This was my Safety Day recertification sky dive (gotta love the irony). I hadn't jumped in a few months, so I needed an instructor to jump with me (you need to jump every 30 days up until you get 50 or more jumps). Unknown to me, my altimeter failed (it got stuck showing 10,500 feet), and I was not altitude aware (BIG mistake) as I was focussed between my instructor and a broken altimeter. My instructor also had an all black suit on and was wearing black gloves. So every time he pointed at me, all I saw was his elbow emanating from his silhoutte. When it finally dawned on me that something was wrong, we were at approximately 1,200 feet when I waived off. We figured I pulled my main around 1,000 feet, which was just a second or so before my reserve chute deployed automatically, being fully deployed at approximately 850 feet! Nothing like landing under two chutes (which I did due to a downplane as I went to release the main). Do NOT try this on your own!!