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Messages - sagittariansrock

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211
Technical Support / Re: Another my Stupid question = Sensor Sizes
« on: August 24, 2014, 12:30:22 AM »
Pixel size is irrelevant. SNR, and therefor dynamic range (assuming you have no other source of noise than what is inherent to the image signal itself) and noise are ultimately relative to total sensor area. That's it.

If that is so, what is stopping Canon from making a 46 MP FF camera with the same sensor tech as, say 7D?
I am not really an expert on this, but I think every pipeline (pixel-->signal processor) must add its own bit of noise. So noise from 4 1x1micron pixels > noise from 1 2x2 micron pixel.
It also has a bearing on processor power, but that's another topic.
Maybe an expert can chime in on this?

212
EOS Bodies / Re: 6D MKII
« on: August 23, 2014, 08:08:54 PM »
I'll settle for any 6D II, don't care about the features as long as it allows me to buy the current 6D (which will suit me fine) for a lower price...

213
EOS Bodies / Re: Are These The EOS 7D Mark II Specifications?
« on: August 23, 2014, 08:06:53 PM »
Particularly like the built-in RT function... damn, I want it...

The more recent rumor update suggested that the -RT master would not be a feature, it'll be optical master only.

Oh, I don't really care about the 7D II.
All I want is a compact RT master built-in. Almost caved in and got the 90EX for $ 42 today, but remembered how crappy forum members had admitted it was, and how it's GN is worse than a pop up flash.
Maybe the 6D II will have an RT master? Or a 280EX-RT?

214
EOS Bodies / Re: Are These The EOS 7D Mark II Specifications?
« on: August 23, 2014, 01:58:29 PM »
Other than the wifi, the features look great.
Particularly like the built-in RT function... damn, I want it...

215
I would buy a hypothetical 85/1.4L. Heck I would buy any 85/1.4 that doesn't have the AF issues of the current Sigma.
In fact, I have been holding out for an 85/1.4 (well, not entirely true- I did try to get the 85/1.2 II refurb'd when it was on sale, but maybe the two narrow misses was due to a reason...)

216
Might help to indicate the diameter of the 500D filter.

Thanks for noting that.
Work in process... LOL! This is the third time I had to type up the post as the system ate it :)

217
5D Mark II
27.5K shutter count, great condition (9.5/10), mode dial lock
Box and accessories included, one additional (third party) battery included
Also includes RRS L bracket for 5D Mark II and hand strap.

$ 1225 sold locally (Houston), $ 1250 shipped to CONUS + Paypal fees.
Username sagittariansrk in Fredmiranda (20 'Great' feedback) and deepsbid in ebay (50+ positive feedback)

218
EOS Bodies / Re: Canon 6D True High ISO King?
« on: August 23, 2014, 12:01:27 PM »
Kudos to the 6D, but the review also mentions 7D as having an excellent sensor for low-light work, so I don't know what to say...

219
Portrait / Re: Little girl looking at flowers
« on: August 23, 2014, 01:39:17 AM »
Beautiful images, but JD you are right. It is a little blue, which I am guessing the OP might have done to prevent the oversaturation of the orange flowers. One obvious way would be to warm the image and lower the saturation of the orange and yellow channels.
This might not be applicable here, but a friend of mine had excellent prints of Bryce and Arches, with one problem- too much yellow and orange saturation. He was just using DPP and when started using LR, he was able to balance the colors perfectly.
You have a great model, Vossie. God bless!

220
Technical Support / Re: Another my Stupid question = Sensor Sizes
« on: August 23, 2014, 01:33:45 AM »
jrista: Of course, sensor size does matter. Pixel size matters too, but that is not the topic of the OP's question. Now I can see how that got transformed over the few pages.
Lee Jay: You are right in considering a real world situation where an equally framed image should be the parameter of comparison, whereas I am supporting Don Haines' theoretical consideration that a larger pixel will gather more light than a smaller pixel, and that the same sized pixel will gather equal amount of light irrespective of the total area of the sensor it is a part of.

I think we all understand the physics, essentially, and also the real world fact that a larger sensor provides a ton of benefits under certain conditions, and a smaller sensor provides benefit in one specific situation. Good for us...


221
Technical Support / Re: Another my Stupid question = Sensor Sizes
« on: August 22, 2014, 02:01:32 PM »
@sagittariansrock: There is a difference in your explanation than the standard one: Your explanation does not utilize the full sensor area of larger sensors. Your explanation is based on the subject filling the same absolute area of the sensor, regardless of the total sensor area. That is the reach-limited argument. That is the ONE AND ONLY case where smaller sensors can achieve the same image quality as a larger sensor.

