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01-23-2011, 02:20 PM   #1
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Sigma 30mm/1.4 + SAFOX IX? Low-EV AF speed

Anyone used a Sigma 30mm f/1.4 on a K-5/K-r that has faster low-EV AF? That seems to be one of the main cons to this lens, I was just wondering if the new AF system improves it any.

01-24-2011, 02:00 AM   #2
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QuoteOriginally posted by lavascript Quote
Anyone used a Sigma 30mm f/1.4 on a K-5/K-r that has faster low-EV AF? That seems to be one of the main cons to this lens, I was just wondering if the new AF system improves it any.
What do you mean exactly? I have Sigma 30 and K-5, I'm satisfied with the AF speed, locks focus fast enough for me in EV4 and EV2-3.
01-24-2011, 08:39 AM   #3
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I don't know, I just know that one of the complaints people have about this lens is its low-light AF speed. Some say it hunts, some say it will only lock when using center focus. Any thoughts/comments?
01-25-2011, 01:40 AM   #4
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I haven't noticed any significant difference between "good light" and "low light" AF speed on my K-5 in similar conditions. At home I can check the exif for the AF lock value of a few photos shot at the same location in good and low light.
It's the camera that hunts, not the lens - if it hunts then it would do that with any similar f/1.4 lens. It's more of a question of subject contrast, light level, subject distance and how much change is required in focus distance (i.e. does the cam have to adjust from infinity to 15m or from 0.5m to 15m).

It's true that the leftmost and rightmost AF sensor doesn't always work great with this lens, but I never had problems using the remaining 9 sensors, although I mostly use the center one or the next one to the right (in portrait orientation).

01-25-2011, 02:32 AM   #5
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Tried it on a canon 7d and it's slower than my 16-45 on my K-7. K-5 shouldn't be faster.
01-25-2011, 05:21 AM   #6
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QuoteOriginally posted by fikkser Quote
Tried it on a canon 7d and it's slower than my 16-45 on my K-7. K-5 shouldn't be faster.
Well, the K5 is in fact a tad faster than the K7...
I've done head-to-head tests with two 18-55WR lenses, and the K5 has a slightly higher pitched sound, and the lens obviously moves faster.

Nothing earthshaking, though, and it has a slightly longer delay before focusing, so the overall focusing time was nearly the same between the two camera (at least with the 18-55).
But with long-throw lenses (such as macro lenses), the K5 would end up first, I think.
01-26-2011, 01:12 AM   #7
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QuoteOriginally posted by dlacouture Quote
Well, the K5 is in fact a tad faster than the K7...
I ment the 7d, k-5 should not be faster than 7d with 30 1,4. The k-7 with 16-45 was just a reference.
01-26-2011, 02:26 AM   #8
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QuoteOriginally posted by fikkser Quote
Tried it on a canon 7d
And you used the screwdrive AF on the 7D to focus the Pentax mount lens, right? lol
Sorry, comparing apples to oranges is useless...

01-26-2011, 06:53 PM   #9
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QuoteOriginally posted by simico Quote
And you used the screwdrive AF on the 7D to focus the Pentax mount lens, right? lol
Sorry, comparing apples to oranges is useless...
i agree with this statement. i have this lens in nikon mount and it is blazing fast and currently it is my favorite lens for my nikon bodies. yet here i am researching this lens for my k20d. i really want it, but just because it kicks ass in my nikon systems, does not mean it will work the same in pentax mount.
01-27-2011, 03:10 AM   #10
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Simico,
I'm trying to say that the k-7 with 16-45 beats the 7d with sigma 30 1,4 in AF speed. So it's not very fast on the 7d. That means the 30 1,4 is most likely slower on a k-5. RIGH LOL?

"Tried it" meaning I tried the 30 1,4 (that was the IT you were talking about), the 16-45 wasn't mentioned before in the tread, you just got a retarded attitude. Sorry if my English is as inaccurate as your reading. That it usually ends up RIGHT LOL?

Some person here on the forums claim the sigma 50-150 ex II hsm is fast as hell on his/her nikon d90. And I find it kind of average on my K-7. Not as fast as the faster screw drive lenses. Often hunts. Probably different from system to system.
01-27-2011, 07:49 AM   #11
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one thing to keep in mind is that nikon has the fastest auto focus system period, so auto focus speed will not compare to pentax or canon for that matter. when i did own a k-7 it was a hair faster than the k20d to af, but not that much faster.
01-27-2011, 11:35 AM   #12
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QuoteOriginally posted by fikkser Quote
I'm trying to say that the k-7 with 16-45 beats the 7d with sigma 30 1,4 in AF speed.
Dude, you still don't get it. Canon doesn't have screwdrive AF, while the Pentax version of Sigma 30mm is screwdrive AF and not HSM! Got it? You're comparing HSM on Canon body to screwdrive AF on Pentax body - totally useless and meaningless. Therefore the AF speed of Canon mount Sigma 30 HSM is totally irrelevant to Pentax users. If you still don't understand it then you're the only retard in this thread.
01-27-2011, 11:41 AM - 2 Likes   #13
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For those who understand the difference between HSM and screwdrive AF , and also between different camera systems, here's a quick and dirty video of my K-5 focusing Sigma 30mm f/1.4 (screwdrive AF since there's no HSM version for Pentax mount). Two quick tests in a room lit by only one 20W desk lamp, first focusing on bear (~2m away) and my mug (~50cm away), then focusing on mug and heat radiator/drapes. As you can see it was dark enough for the camera to struggle focusing a few times.

[YT]http://www.youtube.com/watch?v=2oOeC0Qt2aw[/YT]
01-27-2011, 11:53 AM   #14
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QuoteOriginally posted by simico Quote
For those who understand the difference between HSM and screwdrive AF , and also between different camera systems, here's a quick and dirty video of my K-5 focusing Sigma 30mm f/1.4 (screwdrive AF since there's no HSM version for Pentax mount). Two quick tests in a room lit by only one 20W desk lamp, first focusing on bear (~2m away) and my mug (~50cm away), then focusing on mug and heat radiator/drapes. As you can see it was dark enough for the camera to struggle focusing a few times.

[YT]http://www.youtube.com/watch?v=2oOeC0Qt2aw[/YT]
Thank you so very much for this. You also answered a question I had. Sigma has on their site that this lens ''does'' have HSM but I had my doubts unless they upgraded it. The screw drive lenses are pretty loud and a turn off to me.
Product Finder - SigmaPhoto.com
01-27-2011, 12:55 PM   #15
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QuoteOriginally posted by simico Quote
For those who understand the difference between HSM and screwdrive AF , and also between different camera systems, here's a quick and dirty video of my K-5 focusing Sigma 30mm f/1.4 (screwdrive AF since there's no HSM version for Pentax mount). Two quick tests in a room lit by only one 20W desk lamp, first focusing on bear (~2m away) and my mug (~50cm away), then focusing on mug and heat radiator/drapes. As you can see it was dark enough for the camera to struggle focusing a few times.
Thank you for this! Looks like it focuses fast enough for my taste, need to sell a couple things to fund this purchase though...
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