Sharpest aperture for Hasselblad HC Lenses

[Johnphoto]

Sharpness in one thin plane is pretty worthless unless you want this effect. Otherwise f11 or f16 is perfect for MF photography. Sharp enough with sufficient d.o.f.

[ErikKaffehr]

Hi,

The original poster asked about optimum aperture.

The other point is that anyone buying high quality equipment may be interested in extracting best image quality from it. Best image quality can only be achieved by careful work.

Another way to see it is that if you stop down an MF camera to f/16 you may end up with less resolution than with f/8 on a much cheaper DSLR.

Best regards
Erik

If photography is simply an object lesson in resolving power, then that would be true. But for me, it is a creative medium used to make an image. My cameras are here to serve me and my vision, not to replicate MTF plots, which seems to be a very strange concept in photography today.

[JV]

Sharpness in one thin plane is pretty worthless unless you want this effect. Otherwise f11 or f16 is perfect for MF photography. Sharp enough with sufficient d.o.f.

Not everybody is shooting landscapes, just saying...

[theguywitha645d]

Hi,

The original poster asked about optimum aperture.

The other point is that anyone buying high quality equipment may be interested in extracting best image quality from it. Best image quality can only be achieved by careful work.

Another way to see it is that if you stop down an MF camera to f/16 you may end up with less resolution than with f/8 on a much cheaper DSLR.

Best regards
Erik

Optimum for what? Best image quality for what? MTF? How about the background?

So, it still come down to whether you think photography is an object lesson in resolving power, as you seem to believe. Or whether the image itself is the point of photography where how you control the camera and and other factors are important in image quality such as depth of field, viewing distance, etc. Personally, I take a systemic view in photography where the process is in service of the photographer and his/her judgement that best interprets the object. The other point is the "best" aperture in regards to resolving power will not even be noticed in comparison to "worse" apertures under normal viewing conditions. What will be more important is whether the view perceives the image to be sharp, which is not the same as having the highest resolving power.

BTW, I have shot my camera at f/22 and made 36" test prints. I am still getting more detail and sharpness than generic DSLR at f/8. But if the resolving power is both the same, but greater than the ability of the viewer, who cares. You seem to be saying that 100% monitor view is some kind of absolute reference to image quality. Well, sensor size and pixel resolution is going to really skew that view.

[ScubaZ]

Lets put it this way: If you care about buying the best camera with the best lens and put it on a stable tripod use mirror lockup and focus by live view you should also mind optimal aperture. Stopping down a bit to far may loose quite a lot of the resolution. On the other hand, if subject is out of focus optimal aperture will not help.

This is exactly what I'm concerned with, stopping down too far.  If I focus is at infinity, I understand the depth of field and agree with the other posters thats a matter of creativity, but where I decide I want everything in the frame as sharp as possible I would assume as you have suggested that shooting at f22 with a slower shutter speed likely is not going to get me as good a results in that particular situation as shooting at f8 or f11.

[theguywitha645d]

This is exactly what I'm concerned with, stopping down too far.  If I focus is at infinity, I understand the depth of field and agree with the other posters thats a matter of creativity, but where I decide I want everything in the frame as sharp as possible I would assume as you have suggested that shooting at f22 with a slower shutter speed likely is not going to get me as good a results in that particular situation as shooting at f8 or f11.

You could actually get a better result at f/22 because what you need in the image will have a higher resolution, not just some of it. Why don't you actually try shooting at different apertures and print out the results. Experience is the best teacher. Saying x is the sharpest aperture is the photographic equivalent of painting by numbers.

[bryanyc]

If photography is simply an object lesson in resolving power, then that would be true. But for me, it is a creative medium used to make an image. My cameras are here to serve me and my vision, not to replicate MTF plots, which seems to be a very strange concept in photography today.

You are missing the point.  Because photography is a creative medium it does not mean that knowing how to achieve the highest possible performance that ones tools are capable of is necessarily at odds with this creativity. 

The high level of technical experience and knowledge of members of this forum is highly impressive and appreciated as far as I am concerned.  And this coming from a guy who has frequently used zone plates, which use diffraction itself to resolve the image - AND likes to know if I want to capture some texture on a wall behind a subject what the best aperture choice would be.

[theguywitha645d]

You are missing the point.  Because photography is a creative medium it does not mean that knowing how to achieve the highest possible performance that ones tools are capable of is necessarily at odds with this creativity. 

The high level of technical experience and knowledge of members of this forum is highly impressive and appreciated as far as I am concerned.  And this coming from a guy who has frequently used zone plates, which use diffraction itself to resolve the image - AND likes to know if I want to capture some texture on a wall behind a subject what the best aperture choice would be.

I am missing the point?

