The Trip is a little… particular. The following is what I gleaned from the internet some time ago trying to hunt down the technical details. There is no single document to back up my statements below, so take them prudently 😉
The default exposure time on a Trip 35 is around 1/100s
When you set aperture to ‘A’ it will auto-expose using the selenium cells around the lens by varying the aperture for an overall even tone. You may already know that if it judges the picture to be too dark, it won’t release the shutter. The inset picture is mostly dark, the auto-expose would not capture that.
To force the shutter to release, you need to use a “manual” aperture setting.
The manual setting of the aperture is not an imperative – it informs the camera that the maximum aperture you want to allow is what you have set. If it can achieve a balanced picture with a narrower aperture, say f8 instead of f5.6, then it will use the narrower f8.
If it reaches your maximum aperture and still is not satisfied that the picture is bright enough, it switches to a 1/40s exposure.
You can also insert ISO 400 film but set the camera to ASA 200 for example – in this case since the camera will automatically calibrate for a less sensitive film, the aperture will open up further than if you had set it to ASA 400 (to match your film). In “normal” lighting conditions, this means that with ISO 400 film and ASA 200 setting, your picture will be brighter.
For night-time street captures then, ISO 400 film with settings at ASA 400, f2.8 and exposure 1/40s should yield the right results. Certainly, I always buy ISO 400 film these days, as I nearly always have a want to take photos in low-light.
I hope that serves as a useful summary of the basic considerations for using a Trip 35. It’s a good little camera, albeit a little heavy…