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Messages - rs

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346
As higher pixel density sensors and faster lenses seem like a bad combination according to this, I wonder if it makes small sensor high MP bodies such as the OM-D E-M5 with lenses such as the SLR Magic 50/0.95 hyperprime not all as advertised?

With the pixel density of a 16MP m4/3 body (pixel pitch equal to a 64MP FF body) it is probably a long way off the f0.95 light capturing levels it claims. Could this effect make it nearer to f2.8?

347
Software & Accessories / Re: Benefits of using a grip?
« on: July 12, 2013, 05:04:25 PM »
I have them on both my bodies. With my large hands, I find even a large camera like the 5D2 only sits in part of my right hand - only three of my fingers comfortably fit on the grip, and a large part of my palm isn't in contact with anything. With the grip, all my hand has something to grip onto. Even though the camera weighs more with the grip, the extra stability the grip gives makes it easier to handle. With larger lenses such as the 70-200 II, it makes a world of difference.

Other advantages include vertical shooting is greatly simplified, the ability to use AA batteries should you end up on a long trip away from the mains (or if you want to pack a set of cheap duracells for backup at an event), and also a worry free way of putting the camera down on whatever surface you want, such as rocks. This means only the grip and lens hood are likely to take the brunt of your carelessness - the cheaper to replace parts of the camera/lens system.

348
Well I decided to rent the Canon 6D and shot with it at a car show today using my old 28-80 L lenses. Wow, did the pictures stink! Vignetting on almost all the pictures and none of the images were really "sharp". I have the camera until Monday and will continue to test it with my other lenses on Sunday.

I was really hoping I wouldn't have to replace my 28-80 L with a newer L lens. It's great on a APS-C body but is horrible on a FF camera.


Did you run AFMA on this lens/body combination?  If not that might help.  There are a number of good on-line instructions on how to perform this.


What is AFMA?

http://www.the-digital-picture.com/photography-tips/AF-Microadjustment-Tips.aspx

349
EOS Bodies / Re: A bit confused on what to buy!
« on: July 12, 2013, 10:59:16 AM »
I am looking for something that will be able to get these shots in focus, have better low light focusing, and possibly better low light performance.

I have considered the following:
Don't do anything at all! (Parents would love this!  ::) )
Purchase a few fast primes. (Sigma 50mm f1.4)
Buy a Fujifilm X-E1 due to it's size and low light performance. Then down the road, buy a 7D Mark II or some "upgrade" to my T2i. <--- Most money spent here
Buy a Canon 70D during black friday. (No tax day at two of my local camera stores)
Wait for a 7D replacement
Low light AF of stationary subjects is very different to low light AF of moving subjects. For that reason, I'd stay clear of anything which can't keep up with very rapid moving subjects, which means forget the X-E1 and the Sigma 50/1.4 as they'll both give worse performance that your current kit. (I have a good copy of the Sigma 50/1.4 which AF's very accurately. However, AF is slow, and in AI Servo mode, just forget it)

I'd recommend a fast focusing lens of at least f2.8 - if you stick with crop, the Canon 17-55/2.8 IS springs to mind, or the 24-70 II if you have money to burn and something like a 5D3 might be on the horizon soon. Both give very fast and accurate AF, even in challenging conditions. If you're after a fast prime, steer clear of slow focusing lenses like the Sigma 50/1.4 or 85L.

As for the body, the 70D with what appears to be an inherited 7D AF system should be a huge step up from your 550D. While rumours suggest the 7D mk II will have an even better AF system, that is largely an unknown at the moment. However, a camera with a good AF system still can't operate at its best with an f4 lens or with a painfully slow focusing lens such as the Sigma 50/1.4.

If a 7D mk II is potentially just about affordable for you, what about instead getting a 70D and 17-55? The combination of lens and body will bring big benefits to you.

350
Well I decided to rent the Canon 6D and shot with it at a car show today using my old 28-80 L lenses. Wow, did the pictures stink! Vignetting on almost all the pictures and none of the images were really "sharp". I have the camera until Monday and will continue to test it with my other lenses on Sunday.

