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07-15-2010, 03:04 AM   #1
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Pentax K-7 AF

This happened to me last week. I love the K-7 and look forward to improvements so I am not unhappy. But never the less this did happen.

I shoot birds with a K-7 and sigme 300mm f2.8 ex dg apo.

That out of the way. I was in a forest under the canopy with 4 other canon users. All with 100-400 and 400mm 5.6 lens. So i was confident i could hold my on with them with auto focus. Wrong!!!

While they were using 5 year and older cameras. I was sporting a K-7. They were banging away just blazing. I many times had to put my camera in manual focus to get close then AF would hit. After doing about 10 times they all looked at me kiinda funny. But didn't say anything.

This was at 5:30 in the evening and in the jungle verrrry dark. But this is a real situation where i found the really bad AF of Pentax. Now i got some birlliant shots.
Fast glass is the factor. And,,,, I had to take off the 1.4 T.C. at F4 to even get focus.

I hope Pentax works on this.

I have invested in Pentax and love the color and pix. But I would say they are 3-5 years behind in this area.

My opion only.


Last edited by garyk; 07-15-2010 at 03:30 AM.
07-15-2010, 03:37 AM   #2
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nothing new here.

The lower the light, the greater the Pentax focus speed difference vs canikon

In bright light things tend to even out for the k7 so that may be a sign of improvement

One other thing is the USM better AF speed vs screwdriver/SDM
07-15-2010, 03:47 AM   #3
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I agree. I am new to dlsr's. Six months ago i bought my first camera. But I did not do my homework.
I like the sealing. I have a friend that shoots with me that shoots a non sealed camera and when in the jungle ( verrrry humid ) he has problems. I do not!!
Sometimes I have trouble with the foging of the outer lens. but only on rainy and high altitudes when the fog is heavy.
Oh well. I am happy... I like the screw for simplicity. I feel even though it is slower i have some advantages. In very rough treaking and reliability.
I have dropped a k-20 with the lens attached. That crushed the camera and the lens was unaffected.
I will sign off. time to get ready for sleep here.
07-15-2010, 04:25 AM   #4
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a sealed canon would have been much pricier than the Pentax, and the sealed lenses come only in the L version (quite expensive). So, for those extreme conditions you shoot in, the K7 is the best value for money

07-15-2010, 06:23 AM   #5
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The K-7 has the fastest AF of any Pentax body I've used, but its still a bit behind the competition....
The shut-down point for the K-7's AF i.e. the dimmest light at which it stop functioning is about 1 EV over that of equivalent Nikons and Canons, that's an unavoidable fact.

For Indoor shots it evens out due to the K-7's AF assist light.

Did you mention the others were using older model Canons ? You might want to take a peek out how well focused their shots are....my experience is their AF accuracy suffers considerably in low light, though they can still take the shot where the Pentax might just give up altogether..
07-15-2010, 06:32 AM   #6
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QuoteOriginally posted by garyk Quote

I have invested in Pentax and love the color and pix. But I would say they are 3-5 years behind in this area.

My opion only.
I think this is called "preaching to the choir"
07-15-2010, 06:42 AM   #7
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You know. I did not look at the final prints in the computer.... I will definately do that. Who knows maybe mine are better. I really did get some killer shots. I used a sigma 530 super flash K-7 in manual mode. But i am really happy. I could not even see the birds in the finder it was so dark. I had to manual focus then i could see them and then the k-7 snaped the AF... So if it was any darker i could not have seen the birds anyway.
I am old......

Here some from the shoot.





07-15-2010, 06:52 AM   #8
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and you are saying that the canon shooters got focus in that light you just described with consumer lenses and no assist light?

ok, I got to switch now, because of you - but not before some testing

07-15-2010, 06:54 AM   #9
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I'm telling you not only were they focusing but I was looking at the pics on the camera they looked pretty good. Now about 6:00 and when a light rain. All said they could not AF. But by then i had given up.

I am on an avion forum and have seen pics from the nikon d3s at 6400 and 7:00 at night with a 2xT.C. That is just beautiful. Of course the set up costs about 5,500 for the camera and he was using the nikor 600mm IS... I don't know what that cost. But i cannot afford it. I am happy with Pentax and Sigma. Also My body is sealed and i do not worry too much about it. While canon and nikon really scramble with a mist...

Last edited by garyk; 07-15-2010 at 07:02 AM.
07-15-2010, 07:13 AM   #10
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One more thing - the 1.4x Teleconverter introduces a light penalty of 1 stop, and certainly doesn't help the AF.
About 1/1.4 of the light brightness falls on the digital sensor compared to the normal lens w/o teleconverter - and the same applies to the AF sensor.

Last edited by kittykat46; 07-15-2010 at 07:20 AM.
07-15-2010, 07:15 AM   #11
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QuoteOriginally posted by garyk Quote
I'm telling you not only were they focusing but I was looking at the pics on the camera they looked pretty good. Now about 6:00 and when a light rain. All said they could not AF. But by then i had given up.

I am on an avion forum and have seen pics from the nikon d3s at 6400 and 7:00 at night with a 2xT.C. That is just beautiful. Of course the set up costs about 5,500 for the camera and he was using the nikor 600mm IS... I don't know what that cost. But i cannot afford it. I am happy with Pentax and Sigma. Also My body is sealed and i do not worry too much about it. While canon and nikon really scramble with a mist...
post a link please, really curious to see those pics.

Anyway, don't compare that setup with a K7+Sigma....
07-15-2010, 07:52 AM   #12
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what I don't get here, is if you had a flash, does the flash offer an AF assist light?

The pentax flashes do?

I have shot with my *istD, and a 300F4 plus 1.7x AF TC in the shadows and it had no issue at all achieving focus when using my AF500FTZ.

Now, one thing to consider here, and I will ask, because I think it might be relevant, were the canikons all shooting with optically stabalized lenses??

the reason I ask is that OS does help the AF performance, because the OS system keeps the image stable for the focusing sensor. If you are hand holding, and moving the camera up and down, you will have trouble achieving AF lock because you are moving the target the AF sensor sees.

Just a thought
07-15-2010, 04:03 PM   #13
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I think those shots you posted are nice.

But, the only way to tell how they were doing if to post thiers.

I am very interested.
07-16-2010, 12:22 AM   #14
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Here is a link to a guy that shoots a Nikon and d3s 600mm f4. this is really a nice shot for 600mm at 7:00 and 2x tc at 3200 iso
He says he soot at 6400 alot. But I cannot think where i saw a pic. Go to the link and then I think you can go to his web site.
This guy is a semi pro i think. I have never met him but he is very respected in the bird photo community.

http://www.avianwatchasia.org/forums/showthread.php?t=12169

All were shooting on a tripon using an external flash. Next time I am there i will ask for there web sites. And they all had lens stabilazation i think. I know of two for sure.
As far as the flash being of assistance I did not know of this. I was using the sigma 530 super flash not the pentax. I am too cheap i guess. Verry good to know though. I will open the book and see if i can find some reference to it.

Now i did see the green light but i am not sure if it helped or not? Maybe it did. But i do not know for sure.

The pentax is a pretty good camera for birding. I like the weather sealing. Verrry much. and the price is deffinately right. I think before i buy another body i will make sure it is a good upgrade to the K-7 though. I think the glass of sigmas EX series is almost equal to canon and nikon personally. The 300 is excellent and the 500 f4.5 is even better. If used properly i cannot tell the difference in the three.


G

Last edited by garyk; 07-16-2010 at 12:44 AM.
07-16-2010, 01:21 AM   #15
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Guys, get real, just look at this guy's setup - he is the one garyk is referring to...

Philip Tang
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