nifty50 stocks

I generally preferred Nifty50 stocks/futures for any trade. I have observed that the spread is generally huge (more than 50 paise at times) for non-Nifty stocks/futures. What is the reason? Or am i missing something? Please see screenshot below (for a Nifty50 future versus non-Nifty50 future)

sir, for trading TD sequential in futures on daily chart, the setups etc should be monitored on cash to maintain continuity or respective future series only? thanks