I was really hoping I wouldn't have to replace my 28-80 L with a newer L lens. It's great on a APS-C body but is horrible on a FF camera.
Are you shooting jpeg? If so, there might be a lens profile you could install on the camera to sort out vignetting and CA. Use the free Canon EOS utility, plugged into the camera to update it. If you're shooting raw, try the same automatic lens correction in LR or whatever you're using. It might well tidy it up quite bit.

Also remember to feel free to stop it down about one a third stops beyond what you'd use on crop - that way you maintain the same DoF, and the lower noise levels of the FF sensor will allow you to boost the ISO to shoot in the same low light situations (or even darker). Stopping it down will reduce these issues you've noticed. If you want to open it up, just remember you're in territory that the crop camera couldn't go to.

351
EOS Bodies / Re: The Next EOS M Camera(s) [CR1]
« on: July 08, 2013, 11:09:07 AM »

I'm guessing this whole telecompressor thing is a stepping stone to Canon fitting a FF sensor in an EOS-M sized body. If they believe there's a market for people to mount FF glass on a mirrorless, why not make the body/adapter smaller and optically better by fitting a bigger sensor in leu of the glass - and then native wide angle FF glass can be made to take advantage of the shorter flange distance. If a crop dual pixel sensor is possible, so is a FF version.

If your proposed system allowed EF lenses to be mounted at a shorter flange distance, wouldn't it require sensors larger than our FF sensors? Sounds like a challenging and expensive proposition! Not an unwelcome one though.  ;)
I was thinking of using a glass-free tube, much like the current EF to EF-M adapter to use FF glass on a FF sensor and retain the normal focus range. Focal lengths above about 40mm can't really be made smaller with a reduction in the flange distance (just look at the shorty forty), so just use EF glass with a tube adapter. But the EF-M flange distance lends itself well to shorter lenses such as 22mm pancakes. There's little reason why a similar sized 22mm pancake couldn't have a larger imaging circle for FF. That would make it more compact than even a crop M for wide angle.

352
EOS Bodies / Re: The Next EOS M Camera(s) [CR1]
« on: July 08, 2013, 10:51:48 AM »
BTW ...

How about focus peaking and a swivel screen ?
With on chip PDAF covering the whole area, I see no reason why canon couldn't do on-screen split focus, as Fuji have implemented with the X100S. But with Canons resistance so far to implement focus peaking, I'm guessing neither will appear anytime soon

353
EOS Bodies / Re: The Next EOS M Camera(s) [CR1]
« on: July 08, 2013, 09:36:03 AM »
The easiest way to think of what a speedbooster does to your sensor size and focal length is the following:

When you don't use a speedbooster, you constantly multiply your focal lengths by 1.6 to get the "equivalent focal length". With a speedbooster that is no longer necessary.

WITH A SPEEDBOOSTER, YOUR APS-C CAMERA JUST BECAME A FULLFRAME CAMERA, AND ISO IS ACTUALLY TWICE AS HIGH AS WHAT THE CAMERA SAYS

So, when I use a 50mm on my NEX-5N with a speedbooster, set at f/1.4 and with ISO 200, I get an image with the same field of view, depth of field, and exposure, as I'd get with that same 50mm on a 5D3, set at f/1.4 and with ISO 400.
There, no more math. It becomes a FF camera, end of story.

That's the exact way Nikon did it with its E series DSLR's. (http://en.wikipedia.org/wiki/Nikon_E_series). Built in 4x telecompressor, with a sensor to match. The tiny sensor started at ISO 50, but the camera instead called it ISO 800 so it could report the lenses aperture and focal length in 35mm units.

I don't know whether Canon will do it that way (which in many ways makes the most sense), or let it report these compressed imaging circles with their brighter f numbers and shorter focal lengths instead.

I'm guessing this whole telecompressor thing is a stepping stone to Canon fitting a FF sensor in an EOS-M sized body. If they believe there's a market for people to mount FF glass on a mirrorless, why not make the body/adapter smaller and optically better by fitting a bigger sensor in leu of the glass - and then native wide angle FF glass can be made to take advantage of the shorter flange distance. If a crop dual pixel sensor is possible, so is a FF version.

