When it comes to medium format photography, two names consistently dominate the conversation: Pentax and Fujifilm. As a professional photographer who’s spent countless hours with both systems, I’m here to break down the Pentax 645Z vs Fujifilm GFX 100S comparison in a way that actually matters to shooters like you and me.
The Pentax 645Z has been a trusted workhorse for years, while the Fujifilm GFX 100S represents the newer, more technologically advanced contender. Both cameras produce stunning images, but they cater to different shooting styles and priorities. In this comprehensive comparison, I’ll share my hands-on experience with both systems to help you make an informed decision.
Quick Comparison: Pentax 645Z vs Fujifilm GFX 100S at a Glance
| Feature | Pentax 645Z | Fujifilm GFX 100S |
|---|---|---|
| Sensor | 51.4MP CMOS | 102MP CMOS |
| Sensor Size | 44×33mm | 44×33mm |
| ISO Range | 100-51200 | 100-12800 |
| Autofocus | 27-point AF | 425-point hybrid AF |
| Image Stabilization | None | In-body 5-axis |
| Burst Shooting | 3 fps | 5 fps |
| Video | 1080p at 60i | 4K at 30p |
| LCD Screen | 3.2″ 1037k dots | 3.2″ 2360k dots |
| Weight | 1550g (with battery) | 900g (with battery) |
| Battery Life | 650 shots | 460 shots |
| Price (Body Only) | ~$6,999 | ~$5,999 |
Sensor Deep Dive: More Megapixels vs Proven Performance
The most obvious difference between these two cameras lies in their sensors. The GFX 100S boasts an impressive 102MP sensor, doubling the Pentax’s 51.4MP. But does more megapixels automatically mean better images?
In my experience shooting landscapes with both cameras, I discovered that the GFX 100S certainly delivers incredible detail when conditions are perfect. The sheer resolution allows for massive cropping while maintaining excellent detail. However, the Pentax 645Z’s sensor, while older, produces images with a certain character that many photographers, myself included, find appealing.
What’s interesting is that both cameras use the same 44×33mm sensor size, so neither has a true advantage in terms of light-gathering capability based on size alone. The difference comes down to pixel density and processing.
I’ve found that the Pentax 645Z handles highlights beautifully, with a gentle roll-off that reminds me of shooting film. The GFX 100S, on the other hand, offers more dynamic range overall, especially in shadow recovery. When I was shooting a high-contrast sunset last month, I could pull back incredible detail from the shadows in the GFX files that simply wasn’t recoverable in the Pentax files.
Design and Ergonomics: Old School vs Modern Innovation
Pick up both cameras, and you’ll immediately notice the difference. The Pentax 645Z feels like a traditional medium format camera – substantial, solid, and built like a tank. At 1550g, it’s significantly heavier than the GFX 100S, which tips the scales at 900g.
I remember my first shoot with the Pentax 645Z – a wedding where I was second shooting. After 8 hours, my arms were definitely feeling the weight. The GFX 100S, by contrast, is much closer to handling a full-frame DSLR in terms of weight and size.
The Pentax features a deep handgrip that provides excellent stability, while the GFX 100S has a more minimalist design that still manages to be comfortable for extended shooting sessions. One area where the Pentax clearly wins is weather sealing – it’s built to withstand harsh conditions, which I’ve tested during rainy outdoor shoots.
The GFX 100S incorporates a more modern control layout with a touchscreen LCD that’s fully articulated. The Pentax’s screen is fixed and less responsive, though still perfectly functional for image review and menu navigation.
Autofocus Performance: Where the Gap Widens?
This is where the newer technology of the GFX 100S really shows its advantage. With 425 hybrid AF points covering almost the entire frame, the GFX 100S offers autofocus performance that rivals modern full-frame cameras.
The Pentax 645Z’s 27-point AF system, while reliable for its time, feels dated by comparison. During a portrait session with a moving toddler, I found myself frustrated with the Pentax’s tendency to hunt for focus, while the GFX 100S tracked the child’s movements with confidence.
That said, for stationary subjects like landscapes or studio portraits, both cameras perform admirably. I’ve captured tack-sharp images with both systems when I have time to carefully compose and focus.
