Yes — a camera app with manual controls is likely the best fix. The main issue is often that the iPhone may change lenses automatically, and the app may also keep adjusting focus/exposure in ways that make digiscoping harder.

A manual camera app can help you:

• choose the lens explicitly
• lock focus
• control other settings more reliably

One community recommendation was Pro Camera by Moment, which reportedly works well for this kind of setup.

Practical approach:

• align the phone carefully over the eyepiece
• use an app that lets you select the desired lens manually
• lock focus once the scope image is sharp
• avoid excessive digital zoom on the phone, since that can worsen image quality and may contribute to vignetting/black edges if alignment is off

If the image goes black, it’s commonly a sign of lens misalignment or the phone switching to a different camera module than the one centered on the adapter.