Hasselblad CXD 38 mm f/2.5 OOF PSFs

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JimKasson
MOD JimKasson Forum Pro • Posts: 41,620
Hasselblad CXD 38 mm f/2.5 OOF PSFs
4

There are two pieces to bokeh. The first is what things look like when they are well out of focus (OOF), and the second is how the transition from OOF to in-focus happens. The second is complicated, but the first is very simple. What you see when part of the image is well OOF is each point in the image times the OOF point spread function (PSF, in this case, aka bokeh balls). So you can understand what the bokeh in the OOF regions is gonna look like by looking at the OOF PSF across the frame. After you’ve looked at a few of these images that I’m going to show you here, you can see how the deep-OOF bokeh of just about any lens is going to look like with just about any scene.

The technique that I used to obtain the images below is explained here. I moved the camera around and captured the PSFs in one quadrant, then mirrored and assembled them in Photoshop. I used an X2D for the captures.

I’ll just show you the lower left quadrant, since the PSFs are rotationally symmetric.

First, note that the aperture blades don't intrude on the bokeh balls. Also note that there is mechanical vignetting as you move off axis. In the corners, it's bad enough that the PSF has about half the area that it has in the center.

This is good, but not superlative performance.

If you stop the lens down to f/2.8, you can see the diaphragm blades.

There are only seven segments.

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Leica Q2 Monochrom Nikon Z7 Fujifilm GFX 100 Nikon Z9 Hasselblad X2D 100c +1 more
itsdoable Junior Member • Posts: 38
Re: Hasselblad CXD 38 mm f/2.5 OOF PSFs

JimKasson wrote:

<snip>....

If you stop the lens down to f/2.8, you can see the diaphragm blades.

There are only seven segments.

Eight?

JimKasson
OP MOD JimKasson Forum Pro • Posts: 41,620
Re: Hasselblad CXD 38 mm f/2.5 OOF PSFs

itsdoable wrote:

JimKasson wrote:

<snip>....

If you stop the lens down to f/2.8, you can see the diaphragm blades.

There are only seven  segments.

Eight?

Oops. You're right.

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Leica Q2 Monochrom Nikon Z7 Fujifilm GFX 100 Nikon Z9 Hasselblad X2D 100c +1 more
JimKasson
OP MOD JimKasson Forum Pro • Posts: 41,620
Re: Hasselblad CXD 38 mm f/2.5 OOF PSFs

JimKasson wrote:

itsdoable wrote:

JimKasson wrote:

<snip>....

If you stop the lens down to f/2.8, you can see the diaphragm blades.

There are only seven segments.

Eight?

Oops. You're right.

You can see that in the sun stars.

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Gandolphi Senior Member • Posts: 2,746
Re: Hasselblad CXD 38 mm f/2.5 OOF PSFs

There is an option with the XCD II 50c, to open the diaphragm fully, when using maximum aperture, to show round bokeh. Is this available on the new camera and do the new V range of lenses support this?

JimKasson wrote:

There are two pieces to bokeh. The first is what things look like when they are well out of focus (OOF), and the second is how the transition from OOF to in-focus happens. The second is complicated, but the first is very simple. What you see when part of the image is well OOF is each point in the image times the OOF point spread function (PSF, in this case, aka bokeh balls). So you can understand what the bokeh in the OOF regions is gonna look like by looking at the OOF PSF across the frame. After you’ve looked at a few of these images that I’m going to show you here, you can see how the deep-OOF bokeh of just about any lens is going to look like with just about any scene.

The technique that I used to obtain the images below is explained here. I moved the camera around and captured the PSFs in one quadrant, then mirrored and assembled them in Photoshop. I used an X2D for the captures.

I’ll just show you the lower left quadrant, since the PSFs are rotationally symmetric.

First, note that the aperture blades don't intrude on the bokeh balls. Also note that there is mechanical vignetting as you move off axis. In the corners, it's bad enough that the PSF has about half the area that it has in the center.

This is good, but not superlative performance.

If you stop the lens down to f/2.8, you can see the diaphragm blades.

There are only seven segments.

 Gandolphi's gear list:Gandolphi's gear list
Leica SL (Typ 601) Hasselblad X1D II 50C Leica SL2-S Leica Super-Vario-Elmar-SL 16-35mm F3.5-4.5 ASPH Leica APO-Summicron-SL 35mm F2 ASPH +2 more
SrMi
SrMi Veteran Member • Posts: 4,199
Re: Hasselblad CXD 38 mm f/2.5 OOF PSFs
1

Gandolphi wrote:

There is an option with the XCD II 50c, to open the diaphragm fully, when using maximum aperture, to show round bokeh. Is this available on the new camera and do the new V range of lenses support this?

