More Pixels Require Better Lenses
There’s a simple truth in digital imaging: the more pixels you have, the better lenses you need to be carrying. So lenses that look “great” with a 22 megapixel sensor may show unexpected weakness at 150mp. With the release of the Phase One IQ4 150mp we wanted to provide our clients with some actionable information on which lenses they can expect to be “extraordinary” “great” “good” or “okay” on this new ultra-high-res sensor.
If you’re just looking for a quick-hit on which lenses you should be buying for 150mp, and which you should be avoiding, you can jump to our comparison chart. Otherwise read on for some definitions, caveats, and background. As you might expect, the question “how good is this lens?” is more complicated than it sounds.
Defining Lens “Quality”
In this article we are defining and discussing lens quality in a purely technical way. So before we get to that we should acknowledge that technical lens quality is not always important, and in fact can sometimes run against the desired aesthetic. For example, we wrote an article that paid homage to, among other lenses, a Cinelux 130/2 fixed-aperture IMAX projector lens; this lens is not sharp in the corners, or even sharp in the center, and has a lot of abberation, but it’s beautiful in its own way. Also, for some kinds of imaging the character of out-of-focus areas (bokeh) or other subjective characteristic elements of a lenses rendering/look matter a lot.
But for the purpose of this article we’re looking at lens sharpness, because this is what’s relevant to the question “I use and love lens X on my 100mp camera; will it still look good on the Phase One IQ4 150mp?” The color, draw, bokeh, physical feel, focus speed, etc of a lens does not change when you put it on a higher resolution camera (assuming the sensor size is the same) but the sharpness a lens provides can change when you put it on a higher resolution camera. So we will limit ourselves here to sharpness.
Sharpness can be measured in a variety of ways which will be more or less important to you depending on what kinds of images you shoot, how you shoot them, and how you use the resulting images. It’s reasonable to assume that any lens worth a darn will be sharp in the center stopped down. That’s like driving a car down a straight highway with cruise control on; it tells you very little about the car’s performance. Three better measures of how well a lens’ sharpness hold up are:
- Sharpness in the center, wide open
- Sharpness in the corner, wide open
- Sharpness in the corner, stopped down (e.g. at f/8)
While we don’t break down these metrics separately in this article (favoring simplicity in the chart over detail) we do keep track of them for in-house reference.
We’re also going to assume, for this article, that what we care about is maxing out the quality of the sensor; in other words, how does the resulting image look at a 100% pixel view? This would not be relevant if, for example, you’re only making 11×14” prints, where the full resolution of the camera isn’t visible anyway. A higher resolution camera doesn’t make the lens worse; it simply shows you whether the lens can meet a higher standard than you’ve previously held it to. Imagine you own a car that maxes out at 100mph and find its tires provide plenty of grip around corners. Then you upgrade to a car that can go 150mph and decide to reuse those tires. You may find the tires now slip when you’re going around corners at max speed, but, importantly they work just as well as the old car when you limit yourself to 100mph. It’s not that the tires got worse; they just show weakness when you push them harder than you previously could. Making the same small print from a 150 megapixel and 100 megapixel camera is like driving them both at the same slower-than-max speed; the tires won’t matter. Reviewing a 100% pixel view image from both cameras is like taking the corner at the max speed of each car. In this article we only answer the question “how well does this tire perform at 150mph”?
The Breadth of Lenses
The Phase One IQ4 150mp is only available in an XF mount. But that doesn’t mean that XF lenses are the only lenses it can be used with. Thanks to a variety of tech cameras, lens adapters, and the electronic shutter, a large range of lenses can be used with the IQ4 150mp. That said, when looking for the highest performance the three most relevant are the XF Schneider LS Blue Ring series (as used on an XF), the Hasselblad HC series (as used on a tech camera such as the Alpa FPS), and the Rodenstock HR series (as used on a variety of Arca Swiss, Cambo, and Alpa tech cameras).
It’s easy to overthink lens performance on a new higher-res sensor. Typically you can make a pretty good guess at their future performance (on a higher res camera) by looking at their current performance (on a lower res camera). If a lens is an “A++” at a given resolution it’s not going to suddenly become a “C” at the next generation of resolution. For example the Schneider 35mm LS Blue Ring lens was released in the era of 80mp and was widely hailed as an extraordinary lens, held up as extraordinary at 100mp, and continues to be extraordinary at 150mp. The opposite also holds true; for example, the Hasselblad HC35mm and Schneider 28mm LS were both only “okay” lenses at 100mp and using them at 150mp isn’t going to improve their performance.
Grading on a Curve; What Does this Chart Mean?
What the heck is an “A” vs a “C” when it comes to a lens? These are obviously subjective and relevant terms. Moreover, they should be taken entirely as relative within the available options. They shouldn’t be compared to, for example, anyone else’s grading scale, and certainly not to lenses on other formats. Medium format lenses are in a league all their own; the worst lens on this list, when used with a small-format camera, would absolutely sing.
