November 28, 2014, 09:20:01 PM

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Messages - weixing

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   IMHO, in the real world, it's hard to actually see the advantage of the extra resolution of the APS-C over the FF as a lot of environmental condition will limit the maximum resolution you can get... the lighting condition, air turbulence and etc. I think you can only see the advantage of the extra resolution of the APS-C over the FF is when the subject is very, very close... when all the environmental resolution "limiter" is minimize.

   I had both the 60D and 6D and shoot them both together a few times and todate, I still haven't see one image from the 60D that show the advantage of the extra resolution even when pixel peeping... the subject in the 60D image is larger, but any details I can see in the 60D, I can see it in the 6D although it's smaller.

   Anyway, the only advantage I find the 60D had over the 6D is that AF is more accurate when your subject is very small... I think that may be because from the AF system point of view, the subject is bigger in the 60D, so the AF is more accurate... I also see the same result in live view AF... that's why I'm consider to change my 6D to a 7D2 when it become available... I don't print my photo, so I think I can live with the inferior high ISO performance of APS-C sensor.

   Have a nice day.

Photography Technique / Re: Tripod/camouflage for birds/wildlife?
« on: August 30, 2014, 08:05:15 AM »
Hey Tayassu,
Thanks for the kind words, glad to be of help.
I have been hanging out with other birders and have picked up some other tips from them.
One guy has a  few things he does .... firstly he has a small speaker connected to his Ipod and plays bird calls.
He also had a hand full of mealworms and other bait he throws out where he wants them.
Another guy told me of a friend of his who places water trays in spots and comes back after a while to take shots of the birds that congregate near it. Though I think these methods cheating !

I do use a monopod,  I find it easy to walk around with, light weight etc.
I do use a flash (580EXII) most times, as the birds can tend to flit about between the shadows and it does bring out the colours in their plumage, I don't have a better beamer, and don't seem to need it yet.
I'm seriously considering a new lens, I'm just using the 70-200ISF2.8L just now, I have a 2xIII but not that happy with the quality, I think the 300F4 or the 400F5.6 would be sweet ... I don't have the money to get a "Big White" and I am leaning towards the 300F4 as it can focus down to 1.8M and perhaps a 1.4 converter ... the 400F5.6 is about 3.5M min focus and I can regularly get much closer than that so I think I would get pretty frustrated being so close and not be able to focus down to that close, thus losing a shot so close.

Images attached,
Eastern Spinebill 70-200 flash at min focus distance 1.4m
Eastern Yellow Robin 70-200 flash at min focus, 1.4m
Lewins Rail 70-200 flash at min focus 1.4m
Variegated Fairy Wren 70-200 flash 1.4m
All these birds are tiny, I didn't use any sort of camo, just sit or stand and wait, the longer min focal distance of the bigger lenses would have made these shot possible .. save perhaps using a tele converted on a 600 or 800.
    Nice shot... when I start birding, I also use flash as most birding book/website out there said so, but after I flash a juvenile kingfisher and it's nearly fall off from the branches  :P , I become a nature light shooter now... ha ha ha  ;D

   Anyway, I personally don't like the result of flash as the colour of some birds will change (may be my flash skills are lousy) and look different from what you see from your naked eye. I like my birds image to look as close as to what I see with my eyes.

   Have a nice day.

Photography Technique / Re: Tripod/camouflage for birds/wildlife?
« on: August 30, 2014, 07:48:44 AM »
   I now use a video monopod most of the time as I like to walk around and I find video monopod are more stable and easy to use than normal monopod. I bring my tripod if I intend to stay at one location for extended period time.

    About camo, as long as you don't wear super bright shirt, you should be fine... field craft are more importance. I waer long sleeve camo shirt mainly because I don't have a dull colour long sleeve shirt, so I brought the long sleeve camo shirt... also, long sleeve shirt and long jeans are good as it can provide some protection against insect bites.

   Enjoy your birding and have a nice day.