The point of technical knowledge is just not to give an easy answer to achieve one thing, in this case the highest MTF, but to tell you how photography works so you can function in your medium and create the best result for yourself and your image. Everyone wants to be told what to do because that is easy--this is what the OP wants. Well, photography is not easy and you need to learn to control your medium. "F/11 and be there" is not control.

And you really can see now one really understands the medium. No one has brought up how the image will be perceived by a viewer. Sharpness is more important in giving the perception a photograph is detailed than resolving power. Yes, there are many experts here. I happen to be one of them--as Erik is. I am not advocating the wishy-washy idea that photography is a creative art and you should just let it all hang out and technique is irrelevant. I just don't believe in a formalistic approach to technical quality, mostly because it is not true.

If you want the formalist answer, I can give it to you--base ISO, 1/250s, f/11, on a 200lb tripod, in front of a high-contrast test target. Your images will always be the "best."

[ondebanks]

I also ran across the MTF charts for some of the Mamiya RZ lenses some time ago and noticed something very strange for the 350 APO: its wide open measurements were even better than stopped down! How do the boffins explain that?

Speaking as a boffin (ahem...hate that word - thankfully it's rarely used in my country), the explanation is that in the absence of aberrations, every lens would perform at its best wide open, and become progressively less resolute as you stop down. So the 350 APO would appear to be a virtually unabberated lens at its wide open f5.6 setting.

One of the goals of lens design is to make the lens diffraction limited at the widest possible aperture. Hitting a diffraction limit is good, and the sooner you hit it the better - this tends to confuse some photographers, who have been often warned off stopping down too far "in case you hit diffraction", and for whom the word diffraction has only negative connotations.

I say "a diffraction limit" because there is no single diffraction limit for a lens with an iris. Every time you change the f-stop, there is a new diffraction limit; hopefully the lens performs to this limit at this f-stop.

Ray

[Paul_Claesson_HasselbladUS]

Hello ScubaZ,

Hasselblad provides an excellent resource on our website (hasselbladusa.com > downloads > datasheets) HC Lens book. It offers an informative and easy to understand guide on how to read and interpret an MTF (Modulation Transfer Function) chart. Traditionally HC/HCD lenses are tested at maximum aperture and two stops down. The information provided in the MTF will show the resolution in LP/mm from the center of the image area to the image edges and corners. You can see where or at what point the resolution start to decline as it nears the edge of the image, most noticeable with a wide angle optic.

[jonathan.lipkin]

Spurred by this discussion, and for my own curiosity, I did a very un-scientific test of my three lenses (35, 50 mk.i and 80) with and without HTS. I shot my bookcase at a distance of about 5 feet and simply looked at the results at 100% on the screen in the center and corners at the plane of sharp focus (as well as I can focus the camera and align it with the shelf, assuming the shelf is straight, etc). I've posted the spreadsheet with my observations, again very un-scientific. They are more or less in line with what's been observed in this thread: best results from 8-16.

[Steve Hendrix]

Spurred by this discussion, and for my own curiosity, I did a very un-scientific test of my three lenses (35, 50 mk.i and 80) with and without HTS. I shot my bookcase at a distance of about 5 feet and simply looked at the results at 100% on the screen in the center and corners at the plane of sharp focus (as well as I can focus the camera and align it with the shelf, assuming the shelf is straight, etc). I've posted the spreadsheet with my observations, again very un-scientific. They are more or less in line with what's been observed in this thread: best results from 8-16.

Very good Jonathan - that's the way to do it.

Question though - on the 80mm with the HTS, at f/16 and f/22 you describe the center as "Good" and the edges as "Excellent". By this did you find the edges sharper than the center? Or was this meant as relative to expected performance for the edge, and the performance was better than your expectation?


Thanks,
Steve Hendrix

[jonathan.lipkin]

Steve -

I'm traveling now and don't have access to the image. The impressions were absolute, not relative. That is to say excellent meant that the image was very sharp, good meant sharp, and so on.

However, it is entirely possible that my method of comparison may have colored the results. I looked at each section of the image (center, corners) and compared the sharpness at various apertures. I can't recall if I made a careful comparison between the corners and center of the 80.

I was quite impressed by the 80. I found it to be extremely sharp in comparison to the others.

Having said that, I've blown up images from the 50mm and HTS at f/22 to 44x60 inches and found them to be excellent from corner to corner.

[Pingang]

The modern H lenses are designed with more specfic reasons and are all quite good, of course, some better than the other.
The sharpness is not achieved just by f setting but also the focusing distance. I am very happy with most of the H lenses so it did not bother me to try to find the sharpest apeture, but I would assume except for wide angles H (28/35/50) and the 35-90 zoom the best sharpness will be at more dustant focusing while lens ideal for portraits (100. 150, 210) will be best at common portrait focusing distance.

Pingang
Shanghai