354
EOS Bodies / Re: The Next EOS M Camera(s) [CR1]
« on: July 08, 2013, 02:49:33 AM »
A one stop focal length reducer would create some really interesting effective lenses. I'm thinking a one stop focal length reducer would be the opposite of a 1.4X teleconverter. If so, I come up with the following, assuming my math is correct.

85mm f1.2 would become a 60.7mm f0.86.

Here is my math...
85mm / 1.4 = 60.71mm

f-Stop = f/d (f-Stop = focal length / diameter). Solve for 'd':
  1.2 = 85/d
  1.2d = 85
  d = 85/1.2
  d = 70.83

Plug in the new focal length. I expect the diameter would remain the same since it's the diameter at the front of the lens:

f-Stop = 60.71 / 70.83

f-stop = .857

Your answer is pretty close (one stop faster than 1.2 is .84), the math is actually quite a bit more complicated though.

Actual formula:

sqrt(2)^((log(OLDF)/log(sqrt(2))+CHANGE)

Since OLDF = 1.2 (actually it's sqrt(2)^.5 if you want exact numbers, or approx 1.18920711500272)
And CHANGE = -1

sqrt(2)^((log(1.2)/log(sqrt(2))-1) =~ 0.848528137423857
or
sqrt(2)^((log(sqrt(2)^.5)/log(sqrt(2))-1)) =~ 0.840896415253714
However, if Canon want to retain the same field of view, depth of field and light gathering capabilities that EF lenses enjoy on FF, they'll need to develop a 1.6x telecompressor instead of a 1.4x. That would make an EF 85/1.2 into an EF-M 53/0.74 lens.

Lets hope that an EF lens, telecompressor and dual pixel AF sensor combine to make a quick and accurate AF system, as well as good image quality.

355
EOS Bodies - For Stills / Re: 70d for stills - IQ Improvement ?
« on: July 02, 2013, 05:03:55 PM »
ISO range has less to do with the capabilities of the sensor and more to do with the marketing department. Two cameras with different sensors featuring the same ISO range won't necessarily give the same noise levels at each ISO setting. It's a bit like guessing how fast a car is by seeing what numbers are written on the speedo - just because 160mph is written at the far end of the needles range doesn't mean it can climb Pikes Peak in less than eight and a quarter minutes. We'll need to wait for reviews before we get an indication of what Canon have achieved in terms of SNR with this new sensor.

There are rumours about it being a big improvement, but as to how much of that is more NR in the jpgs as opposed to real improvements, we'll have to wait to find out.

356
EOS Bodies / Re: Canon Dual Pixel Liveview Autofocus
« on: July 02, 2013, 10:17:30 AM »
Interesting development.

For some number of pixels, it is going to reduce (halve?) the amount of light that is received by the photo diode.

If this is the green pixels, as suggested by some diagrams, then it may make little/no overall difference as there are already twice as many green receptors as there are red/blue.

Additionally, this means that there will be some pixels that do not record the same level of light as others. This will need a bit of new fancy footwork for raw converters to properly evaluate what it means to have a pixel that is not and will never have the same luminosity as all of the others around it.

This has potential to have an adverse impact on noise simply due to there being less signal available.

Will be interesting to see the outcome!
Each and every of those 20.2 million active pixels that makes up the picture (whether red, green or blue) is divided into two pixels. One for the left phase, and the other for the right phase. They both hide behind one micro lens, and are positioned next to each other (hopefully without any appreciable gap, as that might cause a strange bokeh effect) to receive the phases. Combined, they theoretically cover pretty much the same area as a conventional photodiode, and should give the same light gathering capability. Its no more than pixel binning to recreate a normal image from this sensor, with normal light gathering capabilities.

So in theory this dual pixel configuration should have no detrimental effects on SNR over a conventional 20.2MP APS-C sensor. Let's hope they've used a new sensor fabrication process to manufacture this sensor, to bring along the much anticipated (and reported) improvements in SNR - I'm guessing that was is in effect a 40.4 MP APS-C sensor would be next to impossible to make with the old sensor fabrication process.

