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Messages - AlanF

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136
The remark was made that no one understands the physics. Here one person who knows enough: Roger Clark. Read his review of the 7D II and follow the links in it:

Roger Clark seems to be a very bright fellow. But the resolution issue ultimately comes down to the problem that light does not behave entirely like a particle nor entirely like a wave. It's both at once. But not really. And if you look at light too closely, it responds by changing what it is.

Not even the worlds best physicists have managed a complete solution to explain this phenomenon. So, no one really does understand the Physics. Obviously, lots of people understand it better than I do. Roger Clark certainly seems to be one of them.

What are the problems with the wave-particle duality of light and the Heisenberg uncertainty principle and quantum effects at a level that is going to affect the observed resolution of a lens and sensor that we can detect in our images? The wave nature of light is sufficient that we can calculate the diffraction patterns at different wavelengths and work out the how they depend on f number, the particle nature means that we can apply Poissonian statistics to photon noise, and regarding the uncertainty and effects; are they large enough to affect us in any practical way?

Even though we don't fully understand the laws of physics, we can design a car without using Einstein's theory of relativity, just based on Newtonian mechanics, and land a space vehicle on a comet. We are dealing with practicalities, not metaphysics. You don't need a "theory of everything" for most practical aspects of engineering.
Whatever, I find this constant bickering over non-existent issues tiresome.

In which case, stop bickering. You raised the non-existent issue of the inadequacy of physics.

137
The remark was made that no one understands the physics. Here one person who knows enough: Roger Clark. Read his review of the 7D II and follow the links in it:

Roger Clark seems to be a very bright fellow. But the resolution issue ultimately comes down to the problem that light does not behave entirely like a particle nor entirely like a wave. It's both at once. But not really. And if you look at light too closely, it responds by changing what it is.

Not even the worlds best physicists have managed a complete solution to explain this phenomenon. So, no one really does understand the Physics. Obviously, lots of people understand it better than I do. Roger Clark certainly seems to be one of them.

What are the problems with the wave-particle duality of light and the Heisenberg uncertainty principle and quantum effects at a level that is going to affect the observed resolution of a lens and sensor that we can detect in our images? The wave nature of light is sufficient that we can calculate the diffraction patterns at different wavelengths and work out the how they depend on f number, the particle nature means that we can apply Poissonian statistics to photon noise, and regarding the uncertainty and effects; are they large enough to affect us in any practical way?

Even though we don't fully understand the laws of physics, we can design a car without using Einstein's theory of relativity, just based on Newtonian mechanics, and land a space vehicle on a comet. We are dealing with practicalities, not metaphysics. You don't need a "theory of everything" for most practical aspects of engineering.

138
The remark was made that no one understands the physics. Here one person who knows enough: Roger Clark. Read his review of the 7D II and follow the links in it:

http://www.clarkvision.com/reviews/evaluation-canon-7dii/index.html


Quote: "The 7D mark II has very small pixels for a DSLR. To get all the detail in an image that the sensor is capable of delivering, you need very sharp lenses. Most zoom lenses, especially consumer zoom lenses will result in soft images from this sensor as the lenses can't deliver the image quality. Also, one needs to use excellent technique to take advantage of this sensor. Remember, it is the lens plus the exposure time that delivers the light and the detail to the sensor. The sensor just collects the light delivered by the lens and exposure time. Deliver the light to the 7D2 and it will record stunning images."

You need the best lenses, like the big whites (and it looks like the new 100-400mm II is in that category) to get the best out of the small pixel sizes. Shake you can eliminate with good technique, but a soft lens you can't except by getting a better one.

139
Animal Kingdom / Re: Show your Bird Portraits
« on: December 14, 2014, 02:46:26 AM »
Nice shots, Alan F - the grass isn't any greener on my particular side of the fence but those guys in Florida now that's another thing.

Down to novel attempts at chickadee flight shots with a 6D, pretty hit and miss but this one is passable.  you can count on one hand what I see most days.