Lens Ecosystem: The Long Game
When investing in a medium format system, you’re not just buying a camera – you’re committing to a lens ecosystem. This is where Pentax has a significant advantage in terms of history and variety.
The Pentax 645 system has been around since the 1980s, meaning there’s a wide range of lenses available, including many affordable used options. I’ve built a collection of Pentax 645 lenses over the years, and even the older manual focus lenses produce beautiful results on the 645Z.
Fujifilm’s GFX lens lineup is newer but growing rapidly. The GF lenses I’ve used are exceptionally sharp and modern, with coatings designed specifically for high-resolution sensors. However, they come at a premium price, and there aren’t as many options available yet.
One advantage of the GFX system is the ability to adapt certain full-frame lenses with a speed booster, effectively expanding your lens options. I’ve experimented with adapting some of my favorite full-frame lenses to the GFX 100S with surprisingly good results.
Image Quality in the Real World
Numbers and specifications only tell part of the story. What really matters is how these cameras perform in actual shooting conditions.
I took both cameras on a recent landscape photography trip to test them side by side. The GFX 100S’s 102MP files are simply breathtaking when viewed at 100% – the level of detail is almost surreal. However, these massive files require a powerful computer to process and take up significant storage space.
The Pentax 645Z’s 51MP files are more manageable while still delivering excellent detail and that medium format “look” that’s hard to quantify but easy to recognize. There’s a certain three-dimensional quality to the images that makes them feel more lifelike.
In terms of color science, both cameras produce beautiful files, but with different characteristics. The Pentax tends to render colors in a more traditional, slightly muted way that many photographers associate with medium format film. The GFX 100S produces more vibrant, modern-looking files straight out of the camera, though they’re easily adjustable in post-processing.
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Video Capabilities: An Afterthought or a Feature?
If video is important to you, the choice between these two cameras becomes much clearer. The GFX 100S offers 4K video recording at up to 30p, with the ability to use the full width of its medium format sensor for cinematic depth of field.
The Pentax 645Z, being an older design, is limited to 1080p video at 60i. While it’s capable of decent video quality, it’s clearly not designed with videographers in mind.
During a recent product shoot, I used the GFX 100S to capture some behind-the-scenes footage, and I was impressed with the quality. The ability to shoot 4K video with medium format aesthetics is something that simply wasn’t possible just a few years ago.
Battery Life and Storage: Practical Considerations
For all-day shooting sessions, battery life matters. The Pentax 645Z’s larger body accommodates a bigger battery, delivering approximately 650 shots per charge. The GFX 100S manages about 460 shots per charge, which is still respectable but requires more frequent battery changes during long shoots.
Both cameras use dual SD card slots for backup or overflow storage. However, the GFX 100S’s high-resolution files fill up cards much faster. I’ve found that 128GB cards are a practical minimum for the GFX 100S, while the Pentax 645Z can get by with 64GB cards for most shooting situations.
Price and Value Analysis
At first glance, the GFX 100S appears to be the better value at approximately $5,999 for the body, compared to the Pentax 645Z at around $6,999. However, this comparison doesn’t tell the whole story.
The Pentax 645Z has been on the market longer, so you can often find it discounted or as part of a kit with lenses. Additionally, the availability of used Pentax 645 lenses at reasonable prices can significantly reduce the total cost of ownership.
The GFX 100S, while newer, represents a more modern technological package with features like in-body stabilization and a much more advanced autofocus system. If these features are important to you, the extra investment might be worthwhile.
Who Should Buy Which Camera?
After extensive use of both systems, I’ve developed clear recommendations for different types of photographers:
The Pentax 645Z is ideal for:
- Landscape photographers who prioritize image character over pixel count
- Studio photographers working primarily with stationary subjects
- Photographers who value weather sealing and durability
- Those who already own Pentax 645 lenses
- Photographers who prefer a more traditional shooting experience
The Fujifilm GFX 100S is ideal for:
- Commercial photographers who need maximum resolution
- Portrait photographers who need reliable autofocus
- Hybrid shooters who want both high-quality stills and video
- Photographers who value portability without sacrificing image quality
- Those who want the latest technology and features
My Personal Journey with Both Systems
I’ve been shooting medium format for over a decade, starting with film and transitioning to digital as the technology improved. My first digital medium format camera was a Pentax 645D, and I later upgraded to the 645Z when it was released.