That is exactly right. Except, here we are discussing the capacity of a pixel to collect light, which is why this scenario should be used- that is, where the incident light is exactly the same in terms of intensity and quality.

The fair comparison is when your subject is framed the same, which means that for progressively larger sensors, a greater absolute area of sensor covers the subject. In that case, everything Orangutang, Lee Jay, and myself have stated is true. There is no circumstance where smaller sensors, regardless of their pixel size, can ever outperform a larger sensor.

I don't know if I will call it a fair comparison, but I can call it a real-world comparison. And as I said before I am sure everyone agrees with what you, Lee Jay and Orangutang are contending here- larger sensors have better IQ. No way can a smaller sensor collect the same amount of light. Except that is not the point here- the point is, would a smaller pixel collect less light than a larger pixel? Yes. Would a pixel collect the same amount of light whether its part of a large sensor or a small sensor? Of course!
This is why I said you all are disputing each other while everyone being right at the same time ;)

222
Lenses / Re: 100mm 2.8 vs 85mm 1.8
« on: August 22, 2014, 01:05:46 PM »

The specular highlights produced by the 85 1.8 look angular, not circular. That's part of my consideration when I sold it. Also maximum usable aperture is probably about 2.5 which is too close to my 100L's 2.8. Bokeh is not 135L quality. Nobody should expect that. But it's far better than 50 1.4. Personally like 100mm blur better though. Also it has no weather sealing.

On the good side the 85 focuses faster than the 100L. The focus seems more consistent and reliable. This is only based on my personal experience.

The 85 is a great value lens. You should definitely try it. Nothing to lose.

Don't agree with you on the usable aperture of 2.5.  It's the best lens I own and virtually never take it off 1.8 for professional portrait work - it's a belter of lens, I reckon by far the best bang for buck in the Canon line up.

85 f/1.8 is great value but I agree with the previous poster that if you need to stop it down to f/4 for a group shot the angular bokeh is ugly.  I wish Canon would update this with a 85mm f/1.8 IS design similar to the 35mm f/2 IS.

I personally would rather have the 100L of the two for its dual purpose macro/general as well as more pleasing bokeh stopped down.

Interesting that you liked the 100L bokeh stopped down? I didn't like it even wide open. Can you share some images- in case it was my technique which was the issue (and it might well be... :) )

223
Technical Support / Re: Another my Stupid question = Sensor Sizes
« on: August 22, 2014, 01:00:23 PM »
Here are the problems: as I said above, the comparison is irrelevant and misleading unless it's the same framing.  I will clarify that to say that it must be photographed initially at the same framing, without any cropping.  If you don't start with the same framing you are not comparing the IQ of the sensors, and the comparison is invalid.

You must start with the same frame from on each sensor, or you have no valid data on which perform comparisons.

Why is the comparison irrelevant unless it's the same framing? Last time, you used "to me" which is understandable, but to understand sensor and pixel properties, it totally makes sense to compare apples to apples where the luminance on the sensors is the same (i.e., same position of the hypothetical camera to capture the same incident light or part thereof in case of the smaller sensor).

You can compare sensors on the basis of equal sensor area. In that case, is the total light on an APS-C sized chunk located in the center of the FF sensor the same as the total light on an APS-C sensor at the exact same location. I'd say it is (it violates the laws of physics to be otherwise). Now, let's say both of these (chunk of FF vs APS-C) have the same number of pixels. Will the images on these sensors have the same noise characteristics. Yes, they will. This is easy to measure, both objectively and subjectively. What do you mean by not having data to perform comparisons!


There are certain reach-limited circumstances (which jrista has illustrated) where a high-density crop sensor can demonstrate superior IQ for a heavily cropped image.  However, that's not a comparison of the sensors themselves.

Exactly, that is completely irrelevant here. An APS-C sensor will never have the same or even close IQ to a same-generation FF sensor, while in reach-limited circumstances a higher resolution will demonstrate advantages. In this case, we are NOT talking about that. We are NOT talking about APS-C sensor being better than FF. This is a very focused argument: the size of pixel defines its light-gathering capacity. This capacity will be the same whether the same pixel resides in an FF sensor, an APS-C sensor or an MF sensor.

224
Technical Support / Re: Another my Stupid question = Sensor Sizes
« on: August 22, 2014, 12:49:24 PM »
You say "with identical technology, size of sensor is all that matters". I disagree. If you simply made a bigger 7D sensor, with the same technology and same pixel density, then it will have the same noise characteristics as the 7D sensor.

This is totally false.  If you make the 7D sensor bigger, you'll have more of the same pixels AND about a stop and a third better noise performance, assuming constant f-stop and constant framing.  That means, for the same image, you're going to have to either get closer or use a longer focal length.