The point here is to help our clients with very practical real-world choices such as “should I buy lens X or Y”. This chart won’t be the end of that conversation or process (we really like setting our clients up with an option to test whatever they are considering, in their own workflow) but it’s a decent start.
Summary of Recommendations for 150mp
|Expected Performance of Lenses Designed for Full-Frame 645 Sensors|
|Rodenstock||Phase One XF Platform||Hasselblad H Platform|
105 HR Macro
|35 LS BR
45 LS BR
40-80 LS BR
120 LS Macro BR
150 LS BR f/2.8
240 LS BR
|HC 50 II
HC 120 II
|75-150 LS BR
80 LS BR
110 LS BR
|55 LS BR
150 LS BR f/3.5
|28 LS||HC 35|
Hasselblad also has three HCD lenses (HCD 24, HCD 35-90, HCD 28) that weren’t spec’d to cover full-frame 645 sensors and will require cropping on the IQ4 150mp, so haven’t been included here.
The age of a lens’ design is not an absolute determinant of its quality. For example the Schneider 28mm LS was released in 2012 and is an “okay” lens in our ratings. But in general, lenses designed long ago will struggle to perform at 150 megapixels far more than a lens that was designed in the last few years.
The reason for this is simple: even if you are designing a very high quality product you don’t want to needlessly overbuild it. For example, if you make tires for a Ford that can go 100mph it doesn’t make any sense to design that tire with 400mph of speed in mind. It might make sense to design it with 120mph or 150mph in mind, in case future models go faster than the current model, but if you design it for 400mph the tire will be more expensive and may be less desirable in other ways (e.g. larger or heavier). So when a camera maker designs it’s lenses it always thinks a few generations of resolution ahead; it would be silly for Nikon to release a lens based on its current highest resolution camera, but it would be equally silly for it to release a lens based on a sensor resolution it doesn’t expect for another 20 years.
Note that what matters here is the age of the optical design, not the age of the lens model/iteration. Many times a new version of a lens is released with new features or a new physical chassis, but without any change to the optical design. For example, the Schneider 40-80 LS Blue Ring zoom lens is an updated version of the Schneider 40-80 LS (non blue ring) lens which added a more robust physical housing, a new focus grip, and new firmware that allows serial-number-based calibration, but the same optical design as the previous model. Likewise a new iteration of the Hasselblad HC and HCD lenses were released a couple years ago with an orange dot with a faster max shutter speed, but the same optical design. In both cases the manufacturer might claim that tolerances have been tightened, but in our experience that will make little, if any, real-world difference, especially compared to recalculated optical formulations, new coatings, or entirely new designs.
Below is a chart of lenses for the Hasselblad H and Phase One XF that shows what resolution camera the manufacturer was making at the time that lens’ optical design was most recently made. So, for example, the Schneider 40-80 LS Blue Ring was released in 2016 (when P1 was shipping a 100mp back) but uses the same optical design as the Schneider 40-80 LS (non blue ring) which was released in 2014 when Phase One’s highest resolution camera was 80mp.
Hasselblad never released an 80mp camera and their 40mp and 60mp backs were released well behind P1 reaching those resolutions. As a result, for example, the HCD 24 is listed as a 60mp era lens despite being released at roughly the same time as the 240LS which is listed as an 80mp-era lens. Since each company was releasing cameras for their own platform this seemed like the most logical approach.
We also omitted lenses from this table that aren’t in the current-generation lineup. So for completeness you can note that the Schneider 28LS was released in the 80mp era (proof that this is not a hard-and-fast indicator of quality).
Finally, the Schneider 80mm LS, Schneider 55mm LS, Schneider 75-150 LS, and Schneider 150mm LS f/2.8 all borrow heavily from non leaf-shutter predecessors. It’s our feeling that they are sufficiently improved from previous iterations that they deserve to be considered “optical improvements” but there is some subjectivity in that decision.
Because of all these caveats, this chart isn’t as useful in answering “which lens should I buy” as the more direct answers found in our “Summary of Recommendations for 150mp” but they do provide an interesting historical perspective.
|Lineage of Current Lens Line for Hasselblad H & Phase One XF
For each of the Hasselblad HC / HCD and Schneider LS BR lenses, what was the highest resolution camera that each maker was shipping when the most recent optical improvement was made?
|Hasselblad H||Phase One XF|
|Released in 100mp Era||45 LS Blue Ring|
|Released in 80mp Era||35 LS Blue Ring
40-80 LS Blue Ring
75-150 LS Blue Ring
|Released in 60mp Era||HCD 24 (designed for crop sensors)
HC 50 II
HC 120 II
|Released in 40mp Era||HCD 35-90 (designed for crop sensors)
HCD 28 (designed for crop sensors)
|120 D MF|
|Released in 22mp Era or Earlier||HC 35