Jack

Chickadees in flight! That is a challenge, Jack. Well done.
There is a preliminary account comparing the 300/2.8  + 2xTC with the 100-400 II + 1.4xTC. The 100-400 is almost as good on the 7D II and much better than the Mk I. I have one on order and will be using it to complement the 300 for walking/hiking. For your chickadees, the extra stop from the 300 will it preferable. 
Alan

140
Animal Kingdom / Re: Show your Bird Portraits
« on: December 13, 2014, 03:24:08 PM »
You lucky guys surrounded by those birds. It's been rather disappointing around here. This afternoon was sunny and I managed to get some portraits of some common species with the 300/2.8 + 2xTC on the 5DIII.

141
Animal Kingdom / Re: The 1200mm Sharpness Test
« on: December 12, 2014, 11:45:51 AM »
The Canon 100-400 could get MUCH sharper than that...and I mean the OLD 100-400...

First of all, the two shots of the chickadees are not necessarily the best I have or even representative of the lens but they are the only two I have of that North American bird (I am in the UK), but they are similar to your shot of the chickadee.

Secondly, the quality is comparable to those of yours from the 100-400, when comparing them side-by-side and certainly not MUCH less sharp.


I was never able to get very sharp shots with the old 100-400 on a 7D. Top is a dunnock at 400 on the 7D, typical of my efforts, below is a dunnock taken on the 300/2.8 + 2xTC III on the 5D3. They are chalk and cheese.

142
Third Party Manufacturers / Re: Tamron 150-600@600.....at distance
« on: December 12, 2014, 08:22:09 AM »
Bryan Carnathan did his measurement at one rather short distance.  Other reviewers, including I think lens rentals gave it the full 600. 

143
Animal Kingdom / Re: The 1200mm Sharpness Test
« on: December 11, 2014, 11:49:11 PM »
Show some much sharper ones you have taken with the 100-400mm. 

144
Third Party Manufacturers / Re: Leica: Trouble in paradise?
« on: December 11, 2014, 06:58:03 PM »
The issue is not with the sensor, but with the glass cover.  If it is scratched thru its coating, them corrosion will form on the glass, not the sensor.  Leica does not yet have a solution that will solve the issue.  In the meantime, they are fixing cameras with a identical part.  Eventually, a permanent solution with a different glass cover will be found.  Owners should refraining from scratching that glass cover if that's even possible.

I am confused. The glass is simply a Schott glass bandpass filter (http://www.howardglass.com/pdf/s_8612_datasheet.pdf). How can glass corrode? It's tough enough to survive strong solvents http://www.dpreview.com/forums/post/52096442

145
Animal Kingdom / Re: The 1200mm Sharpness Test
« on: December 11, 2014, 06:36:37 PM »
To those knocking the sharpness of the Tamron 150-600, here are a couple of shots I took of black-capped chickadees at 600mm f/8. The upper one face on is half the size of Jon's chickadee but, even so, sharper - look at the feet for example. The lower one sideways on is closer and much sharper.

146
Lenses / Re: EF 400mm f/5.6L USM vs Tamron 150-600?
« on: December 11, 2014, 04:33:31 PM »
The comparison at TDP shows the 400L and Tamron IQ the same at 400L f5.6 and the 400L sharper at 560mm f8 with 1.4x converter than the Tamron at 600mm f8:

http://www.the-digital-picture.com/Reviews/ISO-12233-Sample-Crops.aspx?Lens=278&Camera=453&Sample=0&FLI=3&API=1&LensComp=929&CameraComp=453&SampleComp=0&FLIComp=5&APIComp=2

When I purchased my 400L 9 months ago, I was unable to find a single sharp image on the Net taken with the Tamron at 600mm.  The 400L has been very sharp and very fast and accurate AF (on 5D3).

I have 2 friends who shoot the Tamron (on 70D) and they say at 600mm they need to stop it down to at least f8 for decent IQ.  The TDP chart shows it is better at f11.

