October 02, 2014, 07:27:18 AM

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Messages - robbinzo

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1
EOS Bodies / Re: Are These The EOS 7D Mark II Specifications?
« on: August 25, 2014, 02:59:33 AM »
Recently we had some family portraits done. They were stunning.
Of course I was interested in the Pro's gear. He used a 5D mark I with 24-105L lens.

So the point is that yes it's nice to have new gear with all these whistles and bells and nit pick about what we think Canon should or shouldn't do but at the end of the day even someone making a living in this game can use fairly old gear and get good results.

I'm not saying that the 5D mark I is right for sports etc but do we really need the latest and greatest gear?

It made me realise the importance of technique over gear.

2
Technical Support / Re: Another my Stupid question = Sensor Sizes
« on: August 22, 2014, 06:06:28 AM »
Thoughts on the following anyone:

http://www.clarkvision.com/articles/does.pixel.size.matter/

Conclusions

Current good quality sensors in digital cameras are photon noise limited. This means there is no possible improvement in performance for the high signal region (bright things in an image) except to increase quantum efficiency of the devices and/or the fractional active area for which the sensor converts photons to electrons (called the fill factor). As both of these properties are reasonably high already, there is limited room for improvement. And even if these properties were improved, there would still be a big difference between large and small pixels. Larger pixels enable higher signal-to-noise ratios at all levels, but especially at low signal levels, assuming the lens scales with the sensor. The obvious improvement still possible would be to reduce the read noise, but that would likely improve large sensors also, thus large sensors with large pixels will always have an advantage for the same field of view, and correspondingly longer focal length lenses are used. Whether the difference in noise is great enough for you to choose a larger sensor, and thus likely a larger and heavier camera, is a decision you must make for yourself.

When choosing between cameras with the same sized sensor but differing pixel counts, the one with larger pixels (and fewer total pixels) will have better high ISO and low light performance (assuming read noise and fixed pattern noise are similar, which may not be the case), while the camera with more pixels can deliver images with finer detail in good light. You will need to decide where that trade point is. My models show the optimum in DSLR-sized sensors have pixels around 5 microns. You will need to determine what your prime imaging will be. For low light work, I might bias the pixels to a little larger than 5 microns; if low light/high ISO work is not as important, I might bias my choice to slightly smaller than 5 microns. For P&S cameras with small sensors, I prefer cameras with pixels larger than 2 microns.

Because good digital cameras are photon noise limited, the larger pixels will always have higher signal-to-noise ratios unless someone finds a way around the laws of physics, which is highly unlikely. Important to remember, however, is larger pixels enable more light to be collected, but it is the lens that delivers the light. An analogy is buckets of water. A large bucket will hold more water than a small bucket. But if you want to collect more water in a given time, one must turn the faucet on higher. So too with cameras and lenses: the bigger lens collects more light and delivers it to the sensor.

Image detail can be blurred by diffraction. Diffraction is more of an issue with smaller pixels, so again cameras with larger pixels will perform better, giving sharper images with higher contrast in the fine details. A direct example of this effect is a small sensor P&S camera can be diffraction limitied at f/5.6 to f/8, whereas the larger pixels in a DSLR will not show the same effects until f/11, f/16, and slower. And given the same pixel count in the P&S and DSLR, the DSLR will resolve finer details.

3
Technical Support / Re: Another my Stupid question = Sensor Sizes
« on: August 22, 2014, 03:09:04 AM »
I'm no expert on this, so I'll refer you to: http://www.clarkvision.com/articles/does.pixel.size.matter and to jrista's various write-ups.

Scenario 2: normalize for the field of view (20.0 degrees)
FF sensor    - 36x24 mm,     3600x2400 (8.60Mp), 100mm lens
APS-C sensor - 22.2x14.8 mm, 2220x1480 (3.29Mp), 61.7mm lens
4/3 sensor   - 17.3x13.3 mm, 1730x1330 (2.30Mp), 48.1mm lens
1/2.3 sensor - 5.76x4.29 mm,  576x429  (0.25Mp), 16.0mm lens

We now have the same field of view from the cameras. Each sensor will have the exact same IQ, the ISO performance and the noise performance will be identical.
In this case, what sensor size buys you is the number of pixels and over the same field of view, the FF camera has far greater resolving power.

