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Old Jul 20, 2009, 2:19 AM   #1
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Default K7 AF C performance . . . BIF (8 sml images)

Hi All,

I've been playing with the K7 and the Auto Focus Continuous (AF C) mode for the past couple of days, and am pretty impressed.

The usual suspects for this in my case are gulls -- plentiful, they stay around the same area, and are pretty fast flyers. I used the K7, FA* 300/4.5, and sometimes the F 1.7x AFA for this. I previously tended to use the FA* 300 alone or something even shorter since it's just too hard for me to locate a bird in the sky with something longer, but for some reason, the K7 points better for me than any of my other bodies, so I actually find I can go longer if I want.

Some history -- I'm not normally a BIF shooter. Ive tried with all my bodies, but just couldn't get consistent results, so I just concentrated on what I was doing well, and wrote off BIF as something that I just didn't have the persistence to master. The K20's AF performance allowed me to get a decent % of reasonably in focus shots, but I rarely get an opportunity to shoot interesting birds in flight, so I've never really tried to improve my technique in this area, so I still s*ck at it. AT best, with the K20, I could get 2 or 3 shots in focus in a string, and had a hard time keeping the bird in the frame for more. On a good day, I could count on maybe 50-60% of the shots in reasonable focus, and there were a lot of times that I couldn't get even close to a focus lock, so I never even tried to take a shot.

Yesterday, I used the K7 with the FA* 300/4.5 + F 1.7x AFA, center point focus, AF C, and used my normal settings for exposure. I shot about 500 handheld frames, and got over 300 of them reasonably in focus just playing around. I also noticed that I could keep this camera on target easier.

Today, I started with the same lens without the TC, Auto Select Focus Point, Auto ISO from 320-1600 to get faster shutter speeds, and f9 to get more DOF, and continuous high for the shutter mode. I was shooting jpeg *** as usual to keep the file sizes down and the write times to the Sandisk Ex III memory card fast. Out of 354 handheld shots, 33 were significantly out of focus, and other than framing issues which were caused by my utter lack of reasonable technique, most had very good focus and the rest were at least useable IMO. The percentage of shots with very good focus is much better with the K7 than the K20.

It took me a while to realize that my ability to track these birds more easily was due to the shorter mirror blackout times. I also noticed that AF C combined with Auto Focus Point selection slowed down the frame rate to under 3 FPS, which is okay with me, but might disappoint many. Changing to center point or selecting a point brings the FPS back up to 5+.

I tried to concentrate my attention to birds that were at least approaching at an angle to test how well the AF system tracked -- birds that are flying straight across don't really test the tracking. Here are some selected frames from a 19 shot continuous series where all the shots were in focus. The gull wheeled around and started flying towards me. I just got the bird in the frame, waited for the AF system to focus, then mashed down the shutter and held it down until the gull landed. The distances ranged from around 75 feet to around 20 feet, so this seemed like a good example. All shots are full frame, only resized for posting. I need to try shutting SR down for these panning shots. . .

This second set is from a 9 shot continuous series, again, all in focus, distances from about 50 ft to 20 ft, all are just resized for posting.

I seriously don't feel that the K7's AF is as fast as the upper end Canons and Nikons, but I think that it's at least in the same ballpark and useable with good lenses for some more demanding action shots at least. I had set my expectation bar pretty low since most K20 owners/K7 early adopters who've posted impressions haven't had that much to say about the AF speed (which is usually a bad sign ). For me, at least, I'd have to say that the increase in AF performance is going to make a number of previously frustrating situations a lot easier.

Some other impressions after 3 days use. . .

1. Even though I have small hands, I first found the grip on the camera a bit uncomfortable with the big lenses I use. A vertical grip won't help as it would only add to weight. I always use a Camdapter Grip strap, and carry the cam in my hand. For some reason, the K7 body makes the whole thing seem harder to carry for long stretches of time. I am getting used to it though, and don't anticipate a long term problem.

2. I like the AF mode switch on the K7 better than the K10 and K20. The nub on the switch is now on the bottom of the rotating switch, and you pull it away from the back of the body to go from AF S to AF C or MF, and push it towards the back of the body to switch back to AF S. In over two years, I couldn't get used to the K10/20 arrangement, and wished it were a sliding switch like my DS and K100DS, but a rotating switch is much better for WR, so I understand why they chose this alternative.

