September 30, 2014, 06:57:17 AM

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Messages - weixing

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Third Party Manufacturers / Re: SIGMA 150-600!!
« on: September 06, 2014, 03:04:32 AM »
Sigma is into flourite now? Very interesting.

No, its FLD glass - fluorite equivalent. Its what they use in the 120-300 2.8 Sport, 50 1.4 Art, etc.

I'm curious about what they mean by teleconverter compatibility.  Another part of this announcement is the new 1.4x and 2x tc's. Sigma says that this new lens is optimized for them. There is no way the 2x will AF on any body of course, but I wonder if the 1.4 might with f8 focusing bodies. The large 105mm filter size suggests that it may be a "big" 6.3, possibly to enlarge the image circle for better corner sharpness but it could also allow just that bit more light necessary to get reliable f8-ish AF. Or it could be marketing and the TC's are manual focus only. I wonder though because Sigma said specifically that tele's do not work on my 300-800 5.6 zoom and they seem to suggest otherwise with this press release.

Also, this forum is weird. I posted a thread about this in a different sub forum this morning but instead of locking the thread and pointing to this one, they renamed this thread with my title and moved my original post into this thread where it doesn't make sense. That seems like a weird and confusing way of doing things. And there are waaaaay too many sub forums with overlapping topics. Half of them could be merged or deleted and nobody would miss them.
   Sigma had been using FLD lens since 2010, so nothing new...
Anyway, about the TC, 1.4x possible, but 2x?? Who's know... may be Sigma got "inside news" that may be the new generation of DSLR will allow AF at F8, F9 and even F11... :P

   Have a nice day.

EOS Bodies / Re: Are you planning to purchase a 7D2
« on: September 05, 2014, 11:21:26 AM »
    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.

Have you tried the firmware update on the Tammy?  I've not, but I think that may resolve a lot of your problems.  I'll be sending mine in soon!

I have used the 5dmkiii and the 70d on the 150-600.  Results on the 70d are rather disappointing.  Part of the issue is that it just looks like crapola once you go above ISO 1600.  Anything higher than that, I'm much better off going to my 5d and cropping.   

So the 70d has prettymuch collected dust as I bought it for birding, but I need greater than 300-400mm still, so it wasn't exactly the perfect combo with the Tammy I thought it would be.  It does look great on the 70-300L however, but I still don't have the reach I want.

I'll only buy the 7dmkii if there is a substantial increase in quality (iso3200 useable images).    Otherwise, I may just ditch the crop frame all together, and bite the bullet on a used 500F4 and use on the 5dmkiii.
    Not yet, but is there a new firmware??

   Compare 6D with my 60D center point AF, the 60D center point AF is more accurate on small subject... I think may be because the subject is bigger in the 60D AF sensor.  Also, base on my observation, if I scale down the 60D image by 1.6x, the 60D IQ is around the same as the 6D IQ up to ISO 3200, 6D IQ is still better than the 60D scale down image when ISO is above 6400. So if 7D2 AF is much better, I'll consider the switch... basically trade IQ with better AF.

   Anyway, will try out various settings and ways to improve my focus accuracy... if can overcome the problem, I'll keep my 6D as I like it very much especially with the 40mm pancake on it.

   Have a nice day.

Third Party Manufacturers / Re: SIGMA 150-600!!
« on: September 05, 2014, 10:49:00 AM »
    The front element is nearly the size of a 300mm f2.8, but why only f6.3 at 600mm? Or the front element is just a protective element??

    Anyway, the only feature I like about this lens is that it can lock at any focal length which to me is very useful (if I want to use it for Astrophotography), but I already have a Tamron and not 100% convince about the QC of Sigma yet.

    Have a nice day.

Doesn't Sony introduce a new camera every day?
18 e-mount cameras since 2010 (not counting video cameras)....23 e-mount lenses (of which at least 2 were refreshes of existing ones).

Imagine how much better off they'd be if they had just made the NEX5 or NEX7 and build a lens system around it.
    WOW... so many?? They thought they are selling TV??

Anyway, if I buying an electronics product that's I need it to last, it'll not be a Sony product... their support is very bad especially if it's an old model.
    Have a nice day.

