Full-frame or Micro Four Thirds? My Experience With OM-SYSTEM's OM-1 Mark II

November 9, 2025

I have a confession to make. I wrote confidently in my last post about the advantages of full-frame. So much so that I was ready to invest by selling my Fujifilm gear. A few months ago, I was looking through my photo catalog and found old images I had taken in Glacier National Park using my then Olympus Pen E-PL1. While having great memories of that trip, and the camera I no longer have, I was reminded of how good those images looked. The images aren't portfolio worthy, but the color and detail were excellent. I realized that I never reconsidered Micro Four Thirds (M4/3) as an option. Did I have a case of full-frame tunnel vision? In order to find out, I decided to try, with my own money, OM SYSTEM's OM-1 Mark II with the 12-40mm F2.8 Pro II and 40-150mm F2.8 Pro lenses. Why OM SYSTEM and not Panasonic? The OM-1 Mark II seemed to be more focused on photography rather than the hybrid, video and photography approach from Panasonic, so that appealed to me more. Nostalgia played a role, too. While Olympus is no longer in the camera business, their spirit lives on through OM SYSTEM.

As a camera, the OM-1 Mark II is very nice. It's comfortable with a large, ergonomically well-designed grip that feels secure in the hand. Weighing around 500 grams, it's lightweight but also solid. Battery life is excellent and the 5.76 million dot EVF is bright and clear. The stabilization is the best I've encountered. Any visible movement virtually disappears. Equally impressive are the computational photography features. I haven't used all of the computational modes yet, but the Live ND and High Res Shot work very well. There are some limitations to keep in mind. The Live ND has a threshold for how slow the shutter speed can be, and the High Res Shot works best on subjects with little to no movement, otherwise the final blended image may have ghosting artifacts. Limitations notwithstanding, these tools are genuinely useful and add to an already robust feature set.

The two pro lenses have excellent build quality. With full metal housing and splash-resistant weather sealing, they feel every bit as rugged as the camera. Focusing is smooth and responsive. The 12-40 has a manual focus clutch that can be engaged and disengaged with a push and pull of the focus ring. I have found that it is easy to move the clutch when removing it from my camera bag, but that's only a minor annoyance. The 40-150 lens has a clever party trick where the lens hood can be extended and retracted while attached to the lens. Even the 12-40's small petal hood has a nice button release. The attention to small details is something I appreciate.

The lenses also deliver prime lens level sharpness. It's excellent from wide open until diffraction sets in above f/8.0. Both lenses seem to perform their best around f/5.6, although there is some breathing room between f/5.6 and f/8.0 if additional depth of field is needed before taking a trade in sharpness.

Reviewing images that I took from my Olympus E-PL1 reminded me that an M4/3 sensor can be quite capable and that is certainly the case for the OM-1 Mark II. The 20-megapixel sensor produces excellent results. There is a noise penalty at base ISO, but that is easily fixed with some minor noise reduction without any noticeable loss to overall image acuity. Dynamic range is also very good, although I find M4/3 to be less forgiving if you happen to make metering mistakes. This is most noticeable with shadow and highlight recovery during post-processing. With careful metering, though, the OM-1 Mark II seems to have plenty of bandwidth.

After several years of ~80-megabyte RAW images from Fujifilm and Nikon, the ~20-megabyte RAW images from the OM-1 Mark II result in significant space savings, which is an advantage I hadn't considered before. The smaller size contributes to faster load times in Adobe Camera Raw (ACR), too. It's also nice to see that the color recipe used by the OM-1 Mark II has stayed largely the same since my Olympus E-PL1 days. The RAW files have nice contrast and saturation and are easy to edit. The one caveat is the RAW file created by the High Res Shot mode. In ACR, the image is softer than the same file viewed in OM Workspace (OM SYSTEM's proprietary image editing software). I don't notice this as much with standard RAW files. If you have a High Res Shot mode RAW file, it's best to use OM Workspace to get maximum image quality.

Admittedly, I have only scratched the surface of what the OM-1 Mark II can do. There are a lot of other features I haven't covered here, like autofocus and video, for example, so I'd recommend you explore other reviews for more information. With that said, I have been impressed by the OM-1 Mark II. If I had to describe my experience over these last few months in a single word, it's fun. The camera is just plain fun to use. I've thought a lot about why it feels that way and I think it's how well the hardware and software work together. In use, the OM-1 Mark II feels every bit as robust as its IP53 rating suggests, with lens options that are splash-resistant, lightweight, compact telephoto lenses, and software that takes full advantage of the hardware capabilities. There's an excitement in using the camera and it delivers a rather unique user experience. So, what does this mean for my full-frame ambitions? It certainly complicates things.

First, I wish I had been more diligent and thoughtful in my approach in viewing full-frame as the obvious path forward. If I had factored M4/3 as an option then, that path might not have been so obvious. Over the last several years, I had become so focused on achieving maximum image quality, or as maximum as my budget allows, that I rarely considered anything else. Revisiting that post, my confident statement about moving to full-frame for its advantages seems short-sighted considering the current circumstances. I won't delete that post, but I will append a note to inform any stray readers that I should have been more thorough and less dogmatic in my approach and conclusion.

Secondly, I know that full-frame will deliver a better image overall. More resolution, a lower noise floor, and increased dynamic range are big advantages. In other words, I want full-frame. I also want the OM-1 Mark II. While it can't quite match full-frame in terms of image performance, it is still very good, and it remains one of the most enjoyable cameras I have used. If money were no object, the answer to this would be simple. I would have both. Full-frame and M4/3 each serve a specific purpose, and it would be easy to justify having both. I can't afford both. So, the choice becomes a compromise, and the OM-1 Mark II is my preferred choice.

Using the OM-1 Mark II over these past few months reminded me why M4/3 continues to have a dedicated fan base. It is a unique platform and while it has its limitations, it plays so well to its strengths that those limitations start to matter less. The OM-1 Mark II didn't have exactly what I wanted, but it had exactly what I needed: a perfect combination of high-end performance and fun. In photography, that's a good place to be.