3. I really like the LCD -- much more detail available when chimping -- this is one of the main reasons I wanted one of these.

4. Really fast write times, so chimping is faster than with a K20 -- important to the way I use a cam. There's a very significant difference between the write speeds to a "normal" Class6 card (I have a couple of Transcend 4GB Class6 cards too) and the 20MB/sec Sandisk Extreme III. The slower cards are okay for the 6MP and 10MP sensored bodies, but I need the faster speeds for the 14.6 MP bodies.

5. I mentioned this before, but the mirror blackout times are significantly faster, so it's a lot easier to track a moving subject while shooting a continuous string.

6. The shutter is very quiet compared to my other Pentax DSLR bodies. It's also very fast when set to Continuous High. I usually shoot single frames, but keep the mode set to CH in case I need it. I could usually shoot single frames easily with the K20, but I'm constantly shooting doubles with the K7. I will get used to this eventually.

7. It takes some getting used to, but the tabbed menu system is better. You can navigate it with the e-dials, moving through the sub-tabs with the rear dial and through the tabs with the front dial. You have to use the 4way switch to move within a menu screen, but you can skip to the last selection by pressing the "up" button instead of repeated "down" presses. This way, the card format menu option that Harriet mentioned as buried deep in the menus is available with 4 clicks on the e-dials and two button presses.

8. I like having SR on/off in the menus as opposed to a switch on the back. I probably turn SR off more than many users, but I've worked out a tripod setup ritual that hopefully will take care of this.

9. I like being able to both set high ISO Noise Reduction and at what setting it kicks in. I've got my NR set to Medium, and it starts at ISO 1600, but I will probably change this. The K7 shows a lot less chroma (color) noise than the K20, so I feel I can put off when it should kick in to a higher ISO level.

10. I really like the locking mode dial. My K10 and K20 were always getting knocked off my usual Av setting. Something else I don't have to worry about.

I'm sure that there are a lot of other differences that I've noticed, but it'll take some time to get everything sorted out. As usual, I've created a monster post, but I thought that the large number of pics was justified by the subject.

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Old Jul 20, 2009, 3:14 AM   #2
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Good review, the shots look sharper enough although a little dark.

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Old Jul 20, 2009, 4:44 AM   #3
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Scott, don't worry about being lengthy. This post and others you have made are soooo much more valuable than magazine "reviews". Thanks for taking your time doing the job for me!

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Old Jul 20, 2009, 10:27 AM   #4
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Yes thanks a lot Scott, a review from a forum member is much more useful to me than any other review like Kjell mentioned.

Your uses for the camera are much more in line with what I do when taking photos which really works for me. The AF is what I was interested in for the most part since I am completely satisfied with the IQ on the K20 and the K7 seems on par with that.

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Old Jul 20, 2009, 10:30 AM   #5
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Originally Posted by bilybianca View Post
Scott, don't worry about being lengthy. This post and others you have made are soooo much more valuable than magazine "reviews". Thanks for taking your time doing the job for me!

Exactly... I think the reviews here are far better than magazines and some other resources. THank You for taking the time Scott!
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Old Jul 20, 2009, 11:08 AM   #6
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I'm always interested in your opinions and experiences - I learn something every time I read them. I did read somewhere else about the "back" way for getting to the format option and you are right, it is pretty easy to access that way.

It's great to see that you thought AF was better - it confirms my feeling. But I don't shoot with AF all that often so thought it could have been wishful thinking on my part.
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Old Jul 20, 2009, 12:01 PM   #7
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You are doing what I like to do in this post, so I appreciate your thoroughness. Have you used Live view or video to any extent yet?
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Old Jul 20, 2009, 12:34 PM   #8
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Scott, I echo what Kjell and Tom have both said.

You comment about the Camdapter hand strap was of great interest as I also use this strap and was curious about how it would feel on the K7.

Your reviews of the camera are very much appreciated and are well done.

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Old Jul 21, 2009, 7:31 AM   #9
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Scott - just to reiterate what others have said - thanks so much for taking the time to share your experiments. Looks like some great results - a great camera in some skilled hands!
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Old Jul 22, 2009, 2:50 AM   #10
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Thanks Scott
Very detailed report.
The coming straight at you shots ( Predictive AF) are especially interesting and I'd really like to see more without the TC.
I think this is the area where the likes of the Canon 40D previously had an edge.
Cheers: Ian Mc
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