EOS Bodies / Re: EOS 7D Mark II & Photokina
« on: August 28, 2014, 11:33:05 PM »
Hey, I am going on a unicorn photo expedition in January, I need that slightly-better-than-70D high-ISO noise performance.   8)

Bigger pixels give more electron capacity per pixel (say, 4 micron pixel has 30,000 maximum capacity, 7 micro pixel has 100,000 maximum capacity). So, say you have 14-bit ADC, that's roughly 16,000 levels of electrons, or about 2 electrons per level for the 4 micron pixel and 6 electrons per level for the 7 micron pixel. Say you have 30 electrons worth of noise. Noise takes up the first 15 levels for the 4 micron pixel and the first 5 levels for the 7 micron pixel. That's why bigger pixels, all other things being equal, result in less perceptible noise.

This is still wrong. Bigger pixels mean more charge per pixel...but it's still the same TOTAL CHARGE for the WHOLE SENSOR! :P As Lee Jay said, slicing up a pizza into smaller slices doesn't mean you have more pizza, or more pepperoni on that pizza. It's still the same amount of food.

Same for sensors. You can have two APS-C sensors with 10µm and 5µm pixels. One has four times as many pixels as the other. The sensors are 22.3x14.9mm in size. The big pixel sensor is 2230x1490 pixels, the small pixel sensor is 4460x2980 pixels. One has pixels with four times the area as the other. The 10µm pixels gather 100ke- charge FWC, the 5µm pixels gather 25ke- charge FWC. The bigger pixels are better, right? They gather more light than smaller pixels. They mean less noise, right? Nope. Let's calculate the total charge in the sensor for a fully saturated sensor

(2230*1490) * 100000 = 332,270,000,000e-
(4460*2980) * 25000 = 332,270,000,000e-

Hmm. Something MUST be wrong, because these two sensors gathered the same amount of light! If your subject fills the same absolute area of the sensor, then either sensor is going to gather the same total amount of light. The only difference is that one divides the subject into smaller buckets. Each bucket gets less light, but the subject as a whole is resolved at the sensor with the exact same amount of light in total.

Oh, but I purposely used pixels that had a nice, neat little ratio between them. It doesn't work that way in real life, right? Let's prove the point. Let's take the 5D III and 6D, both full frame sensors. Their total charge capacities are:

5D III: (5760px*3840px) * 67531e-/px = 1,493,677,670,400e-
6D: (5472px*3648px) * 76606e-/px = 1,529,197,940,736e-

The 5D III has 49% Q.E., the 6D has 50% Q.E. Dividing the above by 49% and 50% respectively gives us:

1,493,677,670,400/49 = 30,483,217,763.27
1,529,197,940,736/50 = 30,583,958,814.72

Dividing those numbers gives us:

30,483,217,763.27/30,583,958,814.72 = 0.99670608203273169699921873489352

The 5D III and 6D are within 99.7% of each other as far as total charge goes. That means the difference in light gathering capacity is 0.3%...well within margin of error. Differences in technology, cherry picking the best sensors (as in the 1D X/D4 lines), using better companion electronics (again as in 1D X/D4), etc. can create larger discrepancies, but in general, differences in pixel size, until were talking about very small pixels where fill factor becomes an issue, are largely meaningless. It's sensor area that matters first and foremost, then quantum efficiency...then pixel size/fill factor.

The 7D II could employ some new technology to improve Q.E. They could use better materials (i.e. black silicon), control current better, maybe even switch from using a standard RGGB CFA to using something like color splitting, etc. and maybe double Q.E. That would allow them to realize a REAL one-stop improvement in noise performance at high ISO. I think it's doubtful that's happened...if the 20.2mp sensor rumor is true. In all likelihood, Canon has made some minor evolutionary improvements, maybe improved Q.E. a few percent, maybe found a way to recover some die area for photodiodes, improved the efficiency of their circuitry, etc. I don't expect the differences to be huge.