For years, the 645Z was my go-to camera for all professional work. The image quality was fantastic, and the camera felt like a natural extension of my hands. However, as my work evolved to include more portrait sessions with active subjects and occasional video work, I began to feel the limitations of the system.
When the GFX 100S was announced, I was intrigued but skeptical. Could a camera that small and relatively affordable really deliver true medium format quality? After testing one for a week, I was convinced enough to make the switch.
That said, I still keep my Pentax 645Z in my gear bag. There’s something about the images it produces that I can’t quite replicate with the GFX 100S, especially for certain landscape work. For me, having both systems gives me the best of both worlds – the modern convenience of the GFX 100S and the classic character of the Pentax 645Z.
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Pro Tips for Both Systems
Whether you choose the Pentax 645Z or the GFX 100S, here are some tips I’ve learned that will help you get the most out of your medium format camera:
For Pentax 645Z Users:
- Invest in a quality tripod – the camera’s weight and lack of stabilization make handheld shooting challenging at slower shutter speeds.
- Explore the used lens market – some of the older manual focus Pentax 645 lenses offer incredible value and unique rendering.
- Use the dual SD card slots for backup – medium format files are too valuable to risk losing.
- Take advantage of the weather sealing – don’t be afraid to shoot in challenging conditions.
For Fujifilm GFX 100S Users:
- Upgrade your computer – the 100MP files require significant processing power.
- Invest in fast, large-capacity SD cards – the camera deserves quality storage.
- Experiment with the digital teleconverter function – it’s a great way to extend the reach of your lenses without sacrificing quality.
- Use the in-body stabilization to your advantage – it makes handheld medium format photography viable in more situations than ever before.
FAQ: Pentax 645Z vs Fujifilm GFX 100S
Which camera has better low-light performance?
The GFX 100S technically has better low-light performance due to its newer sensor technology, but the difference isn’t as dramatic as you might expect. Both cameras perform well in low light, though the GFX 100S maintains better color accuracy at higher ISOs.
Can I use my existing full-frame lenses with either camera?
The GFX 100S can adapt certain full-frame lenses with a speed booster, though with some limitations. The Pentax 645Z has a longer flange distance that makes adapting full-frame lenses impractical.
Which camera is better for portrait photography?
For portraits with stationary subjects, both cameras excel. However, if you shoot portraits of active subjects like children or pets, the GFX 100S’s superior autofocus system gives it a clear advantage.
Do I really need 100 megapixels?
For most applications, 51MP is more than sufficient. However, if you do commercial work, make large prints, or frequently crop your images, the extra resolution of the GFX 100S can be beneficial.
Which system has better long-term support?
Fujifilm is actively developing the GFX system with new cameras and lenses regularly announced. Pentax has been less active in the medium format space recently, though the 645Z continues to be supported.
How do the files compare in post-processing?
The GFX 100S files have more latitude for adjustment, especially in shadow recovery. The Pentax 645Z files are more manageable in terms of file size and processing requirements.
Conclusion: Making Your Choice
After spending significant time with both the Pentax 645Z and the Fujifilm GFX 100S, I can confidently say that there’s no universal “better” camera – only the better camera for your specific needs.
If you value a traditional shooting experience, weather sealing, and proven reliability, the Pentax 645Z remains an excellent choice in 2025. Its images have a character that many photographers find appealing, and the extensive lens ecosystem offers plenty of options at various price points.
If you prioritize modern features, portability, and cutting-edge technology, the GFX 100S is the clear winner. Its combination of 100MP resolution, in-body stabilization, and advanced autofocus makes it a versatile tool for a wide range of photography styles.
Ultimately, the best way to decide is to try both cameras if possible. Rent them for a weekend, shoot with them in conditions similar to your typical work, and see which one feels right in your hands and produces the results you’re looking for.
Remember, the best camera is the one that inspires you to get out and shoot. Both the Pentax 645Z and the Fujifilm GFX 100S are capable of producing stunning images that will elevate your photography – the rest is just personal preference.