October 25, 2014, 06:52:09 PM

Author Topic: Dustin Abbott Reviews Tamron 28-300 FF  (Read 3520 times)

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Re: Dustin Abbott Reviews Tamron 28-300 FF
« Reply #15 on: August 14, 2014, 04:01:26 PM »
I'm not crazy about f/6.3, either, but it is also 1/3rd of a stop of light.  It is rare that the 1/3rd stop makes much of a difference, and the high ISO performance of the 6D that I use it with means that I can get away with cranking ISO and still get very nice images.

I suspect that the 28-300L probably has higher resolution than this lens...but I doubt the difference is significant.  This lens is surprisingly competent (I wasn't nearly as impressed with the new 16-300 VC for crop).

Does f/6.3 affect AF performance when using off-center AF points?

It doesn't seem to on my 6D (and also on a 60D that I tested it on).  I think there is some kind of trickery that makes the camera "think" it is f/5.6, and it acts accordingly.  AF is actually very good on the lens, and seems accurate.  Other than rather slow apertures, the only downside I've discovered is that resolution/micro-contrast isn't as good as my best lenses at higher magnification, but that's hardly a shock.  I've been more surprised at how good the images actually are.
6D x 2 | EOS-M w/22mm f/2 + 18-55 STM + EF Adapter| Rokinon 14mm f/2.8 | Tamron 24-70 f/2.8 VC | 35mm f/2 IS | 40mm f/2.8 | 100L | 135L | 70-300L -----OLD SCHOOL----- SMC Takumar 28mm f/3.5, Super Takumar 35mm f/3.5, SMC Takumar 55mm f/1.8, Helios 44-2 and 44-4, Super Takumar 150mm f/4

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Re: Dustin Abbott Reviews Tamron 28-300 FF
« Reply #15 on: August 14, 2014, 04:01:26 PM »

TWI by Dustin Abbott

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Re: Dustin Abbott Reviews Tamron 28-300 FF
« Reply #16 on: August 14, 2014, 04:02:08 PM »
JumboShrimp here. No connections to anyone or anything here. ;)

Thanks for sharing.  I assumed that somebody at CR had shared it.  They've shared my last 3 or 4 reviews themselves.
6D x 2 | EOS-M w/22mm f/2 + 18-55 STM + EF Adapter| Rokinon 14mm f/2.8 | Tamron 24-70 f/2.8 VC | 35mm f/2 IS | 40mm f/2.8 | 100L | 135L | 70-300L -----OLD SCHOOL----- SMC Takumar 28mm f/3.5, Super Takumar 35mm f/3.5, SMC Takumar 55mm f/1.8, Helios 44-2 and 44-4, Super Takumar 150mm f/4

dgatwood

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Re: Dustin Abbott Reviews Tamron 28-300 FF
« Reply #17 on: August 14, 2014, 04:34:38 PM »
I'm not crazy about f/6.3, either, but it is also 1/3rd of a stop of light.  It is rare that the 1/3rd stop makes much of a difference, and the high ISO performance of the 6D that I use it with means that I can get away with cranking ISO and still get very nice images.

I suspect that the 28-300L probably has higher resolution than this lens...but I doubt the difference is significant.  This lens is surprisingly competent (I wasn't nearly as impressed with the new 16-300 VC for crop).

Does f/6.3 affect AF performance when using off-center AF points?

It doesn't seem to on my 6D (and also on a 60D that I tested it on).  I think there is some kind of trickery that makes the camera "think" it is f/5.6, and it acts accordingly.  AF is actually very good on the lens, and seems accurate.  Other than rather slow apertures, the only downside I've discovered is that resolution/micro-contrast isn't as good as my best lenses at higher magnification, but that's hardly a shock.  I've been more surprised at how good the images actually are.

On the 6D, outdoors, using the center point, my 70-300L with a 1.4x extender has worked pretty much flawlessly for me even at the long end, where it is equivalent to f/8.  Experimentally, at f/12, it fails reliably, but almost works (gets the focus right, but doesn't acknowledge that it did) much of the time.  So I'd guess that the 6D's daylight focusing limit is somewhere just shy of f/12.  I wouldn't think f/6.5 would even be a challenge for it except in fairly bad lighting conditions unless you stick a TC on it.

Out of curiosity, what does the EXIF tagging show for the f-stop?  From what I've seen when working with MF lenses, I'm fairly certain the lens can't lie to the camera about its wide-open aperture, or else every shot would be underexposed by a stop.  But perhaps it could get around that by lying about every setting equally.  If that were the case, wide-open shots would claim to be f/5.6 at the long end, even though they really can't be.
« Last Edit: August 14, 2014, 05:12:26 PM by dgatwood »

TWI by Dustin Abbott

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Re: Dustin Abbott Reviews Tamron 28-300 FF
« Reply #18 on: August 14, 2014, 08:24:05 PM »
I'm not crazy about f/6.3, either, but it is also 1/3rd of a stop of light.  It is rare that the 1/3rd stop makes much of a difference, and the high ISO performance of the 6D that I use it with means that I can get away with cranking ISO and still get very nice images.

