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Messages - rs

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346
Third Party Manufacturers / Re: Tamron 150-500mm f/5-6.3 VC on Thursday
« on: November 06, 2013, 12:57:54 AM »
How do we know this is not the 150-600mm.

http://translate.google.ca/translate?hl=en&sl=ja&u=http://egami.blog.so-net.ne.jp/2012-10-26&prev=/search%3Fq%3Dtamron%2B150-600mm%2Bhttp://egami.blog.so-net.ne.jp/%26biw%3D1680%26bih%3D820
It's a little difficult to read, but the image appears to read "SP 150-600mm" if you zoom in on the ring with Tamron written on it.

347
Lenses / Re: Canon 70-200mm f/2.8 Mark I vs Mark II
« on: November 03, 2013, 02:59:35 PM »
If sharpness means anything to you, the mk I version of that lens won't make you happy at f2.8. Stop it down to f4 and it's really quite good at all focal lengths. Which begs the question - why not just get the lighter, smaller and potentially cheaper brand-new 70-200/4 IS, which even at f4 is sharper?

I had the mk I version, and upgrading to the mk II was a breath of fresh air. Not only is the wide open sharpness drastically improved, but the IS is noticeably better too.

348
EOS Bodies / Re: Patent: A Pellicle Mirror by Canon
« on: October 31, 2013, 12:02:03 PM »
Is there any difference with the current Sony SLT?
Sony's SLT is very different from the Canon film pellicle mirror cameras.

Canon had a semi-translucent mirror to direct half the light to a viewfinder, and the other half to the film - the upshot is no mirror slap, so higher frame rates are possible and also a more stable camera, and also no viewfinder blackout. The downsides are a darker viewfinder and less light hitting the film.

Sony use the same type of mirror to redirect half the light to a dedicated AF chip, and the other half to the sensor - there is no OVF. So its basically a mirrorless camera in a big body and only half the light sensitivity it should have. A mirrorless camera with on-chip PDAF is much more sensible if you're going to dispense with the OVF - which is precisely what the A7 and A7r are all about.

This new Canon patent is almost a digital version of the film based Canon pellicle mirrored cameras, but with one major difference - the mirror has variable reflectance/transmission. If it could approach 100% reflection while composing, you've got pretty much a conventional bright viewfinder, and if it could electronically switch almost instantly to almost 100% transmission, pretty much all the light can hit the sensor for the shot.

Much higher frame rates, much shorter shutter lag, and no vibration due to mirror slap could be on the cards.

349
Technical Support / Re: Strange artifact in my picture
« on: October 24, 2013, 09:50:05 AM »
If it's a one off and you've taken loads of shots since without the issue, I'd say its nothing to worry about.

Out of curiosity, what body was this taken with?

351
Lenses / Re: Which TS lens is better
« on: October 22, 2013, 05:20:29 AM »
Choosing the correct focal length for your requirements is much more important than chasing absolute optical perfection wide open.

Ignoring perspective control (which is usually used in conjunction with one below), a TS-E lens is primarily used for:

1) tripod mounting and setting up for majority of the scene in focus - this usually involves stopping down as far as you can before diffraction sets in, and tilting the lens to bring that deep plain of focus in line with most of the scene. So no worries about the corners at f3.5/f4 there.

2) limiting apparent DoF by tilting the lens the wrong way, and shooting wide open. In that scenario, you want the corners blurred anyway.

It's not a lens for taking pictures of brick walls or test charts hand held, wide open. While you might be able to, I can't think of many uses for wide open sharp corners with a lens like that. And finally, the TS-E 17/4 is phenomenally good wide open compared to almost any other comparably wide angle lens.

Your decision should be based primarily on what focal length you need, with filter considerations second and wide open corner sharpness differences a distant third.

352
EOS Bodies / Re: Sensor Dust - DSLR vs Mirrorless
« on: October 22, 2013, 04:57:59 AM »
It's more than just the mirror. In normal use (no live view, no video) a DSLR sensor is covered by the shutter at all times except for the duration of the exposure.

In a mirrorless camera, the shutter is only deployed to cover up the sensor just before the exposure, allowing the physical shutter to control the exposure like a DSLR, then it's off out of the way straight away afterwards. And I'm probably wrong in thinking this, but don't some mirrorless cameras leave the sensor exposed to the elements (no shutter covering it up) when changing lenses?

354
EOS-M / Re: Need help, Please " the Lens factor of EOS-M ?"
« on: October 18, 2013, 05:53:36 PM »
The Next Question =  For use the EF  to EF-M  Adaptor, Yes, We can use both EF and EF-S mount to this Adaptor and shoot with EOS-M----How can We use EF-S  with the same space distant from the back of EF-S lens to the APS-C sensor, and work---BUT Can not mount EF-S Lens  on Full Frame Sensor Canon EOS Cameras----In the reverse, We can use all EF Lenses on the SOS Body / Small sensor like 7 D .???
??, May be, Canon try to trick us, Not let us  use the cheap FE-S Lens on the high cost FF Cameras ???.
EF-S has an identical 44 mm flange distance to EF. However, EF-S lenses are specifically designed to create an imaging circle which is not big enough for a 36x24 mm frame. In a bid to prevent strong mechanical vignetting, EF-S lenses have a plastic bung at the back preventing mounting on an EF mount body. This has a second advantage - these lenses can be designed to poke deeper into the body into the area where the larger FF mirror would otherwise clash, allowing some wide angle EF-S lenses to be slightly less retrofocus than the same focal length FF lens would be.

