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Messages - weixing

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106
EOS Bodies - For Stills / Re: 70D Sample photos ISO 100-25600
« on: August 02, 2013, 11:09:05 AM »
I'm looking at the ISO 6400 example between all three camera, and I see virtually no difference. Although, if I may say so, in some areas the 7D looks sharper than the 70D, but there are a variety of factors to consider. In some areas, the lighting or reflections are not exactly the same, so that can skew the results.

Thinking about it though, since the megapixels have increased in the 70D, the image quality has had to improve to some degree to keep up with the 60D and 7D.

Next, I looked at the ISO 100 example between the 70D and 7D, and saw virtually no difference either. Maybe in some cases some of the colors were better in the 70D, but that's really just clutching at straws.

Both the 7D and 70D appear to provide the same image quality is what I'm seeing.
Hi,
    I'm not surprise as some website already mention that the higher MP 70D dual-pixel sensor IQ is same as 60D for RAW.

    Have a nice day.

107
Software & Accessories / Re: External HD Question
« on: August 01, 2013, 01:59:23 PM »
Hi,
   NAS with at least 2 disk (configure as RAID 1 or higher depend on number of hard disk) is a much better choice + at least 2 external hard disk to backup your NAS... One external hard disk for current backup and the other one store at different location.

   This way you'll be well protected:
1) If one of your NAS hard disk failed, your photo will not be lost due to the RAID protection.
2) If your NAS failed, corrupted or all the hard disk failed, you still got your current external hard disk backup.
3) If your NAS failed, corrupted or all the hard disk failed and the current external backup hard disk also failed (example, when something very bad happen to your office), you still got one more external backup hard disk out there.
4) If the world end, forget about your photo... run for your life...

   Have a nice day.

108
Third Party Manufacturers / Re: Sigma Announces Mount Conversion Service
« on: August 01, 2013, 01:44:03 PM »
Hi,
   The better way is to make all their lens having the longest flange focal distance of all major brand interchangeable lens camera and a standard common interface. Then make adapter that will convert the brand lens control signal and info signal to their common interface and also act as spacer to provide the correct flange focal distance.

    This way, if the I shoot with Canon DSLR, I get the Canon adapter and if I want to shoot with Nikon DSLR, I just get the Nikon adapter... plug and shoot.

    Have a nice day.

109
Canon General / Re: People that don't shoot in manual...
« on: August 01, 2013, 10:29:38 AM »
This is the bit that winds me up "The Av/Tv mode will automatically adjust the exposure to get the correct exposure". The camera should never decide the "correct" exposure. That is for YOU as a photographer/artist to decide through experience and defining your own shooting style. I couldn't give a toss if you like my shots or not or the way I post-process, these are decisions I've made from the instant of picking up a camera, choosing a focal length and attaching a lens, deciding on how shallow I want the DoF to be, the composition, how much light the shutter speed should let in and how I need to control them using ISO or if I'd like fill in flash. Or 2 flashes or 3 flashes or rim lighting or shot into the sun for flare or exposing for the light and getting a silhouette. If I need to plan in advance to get "the shot" then I plan in advance and set up my camera in preparation. If a scene is constantly changing then I'm constantly aware that I need to be constantly in control of what I'm doing and constantly aware of my surroundings. I also need to be in constant control of clients/guests/attendees, backgrounds. some things are easier to control than others and it's quick thinking and experience that makes the best of the worst situations, not the decisions of a processor in a camera. At least if it fucks up then it's my fault and I'm not blaming the camera that has chosen to do something at 30th/sec or f16 thus ruining it that way.

/rant

Note: I do not shoot birds in flight or sports...
Hi,
    Cool down a bit... I understand what you mean... I know that the camera meter won't get you the correct exposure in every situation or the exposure that you want... everyone needs and requirement is different, that's the reason why there is a few metering mode for you to choose, exposure compensation for you to compensate and M mode if you want total control of the exposure... the mode is design to make life easier for most of the people using the camera.

    Have a nice day.

110
Canon General / Re: People that don't shoot in manual...
« on: August 01, 2013, 10:15:24 AM »
Av lets the camera pick a shutter speed, which affects the ambient exposure when using flash. So, one instance you could have a coleminers cave @ 1/200 and the next frame it will be light trails @ 1/60 or even slower if you activate 2nd curtain sync. Av doesn't give consistency when using flash with changing ambient light. Its similar to using Av to shoot concerts with flutters in lighting conditions that will ruin the subject with underexposer + the use of flash on top of that.

The rules change alittle bit when using flash because now your exposing for ambient and one for the flash.

Shutter speed = Ambient control (that's why sync speed is so important to a flash photog)

ETTL or M controls on flash = Flash exposure.
Hi,
   Since shutter speed control ambient lighting, so if your ambient lighting change, you'll need to adjust your shutter speed to get the correct exposure, right? If that the case, in Av mode you need to set exposure comp if you think it's necessary, but in M mode, you had to set the shutter speed since the flash exposure cannot use to compensate the change of ambient lighting, right?

  Have a nice day.

111
Canon General / Re: People that don't shoot in manual...
« on: August 01, 2013, 08:56:37 AM »
I'm surprised to see everyone saying they only use flash in M mode. While I am normally in M for flash work, I sometimes shoot flash in Av mode with a locked ISO so that the changes in ambient light will be picked up automatically by the shutter changes. Of course, I guess that is assuming manual flash; many people probably stick to E-TTL?

