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10-27-2011, 01:48 PM   #1
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Unhappy with my Tamron 28-75 f2.8

I've pretty much given up on my Tamron 28-75 f2.8. It takes lovely pictures when it focuses properly, but getting it to focus correctly is a crapshoot. On paper, with a chart, under all lighting conditions, the lens front-focuses. At the short end it front-focuses less than the long end. I can adjust it to be right in the center, so I have some back on the short end and some front on the long end. But in real-life usage, it doesn't matter what adjustments I make, it's just not going to focus correctly. It also doesn't play well with a flash, especially at f2.8. Sometimes it blows the entire image out, sometimes it's too dark, rarely it's right on the money. This is using a pTTL Sigma flash. Basically, my keeper rate is barely 30% with the Tamron.

I photograph a lot of stage productions, with and without flash (with only during dress rehearsals). The Tamron is just abysmal at this - and this is the work I bought it for in the first place. Well, I've been loving my Promaster 100mm f3.5 for macro work, and I decided to give it a shot on stage this time.... and I was floored. My keeper rate is 70-80%, the throwaways are because the flash was recharging and didn't fire, or there was too much movement that blurred the shot. The ones I missed focus lock on are around 10% - and these are difficult lighting conditions. Shot after shot after shot, it just took amazing photos. Each one razor sharp and in focus. I'm beyond pleased with the Promaster 100mm... which I paid $100 for. I paid upwards of $400 for the Tamron, and it's a dud. Did I get a bad one, or are they all like this?

Charles.

10-27-2011, 01:53 PM   #2
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You've got a bad one.
If you can, I suggest you return it and hope you get a better one. Or skip it entirely.
I don't shoot with zooms anymore since my last zoom (Sigma 24-70mm) was a dud and the results were embarrassing due to irregular FF/BF issues.

However, Tammy's 28-75 has a better reputation with QC and sharpness open wide.
I don't think the 28-75 is the fault. It just may be your copy of it.

also, just because the lens is cheap, it doesn't mean the lens is bad!
Manual Focus lens can be found cheap with great results!
10-27-2011, 01:59 PM   #3
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Charles

Last edited by Marc Sabatella; 10-27-2011 at 03:04 PM.
10-27-2011, 02:00 PM   #4
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My Tammy 28-75 is one of my favorite lenses and I use it extensively in the studio. It's also my go-to walkaround lens. Sounds like you got a bad copy...

Mike

10-27-2011, 02:04 PM   #5
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I got mine in summer 2011. The lens surpriced me of its performance. Your copy may be bad.
Also i run through fine AF adjustment on each body i have (k5/k20). The body may have different values of fine adj.
The only thing i complain is low light focusing of pentax in general, and slow, too slow, too inaccurate.
Shooting moving kids is a nightmare, even they just move slowly.
10-27-2011, 02:05 PM   #6
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Manual focus lenses can be found cheap, but my results with manual focus are abysmal. :P

Some of my favorite lenses are the cheap ones though. I can't take the Tammy back, I bought it quite a while ago on eBay used, and thought it was just me getting used to the lens. But I don't have any problems with other lenses, and I find myself leaving the tamron at home and bumping the iso. Because noisy is preferable to OOF.

Charles.
10-27-2011, 02:09 PM   #7
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sell it on ebay and mention the problem. there will be someone out there who will pay a decent amount for it who won't be bothered much by the defect.
10-27-2011, 02:16 PM   #8
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The scenes you shoot are difficult. I got problem in similar scenes with DA50-135. Also the DOF at 2.8 is still shallow. Moving objects will always be a challenge for pentax. My friends are canikon shooters. They too complain about low light AF in their 5Dm2. 7D is just a bit better but not recommended. Nikon shooters, with D700, are quite happy with the same light condition.

I dont use the tamron in scenes like this anymore, and have to depend on MF lenses preferred faster than 2.8

10-27-2011, 02:25 PM   #9
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QuoteOriginally posted by ChopperCharles Quote

Charles
Gack!!!

Pls don't post big 4.1MB images directly into forum posts.
10-27-2011, 03:08 PM - 1 Like   #10
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I edited the post with the huge images to use imgwide tags. Please do this in the future when it is neessary to post such large images - but also, don't post such large images when not necessary, and it wasn't necessary here.

