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08-15-2009, 09:39 AM   #16
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QuoteOriginally posted by kunik Quote
i'll be busy for the next few days so I won't have a chance to write it up properly with examples for a while but the Predictive AF definitely works on the K-7. I tested it against K20 with a bicycle coming down at hill at 20mph. I used both bodies and I used DA*200/2.8, FA*300/2.8, and DA*50-135/2.8. The results are not 100% perfect but the K20 had almost 0% in focus shots while the k-7 had anywhere from 50% - 100% in focus shots depending on the lens and the particular run. The fps takes a huge hit in this mode but it is sufficient - I need to double check but I think k20 and k7 had almost the same frame rate during these tests.

Although 20mph is not super fast, the closing rate (distance between rider and camera) on the tight crop shots I was taking is extremely fast. Remember camera focusing is not linear so tight crops focused all the way down to minimum focus distance is quite difficult. People shooting race cars and motorcycles do not stand directly in front of the vehicle so closing rates are usually significantly less and the DOF is usually greater.

edit
here's a quick and dirty look - all shots wide open (F2.8) at ISO 100
K20



K-7

This is a big difference thanks for sharing, next week i will have my K-7

08-15-2009, 04:30 PM   #17
TJOS
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I've used my camera with overally good results. I usually need to do a lot of ev adjustments to RAW files in Lightroom and some minor fine tuning. Naturally the additional megapixels in the upgrade will be a minor beneficial thing as well.

The main issue usually is the out of focus issue, which forces me to use the AF-S mode. It does work when you know what you are doing and predicting what happens, but having a more reliable AF-C would help me. Thus I have a tendency of taking single great shots instead of trying to get a burst of hopefully interesting situations, which end being some 3-5 photos with not much photographic value.

The other issue is currently being on the border line of having the minimum required light to functionally freeze the moment (basically 1/250) in ISO 800, which produces ok quality for my purpose. Having that extra little in noise control would allow me to get to ISO 1600 and thus gain more options regarding the aperture, which would be beneficial in certain situations. The ISO 1600 is way too noisy.

So basically what I want to know is how the K-7 performs in artificial lighting. Is the AF-S faster and how the AF-C functions? Does the capture speed take a tremendous hit on the AF-C as some here stated? On the other hand, how much better the light sensitivy / noise control is when compared to the older flagship models?

Last edited by TJOS; 11-24-2011 at 06:16 PM.
08-15-2009, 09:50 PM   #18
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QuoteOriginally posted by kunik Quote
i'll be busy for the next few days so I won't have a chance to write it up properly with examples for a while but the Predictive AF definitely works on the K-7. I tested it against K20 with a bicycle coming down at hill at 20mph. I used both bodies and I used DA*200/2.8, FA*300/2.8, and DA*50-135/2.8. The results are not 100% perfect but the K20 had almost 0% in focus shots while the k-7 had anywhere from 50% - 100% in focus shots depending on the lens and the particular run. The fps takes a huge hit in this mode but it is sufficient - I need to double check but I think k20 and k7 had almost the same frame rate during these tests.

Although 20mph is not super fast, the closing rate (distance between rider and camera) on the tight crop shots I was taking is extremely fast. Remember camera focusing is not linear so tight crops focused all the way down to minimum focus distance is quite difficult. People shooting race cars and motorcycles do not stand directly in front of the vehicle so closing rates are usually significantly less and the DOF is usually greater.

edit
here's a quick and dirty look - all shots wide open (F2.8) at ISO 100
K20



K-7

Superb, thanks for posting


QuoteOriginally posted by Gaelen Quote
I can't testify to the K-7, but I've shot drifting events with a K100D mostly, and a K20d once

the AF-C has always worked great, only drawback has been the lense speed, not the camera.

That is an awesome shot !


For the OP, here are some Volleyball action from Dominique :
K-7 does sports, World Championship Beach Volley (8 shots): Pentax SLR Talk Forum: Digital Photography Review
08-16-2009, 06:01 PM   #19
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QuoteOriginally posted by Clem Nichols Quote
I seem to recall having read somewhere that the K-7 slows to about 2 fps when using AF-C in burst mode. Does that sound about right? I don't know which is better (or worse?). Getting 50% in focus at 2 fps or 20% in focus at 5 fps. I guess it's the old "Is the glass half full or is it half empty" quandry.

CN
Definitely not the case for me. I use AFC exclusively for sport, and the fps is definitely faster than K20D. Can't tell you exactly what rate it is, but I'm guessing it's close to 5fps for me, that's even holding the AF button down and firing at the same time!

08-17-2009, 02:16 PM   #20
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QuoteOriginally posted by Arpe Quote
Definitely not the case for me. I use AFC exclusively for sport, and the fps is definitely faster than K20D. Can't tell you exactly what rate it is, but I'm guessing it's close to 5fps for me, that's even holding the AF button down and firing at the same time!
Phew. If it would slow down due to AFC, it would make no sense to market it as 5 FPS camera body.

By the way, is it better to use the dedicated AF button and then fire, instead of the regular first half way and fire? I've found it harder to handle when using the dedicated AF button on the back. Maybe it's just lack of practice for me.

