Most AI tools still produce photos that look expensive until you notice the shadows point in two directions at once.

The Setup: My First 40 AI Ad Tests

I ran 40 product shots through various generators last quarter for a cosmetics client. Every image looked studio-grade on my screen. The moment we pushed them live, CTR sat at 0.9%. Real studio photos from the same brand averaged 2.1%. Something invisible to me was killing trust.

I started measuring the one variable I had ignored: light direction relative to product edges. AI models love to mix a key light from the top-left with a fill from the right, creating conflicting catchlights. Viewers sense the lie even when they cannot name it.

The Action: One Prompt Change, Tested 12 Times

I built a simple lighting spec into our workflow: single 45-degree key light, softbox modifier, and a small reflector only on the shadow side. Then I fed that exact spec through our AI ad creative generator using consistent negative prompts for multiple light sources.

Each new batch went head-to-head against the old “studio quality” versions. I tracked impressions, CTR, and add-to-cart on identical audiences. No other variables changed.

Results After Two Weeks

  • CTR rose from 0.9% to 2.4% (167% lift)
  • Add-to-cart rate increased 31%
  • Time spent creating usable assets dropped from 11 hours to 4 hours per campaign

The only difference was removing the phantom second light source. Everything else stayed the same.

Why This Mistake Persists in AI Tools

Training data contains thousands of multi-light beauty setups. Models average those setups instead of obeying a single direction. The result is technically bright but physically impossible lighting that erodes conversion.

Once I forced a single light vector and documented the exact angle in every prompt, consistency returned. The same products now pass the “thumb test” — they look real even when scrolled past quickly.

I’m Didar, the founder of AdLoft — an AI ad creative platform turning product photos into professional ads. I write here about the stuff I’m building and what’s working.