Using Av for flash and with a locked ISO will affect the one thing flash photographers need to control the most... shutter speed. If we can't control our shutter speed, we can't control how much ambient is mixed with our flash.

IE: Bounced flash mixing with ambient at a reception, event or mixed lighting situation.

Yes, that's my point, let the camera choose the ambient via the shutter speed. You can control the ratio of ambient to flash with exposure compensation, and control the flash power with aperture. That way, when the ambient changes, the camera compensates while keeping the same flash ratio/power/etc.

Yeah that's great but you'll still have wildly different exposures if the meter catches a bright light, and guess what? You have to dial in expo comp, then flash expo comp. then again when the light goes away... It's great if you like to fiddle a lot with that.

I find it easier to just set my settings in M mode, then simply control the flash exposure comp of the guests with ETTL. Then I have control of the ambient and the flash will be variable to changing light to get a good exposure on the guests. This works way better and I can concentrate on composition more than twiddling dials all night.
Hi,
   Although I'm not using flash, but I thought it's the other way round?? The Av/Tv mode will automatically adjust the exposure to get the correct exposure due to the additional light in the scene, but in M mode, you need to adjust manually to get the right exposure, right? If you don't adjust your exposure in M mode, won't you get an overexpose image?

  Have a nice day.

112
Canon General / Re: People that don't shoot in manual...
« on: July 31, 2013, 01:00:39 PM »
Hi,
    Just wonder when there will be a thread on:
1) Why use calculator when you can count manually?
2) Why use accounting software when you can do the book manually?
3) Why use word processing software when you can write?
4) Why travel in vehicle when you can walk?
5) Why take the lift when you can climb up the stairs?
6) Why take photograph when you can draw?

    I think I must be too free to post on this thread...  :P

    Have a nice day.

113
Hi,
I thought we are not supposed to trust DxO considering they are in the pocket of everyone-not-canon.

Seriously, this is a SWEET lens, perfectly suited for 7D..
    Just don't look at their single finally DXOMark Score, but their measurement result should be valid.

    What is interesting is their sharpness score for various body:
1) 7D: 13P-Mpix
2) 700D: 15P-Mpix
3) 100D: 14P-Mpix

    All 3 are supposed to have the same 18MP sensor... different due to AA filter or it's just a variation between the same sensors or may be due to different image processing done internally by the DIGIC processor?

    Have a nice day.

114
Canon General / Re: Fake UV filters?
« on: July 23, 2013, 10:30:02 PM »
It's not about 'fake' - it's about transmission curves.

Can't speak for the 'Rocketfish' or Canon, but Hoya, Zeiss, and B+W all publish their transmission curves. No filter has a perfectly vertical cutoff on a transmission curve - most good commercial multicoated filters that 'block' wavelengths ramp from ~0% transmission to their max of >99% over a 25-125 nm range (although some of the longpass and bandpass filters I use in microscopy are close to vertical, with a slope covering <5 nm - and they come with a price tag commensurate with that performance). 

The Zeiss has the steepest slope of the three, ramping up over the 410-435 nm range (in fact, it's cutting out some blue light, which is considered to start at 400 nm). The Hoya has the least steep slope, running from 350-460 nm or so, meaning its passing some UV in the 350-399 nm range, and blocking a bit of blue light as well.  The B+W is intermediate, ramping up from 360-430 nm.

So, with the '395 nm flashlight' (which actually uses an LED that emits at 380-385 nm, but what's 10-15 nm among friends?), you can see from the transmission curves that the Zeiss will block that, while the Hoya and the B+W filters will pass some of it.

Of course, while that might be good to know if you're shooting film, none of that matters if you've got a dSLR.  The dSLR's sensor is insensitive to UV light, so there's no difference between a UV filter (be it the 410 nm Zeiss or the 360 nm B+W) and a clear filter that fully passes the long end of the UV spectrum.  I have empirically tested my 7D and 5DII for UV sensitivity with calibrated UV/Vis light sources (costing a hell of a lot more $$ than a flashlight to detect cat urine!) and some of those precise bandpass filters mentioned above (running a lab that has such equipment comes in handy sometimes) - there's no need for a UV filter.  I do use UV filters for protection (B+W MRC or Nano), instead of clear - but that's only because every time I've needed to buy one, the UV version was cheaper than the clear one (although that's not the case with all brands or in all geographies).

So, my advice is to just buy whichever is cheaper, clear or UV.  I'd still pass on the Hoya - it blocks a bit too much blue (and that's the least sensitive color channel).  Since it blocks less of the visible blue light, the B+W is actually a bit better than the Zeiss in that regard (because sometimes 5-10 nm does matter among friends).
    +1. If you do Astronomy, you'll know that different brand filter had slightly different transmission curve even they are the same type of filter... you had to look at the transmission curve.

    Anyway, I found a website that had publish some UV filters test result with transmission and absorption curve:
https://ww2.chemistry.gatech.edu/~nmakarov3/INTERESTS/Photo_Filters/index.htm

   Interesting to see the EF 50mm 1.4 lens also block UV light...

   Have a nice day.

115
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.

116
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.

117
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.

118
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.

119
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.

120

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.



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