more bokeh between these two cameras:

Any M43 camera with Olympus 75mm F1.8

versus

Any Emount APSC with Sony 50mm F1.8

COnsidering the effective aperture calculation for both?

I read that you can compare the background blurriness by dividing the focal length and the aperture.

So the Olympus combo will yield a ratio of ~42 and the Sony combo will yield ~28. That's a lot!

But they are from different systems, so if I will use their effective apperture..

Olympus 75mm will have 21[75/(1.8x2)] and SEL50 will have 18[50/(1.8x1.5)].

Then they are almost the same! WIth the sony combo, I dont need to be much farther to the subject and the body+lens combo is lighter. (Of course, I would be needing a good IBIS body like GX7, EM5, EM1, EPM2 etc and not GM1/GM5)

It's a bit more complicated than that. Which of the two will give more background blur depends on the magnification as well as the distance between the subject and the background. For example, for a head-and-shoulder portrait, the 50/1.8 on APS-C will give slightly more blur if the background is less than 2 meters from the subject whereas after that point, it is the other way around. You can experiment with other cases by means of this background-blur calculator:

http://howmuchblur.com/#compare-1.5x-50mm-f1.8-and-2x-75mm-f1.8-on-a-0.9m-wide-subject

Anders W wrote:

It's a bit more complicated than that. Which of the two will give more background blur depends on the magnification as well as the distance between the subject and the background. For example, for a head-and-shoulder portrait, the 50/1.8 on APS-C will give slightly more blur if the background is less than 2 meters from the subject whereas after that point, it is the other way around. You can experiment with other cases by means of this background-blur calculator:

http://howmuchblur.com/#compare-1.5x-50mm-f1.8-and-2x-75mm-f1.8-on-a-0.9m-wide-subject

Thanks a lot! Very useful link! Instant bookmarked!

After playing with the graph, I concluded that the effective aperture/sensor format matter most if the background is near.

But the focal length matters most if the background is far(like what the author said). Perhaps you need to be farther from the subject and compresses the background more causing more blurriness.

So I guess Olympus 75mm wins this one!

linux99 wrote:

Fetishising Bokeh is one way to go for taking portraits.

The other is to learn about composition.

Agree!

And what exactly is more bokeh?

If I had a dollar for every poster using thin DOF and bokeh interchangeably, I'd be very weathy.

Anders W wrote:

ageminmo wrote:

I read that you can compare the background blurriness by dividing the focal length and the aperture.

It's a bit more complicated than that. Which of the two will give more background blur depends on the magnification as well as the distance between the subject and the background.

There is also the look of the OOF areas, which is what traditionally has been called "bokeh", and that also depends on the spherical aberration corrections. You can have more blur with hard outlines, or less blur with very soft edges, and it's difficult to tell without testing which case you will like better.

Vlad

linux99 wrote:

Fetishising Bokeh is one way to go for taking portraits.

The other is to learn about composition.

+1 for sure. Bokeh is really an obscure or undefined term and when we think we know what it means (creamy bokeh or what have you) as a significant variable, we all have something else in mind depending on our interests or fetishes....Portraits can be headshots or full body shots where subject and surrounds does depend on composition a whole lot... It is true that background appearance (has to be illustrated to define) depends on focal length, size of sensor and f stop.... And more-distances to subject and BG.

That is how I look at the argument of composition control;  space background to foreground as a parameter.

We seem to now have a standard in our eye that like other things is a residue of the 35mm film appearance.

Now when I used medium format, the equation changed and ultra fast lenses were not always suitable in portraits.  Or affordable....

Lenses now tout circular aperture blades, good for them,  and claim to give prettier appearance re circularity of light blobs.
As photographers we are also obliged to take  a more sophisticated approach to the subject.  But it takes some complexity of mind.

Gerry Siegel wrote:

linux99 wrote:

Fetishising Bokeh is one way to go for taking portraits.

The other is to learn about composition.

+1 for sure. Bokeh is really an obscure or undefined term and when we think we know what it means (creamy bokeh or what have you) as a significant variable, we all have something else in mind depending on our interests or fetishes....Portraits can be headshots or full body shots where subject and surrounds does depend on composition a whole lot... It is true that background appearance (has to be illustrated to define) depends on focal length, size of sensor and f stop.... And more-distances to subject and BG.

That is how I look at the argument of composition control; space background to foreground as a parameter.

We seem to now have a standard in our eye that like other things is a residue of the 35mm film appearance.

Now when I used medium format, the equation changed and ultra fast lenses were not always suitable in portraits. Or affordable....

Lenses now tout circular aperture blades, good for them, and claim to give prettier appearance re circularity of light blobs.
As photographers we are also obliged to take a more sophisticated approach to the subject. But it takes some complexity of mind.

Medium format doesn't actually have ultrafast lenses.  The fastest lenses in DoF terms are all found in 35mm systems (there is nothing as fast as an 85/1.2 or 50/1.2 or 35/1.2 on 645 for example, let alone f/0.95 lenses).

OP isn't clear about whether he means the most blurring or the nicest blurring with bokeh.  They are not the same things.

