Bokeh comparisons crops vs full frame sensors...

Its the old age question. Can you reproduce the same bokeh rendering using a crop sensor to that of a full frame. The FF looks like it produces more of it and for some time I though it was the sensor but after diving more into it it looks like its not the sensor but the distance allowed from camera to subject. For some it is not of value but many portrait photographers crave this. Me being one of them. Of course, FF has other benefits like low light performance but I don't do enough of it so this is a great option to stay with the crop by making the lens say a 50mm 1.4 to a 35mm 1.4. Here is a link to the video I am talking about from Manny.

StarPortraits said:

Its the old age question. Can you reproduce the same bokeh rendering using a crop sensor to that of a full frame.

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Not exactly age-old. Pretty recent, actually.

StarPortraits said:

The FF looks like it produces more of it

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More bokeh. The language is going to hell.

StarPortraits said:

and for some time I though it was the sensor but after diving more into it it looks like its not the sensor but the distance allowed from camera to subject.

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And also the choices of focal length and aperture.

StarPortraits said:

this is a great option to stay with the crop by making the lens say a 50mm 1.4 to a 35mm 1.4.

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You would need to use different f-stops to obtain the closest match.

There's another way of looking at this. How much blur do you need? Also, what lenses do you have and which can you afford in your pursuit not just the greatest amount of blur but also its quality (bokeh). The quality of the blur depends a great deal on the design of the lens. For example, two lenses that are the same speed and focal length are the Tamron and Sigma 35 1.4's. Reviews of the Tamron tend to agree that the bokeh is smoother with nicer bokeh balls.

My own comparisons of the blur attained by my dx and full frame cameras show a bit more blur with the full frame but the overall aesthetics were too close to call for me. But, I don't shoot portraits. Your miles may vary.

Plus, I am not sure the max narrow dof is always desirable in portraits. Very popular though. Update us on what you decide to do.

StarPortraits said:

Its the old age question. Can you reproduce the same bokeh rendering using a crop sensor to that of a full frame. The FF looks like it produces more of it and for some time I though it was the sensor but after diving more into it it looks like its not the sensor but the distance allowed from camera to subject. For some it is not of value but many portrait photographers crave this. Me being one of them. Of course, FF has other benefits like low light performance but I don't do enough of it so this is a great option to stay with the crop by making the lens say a 50mm 1.4 to a 35mm 1.4. Here is a link to the video I am talking about from Manny.

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Just to be clear we are talking about depth of field (how much is in focus vs out of focus) rather than the quality of the bokeh (which is more dependent on the design of the lens).

It's very easy to get shallow depth of field and plenty of background blur for portraits using a longer lens on a smaller sensor, but if you want to blur the background on wider portraits you need wider apertures on the smaller sensors. For example my 45mm f/1.8 or 40-150mm f/2.8 lenses can produce portraits with nicely blurred backgrounds on my m4/3 sensor cameras. If I want to take a wider environmental portrait without getting too close to the subject, I have my 20mm f/1.7. It blurs the background a little, but not a lot. I can move closer to the subject, but that will introduce some perspective issues. A lens like the Olympus 25mm f/1.2 (or 17mm f/1.2 for a wider FOV) would help achieve more background blur while keeping my distance. If that still isn't enough I could go to the Voigtlander Nokton 25mm F0.95. None of these are as affordable as say an Olympus 25mm f/1.8 or a 50mm f/1.8 for full frame.

So a FF sensor paired with inexpensive 24mm, 35mm and 50mm primes will give you more depth of field control at the wide to normal focal lengths without requiring you to get so close to your subject that you end up with perspective issues. On a m4/3 sensor camera you're going to need to spend some money on the ultrafast primes to get similar DOF control at the 12mm, 17mm, and 25mm focal lengths. APS-C will be somewhere in between. On the zoom side of things, a 24-70/80mm f/2.8 will give you more DOF control on FF than my Olympus 12-40mm f/2.8 gives me on m4/3. On the other end of things: I used to shoot outdoor portraits and action with a Nikon 80-200mm f/2.8. My current Olympus 40-150mm f/2.8 is lighter, smaller, and gives me plenty of background blur when I want it.