I have tried my Canon EF-S 10-22 on my 5D mk II - I had to pull the bung out of the back of the lens, and as long as the lens is zoomed into about 12mm or longer the mirror doesn't hit. From about 13mm onwards, with no filter there's no mechanical vignetting, and at no focal length or aperture is the corner performance anything but beyond a joke.

EF-M has an identical sized sensor to EF-S bodies, but due to the lack of mirror the flange distance is just 18 mm. All that's needed to make an EF-S lens fit then is a 26 mm long spacer with the appropriate mount at either end. The sensor size and position relative to the lens is then identical to an EF-S body. The adaptor also takes EF lenses, in much the same way as an EF-S body does.

355
Lenses / Re: 16-35 2.8 vs 70-200 4 on 650D
« on: October 17, 2013, 06:45:38 PM »
On your crop camera, the 16-35 frames the same as a 26-56mm lens would on FF, and although it loses its raison d'ĂȘtre with the 1.6x crop, it does act like a normal lens with a questionably more useful range as a main lens. The 70-200 frames like a 112-320, a bit long for people shots unless you're planning on head shots or stepping back a very long way.

Assuming you're on about the 70-200/4 L IS and the 16-35/2.8 L II, here is a comparison of IQ on an 18MP crop camera - showing the 16-35 at its worst ( 28mm, f2.8 ):

http://www.the-digital-picture.com/Reviews/ISO-12233-Sample-Crops.aspx?Lens=412&Camera=736&Sample=0&FLI=3&API=0&LensComp=404&CameraComp=736&SampleComp=0&FLIComp=0&APIComp=0

If you're planning on architecture and landscape uses for a wide angle lens, a large DoF is key, so there's little point in having an f2.8 aperture. What about the 17-40L? Just as good at f8, and much cheaper.

However, any image quality differences are much less important than the focal length - and only you can answer this one - if your 50 was a zoom, which way would you mostly try to turn that zoom ring? Wider or longer?

356
Canon General / Re: Official: Sigma 24-105mm f/4 DG OS
« on: October 14, 2013, 01:51:37 PM »
how do these charts compare to canon charts?
Canon:


Sigma:


However, comparing MTF charts from one manufacturer to another is largely meaningless due to differences in the way they measure it.

Canon MTF source: http://www.usa.canon.com/cusa/support/professional/lenses/ef_lenses/ef_24_105mm_f_4l_is_usm#Overview

357
EOS Bodies - For Stills / Re: "Downgrading" for a very specific reason
« on: October 14, 2013, 07:59:44 AM »
What profile was enabled on the camera? These settings get recorded in the raw file, and if you use DPP, unless told otherwise it will obey these settings. Lightroom likes to ignore any in camera settings. 

And if you're using something like LR, you can spend time fine tuning your look and feel, and then get it to apply it to all raw files when imported.

358
Lenses / Re: Questions on EF 24-70mm II on 5D Mk3 vs EF-S 17-55mm on 7D
« on: October 14, 2013, 01:14:31 AM »
There's a huge advantage. The 17-55 on crop is a closer match to the 24-105 on full frame, but the L lens and FF sensor combo captures more light, has a wider zoom range and is sharper. Think of the 24-70 II and 5D3 combo as an optically better, wider zoom range version of the Sigma 18-35/1.8 and 7D.

The same aperture combined with the much improved high ISO of the 5D3 will allow you to get access to action stopping shutter speeds much easier. If shooting moving people, you'd typically want a shutter speed faster than 1/50th of a sec, so IS isn't of much use on that focal length range for that sort of subject anyway.

I have a 5D2 and 40D with both the lenses you mention - not quite the same camera/sensor line up as you, but the 17-55 doesn't get a look in these days.

Or to put it another way - it's optically equal to the 70-200 II. If you notice any image quality difference between your 5D3/70-200 II and your 7D/17-55, expect that same step up when moving to the 5D3/24-70 II.

359
Hmmm! ... can you repeat the question please!
Sorry, I got a bit side tracked there.

I personally use a 1.4x TC (mk II) to complement my 70-200 II - the IQ is so insignificantly worse than the 300/4 that its not worth splitting them:

http://www.the-digital-picture.com/Reviews/ISO-12233-Sample-Crops.aspx?Lens=687&Camera=453&Sample=0&FLI=4&API=1&LensComp=111&CameraComp=0&FLIComp=0&APIComp=0

The main advantage is whenever I'm shooting a wedding the 70-200 is always with me, and the TC is so small and light I don't have to worry about carrying it around - my back/shoulder pain would feel all the worse if I was carrying a 300/4 with me all day and the situation never arose for me to use it. Plus its cheaper, I retain a zoom when its on, and the IS is two stop better.

360
Lenses / Re: Haze filter - will it cut though the smog?
« on: October 13, 2013, 02:01:57 PM »
Just to confuse the issue - you may find that a polarising filter will do a better job of cutting through the haze.

Have a look here for an example:

http://www.dslrtips.com/workshops/How_to_use_polarizing_filters/reduce_haze_deep_blue_sky.shtml
+1

Digital sensors aren't susceptible to UV light like film is, so UV filters are unlikely to have any positive effect.

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