The 70D has 45% Q.E. The 7D II might have around 49% Q.E., and they may better utilize the sensor die area for photodiodes. We might see a boost from ~26ke- FWC to maybe ~30ke- FWC. That is not going to change things much...and accounting for the differences in quantum efficiency, the two sensors are still going to come within a fraction of a percent of each other as far as total light gathering capacity goes.
    Err... I think you forget to consider the noise factor... if the noise for every pixel is the same, the larger pixel (more signal) will have better Signal-to-Noise ratio... that's mean more pixels equal more noise and since the total signal for the both sensor is the same, the sensor with less pixels will have better Signal-to-Noise ratio. Also, since smaller pixels hold less charge, the chance of blowing highlights is higher than a larger pixel sensor.

   As a result, sensors with larger pixel have better dynamic range than sensors with smaller pixel even if the total sensor size is the same.

   Have a nice day.


EOS Bodies / Re: Are you planning to purchase a 7D2
« on: August 27, 2014, 02:19:46 PM »
    I use my DSLR mainly for birding and now using 6D with Tamron 150-600mm. I feel the center point AI Servo AF of 6D is slow, but I'm not sure whether is it the 6D center point AF is slow. If 7D2 AI Servo AF is faster, more accurate and more reliable, most likely I'll sell my 6D and get a 7D2 (unless the 7D2 is as expensive as a 5D3).

   Have a nice day.

EOS Bodies / Re: Do Sensors sell the Camera?
« on: August 26, 2014, 01:01:31 AM »
I know.... it's not like it's hard to do....
I can't think of anything at work that does not use at least 24 bit A/D and we have some test equipment that has 64 bit A/D and others that have 48 bit A/D running at 60Ghz sampling rates... I think that the last time I designed something with only 16 bit A/D was back in the 1980's....
Even though I don't know a lot about electronics I'll go ahead and wade in to water over my head.  While it may be easy to implement, it may have implications for the rest of the body.  Presumably, more precise sampling will draw more power proportional to the increase in precision: more bits of A/D will mean more components, all of which draw power.  Then the digital circuitry all the way from A/D to flash card has to be scaled-up to match which also draws more power.  All of this also generates heat which must be dealt with.  In my sophomoric opinion, this would result in slower framerate and heat issues for the sensor.  And that's not even considering the effect on battery life.  It's not impossible, but it's an extra set of engineering problems which incur greater cost, which affects retail cost and profit.

Also, why jump straight to 20 bit A/D when you can sell 14, then 16, then 17, then 18, then 19, then 20.   8)
    Hmm... Pentax use 22-bits ADC many years ago... on the Pentax K10D, but the raw file is only 12-bits... then Pentax K20D use back the 14-bits ADC... just wonder why they change back to 14-bits??

   Have a nice day.

EOS Bodies / Re: Are These The EOS 7D Mark II Specifications?
« on: August 22, 2014, 08:36:42 PM »
   The specification look good to me:
1) No GPS - fine with me... I already had an external GPS unit which capture GPS signal way faster than 6D GPS and got map function.
2) No wifi - not importance to me... may be they got built in radio trigger, that's why cannot put wifi??
3) No 4K - no problem... running out of hard disk space, 1080p is good enough for my use... 1080p file size is already too large for me, but I do hope they had 1080p 1:1 video crop mode.
4) 20.2MP - enough for me, but I do hope they can improve the high ISO performance by at least half a stop compare to 70D and I might change my 6D to it.
5) Hope 7D2 had a silent shutter mode... very useful for shooting shy birds.

   Hope the pricing will be close to 6D, so I can just sell my 6D and get this one without spending too much...

   Have a nice day.

Third Party Manufacturers / Re: Sigma and Tamron OS/VC quirks
« on: August 22, 2014, 01:18:24 PM »
I now own two third party stabilized lenses, the sigma 70-200 2.8 EX (there are a lot of letters and I always forget them) and the tamron 150-600. I've noticed a quirk they both exhibit that none of my canon IS lenses do: when the stabilizer engages, the frame tilts down what visually feels like about 5-10°. With the 70-200, it's not that bad, but at 600mm with the tamron, 10° is a lot.