Good point. The setting is in Configuration>Lens>Max Aperture. The option is discussed in the manual on page 82.

JimKasson wrote:

There are two pieces to bokeh. The first is what things look like when they are well out of focus (OOF), and the second is how the transition from OOF to in-focus happens. The second is complicated, but the first is very simple. What you see when part of the image is well OOF is each point in the image times the OOF point spread function (PSF, in this case, aka bokeh balls). So you can understand what the bokeh in the OOF regions is gonna look like by looking at the OOF PSF across the frame. After you’ve looked at a few of these images that I’m going to show you here, you can see how the deep-OOF bokeh of just about any lens is going to look like with just about any scene.

The technique that I used to obtain the images below is explained here. I moved the camera around and captured the PSFs in one quadrant, then mirrored and assembled them in Photoshop. I used an X2D for the captures.

I’ll just show you the lower left quadrant, since the PSFs are rotationally symmetric.

First, note that the aperture blades don't intrude on the bokeh balls. Also note that there is mechanical vignetting as you move off axis. In the corners, it's bad enough that the PSF has about half the area that it has in the center.

This is good, but not superlative performance.

If you stop the lens down to f/2.8, you can see the diaphragm blades.

There are only seven segments.

yogi4fitness
yogi4fitness Contributing Member • Posts: 690
Re: Hasselblad CXD 38 mm f/2.5 OOF PSFs

JimKasson wrote:

There are two pieces to bokeh. The first is what things look like when they are well out of focus (OOF), and the second is how the transition from OOF to in-focus happens. The second is complicated, but the first is very simple. What you see when part of the image is well OOF is each point in the image times the OOF point spread function (PSF, in this case, aka bokeh balls). So you can understand what the bokeh in the OOF regions is gonna look like by looking at the OOF PSF across the frame. After you’ve looked at a few of these images that I’m going to show you here, you can see how the deep-OOF bokeh of just about any lens is going to look like with just about any scene.

The technique that I used to obtain the images below is explained here. I moved the camera around and captured the PSFs in one quadrant, then mirrored and assembled them in Photoshop. I used an X2D for the captures.

I’ll just show you the lower left quadrant, since the PSFs are rotationally symmetric.

First, note that the aperture blades don't intrude on the bokeh balls. Also note that there is mechanical vignetting as you move off axis. In the corners, it's bad enough that the PSF has about half the area that it has in the center.

This is good, but not superlative performance.

I would have expected better performance from a lens at this price.

If you stop the lens down to f/2.8, you can see the diaphragm blades.

There are only seven segments.

If thats the shape of bokeh balls at f2.8, i am disappointed.

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JimKasson
OP MOD JimKasson Forum Pro • Posts: 41,620
Re: Hasselblad CXD 38 mm f/2.5 OOF PSFs

yogi4fitness wrote:

JimKasson wrote:

There are two pieces to bokeh. The first is what things look like when they are well out of focus (OOF), and the second is how the transition from OOF to in-focus happens. The second is complicated, but the first is very simple. What you see when part of the image is well OOF is each point in the image times the OOF point spread function (PSF, in this case, aka bokeh balls). So you can understand what the bokeh in the OOF regions is gonna look like by looking at the OOF PSF across the frame. After you’ve looked at a few of these images that I’m going to show you here, you can see how the deep-OOF bokeh of just about any lens is going to look like with just about any scene.

The technique that I used to obtain the images below is explained here. I moved the camera around and captured the PSFs in one quadrant, then mirrored and assembled them in Photoshop. I used an X2D for the captures.

I’ll just show you the lower left quadrant, since the PSFs are rotationally symmetric.

First, note that the aperture blades don't intrude on the bokeh balls. Also note that there is mechanical vignetting as you move off axis. In the corners, it's bad enough that the PSF has about half the area that it has in the center.

This is good, but not superlative performance.

I would have expected better performance from a lens at this price.

If you stop the lens down to f/2.8, you can see the diaphragm blades.

There are only seven segments.

If thats the shape of bokeh balls at f2.8

It is.

, i am disappointed.

Pretty much what you expect with eight straightish blades.

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 JimKasson's gear list:JimKasson's gear list
Leica Q2 Monochrom Nikon Z7 Fujifilm GFX 100 Nikon Z9 Hasselblad X2D 100c +1 more
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