Last edited by TJOS; 11-23-2011 at 12:29 PM.
08-17-2009, 04:24 PM   #21
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I can tell you without a doubt that AFc slows down fps on my camera under certain conditions. I haven't tested it yet to see how much. For the record (not an excuse) ai servo also seems to slow down my Canon. I'm not an engineer so I don't pretend to understand it but it seems to be common across platforms.
08-17-2009, 05:43 PM   #22
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Yeah, as I said I haven't timed it! But faster than K20D. Whereas with the K20D I could always get a single shot when I wanted, even if in 3fps, but with the K-7 I'm finding I often get 2 instead!

I use the AF button and turned off AF on the shutter. I find it way easier for sport, but it may depend what sport your doing. You can then focus, hold the button half way to invoke SR (and to be quicker when you do fire the shutter), and shoot when you want. If somebody gets in the way it won't then refocus as it would if AF was on shutter button. Or prefocus a spot, then when you go to shoot it won't try and focus again. It is a little less comfortable, I wish the AF button was higher up closer to the natural thumb position as its a button that is used constantly, not just when you want to change modes etc., so it should be better positioned, but it's not.
08-18-2009, 01:24 AM   #23
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QuoteOriginally posted by Arpe Quote
I use the AF button and turned off AF on the shutter. I find it way easier for sport, but it may depend what sport your doing. You can then focus, hold the button half way to invoke SR (and to be quicker when you do fire the shutter), and shoot when you want. If somebody gets in the way it won't then refocus as it would if AF was on shutter button. Or prefocus a spot, then when you go to shoot it won't try and focus again. It is a little less comfortable, I wish the AF button was higher up closer to the natural thumb position as its a button that is used constantly, not just when you want to change modes etc., so it should be better positioned, but it's not.
Not long ago I read that the SR works better when used via the AF button, so I might try want to get used to it. Sometimes I do also prefocus as the AF hunts too much and ends up messing up the focus.


Last edited by TJOS; 11-23-2011 at 12:26 PM.
08-18-2009, 05:59 PM   #24
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The AF button does not invoke the SR, hence having to keep the shutter button half-pressed. It would be nice to be able to turn it on and off some other way as well.
08-25-2009, 04:36 PM   #25
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QuoteOriginally posted by kunik Quote
I have to disagree with the statement on lens speed. The DOF in your shot is huge and the closing rate on that car relative to you is not that great. Look at how far the lens has to move to go from Infinity to 5 meters on your lens (not very far). You don't need a fast lens or a fast camera to make that shot work - you just need a skilled photographer. People have always said that Pentax lenses were slow because of the example I showed with the K20 (any target approaching you at moderate speed will ALWAYS be OOF on k20 using AF.c if the DOF is narrow). I have always believed that the Pentax lenses were "fast enough" (I would not call them fast) but that the lack of predictive AF in the camera was the weak link in the system. My tests with the k-7 prove my point. The DOF in that shot is about 12 inches and it still came out razor sharp.
I agree with you there, by lense speed i was refering to the AF.C...but it does depend on your DOF as well. I use some pretty "cheap" lenses compared to most of the guys I shoot with (canon lovers), so it's nice to see it when mine comes out a little sharper than theres using a large DOF to compensate slightly. A lot depends on how you use the equipment you have. A good lense and a good body make a big difference, but it's not everything.

QuoteOriginally posted by dugrant153 Quote
That's with the K100D??

That's hawt.
Yes, a K100d and my 80-320mm....not by any means a great lens, but for now it works just fine.

Thanks
08-28-2009, 12:41 PM   #26
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Rogue III Race

I took photos of the R.O.G.U.E. Race in Edmonton. Its a 20km race thru Edmontons river valley, and especially on the hills the longboarders can reach some decent speeds. The record holder did it this year in 53ish minutes.

Here are my pictures.

Edmonton 2009 R.O.G.U.E. Longboard Race - a set on Flickr
08-28-2009, 01:05 PM   #27
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Original Poster
Nice series. Thanks for posting. Did you use AF-C, center focus or what? Certainly the posted images are in nice, sharp focus. What about your success rate? 50% or better? I didn't see any panning shots where the background was intentionally blurred to enhance the feeling of speed. Did you try any? I hope you don't mind my asking so many questions, and do appreciate your taking the time to answer.

Regards,
CN
08-28-2009, 01:27 PM   #28
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I was specifically taking pictures of a friend in the race, and the hill curves at the bottom so I could have been in another spot to get more panning shots but then I'd have a blind spot and not see when my friend was coming so I picked the more safer spot in spotting him. Also my first try doing that sort of thing and will be more willing to experiment in the future.

I did attach 2 images of my friend going down the hill a week before for practice as its a steep hill, *they had a first aid station on standby during the race at the bottom of the hill. These 2 photos are more panning as you asked but also I was using the DA* 50-135 which people say is slow so I guess its up to debate. Probably get alot better results with a different lens for fast moving objects but I really do like that lens. Again thou I knew he'd be coming down the hill and did it a few times where in the race it was a one shot deal.

Last edited by Dr_who; 10-12-2013 at 12:51 PM.
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