In my AS Level chemistry class we had tried some DIY spectroscopy of flame tests with the aim of identifying anions in certain salts. We got as far as building the spectrometer inspired by Paper Craft Spectrometer (though we built a much bigger version such that a DSLR could be used) and performing the experiment and collecting the data. The problem was that I couldn't manage to get many of the spectrograms to line up with those sourced from the web. Many of our spectrograms, while plenty bright and with lines covering the whole visible range, had too few lines and those that were there didn't align with any real data we could find.
For instance with the following recorded spectrogram: Some processing was done on the above image to produce the spectrum below it. The scale is calibrated from an LED which was also recorded and then confirmed my matching it against the emission of sodium which also roughly lined up to this scale +-10nm. From the colour of the flame we assumed it was calcium, given that all salts tested were chlorine salts, and the metal is one of: Ca, Cu, Cs, K, Li, Na, Sr. I don't know if there was an experimental error or if we were not looking at the correct reference spectrograms but nothing I could find would line up with that,does anyone have any insight into this?