I suspect that the 28-300L probably has higher resolution than this lens...but I doubt the difference is significant.  This lens is surprisingly competent (I wasn't nearly as impressed with the new 16-300 VC for crop).

Does f/6.3 affect AF performance when using off-center AF points?

It doesn't seem to on my 6D (and also on a 60D that I tested it on).  I think there is some kind of trickery that makes the camera "think" it is f/5.6, and it acts accordingly.  AF is actually very good on the lens, and seems accurate.  Other than rather slow apertures, the only downside I've discovered is that resolution/micro-contrast isn't as good as my best lenses at higher magnification, but that's hardly a shock.  I've been more surprised at how good the images actually are.

On the 6D, outdoors, using the center point, my 70-300L with a 1.4x extender has worked pretty much flawlessly for me even at the long end, where it is equivalent to f/8.  Experimentally, at f/12, it fails reliably, but almost works (gets the focus right, but doesn't acknowledge that it did) much of the time.  So I'd guess that the 6D's daylight focusing limit is somewhere just shy of f/12.  I wouldn't think f/6.5 would even be a challenge for it except in fairly bad lighting conditions unless you stick a TC on it.

Out of curiosity, what does the EXIF tagging show for the f-stop?  From what I've seen when working with MF lenses, I'm fairly certain the lens can't lie to the camera about its wide-open aperture, or else every shot would be underexposed by a stop.  But perhaps it could get around that by lying about every setting equally.  If that were the case, wide-open shots would claim to be f/5.6 at the long end, even though they really can't be.

First of all, the EXIF data is always correct.  But somehow third party lenses have had a workaround that bypassed the f/5.6 maximum aperture limitation for many years.  I understand that the trickery is not so much about metering as it by bypassing that limitation.  Magic Lantern software also can bypass that same limitation for all lenses, so it obviously more of a software limitation than it is a physical limitation.
6D x 2 | EOS-M w/22mm f/2 + 18-55 STM + EF Adapter| Rokinon 14mm f/2.8 | Tamron 24-70 f/2.8 VC | 35mm f/2 IS | 40mm f/2.8 | 100L | 135L | 70-300L -----OLD SCHOOL----- SMC Takumar 28mm f/3.5, Super Takumar 35mm f/3.5, SMC Takumar 55mm f/1.8, Helios 44-2 and 44-4, Super Takumar 150mm f/4

dgatwood

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Re: Dustin Abbott Reviews Tamron 28-300 FF
« Reply #19 on: August 14, 2014, 11:47:44 PM »
Out of curiosity, what does the EXIF tagging show for the f-stop?  From what I've seen when working with MF lenses, I'm fairly certain the lens can't lie to the camera about its wide-open aperture, or else every shot would be underexposed by a stop.  But perhaps it could get around that by lying about every setting equally.  If that were the case, wide-open shots would claim to be f/5.6 at the long end, even though they really can't be.

First of all, the EXIF data is always correct.  But somehow third party lenses have had a workaround that bypassed the f/5.6 maximum aperture limitation for many years.  I understand that the trickery is not so much about metering as it by bypassing that limitation.  Magic Lantern software also can bypass that same limitation for all lenses, so it obviously more of a software limitation than it is a physical limitation.

After studying the lens protocol, I think I get it.  The camera asks the lens to report its maximum aperture, but that's the maximum aperture for the whole lens, not for the current zoom setting.  When the camera sends a command to fully open the lens, the lens reports the actual aperture.  I'd imagine that the check to decide whether to autofocus or not is based on the maximum aperture reported by the lens, rather than the aperture that the lens reports when the camera tells it to open all the way at the beginning of focusing.

So as long as the lens says that it can open up to f/5.6 or wider, even if it really fails 100% of the time in practice, the camera will make the attempt.

With that said, I only spent about three minutes looking over the lens protocol, so I could be wrong.

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Re: Dustin Abbott Reviews Tamron 28-300 FF
« Reply #20 on: August 15, 2014, 02:09:04 AM »
Out of curiosity, what does the EXIF tagging show for the f-stop?  From what I've seen when working with MF lenses, I'm fairly certain the lens can't lie to the camera about its wide-open aperture, or else every shot would be underexposed by a stop.  But perhaps it could get around that by lying about every setting equally.  If that were the case, wide-open shots would claim to be f/5.6 at the long end, even though they really can't be.

First of all, the EXIF data is always correct.  But somehow third party lenses have had a workaround that bypassed the f/5.6 maximum aperture limitation for many years.  I understand that the trickery is not so much about metering as it by bypassing that limitation.  Magic Lantern software also can bypass that same limitation for all lenses, so it obviously more of a software limitation than it is a physical limitation.

After studying the lens protocol, I think I get it.  The camera asks the lens to report its maximum aperture, but that's the maximum aperture for the whole lens, not for the current zoom setting.  When the camera sends a command to fully open the lens, the lens reports the actual aperture.  I'd imagine that the check to decide whether to autofocus or not is based on the maximum aperture reported by the lens, rather than the aperture that the lens reports when the camera tells it to open all the way at the beginning of focusing.