357

I would adjust my aperture, filtration, lighting, iso before I would deviate from 1/50th.
I would only shoot at a speed other than 1/50th for a very specific purpose and it would be limited to when absolutely required.


Would an example of that be slow motion?
Slow motion would typically be shot at a frame rate much faster than 25fps to make it the motion appear smooth when played back - the rule of thumb Paul quoted still holds true - have a shutter speed equal to approx half time the frame represents. So, 24fps and 25fps at 1/50th of a sec, 30fps at 1/60th of a sec, and if you're shooting slow motion at 60fps, 1/120th of a sec. If you have a camera capable of filming at 1000fps, 1/2000th of a sec shutter speed would do the trick.

what does the shutter speed control while shooting video? i have no idea. It's not controlling my camera's shutter. if that is what you are asking, again, i have no idea.
When shooting video (or previewing the scene in live view), the mechanical shutter stays open and an electronic shutter operates instead. That's what's controlled here.

358
AF speed is a combination of the AF system, what mode it operates in, and the lens.

The 5D3 has 5 of its central AF points which work as dual cross type AF points with lenses having an aperture of f2.8 or greater.  So I'd recommend staying well clear of anything slower than f2.8.

With my 5D2, 24-70 II and a Sigma 50/1.4, the results are about the same with either combo in low light. Even though the Sigma has much slower AF than the 24-70 II in good light, in very low light it seems about the same as the Canon when shooting stationary subjects. And when the light levels get so low that the Canon starts to hunt without being able to lock on, the Sigma gives up at that point too. However, to keep the ISO lower or gain faster shutter speeds, the Sigma 50/1.4 is my preferred low light choice.

What lenses can you choose from? You talk about an f4 lens being available, and I can't see an f4 lens in your equipment list - so while the Sigma 50/1.4 and 135L both look like the pick of the bunch, I'm guessing there are other fast lenses for you to choose from.

A bright lens with better AF than the Sigma (such as a 24 L II or even a Canon 50/1.4) should focus faster than both the Sigma 50/1.4 and 24-70 II in very low light. And as to how a 5D3, the lenses you've got available and the lighting/subjects all differ, that just all mixes it up and makes it next to impossible to give you a definitive answer. I'd suggest making an educated guess to pick a couple bright lenses which are known for fast AF from whatever selection you have available to you, and find out the answer to your question while you're there.

359
EOS Bodies - For Stills / Re: Which body/lens combo for this event?
« on: June 21, 2013, 03:53:27 PM »
Your plan sounds good. While you won't get overlap in effective focal lengths, you'll only have the 105mm to 112mm range missing between the two. Quite a nice combo really :)

However, if you can borrow or rent another FF body for the 70-200, it'd be even better. In my opinion, the range of the 70-200 on FF excels at indoor events.

If you can physically carry the two cameras all day, working with the two bodies will really speed up your work - and with so many moments happening, it helps to be ready in an instant for whatever unfolds in front of you. Especially if its your first wedding.

360
Well that's not an FF equivalent to a 18-35 f/1.8, that's a 18-35 f/1.8 mounted to a teleconverter.

If you scale the design of the lens up by a factor of 1.6, then you'll have a 28-55 f/1.8 lens for full frame, which is what we want. The question is whether or not such a lens would be reasonable in size, weight, and price.
I get your point. From a scale point of view, the Sigma 18-35/1.8 with a built in 1.6x TC is a 29-56/2.88, so to go from that to a 29-56/1.8 lens is an aperture increase of 1.6x. Not too far out from the 1.4x difference between an f4 70-200 and an f2.8 70-200. Therefore the differences need to be scaled up by a small factor to get from 1.4x to 1.6x, and apply that to the sigma.

70-200/2.8 IS II vs 70-200/4 IS:
Price: 2x
Weight: 2x
Length: 1.15x
Width: 1.17x

Scale those up from 1.4x to 1.6x, and you end up with a 29-56/1.8 FF lens which is 2.3x the price, 2.3x the weight, 1.31x the length and 1.34x the width of the Sigma. Or in other words, a £1840 1.9kg lens which is 160mm long and 104mm wide. Very heavy for a normal zoom, but similar price to the Canon 24-70 II.

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