As for the focus problem, i maintain that there is practically nothing that can be physially wrong with a lens that would cause it to misfocus wide open. Misfocus is either camera's AF sensor out of alignment, or - and this is *much* more likely - simply a case of not controlling sufficiently where the camera is trying to focus, or other technique-related issues.
10-27-2011, 03:45 PM   #11
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I'm very happy with my copy, but I'd also be really happy with a 30% keeper rate . I'm usually really happy with maybe 10% of what I shoot with any lens, but that's more composition or the subject moving (my daughter mostly).
10-27-2011, 03:50 PM   #12
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QuoteOriginally posted by Marc Sabatella Quote
As for the focus problem, i maintain that there is practically nothing that can be physially wrong with a lens that would cause it to misfocus wide open. Misfocus is either camera's AF sensor out of alignment, or - and this is *much* more likely - simply a case of not controlling sufficiently where the camera is trying to focus, or other technique-related issues.
My experience with this lens (and other fast lenses) is the same. I love this lens, but it will have difficulty with stage scenes at f/2.8. The DOF in the photos you posted is very narrow, the subject does not always cover the AF sensor, and the camera is trying to decide what part of its AF sensor to maximize contrast. In most cases, it will pick the background in a stage situation unless you help it.

Try prefocusing (even manually with a split focus screen), then turning off autofocus (I use the AF button to turn off AF). Another, perhaps better option is to stop down at least to f4 which will increase the DOF so if the AF misses slightly, your subject is still in focus. The extra noise can easily be fixed with DeNoise or other software.

Last edited by klh; 10-27-2011 at 04:37 PM.
10-27-2011, 04:31 PM   #13
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I shoot live plays quite often during dress rehearsals for media promos and lobby use. My Tamy 28-75f2.8 is my most often used lens for such work - prob. 90% of the time. They don't allow us to use flash, anytime.

My keeper rate is probably 90%, very sharp, quality stuff. The way i get that high rate is NOT to use f2.8. and NOT to focus at every shot. I only focus once every 5-6 shots use AF button. A large depth of field is used via f3.5 to f7.1 depnding on lighting. The larger depth of field helps ensure everything within that area is sharp. So i often autofocus areas such as at a desk or chair or sometimes people, rather than task my camera to perform AF wtih very shallow focus areas on each shot. Then i use fast speeds to allow for people movement, 1/128, 1/160 or 1/200, depending on what latititude i have.

My advice: sell your tamron, sell your Kx and buy a K5, that way you'll have high iso's to allow deeper dof and faster people speeds. The files are a delight to work with compared to my old K20 and noise is much easier to clean.

Yes my Tamron frontfocuses about 4 or 5 as well. But its not a problem, i just adjust fine focus that amount with the K20 a year ago, and k5 now. Pentax and Nikon and Canon should sell ALL their dslrs with fine focus capability - they don't. Please read the article "Lens Softness is a Myth" by LensRentals, that i posted a link to in the lens forum. Search on my recent posts and you should find it - down 10 or 15 posts. You'll find out that all makes have these focus problems with the lenses and the only way to compensate is put in a fine focus adjustment, or send the camera and lens in for an adjustment together. (or adjust with hack information-if you can do it that way)

Realize that stage work is a most demanding application for dslrs because of the low light and flash limitations. The problem with your flash work could be the reflective surfaces on the stage, or the actor dresses as i see in your pictures. I've been quite amazed about how reflective surfaces can badly affect flash metering. Not to mention the occasional spot light areas can fool the lighting. I'm not allowed to use flash in the theatre so can't estimate any success rate in using it, however.
10-27-2011, 07:27 PM   #14
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Problem is, even at f4 or f5.6 the Tamron is still missing focus, where my 100mm macro was dead on. Buying all new gear is not in the cards, that's serious cash and I like my Kx and its ISO performance. This is a hobby, not a living, after all. I may try another copy of the tamron, but right now I'm thinking a 50mm f1.4 or f1.7 might be nice for this instead. And I've already said I adjust the microfocus, but in real world conditions, it just is unreliable.

Also, the imgwide tag is NOT in the "go advanced" post menu. There's img, but not imgwide, and without a button for it how am I supposed to know? (also, why doesn't the IMG tag do this by default - it does on the invision powerboard forums I run!)
charles.
10-27-2011, 07:28 PM   #15
Brooke Meyer
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Stage Scenes are difficult at 2.8.

I can't imagine being allowed to use a flash in a dress rehearsal. I upgraded K-20's to K-5's for high ISO & it being quiet. Dress rehearsals, when I can get close, I use 12-24 I 28-75. From the back of the house, 50-135 & 100-300. Most stage lighting will allow you to shoot f4 / 1/320 / ISO 3200. The Jazz company tortures me by dancing in the dark so I shoot up to 12,800.

Here is a Tamron 28-75/2.8 shot at 2.8 & ISO 3200. I have a callous on my right thumb from the rear AF button so I follow dancers and in this case, focused and re-composed. When I know the choreography, my success rate is very high so just accept that you'll miss a lot unless you know the production. Regardless of the lens, you'll have a lot of throw away, especially with dance.

And lose the flash unless its a staged promo shot for fill. It is not allowed for any dress rehearsal I've ever shot: Ballet or Jazz dance, Adult & Youth Theater or Concerts
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