To me this is the only case that matters -- the question is irrelevant and misleading unless we're talking about identically-framed shots.  With identically framed shots, a larger sensor will collect more light from the overall field of view (and therefore per-unit-area of the scene), even if the smaller sensor has larger pixels.  With our hypothetical identical technology, a smaller sensor with larger pixels simply cannot collect the same amount of light as a larger sensor.  Compare this to 35mm film vs MF film using identical emulsion.  To what degree that's important depends on the lighting of the scene.  Higher pixel density may give higher resolution (if the lens allows it).

This is something that I have had many discussions about. My understanding from talking to more experienced togs is that the pixel size is what affects light gathering capability, not the sensor size.
A larger sensor (say FF vs APS-C) will capture more light because obviously it is bigger. However, the intensity of light reaching the pixels on each sensor will be identical for a given lighting scenario. Therefore, the light reaching the sensor "per-unit-area of the scene" will be identical. The light entering the pixels will not be identical, however.
So how does sensor size alter exposure? For example: Generally F/4 on FF means you will require F/2.8 for the same exposure on APS-C but from what I have been lead to believe that is due to pixel size, not sensor size.
Thoughts?

4
Photography Technique / Re: APOLLO missions - image inconsistencies
« on: August 18, 2014, 02:29:45 PM »
Actually this conspiracy theory was debunked by Myth Busters.

Of course a couple of movie special effects guys know all about photography and lighting, how silly of us all. Case closed.
Not so fast.

I didn't really give this much thought until I looked in to it and frankly a lot of the photos have been faked using studio lighting. No doubt about it.

However, that does not mean that we didn't land on the moon. It means that NASA wanted some pro-shots for publicity. And some of those shots are beautiful - the colours, framing of subject and lighting are all spot on. Not easily done without a view-finder in such a high contrast environment.

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Photography Technique / Re: APOLLO missions - image inconsistencies
« on: August 18, 2014, 07:25:45 AM »
I also like the part about how it was too dangerous so it would not have been done for real....

Imagine sitting on the top of a 363 foot high tube filled with 6,030,000 pounds of high explosives, knowing that someone was going to ignite it and the blast would send you into orbit. That takes real bravery. If they are prepared to accept that, then they were probably ready to accept a bit of radiation... The plan for a solar storm was to shelter behind the heat shield of the re-entry module and if a solar storm happened while on the moon, to abort the landing mission and return to the orbiter.

These people were prepared to die, but hoped that they didn't. They had seen friends die in rockets and they went anyway.... and then someone in their nice comfy chair says it must be faked because it was too dangerous..
Show some respect!
Firstly let me say that I have no interest in whether or not man landed on the moon. However, the whole did we didn't we debate is rather complex.
I think the conspiracy theories say that the Van Allen radiation belt would have killed the astronauts or sickened them to the point that they would have a very short life expectancy. Buzz Aldrin says they passed through fast enough for them to be safe.
So the mission would have been to orbit the earth in space but below the Van Allen radiation belt and then land later on, having first faked all the footage on earth somewhere.
Who was panning the camera when they took off from the moon to come home? Was that remotely controlled by NASA? - The "What a ride, what a ride" bit. My sister reckons it was the aliens. Haha.
No doubt that the Apollo missions went to space but the doubt is whether they landed on the moon.
Are the recent Chinese probe photos similar to the Apollo Mission ones? I've read yes and no answers to this question.
Surely someone has photos of the LEM on the moon and all the other paraphenalia that NASA left behind? I've seen some bad photographs showing blobs and tracks on the moon, however.
From what I remember, some of the crosses on the photos were missing, whereas they should have been in front of the subject. What does that mean?
And what about the fact that cosmic rays would make streaks across the exposed plates? Who has these answers?
My friends at school used to debate all this stuff but alas some of it stuck in my head.

6
Lenses / Re: Need help deciding on my next lens
« on: July 10, 2014, 07:52:17 AM »
I own the 70D and have both the 15-85 and 10-22mm EFS lenses. Both lenses are excellent.  :D
To be perfectly honest, the 10-22 doesn't get much use now that I own the 15-85mm and I would suggest that you either have one or the other.
The 15-85mm is a very good lens and feels well balanced on a 70D. You will like it.

7
EOS Bodies / Re: Canon EOS M Vanishes from Canon USA Web Site
« on: May 30, 2014, 05:10:05 AM »
Dual pixel AF system in the next EOS M = winning product.
My ha'penny worth.