The reason some call these crop sensor cameras is because they yield the same image only "cropped".  Using a micro43 camera vs. an APS-C camera means using a different aspect ratio and little bit of a crop with a smaller field of view.   You lose a little background but the "blur" is about the same - some say greater, but that is another story.

If I want a little more subject isolation, I can have a subject take a step closer, make the background a little more distant, add some vignetting, or add a touch more blur when post processing.

About 6 years ago I used an old Olympus 4/3rds camera with a 300mm F/5.6 zoom and was able to get the shallow depth of field look some crave. I am not a big fan, but when you want it there are many options with any camera.

If you really love always having a blurred background then maybe a full frame camera is the way to go.  I found it more of a nuisance because it was another factor I had to worry about.  Anytime I had more than one subject if I didn't factor in DoF, there was a good chance one would end up slightly blurred.

Sergey_Green wrote:

linux99 wrote:

Fetishising Bokeh is one way to go for taking portraits.

The other is to learn about composition.

Is not bokeh a part of the composition?

No, it's a tool allowing you to avoid composing your puctures. Although it can be a nice feature when it comes to shooting portraits.

ageminmo wrote:

Anders W wrote:

It's a bit more complicated than that. Which of the two will give more background blur depends on the magnification as well as the distance between the subject and the background. For example, for a head-and-shoulder portrait, the 50/1.8 on APS-C will give slightly more blur if the background is less than 2 meters from the subject whereas after that point, it is the other way around. You can experiment with other cases by means of this background-blur calculator:

http://howmuchblur.com/#compare-1.5x-50mm-f1.8-and-2x-75mm-f1.8-on-a-0.9m-wide-subject

Thanks a lot! Very useful link! Instant bookmarked!

You are welcome!

After playing with the graph, I concluded that the effective aperture/sensor format matter most if the background is near.

But the focal length matters most if the background is far(like what the author said). Perhaps you need to be farther from the subject and compresses the background more causing more blurriness.

Right!

So I guess Olympus 75mm wins this one!

Don't think you will be disappointed.

Vlad S wrote:

Anders W wrote:

ageminmo wrote:

I read that you can compare the background blurriness by dividing the focal length and the aperture.

It's a bit more complicated than that. Which of the two will give more background blur depends on the magnification as well as the distance between the subject and the background.

There is also the look of the OOF areas, which is what traditionally has been called "bokeh", and that also depends on the spherical aberration corrections. You can have more blur with hard outlines, or less blur with very soft edges, and it's difficult to tell without testing which case you will like better.

I too prefer to reserve the word "bokeh" for the quality rather than quantity of the blur. They are of course two completely different things. The quantity is something you can deduce from the lens specs and the shooting situation. For the quality, you have to look at how the lens actually performs.

Christof21 wrote:

Anders W wrote:

ageminmo wrote:

I was researching to buy a light combo for doing portraits and I enjoyed using GM1 with Olympus 45mm but I know the bokeh of Sony 50mm is better. The question now is when compared to Oly 75mm, which has more bokeh between these two cameras:

Any M43 camera with Olympus 75mm F1.8

versus

Any Emount APSC with Sony 50mm F1.8

COnsidering the effective aperture calculation for both?

I read that you can compare the background blurriness by dividing the focal length and the aperture.

So the Olympus combo will yield a ratio of ~42 and the Sony combo will yield ~28. That's a lot!

But they are from different systems, so if I will use their effective apperture..

Olympus 75mm will have 21[75/(1.8x2)] and SEL50 will have 18[50/(1.8x1.5)].

Then they are almost the same! WIth the sony combo, I dont need to be much farther to the subject and the body+lens combo is lighter. (Of course, I would be needing a good IBIS body like GX7, EM5, EM1, EPM2 etc and not GM1/GM5)

It's a bit more complicated than that. Which of the two will give more background blur depends on the magnification as well as the distance between the subject and the background. For example, for a head-and-shoulder portrait, the 50/1.8 on APS-C will give slightly more blur if the background is less than 2 meters from the subject whereas after that point, it is the other way around. You can experiment with other cases by means of this background-blur calculator:

http://howmuchblur.com/#compare-1.5x-50mm-f1.8-and-2x-75mm-f1.8-on-a-0.9m-wide-subject

The op has the correct formula (except that he made a mistake with the crop factor) for the background at infinity..

... but since background at infinity is but one possibility (and perhaps not the most likely one), the calculator is pretty handy.

Sergey_Green wrote:

ageminmo wrote:

I was researching to buy a light combo for doing portraits and I enjoyed using GM1 with Olympus 45mm but I know the bokeh of Sony 50mm is better. The question now is when compared to Oly 75mm, which has more bokeh between these two cameras:

Any M43 camera with Olympus 75mm F1.8

versus

Any Emount APSC with Sony 50mm F1.8

Take APSC with 50/1.8, this will make it 75mm equivalent, which if framed well will in the majority of cases look better than 150mm (75/1.8) equivalent.

On what grounds would it look better?

The totale amount of blur is hardly relevant here.

Why isn't it relevant?