The Pentax 645Z is a digital medium format DSLR with an optical viewfinder, while the Fujifilm GFX 100S is a more compact mirrorless camera with an electronic viewfinder and a higher resolution class. Choose the 645Z for a traditional, rugged shooting feel, and the GFX 100S for modern features and a smaller body.
Two generations of medium format
Both cameras use a sensor larger than full frame, which gives wide tonal range and fine detail when used well. The 645Z follows the DSLR tradition, with a mirror, a pentaprism and a body built around weather-sealed handling. The GFX 100S is mirrorless, so it uses an electronic viewfinder and a rear screen, and it is smaller for its sensor size. Confirm exact numbers on each maker’s page, as specs are best checked at the source.
Key differences
- Viewfinder: the 645Z has an optical finder that many people find calm and natural. The GFX 100S has an electronic finder that shows exposure before you shoot.
- Resolution class: the 645Z sits in the roughly 50 megapixel range, while the GFX 100S sits around 100 megapixels, which gives more room to crop and print large.
- Stabilization: the GFX 100S includes in-body stabilization, which helps handheld work. The 645Z relies on technique and fast shutter speeds.
- Autofocus: a mirrorless body generally offers more modern autofocus options, including face and eye detection. The 645Z uses a DSLR style system.
- Size and weight: the GFX 100S is notably more compact. The 645Z is bulkier but offers a sturdy grip.
- Lenses: each uses its own mount and lens line, so you choose a system as well as a body.
Table
| Trait | Pentax 645Z | Fujifilm GFX 100S |
|---|---|---|
| Type | DSLR | Mirrorless |
| Finder | Optical | Electronic |
| Stabilization | Lens only | In body |
| Size | Larger | Smaller |
How to choose
- Decide how large your prints and crops will be. If you rarely print big, extra resolution may not matter.
- Think about handheld work. Stabilization is a real advantage for portraits and travel.
- Look at the lenses you want and whether they are available in each system.
- Check whether you prefer an optical or electronic view of the scene.
- Consider whether you use the camera on tripods in studios or in the field.
FAQ
Is the 645Z still useful today?
Yes, for photographers who enjoy its optical finder and sturdy build, and who shoot mostly on a tripod or with plenty of light. It has an older feature set.
Why does the GFX 100S feel so different?
It is mirrorless, so it is smaller and gives a live view of exposure in the finder. That changes both the weight and the way you work.
The Short Version
Choose the Pentax 645Z for an optical, robust shooting style at a modest resolution class. Choose the Fujifilm GFX 100S if you want a smaller body, stabilization and a higher resolution. We have not used these cameras ourselves, so check the makers’ pages for current specifications.