Regardless of what format you shoot, a wider aperture will allow you to achieve shallower DOF. The quality of the bokeh that lens produces is another question (and may be somewhat subjective). Of course the question of "how much blur do you need?" is also subjective. I feel like I get enough DOF for my purposes with my m4/3 set up. If I want more I can always head to Photoshop, but I almost never bother. That brings up another hot topic: Some folks want camera manufacturers to embrace computational photography like smartphone manufacturers have done... so you can easily change the amount of background blur. Of course portrait mode on smartphones doesn't always produce the best results.

bokeh is overrated. Better off with f8-f11.

StarPortraits said:

after diving more into it it looks like its not the sensor but the distance allowed from camera to subject.

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No, assuming the same camera-subject distance, it's the diameter of the front lens aperture. Look backwards into your lens. You can see it. Generally speaking, FF cameras usually have lenses available with larger front apertures. Consequently, you can achieve a higher degree of blurring of out-of-focus points.

(Note that if you stop down to achieve the same depth of field, the FF advantage is lost. I will not discuss this further.)

The size of the aperture helps determine the diameter of out-of-focus points of light. The lens design, however, determines the appearance of the out-of-focus points, and this is what is called bokeh.

That video is pretty cheesy.

Complaining about lenses being made for Full Frame and not Crop, but he doesn't seem to be willing to invest in Crop specific glass (or a dedicated Crop system).

"after diving more into it it looks like its not the sensor but the distance allowed from camera to subject."

Correct-a-mundo!

Kgluong said:

bokeh is overrated.

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Differently valued. And I think you may be referring to blur since you value apertures that provide more dof/less blur.

Speaking about the actual quality of the blur aka bokeh here are some facts.

1. The projected image circle will have more deformed bokeh balls the further away from the center.

2. A specific lens can produce more pleasing bokeh on a small format because the distances to subject and background are changed to take account for the framing. Taking the lens in and out of its sweet spot. Plus the cropping out the less well behaved edges of course.

3. If the lens is made for full-frame a full-frame camera is needed to get the most of the so called character that is otherwise cropped out. For example a Helios 44 with well known swirly bokeh will show less of it the more the image is cropped.

Have fun!

StarPortraits said:

Its the old age question. Can you reproduce the same bokeh rendering using a crop sensor to that of a full frame.

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With the same field of view and the same subject distance, you can get the same amount of background blur and DOF by using the equivalent focal length and f/stop. On APS-C a 56mm f/1.2 lens will give you the same result as an 85mm f/1.8 on full frame, although the bokeh quality will depend on the individual lenses used.

All of these factors will have the EQUAL effect of doubling background blur:

• Doubling focal length;
• Halving the f/stop;
• Doubling the sensor width; and,
• Halving the focus distance.

This assumes a distant background, at least ten times the focus distance beyond the subject.

With the affordable availability of FF nowadays if bokeh is your priority, skip APSC and go straight to FF. Lenses as well are outstanding and very affordable on FF, even so more affordable than comparable APSC lenses. Sigma and Tamron are making outstanding lenses for FF at very affordable prices.

The biggest difference I noticed between the two with bokeh are with wide angle lenses for portraits. Only if you are into that look. A 35mm f1.4 ART on FF is great and trying to replicate that on APSC will be very expensive even if it is possible at all.

One focal length I noticed being a better deal with good results on APSC is the 85mm f1.8 lenses. Giving you roughly 128mm at 2.8. I can't think of a lens like this on FF except maybe a 70-200mm f2.8 zoom but it's still a zoom quality and big.

ThrillaMozilla said:

StarPortraits said:

after diving more into it it looks like its not the sensor but the distance allowed from camera to subject.

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No, assuming the same camera-subject distance, it's the diameter of the front lens aperture. Look backwards into your lens. You can see it. Generally speaking, FF cameras usually have lenses available with larger front apertures. Consequently, you can achieve a higher degree of blurring of out-of-focus points.

