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11-04-2010, 08:27 PM   #1
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Tamron 28-75mm & 70-200mm focusing speed

I recently got the 28-75mm and I have been happy with it as far as IQ goes. However, in low-light, the lens hunts a lot in auto-focus, sometime so long that I've missed some beautiful shots. AF is fine in day-light though. I Googled about it and found that this is typical with this lens.

Now since I am eying on Tamron 70-200 f2.8 too, I suspect that it will be even slower in focusing than 28-75mm. Can someone used both comment on relative focusing speed? is Sigma HSM significantly better?

I am using it with K-x.

11-04-2010, 10:22 PM   #2
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My 70-200 outperforms my 28-75 on every level including AF performance. Having said that I find they both hunt a bit (sometimes frustratingly so) in lower-light and/or low contrast scenarios.
11-04-2010, 11:25 PM   #3
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@Venturi, great, would love to see some IQ comparison.
11-05-2010, 05:54 AM   #4
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My 28-75 does pretty well in low light. I've even got it to focus with just candle light, it took a while but it did focus. I used to have trouble focusing with my 70-200 for sports. I found that the subject had a lot to do with accuracy/speed. I usually focus center spot and found that if the target wasn't big enough it would focus on the background. This might be do to the camera (K10D) not so much the lens. If you get a target with good contrast and it's big enough both lenses focus pretty fast. The 70 -200 will usually go from one extreme to the other if the focus is way off to begin with, but if it's close it will focus right away.

There's a bit of a learning curve to the 70-200.

I love both lenses, they produce great pictures!
That been my experience hope this helps!

11-05-2010, 09:58 AM   #5
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@alexcam, mine too focuses eventually but it's slow. Glad to know 70-200mm is faster. How do you compare IQ of both?
11-05-2010, 10:58 AM   #6
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Yusuf, I actually feel the contrast on the 70-200 is better sometimes, especially when stopped down to f/5.6 or f/8.0. The 28-75 is sharper wide open.

As far as focusing in low light, I usually use my flash (Metz 48) with AF assist. It helps quite a bit.

The 70-200 is a great lens for the money. If you can, try it out first...it is big and heavy! I have no problem with it, but some might think it's too much for the extra speed it provides.
11-05-2010, 11:02 AM   #7
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Thanks Alex, how would you compare both wide open. If I buy, it will be for wide open only. Are you suggesting that 28-75mm is sharper wide open compared to 70-200?

QuoteOriginally posted by alexcam Quote
Yusuf, I actually feel the contrast on the 70-200 is better sometimes, especially when stopped down to f/5.6 or f/8.0. The 28-75 is sharper wide open.
11-05-2010, 11:16 AM   #8
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Yes, but that's at 200mm. Once you stop it down 1/2 a stop (f/3.5), I feel they start to equal out. At 70/75mm I'd say they are more or less equal. I want to point out that you have to pixel peep to really see this. This lens is sharp wide open considering it's a zoom.

Also remember lenses vary from one copy to another. You might see different results.

11-05-2010, 11:31 AM   #9
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My 28-75 focus fairly well, although once in a while it hunts in low light if there isn't enough contrast. It's also quite sharp from wide-open. I only used the 70-200 briefly, but as I recall the focus is on par (although if I had to guess I'd say the 70-200 was faster).
11-05-2010, 12:33 PM   #10
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Both lenses are excellent.
Both lenses focus fast. The 70-200 has a longer focus throw, but rarely has this posed an AF speed problem for most situations, even low light.
Wide open, these lenses perform good, but not excellent (perhaps not to 50-135 standard). Nevertheless I have used both wide open and gotten acceptable results after PP - 70-200 is very good in this regard.
11-05-2010, 01:06 PM   #11
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In my experience both lenses focus on the subjects pretty quickly. I've always thought that it may be more of an issue of lack of contrast rather than just low light. This is using my K7 and not the K20 but i wonder if there'll really be a difference. Unfortunately, I only rented the 70-200 while I own the 28-75 so I cant test it.
11-05-2010, 10:46 PM   #12
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QuoteOriginally posted by Ash Quote
Both lenses are excellent.
Both lenses focus fast. The 70-200 has a longer focus throw, but rarely has this posed an AF speed problem for most situations, even low light.
Wide open, these lenses perform good, but not excellent (perhaps not to 50-135 standard). Nevertheless I have used both wide open and gotten acceptable results after PP - 70-200 is very good in this regard.
Actually I am happy with 28-75 IQ. I am fine if 70-200 can match that wide open throughout the range - as some mentioned, 70-200 is not so performing at longer end, can you share some wide open pictures on longer end.

Here is 28-75mm @75mm f2.8 with a bit of regular sharpening.

11-07-2010, 01:39 PM - 1 Like   #14
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I use the 28-75 Tamron pretty much all the time for my theatre live performance shooting for promo shots for the theatre company.

I haven't noticed a problem with hunting unless the light is really low.

But here's a trick that may help you, it certainly helps me.

I went to the custom menu and disabled half-shutter focusing. I then enabled the AF button for focusing. I always use larger DOF to account for minor focusing problems, like f3.5 to F5.6 if light permits and some shutter speed for human movement. Then i only focus with the button every 5 shots or so. If i need to focus in low light, i'll move the camera till i find a high contrast area in the same distance, press the AF button, and then reframe the actors and take 4 or 5 shots, etc. so for quick action, i've never been delayed by focus hunting.

The mileage of this trick in other situations may differ, but for the work i do, the AF button provides better responsiveness and my acceptance rate has gone up.
11-07-2010, 05:35 PM   #15
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QuoteQuote:
philbaum: I use the 28-75 Tamron pretty much all the time for my theatre live performance shooting for promo shots for the theatre company.

I haven't noticed a problem with hunting unless the light is really low.

But here's a trick that may help you, it certainly helps me.

I went to the custom menu and disabled half-shutter focusing. I then enabled the AF button for focusing. I always use larger DOF to account for minor focusing problems, like f3.5 to F5.6 if light permits and some shutter speed for human movement. Then i only focus with the button every 5 shots or so. If i need to focus in low light, i'll move the camera till i find a high contrast area in the same distance, press the AF button, and then reframe the actors and take 4 or 5 shots, etc. so for quick action, i've never been delayed by focus hunting.

The mileage of this trick in other situations may differ, but for the work i do, the AF button provides better responsiveness and my acceptance rate has gone up.
Thank you Phil--my copy of the Tamron 28-75mm is on order--should have it later this week. This is the kind of information I value, highly. You are very kind to share your tricks! Best!


QuoteQuote:
Yusuf: Here is 28-75mm @75mm f2.8 with a bit of regular sharpening.
Great show of the Tammy's capabilities--thank you.

QuoteQuote:
Ash: Ash Both lenses are excellent.
Thanks Ash, precisely what I need to hear with my copy about to enter transit. Anticipation.................
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