K-7 Machine Gun Demo, Timing Measurbations and Size Comparisons

A Korean site has done an excellent K-7 preview with posted Flash videos which record the continuous shootings of the K-7 in Hi and Lo modes and that of the K20D.

1. Direct link to the video of Continuous Hi mode of the K-7 is as follows:-

http://image.popco.net/Review/DCA/PENTAX_K-7-pre/flash3.htm
(A new browser window will be opened)

I have saved the sound track of the above as wave file here. After some measurbations (detailed explanation on the methodology here), I found that the average time duration between two consecutive shots is 0.19675 sec as sampled. As such, the measured actual shooting rate is about 5.08 fps in this case.

I also note that the continuous shooting rate is not absolutely constant through out the whole continuous shooting period, i.e., sometimes slightly faster and sometimes relatively slightly slower. But anyway in average and as sampled, it is close enough to the specified rate of 5.2 fps. The actual number of shots in a chain before buffer overthrown is counted to be 46 frames, which is more than what has been specified (of 40 frames in a chain maximum). It maybe just because of the slight lower actual shooting rate, so more frames in a chain can be stored. As for the reason for a lower rate, it depends on the battery power condition, ambient temperature, complexity of the scene to be recorded, shutter speed and speed of the SD card used, etc.

2. Direct link to the video of Continuous Lo mode of the K-7 is as follows:-

http://image.popco.net/Review/DCA/PENTAX_K-7-pre/flash4.htm
(A new browser window will be opened)

Wave file here: http://www.geocities.com/ricehigh/blogger/K-7/K-7_3fps.wav

The measured average duration between two shots is: 0.30867 sec

Hence, the measured actual shooting rate is: 3.24 fps, which is still slightly less than the specified rate of 3.3 fps.

The averaged system time lag of the K-7 from this sound file is 64 milliseconds (I took two samples, both at 64ms), which is fairly short, and is the best I have ever seen for a Pentax DSLR! It is well expected because if the system time lag is not shortened, it is impossible to achieve a higher frame rate! For an idea on what this is actually meant, compare to the performance and measured figures by the Imaging Resource of other DSLRs here. And, now the K-7 is comparable to the Canon 20D/30D (65ms) but yet is still a little bit longer than the 40D/50D (59ms), see the posted "shutter lag" figures here.

I suspect this to be the best system time lag figure obtainable with the K-7 as very possibly AF function is disabled by the tester when he meant to test the continuous shooting mode.

Now, let's look at how the K20D can perform and is compared:-

http://image.popco.net/Review/DCA/PENTAX_K-7-pre/flash5.htm
(A new browser window will be opened)

And the wave file is as below:-

http://www.geocities.com/ricehigh/blogger/K-7/K20D_3fps.wav

The measured average duration between two shots is: 0.35175 sec

Thus, the average shooting rate is: 2.84 fps.

System time lag is measured to be 120 ms.

Again, the K20D is slower than specified for the shooting rate and is actually obviously slower than the K-7's Continuous Lo mode, even though it is just observed by feeling without any measurement. The system time lag of the K20D is almost doubled - that what I have been criticising about all the Pentax DSLRs for years (but then I was bashed by the fanboys each time and every time I pointed out this *fact*!)

Last but not least, I heard from different beta testers that the beta K-7 they tested were with firmware version 0.2 of which the Continuous Hi mode is locked. It seems that new firmware of higher version is being distributed (but not to all beta-testers as some of them have already returned their K-7s to Pentax).

As another reference, the system time lag of the K-m was mesaured to be 114 ms by me previously, which is still faster than the K20D by this comparison.

Well, I would give Pentax a "Well Done!" remark for being successful for significantly shortened the system time lag of a Pentax body so that they can achieve a higher frame rate (beside that they needed to find a faster sensor and achieved faster processing).

In the second part of the Preview, they have made some interesting side comparisons with the K-7 against a number of DSLR bodies, namely: Canon 450D, Nikon D80, the K20D, K100D/Super and Fujifilm S5Pro, from different angles of view. The K-7 does look compact, slim and smart and actually much smarter than all others IMO. The closset thing to the K-7 is the K100D, so the K-7 is really compact. Nice!

Edit (5-26): Machine Gun Demo of the K-7 (5.2 fps) Vs Nikon D3 (5.0 fps) at YouTube!

Very obviously, the K-7 gun fires more silently than the D3 but my feeling is that the D3 is just firing faster. Really? I shall measure it later when I have the time! Stay tuned.

Edit (5-30): A "cleaner" portion of the sound track with relatively less unwanted background noise is captured and the measurbation results are as follows:-

Actual frame rate of the K-7 (Beta) in the video clip: 4.2 fps (Only! What? Unstable Frame Rate?? What caused it???)

Actual frame rate of the D3 in the clip: 5.03 fps

Well, sometimes we should not look down at human "feeling"! I have seen on the net that I am not the only one that felt that the D3 is faster. Whilst human feeling is subjective, it could still be quite sensitive! Usually minor difference can be detected!