If you haven't used a lens, don't give advice about it based on your inadequate scanning of the net.  There are now lots of very sharp images from the Tamron at 600mm on the net. Here is a thread from Canonrumors.

http://www.canonrumors.com/forum/index.php?topic=22284.msg426389#msg426389

Many of these shots were taken at distances too close for the 400mm f/5.6 L and under conditions where the lack of IS would have made it unusable. The 400mm L f/5.6 is a very popular lens, much loved by many members of Canonrumors and so must be more than satisfactory. The Tamron 150-600mm is an excellent lens, best used at f/8, and is more flexible than the 400mm L, but heavier and more bulky. My copy of the Tamron is just as sharp at 400mm as was my 400mm L f/5.6. The new 100-400mm L II has far better MTFs than the old 400mm L and four stops of IS and a minimum focus distance much, much shorter. Art Morris, the doyen of bird photography, now insists on IS. You don't have to follow his advice.

147
Lenses / Re: EF 400mm f/5.6L USM vs Tamron 150-600?
« on: December 11, 2014, 04:02:43 PM »
The comparison at TDP shows the 400L and Tamron IQ the same at 400L f5.6 and the 400L sharper at 560mm f8 with 1.4x converter than the Tamron at 600mm f8:

http://www.the-digital-picture.com/Reviews/ISO-12233-Sample-Crops.aspx?Lens=278&Camera=453&Sample=0&FLI=3&API=1&LensComp=929&CameraComp=453&SampleComp=0&FLIComp=5&APIComp=2

When I purchased my 400L 9 months ago, I was unable to find a single sharp image on the Net taken with the Tamron at 600mm.  The 400L has been very sharp and very fast and accurate AF (on 5D3).

I have 2 friends who shoot the Tamron (on 70D) and they say at 600mm they need to stop it down to at least f8 for decent IQ.  The TDP chart shows it is better at f11.

148
EOS Bodies - For Stills / Re: 70D/7DII vs 5DIII + TC
« on: December 10, 2014, 08:41:09 AM »
Agreed that the Tamron is best used at f/8, and my customised settings have f/8 as standard. I am very keen, for that reason, to try the new 100-400 with the 1.4xTC on the 5DIII at f/8 to compare. I'll report back in a week or two when my 100-400 II is delivered.

149
EOS Bodies - For Stills / Re: 70D/7DII vs 5DIII + TC
« on: December 10, 2014, 04:28:25 AM »
Thanks for this comparison, AlanF. I like comparisons that make me feel good about my 70D and don't start me dreaming about getting a 5DIII  ;)

One question, though. You wrote that the Tamron at 400mm on the 70D is quite good and better than the same lens at 600mm on the 5D. I agree that the 70D at 400 looks better than on the 5D (I didn't see the difference at first looking at this on an iPad, but on a bigger screen I do see the difference). They both look quite a bit softer than any of the other shots, though. I know the Tamron isn't going to be as good as the 300, but even with the 2x converter the 300 looks significantly better. What does the difference look like in a real world situation? Do you have any bird shot comparisons between the Tamron on the 70D and the 300 with TC on the 5D?

Maybe I was expecting too much from the Tamron from all the praise it has received.

I made a policy decision not to use the Tamron on crop, based on my experience with the old 100-400: good on the 5DIII, soft on the 7D. DxO said the same in its excellent comparison of the Tamron - very good on FF and better than the 100-400, but both not so good on crop. Here are two 100% crops of a greenfinch. The upper is by me with the 300/2.8 +2xTC at f/5.6 on the 5DIII, the lower by my wife using the Tamron at 428mm f/6.3 on the 70D.

150
EOS Bodies - For Stills / Re: 70D/7DII vs 5DIII + TC
« on: December 09, 2014, 12:57:56 PM »
It would be interesting to compare your 1DX + 600/4 II + 1.4xTC with the 7DII + 600/4 II. A pity TDP is still using the softer 60D as the crop. The competition is getting hotter now.

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