April 17, 2014, 07:23:18 PM

Show Posts

This section allows you to view all posts made by this member. Note that you can only see posts made in areas you currently have access to.


Messages - weixing

Pages: 1 ... 4 5 [6] 7 8 ... 13
76
Lenses / Re: 400mm f5.6 - Why ?
« on: July 16, 2013, 10:54:18 AM »
Hi,
    I also owned the 400mm 5.6L and the reason I choose over the 100-400mm is basically faster AF and cheaper... basically the best budget birding lens out there.

   Also, I try hand holding 100-400mm @ 400mm and the IS really didn't help much @ 400mm, so I figure out I'll be need a tripod even if I had the 100-400mm L, so I go for the cheaper option and had been very happy with it.

   By the way, the 400mm F5.6L can AF with the new Teleplus Pro 300 DGX (the one with the blue dot) without the tapping trick.... Just that on my 60D, the centre point AF don't work well, but the surrounding AF point work very well and AF quite fast.

   Have a nice day.

77
Lenses / Re: Dxo tests canon/nikon/sony 500mm's
« on: July 15, 2013, 11:31:39 AM »
Quote
   DxO should come out a standard testing camera for testing lens... a mirrorless camera should be idea since it'll have the shortest flange focal distance and can use adapter for different vendor lens... then the only variables will be the lens and the result can be valid to compare between different lens.

that wouldnt really be more valid as you still have to mount those lenses on their brand camera for real world purposes. why would i care what the test results of a lens would be mounted to a camera i would never shoot. i would rather see test results from a lens/body combo that i could actually use.

not that i really care about DxO that is....
    Hmm... might not mean anything to Nikon DSLR user, but Canon user can mount Nikon lens to Canon DSLR...  ;)

    Have a nice day.

78
Lenses / Re: Dxo tests canon/nikon/sony 500mm's
« on: July 15, 2013, 06:41:55 AM »
Hi,
   Lens performance result using measurement from different camera body is basically useless since every camera sensor perform differently and every vendor process their RAW file differently.

   DxO should come out a standard testing camera for testing lens... a mirrorless camera should be idea since it'll have the shortest flange focal distance and can use adapter for different vendor lens... then the only variables will be the lens and the result can be valid to compare between different lens.

   Have a nice day.

79
EOS Bodies / Re: 70D or 6D
« on: July 06, 2013, 10:04:59 PM »
The reason  think the 70D's AF is interesting  for me, is mainly because I usually take self-portraits over landscapes, and usually I am off-center. I cannot focus and recompose,  since it's hard to focus on my face while I am not in the frame. So being able to focus off center in live view would be great for me.  Just set f/10-14, focus on me in live view through a mobile phone, and shoot. Not sure how the 6D would behave with that.

And yes, you're very right about the low light capabilities of the 6D. I'd love it for indoor portraits, although it is not the main use I do with the camera.

If only Canon told us when 7DMkII would come out, I'd possibly forget about both and go for it ... ;-)

My main issue is the AF, I generally cannot easily focus and recompose, since I ofen take self-portraitsl.
Hi,
    Hmm... all Canon DSLR that have live view can focus off center, so shouldn't be a main issue...

    Anyway, if taking self-portraits is high priority, then you need to get a DSLR with flip screen (60D, 70D, 700D & etc)... I don't think 7DII will have flip screen.

   Have a nice day.

80
EOS Bodies / Re: 70D or 6D
« on: July 04, 2013, 09:39:11 PM »
Hi,
I like to shoot landscapes, but also with 2 young kids like to photograph them too.

I'm looking at either the 6D or the 70D when it comes out.  I have a friend who shoots with a Nikon D800e and he always recommends the full frame route.

I'm also wondering if the price of the 6D will drop at all when the 70D is released.

I'm just interested in opinions either way.

Cheers
     For your case, I think 6D will be better choice since you mention landscape and people (unless you want to shoot your kids when they are running around).  Canon 6D will have better image quality, better high ISO performance and better low light AF performance than 70D (70D AF should be faster in bright lighting condition).