(Note that if you stop down to achieve the same depth of field, the FF advantage is lost. I will not discuss this further.)

The size of the aperture helps determine the diameter of out-of-focus points of light. The lens design, however, determines the appearance of the out-of-focus points, and this is what is called bokeh.

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You make a good point. However ...

Not to confuse things but really it's the exit pupil "apparent aperture size from the rear" that matters.
At infinity focus it doesn't make a difference but as you focus closer, as we often do, it does. Generally the exit pupil moves away from the sensor and your effective f-number goes up (as if you have stopped down).

...in your case a lack thereof.

StarPortraits said:

Of course, FF has other benefits like low light performance but I don't do enough of it so this is a great option to stay with the crop by making the lens say a 50mm 1.4 to a 35mm 1.4.

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Lowlight performance and shallow DOF are interconnected. That is, you don't get a lowlight advantage just for using a larger format unless you are also using a correspondingly larger aperture. Your example is a case in point because a 50mm f/1.4 aperture has a diameter of 35.7 mm whereas a 35mm f/1.4 aperture has a diameter of 25mm which allows half as much light and has 50% more DOF.

lost me when he said shooting FF shot lower noise . ff 50 1.8 vers crop 35 1.4 ;-)

Don

Kgluong said:

bokeh is overrated. Better off with f8-f11.

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"Bokeh" is over-used as a term for sure. Bokeh itself is not over-rated. The quality of the way things go out of focus, when they do go out of focus is the bokeh. The fact that they are out of focus is not itself "bokeh".

I think everyone can decide for themselves what they like. They just need to know the compromises involved regarding shutter speed and ISO exposure index.

f/8 - f/11, btw, is usually getting into diffraction-limited territory for any half-decent lens, so there is no FF benefit here (unless the FF has more total pixel resolution), to take the same photo with the same FOV and DOF.

Donald B said:

lost me when he said shooting FF shot lower noise . ff 50 1.8 vers crop 35 1.4 ;-)

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Well, that can be true.

50/1.8 = 27.8mm; 35/1.4 =25mm. So, the FF gets more light in an other-wise. Not a lot, but more.

Of course, a modern, low-noise APS-C can still give less noise than a mediocre FF sensor, even some newer ones. Even some recent 1" sensors can do that in equivalence or a slight advantage to FF like the one above, if your DOF needs are in a range supported by available lenses on a 1" sensor.

John Sheehy said:

Donald B said:

lost me when he said shooting FF shot lower noise . ff 50 1.8 vers crop 35 1.4 ;-)

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Well, that can be true.

50/1.8 = 27.8mm; 35/1.4 =25mm. So, the FF gets more light in an other-wise. Not a lot, but more.

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Thanks, i didnt do the math but thought it was close. just though he didnt put much effort into discribing ff advantage of low light shooting.

John Sheehy said:

Of course, a modern, low-noise APS-C can still give less noise than a mediocre FF sensor, even some newer ones. Even some recent 1" sensors can do that in equivalence or a slight advantage to FF like the one above, if your DOF needs are in a range supported by available lenses on a 1" sensor.

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John Sheehy said:

Donald B said:

lost me when he said shooting FF shot lower noise . ff 50 1.8 vers crop 35 1.4 ;-)

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Well, that can be true.

50/1.8 = 27.8mm; 35/1.4 =25mm. So, the FF gets more light in an other-wise. Not a lot, but more.

...

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You're right but as always there is a twist (or two) ...

These entrance pupil values only hold for the center of the image circle.
Wide open almost all lenses have exit pupils that are not fully visible so there is light falloff toward the corners.
You would have to compare two specific lenses to be certain but it's entirely possible that the 50mm f/1.8 would gather less light toward the edges than the 35mm f/1.4 despite gathering more at the center.

And ... as always ... these calculation are for infinity and things change (usually in an unknown way) as you focus closer.