The Petri GX-1 is a reflex camera. The 35mm camera was built by Cosina and also offered under the name “Cosina CT-1A”.
The lenses of the Petri GX-1 are interchangeable. This is made possible by the Pentax K bayonet. You have to focus the lens by hand. The 35 mm camera does not have an autofocus function.
The 35 mm camera has a built-in light meter. It can be used with films from ISO 25 to ISO 1600. Exposure is determined by SLR when measured by the lens (TTL). The shutter speed and aperture can be selected by the photographer.
The camera comes with a Bulb setting option. In this mode, the shutter will open as long as the shutter release button is pressed. Hot shoe flashes can be used with the camera. There is also a PC flash socket.
Films for the Petri GX-1
The Petri GX-1 is an analogue camera and needs to be equipped with 35mm film. For this film format, there is still a good selection of material for color and black and white images. Possible films for the model are the Fujifilm Superia 200* for color pictures and the AgfaPhoto APX 400* for black and white photos.
The 35mm camera has a built-in self-timer. In addition, there is a connector for a cable release and a thread for a tripod. The power supply comes from two LR44 batteries (eBay / Amazon*).
The Petri GX-1 is no longer produced. The prices for the camera vary depending on the condition.
Technical datasheet
| Attribute | Specification |
|---|---|
| Type of Camera | Single lens reflex camera |
| Film format | 35mm |
| Picture format | 24 mm x 36 mm |
| Lens mount | Pentax K lens mount |
| Focus | Manual |
| Exposure times | 1/1000 second to 1 second, Bulb |
| Bulb mode | Yes |
| Light meter | Yes |
| Built-in flash | No |
| Flash Connection | Hot Shoe, PC-Flash |
| Flash sync speed | 1/125 s |
| Tripod mount | Yes |
| Cable release thread | Yes |
| Self-timer | Yes |
| Power supply | 2x LR44 batteries |
| Manufacturer | Cosina |
| Estimated value / Used price | 97,98 Euro Estimate based on used prices of 7 offers (possibly with different scope of delivery and/or condition). As of May 18, 2026 |
| Average used price in the year 2023 | 51,00 Euro (55.20 US-Dollar) |
| Average used price in the year 2024 | 68,78 Euro (73.60 US-Dollar) |
| Average used price in the year 2025 | 103,27 Euro (111.49 US-Dollar) |
FAQ about the Petri GX-1
Is the Petri GX-1 an autofocus camera?
No, the Petri GX-1 is a manual focus camera. You have to focus the lens yourself. It doesn't have any autofocus features.
What kind of film does this 35mm camera use?
The Petri GX-1 uses standard 35mm film. You can use color or black and white film, from various brands like Kodak, Fujifilm, and Ilford.
Can I use a flash with the Petri GX-1?
Yes, you can. The camera has a hot shoe for flashguns and also a PC sync socket for connecting external flashes.
How do I set the exposure on the camera?
The Petri GX-1 has a built-in light meter that helps you determine the correct exposure. You manually select the aperture and shutter speed.
What type of lens mount does the Cosina CT-1A have?
The Cosina CT-1A (also known as the Petri GX-1) uses a Pentax K bayonet mount. This means you can use interchangeable lenses with this mount.