   Have a nice day.

81

And one of the advantages of going mirror less is no more need for AFMA. I, for one, will not miss having to calibrate lenses...... And I can certainly live with F11 autofocus.


Why would there be no more need for AFMA?  Did Canon miraculously find a way to eliminate manufacturing variation in lens and body manufacture while I wasn't looking?
In a DSLR, normal focusing is done by diverting light to a focusing sensor. The camera then focuses accurately to this sensor, not the image sensor. If all is perfectly manufactured and aligned, the image is also focused properly for the image sensor, but as we know, with manufacturing tolerances and wear, this is not always true. aFMA calibration is how we correct for this discrepancy.

In live view, focusing is done on the image sensor so there is no second path to correct for.... Therefore, no mirror, no AFMA.

If that were the only reason for AFMA, then the AFMA value for every lens should be identical (or at least mathematically proportional in a trivially calculable way), because the difference in placement between those two sensors doesn't change when you change lenses.  More to the point, Canon would presumably calibrate out that difference at the factory, because there's no good reason not to do so.

If lenses adjusted their focus until infinite precision was achieved, then yes, it would eliminate the need for AFMA.  Then again, it would mostly eliminate the need if they did that for DSLRs, too.  It would also lengthen the delay before you take a picture, which is why they don't do that.  Instead, at least as I understand it, cameras compute the distance to move the lens, and where it stops, that's assumed to be in focus.  If that computation is off because the lens is even slightly imperfect in any way, then the lens will consistently either front-focus or back-focus.  This is why AFMA varies from lens to lens instead of being a constant value for each body.  Thus, mirrorless cameras won't eliminate the need for AFMA, to the best of my understanding.

Please correct me if I'm misunderstanding.
Hi,
    The AFMA is used to compensate both the distance error between the AF sensor and imaging sensor, and the manufacture tolerance of the lens... that's why the error is different for every lens.

   Mirrorless camera don't require AFMA because the AF system will keep measuring the error and move the lens until it's in focus (or at least within the allowable error), so there is no need for AFMA. If 70D live view phase detect AF also use this method, then AFMA on live view is not required.

  Have a nice day.



82
I wonder how good they can make pancake primes.


Have a look, how small, light, fast and good primes can be made: http://en.leica-camera.com/photography/m_system/lenses/

And contrary to urban legend, adding Ring-USM-AF to those lesnes would not cause additional bulk, but actually make them even smaller and lighter, once the utterly unneccessary manual focusing gear and focus ring will be finally exterminated. :-)

    Ya... saw this video quite sometime ago... see the hair style of the lady assembly the lens... you know who to look for if you find hair inside your leica lens... ha ha ha  :P

   Have a nice day.

83
EOS Bodies / Re: Canon Dual Pixel Liveview Autofocus
« on: July 02, 2013, 09:47:06 AM »
Hi,
    If this dual cmos AF going into their compact camera, it'll be very interesting... ;D

    I'm thinking of getting a SX50 to complement my EF 400mm F5.6L for birding, now I think I'll wait for the next model and hopefully, they'll incorporate this into their next generation of ultra zoom camera... hmm... actually, the SX50 pixel is already so small, just wonder can they still maintain usable ISO 800 if split it into 2???

   Have a nice day.

84
EOS Bodies / Re: EOS 70D a New Benchmark in ISO Performance?
« on: July 01, 2013, 12:08:55 PM »
Hi,
    Just hope Canon don't follow Nikon and Sony to "pre-cooked" the RAW files... I want the RAW files to be as "RAW" as possible.

    Have a nice day.