Has anyone else noticed that kind of this happening? What's the explanation? Misalignment in the stabilizing optic? Maybe I'll shoot a video if nobody can picture what I'm seeing.
    My tamron 150-600mm will usually just "jump" (meaning that it'll return to the initially aiming point) a bit when IS is activated... sometime if the IS is not activated for a long time, the frame will move down a bit, but still very close to my AF point... at 600mm, the distance it move is around the size of my 6D centre AF point... not very much... my handshake is easily 10 times worst than that...  ha ha ha :-P

   Have a nice day.

   Have a nice day.

Technical Support / Re: Another my Stupid question = Sensor Sizes
« on: August 21, 2014, 10:14:05 PM »
Obviously, the FF sensor takes in more light, but it is spread over a wider field of view and the light per pixel is the same.

But the output image (print, projected image, etc) is the same size, so the light gathered by the FF sensor requires less enlargement (attenuation) to achieve that output size, and this negates your argument.

So I believe you're mistaken: with identical technology, the size of the sensor is all that matters for low-light properties.  For ample-light IQ, total MP, AA filter, etc are definitely important for resolution.

I'm sure jrista will jump in here any minute to correct us all.  :-)
    No, for example a 36MP FF and 18MP FF using the same manufacturing technology, the 18MP FF will have better low-light properties as which pixel received more light than the 36MP FF.


Make the pixel smaller and you get more resolving power, but at the expense of less light, worse low light performance, and less flexibility with exposure times and apertures.

I believe the number of pixels a sensor has determines it's resolving power not the size of the pixel.  Large sensors with 18 (large) MP will resolve the same as a tiny sensor with 18 (tiny) MP.

    Pixel size will determine the resolving power (provided the lens and environmental condition are not limiting the resolution), so a smaller sensor will have better resolving power than a larger sensor of the same MP.

   Have a nice day.

Photography Technique / Re: APOLLO missions - image inconsistencies
« on: August 17, 2014, 09:00:54 PM »
Thinking about it now, that would have been an exceptional feat to accomplish with the technology of the time!  So there's room for doubt.. and deception.
   The different between the Apollo period and now is that cost and safety wasn't the highest priority during the cold war period... landing human on Moon first is.

   Anyway, if the Moon landing is fake, USSR will sure know and make a joke out of it...

   Have a nice day.

    Nice setup... I use an old Vixen GPD mount with motor drive... thinking of doing some astrophoto again (that's why I keep my EF 400mm F5.6L when I brought the Tamron 150-600), so thinking of adding GOTO to it...  ;D

    About the lens, IMHO, most telephoto zoom lens are not suitable for long exposure DSO astrophotograph... reason been most of them have zoom creep due to the heavy front element. I think may be the Canon EF 100-400mm is the only zoom lens that's suitable as it can lock the focal length.

    Anyway, there are a lot of low cost decent telescope in the market now that can produce very good result... IMHO, with a field flattener, most of them can produce better result than most super telephoto lens.

   Have a nice day.

    Nice setup... I use an old Vixen GPD mount with motor drive... thinking of doing some astrophoto again (that's why I keep my EF 400mm F5.6L when I brought the Tamron 150-600), so thinking of adding GOTO to it...  ;D

    About the lens, IMHO, most telephoto zoom lens are not suitable for long exposure DSO astrophotograph... reason been most of them have zoom creep due to the heavy front element. I think may be the Canon EF 100-400mm is the only zoom lens that's suitable as it can lock the focal length.

    Anyway, there are a lot of low cost decent telescope in the market now that can produce very good result... IMHO, with a field flattener, most of them can produce better result than most super telephoto lens.

   Have a nice day.

Lenses / Re: Tamron 150 600 woes
« on: August 12, 2014, 12:49:41 PM »

i was told (possibly by a tamron rep ) but don't hold me to that .that the problem is the fact that canon will not let tamron have the lens algorithm table to get it right most of the time ,whereas nikon and sony let them have access to theres .i don't know if this makes sense or is even the truth but most problems with this lens seem to be coming from canon users ,the pics i am seeing from the nikon ones are spot on ,with hardly any complaints from nikon users at all .
   i borrowed one for a day and in all honesty i was not impressed with a/f at all and would rather use a 400mm f5.6 plus 1.4tc on my 1D3 to get the  reach .

