jswilson64 Forum Member







Join Date: Jan 2011 Location: wilson_j_s@sbcglobal.net Photos: Albums Posts: 91

Tested: Battery voltage/type affects K-50 burst rate



Batteries used were: Pentax D-LI109 battery; AmazonBasics High Capacity Rechargeable NiMH AA batteries (black label), and Sanyo Eneloop Pre-Charged NiMH AA batteries (white label). I recorded the voltage of each battery or AA pack before the test. The Pentax battery and the Amazon Black batteries were charged just before the test; the Eneloops had been charged about 6 weeks ago and had been unused since charging.



As instructed by several threads here, I turned off various corrections / compression in the K-50 to maximize burst rate; set the K-50 to manual focus, continuous Hi drive, Tv, 1/400 sec, ISO 200, Jpeg only (to allow more frames to be shot), wired remote, and auto battery type. Test was outdoors on a partly cloudy day, the kit DA 50-200 WR lens gave f5.0 or f5.6 at 50mm for all shots. A San Disk Extreme Pro 64GB SD card was formatted and used for this test. For each battery, I held my iPhone 6 Plus near the tripod-mounted K-50 and recorded video while actuating the shutter on the K-50 remote. The videos included placards indicating which battery was being used. I recorded approximately 7-8 seconds of continuous shutter actuation for each battery. I also recorded a click track using a free metronome app set to 300bpm (5bps) on an Android phone.



After moving the video files to my Windows 10 PC, I extracted the audio from the video files using VLC. I used the select tool in Audacity to select 25 full shutter actuations, attempting to hit the same point on the same peak in the beginning and ending cycle. Audacity tells you the duration of your selected audio so I wrote that down for each track. (as an aside, it appeared that what I'm assuming to be the "mirror up" portion of the shutter cycle was about 30ms longer on the first frame of each recording, so I began my selection with the second frame) I then calculated the average time per shutter actuation cycle, and the average frames per second for each battery pack. As a control, I used the same Audacity methodology to analyze the metronome click track; this gave me some confidence that my phone and/or process wasn't screwing with the timing I was hearing.







The D-LI109 battery was audibly "faster" to me while performing the tests and this was borne out by the measurements. Put simply, higher voltage resulted in higher fps. The difference between the 8.4v D-LI109 and the Eneloop pack at 5.65 volts was over 1 fps (over 18% fewer FPS) while shooting continuously. And the genuine Pentax battery (less than 1 year old, with fewer than 20 discharge/charge cycles) appears to max out at about 5.8 fps or (to the technical writer) "approx. 6 fps."



To me this result is very interesting. For one thing, the K-50 manual doesn't appear to mention anything about different batteries influencing the burst rate. It may be in there but I didn't find it. As a "twitchy critter" picture-taker, though, this is big. I've been shooting birds with whatever battery I grab at the time; simply using the Pentax battery is a free 15% boost in FPS over AAs. And I will re-think purchasing any more rechargeable AAs for my K-50. Unless I can rig up an external pack or hack together a battery grip. If 4 AAs put out approx. 5.5 volts, six AAs should put the voltage right around 8.4v... Right? :-) I should probably sleep on that before acting.



In the interest of full disclosure, here's links to the audio recordings, shared on Sound Cloud. Feel free to download them and analyze for yourself!

Eneloop White by jswilson64 | Free Listening on SoundCloud

D - LI109 by jswilson64 | Free Listening on SoundCloud

Amazon Black by jswilson64 | Free Listening on SoundCloud

5 Bps Metronome by jswilson64 | Free Listening on SoundCloud



As an aspiring picture-taker of birds and small, twitchy mammals (and dogs), I often shoot with my K-50 in Continuous Hi mode. I'm not that picky about my batteries: sometimes I use the Pentax lithium battery (D-LI109) and sometimes I use rechargeable AA batteries. I began to notice what seemed like an audible difference in frame rate when shooting bursts. The book says burst rate is 6 fps (oops, it actually says "approx. 6 fps"). I have all those compression and compensation and filter thingies turned off, so I must be getting that mythical 6fps, right? Since I usually shoot RAW or RAW+, it's hard to tell the difference in a six-shot burst before the camera slows to "buffer full" mode. Still, I couldn't let it go, so I set out to verify my suspicions. The first thing I did was search PF for several variants of "voltage" and "fps," but didn't find anything to confirm or deny my suspicions (but I may have missed something). So I grabbed my camera, tripod, wired remote, two cell phones and some batteries and got to work.Batteries used were: Pentax D-LI109 battery; AmazonBasics High Capacity Rechargeable NiMH AA batteries (black label), and Sanyo Eneloop Pre-Charged NiMH AA batteries (white label). I recorded the voltage of each battery or AA pack before the test. The Pentax battery and the Amazon Black batteries were charged just before the test; the Eneloops had been charged about 6 weeks ago and had been unused since charging.As instructed by several threads here, I turned off various corrections / compression in the K-50 to maximize burst rate; set the K-50 to manual focus, continuous Hi drive, Tv, 1/400 sec, ISO 200, Jpeg only (to allow more frames to be shot), wired remote, and auto battery type. Test was outdoors on a partly cloudy day, the kit DA 50-200 WR lens gave f5.0 or f5.6 at 50mm for all shots. A San Disk Extreme Pro 64GB SD card was formatted and used for this test. For each battery, I held my iPhone 6 Plus near the tripod-mounted K-50 and recorded video while actuating the shutter on the K-50 remote. The videos included placards indicating which battery was being used. I recorded approximately 7-8 seconds of continuous shutter actuation for each battery. I also recorded a click track using a free metronome app set to 300bpm (5bps) on an Android phone.After moving the video files to my Windows 10 PC, I extracted the audio from the video files using VLC. I used the select tool in Audacity to select 25 full shutter actuations, attempting to hit the same point on the same peak in the beginning and ending cycle. Audacity tells you the duration of your selected audio so I wrote that down for each track. (as an aside, it appeared that what I'm assuming to be the "mirror up" portion of the shutter cycle was about 30ms longer on the first frame of each recording, so I began my selection with the second frame) I then calculated the average time per shutter actuation cycle, and the average frames per second for each battery pack. As a control, I used the same Audacity methodology to analyze the metronome click track; this gave me some confidence that my phone and/or process wasn't screwing with the timing I was hearing. Results (google sheet) (sorry, I tried BB code and failed miserably)The D-LI109 battery was audibly "faster" to me while performing the tests and this was borne out by the measurements. Put simply, higher voltage resulted in higher fps. The difference between the 8.4v D-LI109 and the Eneloop pack at 5.65 volts was over 1 fps (over 18% fewer FPS) while shooting continuously. And the genuine Pentax battery (less than 1 year old, with fewer than 20 discharge/charge cycles) appears to max out at about 5.8 fps or (to the technical writer) "approx. 6 fps."To me this result is very interesting. For one thing, the K-50 manual doesn't appear to mention anything about different batteries influencing the burst rate. It may be in there but I didn't find it. As a "twitchy critter" picture-taker, though, this is big. I've been shooting birds with whatever battery I grab at the time; simply using the Pentax battery is a free 15% boost in FPS over AAs. And I will re-think purchasing any more rechargeable AAs for my K-50. Unless I can rig up an external pack or hack together a battery grip. If 4 AAs put out approx. 5.5 volts, six AAs should put the voltage right around 8.4v... Right? :-) I should probably sleep on that before acting.In the interest of full disclosure, here's links to the audio recordings, shared on Sound Cloud. Feel free to download them and analyze for yourself!