So as long as the lens says that it can open up to f/5.6 or wider, even if it really fails 100% of the time in practice, the camera will make the attempt.

With that said, I only spent about three minutes looking over the lens protocol, so I could be wrong.

Of course the lens 'fools' the camera to think it's f/5.6. This is similar to the 'tape trick' on 'reporting' teleconverters or using a 'non-reporting' teleconverter to AF on non- 'pro' bodies even at f/8.
5D3, 5D2, Sony α6000, G16 | SY14 f/2.8, Ʃ20 f/1.8, 24 f/2.8, 35 f/2, Ʃ35 f/1.4A, 50 f/1.8 I, Ʃ50 f/1.4 EX, 100L Macro, 17-40L, 24-105L, 70-200 f/2.8L IS II, 1.4x II, 70-300L, 100-400L | E-mount: SY12 f/2, Ʃ19 & 30 f/2.8 EX DN, 16-70 ZA OSS, 55-210 OSS, Metabones SB | FT-QL, AE-1P | FD(n) & FL lenses

dgatwood

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Re: Dustin Abbott Reviews Tamron 28-300 FF
« Reply #21 on: August 16, 2014, 09:28:41 PM »
Out of curiosity, what does the EXIF tagging show for the f-stop?  From what I've seen when working with MF lenses, I'm fairly certain the lens can't lie to the camera about its wide-open aperture, or else every shot would be underexposed by a stop.  But perhaps it could get around that by lying about every setting equally.  If that were the case, wide-open shots would claim to be f/5.6 at the long end, even though they really can't be.

First of all, the EXIF data is always correct.  But somehow third party lenses have had a workaround that bypassed the f/5.6 maximum aperture limitation for many years.  I understand that the trickery is not so much about metering as it by bypassing that limitation.  Magic Lantern software also can bypass that same limitation for all lenses, so it obviously more of a software limitation than it is a physical limitation.

After studying the lens protocol, I think I get it.  The camera asks the lens to report its maximum aperture, but that's the maximum aperture for the whole lens, not for the current zoom setting.  When the camera sends a command to fully open the lens, the lens reports the actual aperture.  I'd imagine that the check to decide whether to autofocus or not is based on the maximum aperture reported by the lens, rather than the aperture that the lens reports when the camera tells it to open all the way at the beginning of focusing.

So as long as the lens says that it can open up to f/5.6 or wider, even if it really fails 100% of the time in practice, the camera will make the attempt.

With that said, I only spent about three minutes looking over the lens protocol, so I could be wrong.

Of course the lens 'fools' the camera to think it's f/5.6. This is similar to the 'tape trick' on 'reporting' teleconverters or using a 'non-reporting' teleconverter to AF on non- 'pro' bodies even at f/8.

What I'm saying is that I don't think the lens is fooling the camera at all.  It's just telling the truth—that it is an f/4 lens, albeit not at that particular zoom setting.  :)

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Re: Dustin Abbott Reviews Tamron 28-300 FF
« Reply #21 on: August 16, 2014, 09:28:41 PM »

mrsfotografie

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Re: Dustin Abbott Reviews Tamron 28-300 FF
« Reply #22 on: August 17, 2014, 05:17:12 AM »
What I'm saying is that I don't think the lens is fooling the camera at all.  It's just telling the truth—that it is an f/4 lens, albeit not at that particular zoom setting.  :)

Are you in politics by any chance?  ;D
5D3, 5D2, Sony α6000, G16 | SY14 f/2.8, Ʃ20 f/1.8, 24 f/2.8, 35 f/2, Ʃ35 f/1.4A, 50 f/1.8 I, Ʃ50 f/1.4 EX, 100L Macro, 17-40L, 24-105L, 70-200 f/2.8L IS II, 1.4x II, 70-300L, 100-400L | E-mount: SY12 f/2, Ʃ19 & 30 f/2.8 EX DN, 16-70 ZA OSS, 55-210 OSS, Metabones SB | FT-QL, AE-1P | FD(n) & FL lenses

dgatwood

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Re: Dustin Abbott Reviews Tamron 28-300 FF
« Reply #23 on: August 18, 2014, 01:45:18 PM »
What I'm saying is that I don't think the lens is fooling the camera at all.  It's just telling the truth—that it is an f/4 lens, albeit not at that particular zoom setting.  :)

Are you in politics by any chance?  ;D

Ah, I see the confusion.  The camera doesn't ask what the maximum aperture is at a particular zoom setting.  It asks what the maximum aperture of the lens is.  No lying (or even political distortion) is needed; it simply reports the answer accurately.

Later, when you actually take the picture, it says "open wide and tell me what the aperture is", at which point the camera then knows the maximum aperture for that particular zoom setting, but doesn't really care about that detail at that point.

Or at least I think that's what's happening.

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Re: Dustin Abbott Reviews Tamron 28-300 FF
« Reply #23 on: August 18, 2014, 01:45:18 PM »