If you’re new to medium format or new to tech cameras such as the Arca Swiss RM3Di and Cambo Wide series this is not the article to start with. We’d encourage you to, instead, contact us for a private demonstration of tech cameras where we can help answer the basic questions you’ll likely start out with. This article serves primarily as an advanced technical reference to clients who are already familiar with the basics of tech camera usage and just want to know “how does the IQ4 150mp perform with tech camera lenses with movement?” The short answer to that question is “extremely well” and the long answer is the rest of this article.
This is not a test of noise or sharpness
The Phase One IQ4 150mp unit we used for testing was still one of the prototypes. The final shipping units arrive to our LA office just in time for our LA, San Diego, San Francisco, Seattle, Portland, Phoenix, Denver IQ4 Launch Events. The prototypes exhibited significantly more noise than is expected for the final units, so this test cannot be used judge noise or ISO performance. That said, we expect the tech camera color-cast performance to be the same between the prototype and the final shipping unit.
This test also does not address sharpness. We shot all images at f/8 for consistency, but the Schneider 43 XL digitar is more commonly used by our clients at f/11 where corner sharpness improves. Also, this test was executed mostly for the benefit of our clients who have legacy tech Schneider Digitar tech camera lenses; these clients already own these lenses and understand where and when they are sharp. If you’re looking for a test that better indicates sharpness we would direct you to this test with previous or this test with the 150mp and invite you to contact us to arrange your own testing.
Which Corrections were used?
None of the images below have LCC Color Cast correction enabled. “Only Uniform Light correction applied” means the lens falloff is being corrected but color cast is not. When you don’t see color cast in one of the below images, it’s because it natively isn’t there to see. We also did not apply lens corrections, even though the 32HR benefits from distortion correction using the profile built in to Capture One; we chose not to because it would (slightly) affect the framing.
Schneider 43 XL Digitar
The Schneider 43mm XL Digitar is no longer made. It was light and compact, but had a symmetrical design that caused issues with the previous 50mp, 60mp, 80mp, and 100mp backs. But since many of our current tech camera users already have one, so we wanted to see how this lens performed on the IQ4 150mp. Note that it’s stated 113mm image circle is either “generously optimistic” or “a lie” depending on how cynical you are; the f/8 corner sharpness falls off considerably after 10 mm of shift.
Also note that this lens has an optional center filter, which was NOT used for this test. That center filter can make a considerable difference by reducing the amount of heavy lifting the LCC tool has to do. If we owned this center filter we would have used it in this test.
15mm Left/Right. IQ3 100 MP Tri vs IQ4 150mp. No LCC Corrections applied to either.
15mm Left/Right. IQ3 100 MP Tri vs IQ4 150mp. Only Uniform Light correction applied.
Rodenstock 32 HR
The Rodenstock 32HR is, by far, our best selling tech camera lens. It is super sharp, even at the edge of the conservatively-stated 90mm image circle. This lens has an optional center filter, which was NOT used for this test. This is generally considered a less essential center filter than the one available for the 43XL.
15mm Left/Right. IQ3 100 MP Tri vs IQ4 150mp. No LCC Corrections applied to either.
15mm Left/Right. IQ3 100 MP Tri vs IQ4 150mp. Only Uniform Light correction applied.
Rodenstock 28 HR
The Rodenstock 28HR is a cost-effective alternative to the 32HR, and provides a modestly wider FOV in a single frame, without the flare-proneness and extreme perspective of the 23HR. This lens has an optional center filter, which was NOT used for this test. This is generally considered a less essential center filter than the one available for the 43XL.
5mm Left/Right. IQ3 100 MP Tri vs IQ4 150mp. No LCC Corrections applied to either.
5mm Left/Right. IQ3 100 MP Tri vs IQ4 150mp. Only Uniform Light correction applied.
No movements. IQ3 100 MP Tri (left) vs IQ4 150mp (right). Only Uniform Light correction applied.
Rodenstock 70HR
The Rodenstock 70HR is a solid normal-length option for tech camera users. The newer and slightly longer Rodenstock 90HR-SW gets (rightly so) a lot of attention for its very large 120mm image circle and extreme sharpness, but the 70HR is a great performing lens with a 100mm image circle.
We only tested the 70HR with the Phase One IQ4 150mp.
15mm left/right. IQ4 150mp. No LCC corrections applied.
15mm left/right. IQ4 150mp. Only Uniform Light correction applied.
Bonus: Schneider 60xL in the wild
We took the Phase One IQ4 150mp out on an usually warm autumn day after our lab test. The below capture resulted.
20mm rise. IQ4 150mp. Only Uniform Light correction applied.
100% crop from the above.
Summary
This is not the final say on tech camera performance with the IQ4 150mp. Nor does it include the 28XL and 35XL which we do not have in rental/demo to test, and would likely be less forgiving. However, the 43XL is pretty high on the list of “problematic” lenses for previous digital backs, so its performance on this test bodes very well for a variety of lens+movement combinations.
It’s definitely clear that color cast is profoundly reduced on the IQ4 150mp as compared to previous backs. In fact, there were several times during this test where we had to double check that we had the LCC disabled on the IQ4 150mp, because there was so little color cast.
What’s less clear, based on this test alone, is when users should still do an LCC, and when users can safely skip them. While color cast is greatly reduced, the tests with movement showed just enough to be of concern to color-critical work, especially with the Rodenstock lenses.
Separately from color cast, LCC is still very useful in correcting lens illumination falloff, which can be helpful. Use of a center filter (which were not used in this test) can also help with lens illumination falloff.
The reduction in color cast and falloff also means better shadow quality can be expected, and better color accuracy when shifting.
We welcome feedback, especially from early IQ4 150mp users, as to when they opt to continue LCCs and when they skip the process. Please email dep@digitaltransitions.com with your own findings so that we may better serve our future clients.