8
EOS Bodies / Re: Canon 70d center focus point -bug- problem
« on: May 20, 2014, 02:08:13 PM »
I agree with what Neuro said regarding AFMA.
My 70D works just fine once the AFMA is set up for each of my lenses. The main issue was with my 50 f/1.4 which gives much better AF results using liveview AF. I actually now prefer to use the liveview for portraits because the dual pixel AF is so good. It is worth buying the 70D for the liveview dual pixel AF alone. Have I mentioned that the dual pixel AF rocks?
I upgraded from the 550D and it's perfect for me.

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Canon General / Re: In need of a "walk around" camera
« on: March 07, 2014, 06:07:47 AM »
the new Fuji X-T1 all the way
+1

The view finder is massive for such a small camera and is very good for manual focus with twin screens for peaking at detail.

10
Lenses / Re: Strange AFMA results with canon 50 f1.4
« on: February 25, 2014, 05:21:51 PM »
AFMA for my 50 f/1.4 seems to change every time I put it on my 70D.
Using Reikan Focal I get somewhere from +13 to +20 at f/1.4.
My lens also varies with subject distance.
I have sent this lens back to Canon and it came back exactly the same.
I've posted before that I use live view on my 70D with this lens whenever possible because it's so hit and miss through the viewfinder. The dual pixel liveview AF has been much more accurate for me with this lens.

11
I've been thinking about going Sigma because of AF issues with my Canon 50 f/1.4.
I love the shots I get with it but there used to be so many out of focus shots that it was just infuriating. I was teetering on the brink of selling it.
However, since I bought my 70D, I can nail focus most of the time. Why? Dual pixel AF technology. I am almost exclusively using live view AF now with my nifty fifty and I can report that the results are so many times more consistent than even the very good inherited-from-the-7D AF system can produce.
I've been shooting indoors today with f/2.0 with a shutter speed of 1/100 albeit pushing the ISO a bit but the results are very good indeed.
Even adjusting the AFMA doesn't come close to the live view focus because the focus is achieved on the sensor and there are no adjustments necessary in live view. It was a real wow moment.
The live view seems to be pretty quick too. Not much messing around hunting for focus.
I love my 50 again!
This also begs the question: Would the Dual Pixel AF system work well with 3rd party lenses?
Has anyone out there used the 70D with a 3rd party lens and found their results have improved?

12
Lenses / Re: The 10 Oldest Canon Lenses in Production
« on: January 10, 2014, 03:47:51 PM »
I don't think that Canon should replace the 50mm f/1.4 with a f/1.8 IS. The reason being the Sigma Art lenses.
I would hazard a guess that a new Canon 50mm f/1.8 IS would be a similar price to the new Sigma 50mm f/1.4. That would be an interesting choice.

13
Canon General / Re: What you like the most in Canon 70D
« on: January 04, 2014, 10:26:17 AM »
I've just purchased the 70D from DigitalRev. Really good service by the way.
I haven't had a lot of time to play around with it yet, but here are a few thoughts:
I upgraded from a 550D so I really like the autofocus system on the 70D. Outside in reasonanble light with a 17/40mm f/4 lens focus is rapid and accurate with no focus hunting. All the AF points seem to work equally well.
I like the integrated speedlite transmitter. Works well indoors so far.
The ISO performance is not much of an upgrade from the 550D if at all, which I expected. However, ramping up the ISO to 25,600 and shooting B&W gives some interesting results.
I really do like the Dual pixel AF in movie mode. I like the touchscreen for focusing in movie mode, although in low light this system hunts a lot when taking photos in liveview mode. Not a surprise and not really an issue.
Built in electronic level is very helpful and also like the shutter count in the battery info.
All in all I'm really happy with my new camera.

14
Now, I'm sure somebody will correct me very quickly if I am wrong but...
The A7R does not have an optical low-pass filter. This means it struggles with AF but gets cleaner data from the sensor. Doesn't the low pass filter blur the image slightly?
So yes, you get cleaner images from a sensor without a low pass filter but it also has it's drawbacks - i.e. the AF sucks.

15
I read an article in The British Journal of Photography a while ago by someone (haven't got the mag with me so can't check) saying that they preferred the 5D because its ISO noise was closer to film grain. Low noise at high ISO doesn't always convey the feel you want.
I've been tempted to buy a 5D myself but as people have stated, the rear screen isn't ideal and it is a dust magnet.
Good idea. I do like the idea of the 5D for portraits instead of my 550D.

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