Technical Support / Re: star trails etc- - infinite focus
« on: September 01, 2014, 08:19:51 AM »
   I think the infinity focus will change a bit when temperature change, so the scale is not very accurate. Also, with such small scale in modern AF lens, it very easy to misfocus a star... a bit off and the stars is blur... use live view will be easier.

   Anyway, to focus a stars to tack sharp is very challenging, so challenging that there are even software for it... ha ha ha  :P

   Have a nice day.

EOS Bodies / Re: Is Canon now two generations behind Nikon?
« on: September 01, 2014, 02:50:23 AM »
The REAL QUESTION is how many generation is Canon behind Sony, Olympus and Panasonic ???

The photographic world is rapidly changing. Now Video is a BFD with many photographers (and has been for several years). And ALL professional video cameras use EVFs. Even Canon has EVFs on the C100, C300 and C500. So why no EVF on the 7D2 ???

You may want to view this video The Mirrorless Revolution and learn why Michael Reichman has sold all his DSLRs
   Err... I thought all video cameras are mirrorless not just professional ones... didn't see any consumer video camera come with a mirror... ha ha ha :P

   Anyway, 7D2 is supposed to be a sport/wildlife DSLR which IMHO, is not suitable to use a mirrorless design basically due to the power consumption. Not sure about sport photographer, but wildlife photographer use the viewfinder a lot even not shooting as the super telephoto lens can be use as a scope to search for your subjects. If it use an EVF, power will use up very fast and sensor will become very hot after long use... image quality will not be good when sensor become hot.

   Have a nice day.

EOS Bodies / Re: Is Canon now two generations behind Nikon?
« on: August 31, 2014, 09:46:27 PM »
More often there is a thread specifically about sensors or DR or banding and the same set of Canon defenders always comes in and jumps all over

Sorry, but no.  More often it's a thread about anything but DR and one of the DRones comes in and makes it about DR, and others chime in to counter that.  Mikael/ankorwatt hijacked countless threads.  Earlier today jakeymate posted his diet coke box noise images (from this thread) in a thread started by someone wondering about changing the color profile of their Canon on-board LCD.  Nothing to do with sensors or DR, at all...until Dean the DRone showed up, that is.  ::)

     Recently, when I read a thread not about the DR, I always had the feeling that the thread will end up about DR.... ha ha ha  :P

    Have a nice day.

EOS Bodies / Re: Is Canon now two generations behind Nikon?
« on: August 31, 2014, 09:40:16 PM »
Would someone explain to me what is wrong with pointing out the weaknesses of your brand and hoping that future models improve on those weaknesses?

Not a damned thing.


Honestly and fairly pointing out weaknesses is something consumers should do, assuming their products matter to them. 

Many people, myself included, discussed the lack of a sharp-to-the-corners UWA from Canon.  Now, we have the 16-35/4L IS. 

I bitched loud and long about the 5DII's AF system, which was pretty similar to that in the 20D...which was the same system used in the entry level xxxD bodies at the time.  Now, we have 1-series AF in the 5DIII.

For those two examples, a sizable portion of Canon's customer base felt there was an issue to be addressed.  I think the difference in this case is that there is only a very small minority complaining about Canon's lesser low ISO DR.  The other difference is the way in which some members of that small minority seem to exaggerate the issue out of all reasonable proportion.
    Have a nice day.

   Why don't they just add the shipping of compact camera, video camera, security camera, webcam, camera phone and etc to the mirrorless shipping figure (technical speaking they all are mirrorless as they don't have a mirror in them), then the mirrorless figure sure will overwhelm DSLR figure...  ;D

    Anyway, I believe one day all camera will be mirrorless, but that day is not today, tomorrow or next year... may be 10 years later... also, the mirrorless camera will be just as big and bulky as current DSLR because to get good image quality, you need large lens and large lens doesn't go well with small camera... and to have good ergonomics, the camera cannot be small due to the size of our hands (I don't think our hands will be smaller in the near future...) and of course you need space for a large battery as mirrorless "eat" a lots of power.

   Have a nice day.

   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.

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