The problem with that oft-repeated theory is that Tamron makes lenses for Canon. They do for Canon as well. They couldn't very well do that if Canon didn't give them all the information they needed, could they?
They reverse engineer, with obvious shortcomings.

No, they don't. Why would Canon ask them to build a lens for their cameras and then not give them the specs they need?

Remember, it's Sigma that has AF problems with nearly all of their lenses. Most Tamrons work fine.
    No, Canon didn't give Tamron or any 3rd party lens manufacturer their EF mount information and protocol... they (3rd party lens manufacturer) reverse engineer it. Take a look at this article (although it's a very old article, but I think should still be true today):

    Anyway, my Tamrons 150-600mm AF work quite well except that when in AI servo mode, I notice sometime it'll go out of focus momentary even if the subject is not moving... but have not try to reproduce the issue... will try when got some free time.
    Have a nice day.

EOS Bodies / Re: Patent: Dual Pixel Phase Detect AF While in AI Servo
« on: August 12, 2014, 12:23:28 PM »
    I personally won't get a DSLR with EVF for birding/wildlife... it'll "eat" the battery very fast. If it's a hybrid (with option of using either optical or EVF), then I don't mind.

    Anyway, may be the Dual Pixel Phase Detect AF is use to do fine adjustment to the AF when the mirror is up during the image capture phase...

    Have a nice day.

   Today, I do a compare shots on FF vs APS-C on a real bird under real life condition... only manage to try out ISO 1600 and ISO 3200 as start to rain very heavily after this. I just open them using lightroom 4, took a screenshot, paste on paint and saved as jpeg.
Test Condition
Camera: Canon 6D (left) vs Canon 60D (right)
Lens: Tamron 150-600mm @ F8
Subject: Stork-billed Kingfisher at around 18m (this is the only real bird that I can find that will stay at the same place for extended period of time with minimum movement).
Weather: Cloudy

After looking at the compare shots, my initial conclusion is that the 60D sensor doesn't seem to have a significant details advantage (if any) under real life condition (at least this seem to be true when using the Tamron 150-600mm lens) over the 6D and the 6D (up to ISO 3200) doesn't seem to have a real noise advantage if the 60D image was scale down.

   Have a nice day.

PS: The CanonRumors website seem to scale down the screenshot image (actual size is 1920 x 1080) to fit the website frame... to view at actual size, need to click on the image and using the scroll bar below the post to scroll through the image... or is there a setting to show the image actual size??

Very interesting results. Congrats on finding a bird that would sit still the entire time you took the shots. :D That's definitely the kind of bird you need.

To really truly compare, you would need to overlay the two images on top of each other, and upscale the 6D images so the bird was the same size, then overlay them directly on top of each other (Photoshop's difference layer blending mode makes the positioning very easy). Then you can swap back and forth, and really see the difference. It's pretty much impossible to objectively determine any real differences when looking at the images becomes almost a pure subjective judgement.

The only other thought I have is the lens used. The 150-600 is a good lens for it's price class, but I can tell it does not resolve the same kind of detail as the EF 600 f/4 II. I am able to resolve fine feather and fur detail even at very high ISO, something I don't see in your images. It doesn't necessarily invalidate the test, however it does throw in a major factor that affects results. The moon is a bit of a different kind of subject than a bird, given that it is primarily seeing limited rather than diffraction limited, so using 1200mm f/8 does not limit resolution the way it would with a terrestrial subject. If I were to do a bird test...I would probably use the 600 at f/4.5, which seems to be the absolute sweet spot of my lens.
    I had no doubt that EF600mm F4 II with it's 150mm front element will resolve more details compare to my 95mm front element, but I'm $$ limited... ha ha ha  ;D

    Anyway, the sky is cloudy and the bird is under the shade... so I think the details are a bit more difficult to resolve under this flat lighting condition.

    Have a nice day.

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