85
EOS Bodies / Re: the quality of the new sensor will be the key
« on: June 27, 2013, 10:47:32 PM »
the quality of the new sensor will be the key!

i´m a long time canon shooter, but couldn´t help myself to recommend a friend, who was looking for a good midrange body to go with nikon. nikon´s sensor quality is so much better at the moment. from 14ev dynamic-range to 3/4 ev more in high iso. autofocus is better anyway...

but let´s hope, that canon is done with "oldtimer"-sensor technology.

at least I am sick and tired of waiting for a competitive sensor.

we´ll see.
Hi,
   Not sure why so many people in the forum said that Nikon sensor is better than Canon... I compare them from the images in imaging resource and found there is no significant visual different... in fact, IMHO, Canon high ISO is slightly better with more details.

  Anyway, previous xxD spec is now xxxD spec and 7D spec is now xxD spec, so if there is a 7DII, it'll be close to the 1D spec... hopefully, the price is not....  ;)

  Have a nice day.

86
EOS Bodies / Re: Beginning of a new Canon starting with 7D Mk II?
« on: June 27, 2013, 09:50:05 AM »
Hi,
   For me, I'm more realistic:
1) 1 stop better ISO performance
2) 1 stop better low light AF
3) Price and the rest can remain the same

   By the way, since 7D is a sport and wildlife DSLR, GPS will be nice... it'll be good to know where exactly did I shot that birds...

   Have a nice day.

87
Big question - other than the focus being perhaps a hair off, how fast and, most importantly, how accurate do you feel the focus is?
Focus is fast. Not quite as fast as the Canon 400 f2.8 II. But its pretty fast. Fast enough for sports.  As to the accuracy, not ready to put a stamp on it yet due to the back focus. I had some misses.  Not an exceptional number of misses for a softball game. Some that surprised me were the longer shots. For instance shooting an outfielder with center focus, I caught the fence more often than I thought I would. 

Update: I just spent some time tweaking the focus with the doc. I reset the 1Dx micro back to 0. I eventually worked my way up to a -15 setting on over 100'+. At that setting it is sharp!  I then started working on the 120, 150 and 200 mm settings. I did not have time to put on the 5DIII and test it with the updates.   I'll do a full review soon.

Suggestion, if you buy this lens, get the dock. Not sure if my situation is typical, but without it, I'd be calling Sigma or considering returning it.
-Mike
    You mean you can adjust the AF accuracy using the dock? I'm using 60D which do not have the AFMA, so if can adjust the lens AF without using AFMA, it will be very tempting.

   Just wonder how well does this lens take 2x TC?? I'm currently using EF 400mm F5.6L for birding... so really tempted to "upgrade" to this lens if IQ and AF perform reasonably well with TC.

   Have a nice day.

88
Hi,
   May be it's the high temperature that cause the issue?? I once going for birding under a very hot afternoon and most of my shots come out either soft or out of focus, so when I use live view to try to focus, I realize that it's the heat wave that cause the problem... can clearly see that the image in and out of focus in quick succession... like shooting through a wave of water.

    Have a nice day.

89
Lenses / Re: What exactly is a 100% crop?
« on: April 27, 2013, 11:26:13 PM »
Hi,
    Basically, 100% crop mean not resizing or 1:1. Lightroom will always export 100% crop image as long as you don't set the "Image Sizing" (Resize to Fit) during export. Also, to view 100% crop, you need to set 100% or 1:1 for your viewer software.

    By the way, some website will resize the image automatically if it exceed a certain resolution when you post them, so make sure you know the maximum resolution that they allow and limit your photo resolution to that.

   Have a nice day.

   

90
EOS Bodies - For Stills / Re: 5dmk3 shoot burst w/10 second delay?
« on: April 26, 2013, 08:36:43 AM »
Hi,
    Any remote controller with intervalometer function will do:
1) Set your DSLR drive mode to high speed continue shooting and AF mode to AI SERVO or manual focus mode if you want to pre-focus.
2) Set your remote controller intervalometer as:
     a) Initial delay: 10s
     b) Interval: 0s
     c)  Long exposure: 2s (for 6fps)
     d) Shot: 1

   Have a nice day.

Pages: 1 ... 4 5 [6] 7 8 ... 13