I wish people wouldn't be so vehement in their comments, and leave some room for discussion ;P

You lose light when you magnify, so it is not an apples to apples comparison. This is why a macro lens loses half the incident light (with the same aperture) when you move from, say, 1:2 magnification to 1:1. Try using a microscope and go through the different magnifications- it will be immediately apparent.

I am not talking of the same image. I am talking of the same subject distance, therefore I am talking of a different FoV. In this situation, the total luminous flux on the center 1/2.56th of an FF sensor is the same as the total luminous flux on an APS-C sensor placed in the same location. This is why, when you select DX mode on a Nikon FF dSLR, you still get the same amount of light per unit area as before, and don't need to readjust your ISO, shutter speed or aperture, etc.

225
Technical Support / Re: Another my Stupid question = Sensor Sizes
« on: August 22, 2014, 06:03:49 AM »
Scenario 1: Normalize for pixel size
We have a camera that we can swap sensors on. We mount a 100mm lens to that camera.
...
The balance you select between the three is what determines the performance of your camera.

The only thing I would dispute is the regular use of "each sensor will have the exact same IQ". Hate to say it, but that is wrong...at least, so long as another required factor is not specified. :P Sensor size is the primary factor that controls "image quality", not pixel count, not pixel size. You could have twice the Q.E. on a smaller sensor, and the only one that would then only EQUAL the IQ of the larger sensor is the one that is exactly half it's size. A 4/3rds or 1/2.3 could never compare to the IQ of a FF sensor, not even with double the Q.E.

Now, the statement about equal IQ would be true...IF the aperture was specified. The 100mm lens on a FF sensor has to be using a smaller aperture than the 61.7mm lens, by a factor of the differences of the sensor diagonals. If the 61.7mm lens is f/2.8, then the 100mm lens should be f/4.5. THEN, and ONLY THEN, would "each sensor have the exact same IQ." You have to use a smaller aperture to normalize the amount of light reaching the sensor. Otherwise, one has to assume the same aperture. A 100mm lens on FF produces the same FoV as a 61.7mm lens on APS-C, however if they are both f/2.8, the FF sensor is without question gathering more light.

Equivalence. Aperture matters here.

I've said this so man times...but, I think Orangutan is the only one who actually heard it. So I'll just quote his answer:


I am sorry but neither you nor Orangutan are following Don's logic, and are traversing an entirely parallel path. It is funny, because no one is actually disputing anyone, but saying the other is wrong.

1. Forget aperture (or presume DoF to be infinity for comparison purposes)- focus on the question at hand: if the pixel size is the same, with same sensor tech, an APS-C sensor will have same noise characteristics as a FF sensor. Example: DX mode in a Nikon FF dSLR- what happens there is that a portion of the sensor is being used. Exactly the same thing will happen if you have a smaller sensor with same pixel size.

2. I don't think Don or anyone is claiming that a smaller sensor can collect more light than a larger one, if the pixel size is larger in the former. We all know that is quite impossible. The point being made is that the amount of light per pixel depends on the size of the pixel- in case of a larger sensor it is additionally multiplied by more number of pixels. However, if a FF sensor was made, using the same technology as a 7D sensor and with the same pixel size (making it 46MP I think) then it would be equally noisy.

I am not arguing that aperture affects image quality, but for this discussion let's just talk noise characteristics.



This is EXACTLY CORRECT. The only thing that really matters in the end, assuming all the sensors use the same technology, is TOTAL light gathered. More light, less noise. It's as simple as that. Pixel size doesn't really matter from a noise standpoint. Smaller pixels in the SAME sensor size mean you get more resolution, that does increase IQ...but smaller pixels in a smaller sensor DO NOT mean better IQ....they just mean more resolution, but with worse IQ.

This is equivalence. This scientific concept is documented very, very, very thouroughly here:

http://www.josephjamesphotography.com/equivalence/

If you still doubt, please, read the article on equivalence linked above. It's really not that complicated of a concept.

Sorry, but that's only partially true. The pixel size does matter. Quoting from your own link:

Given four cameras, one with...

...an mFT (4/3) sensor,
...another with a 1.6x sensor,
...another with a 1.5x sensor,
...and another with a FF sensor...

...and...

...a photo of a scene from the same position with the same focal point and the same settings (e.g. 25mm f/1.4 1/200 ISO 400) with all cameras,
...the photos cropped to the same framing as the photo from the mFT (4/3) camera,
...and the photos are displayed at the same size...

...then the resulting photos will be Equivalent.  In addition, if...

...all the sensors are equally efficient, then all the photos will also have the same noise,
...the pixels are all the same size, the AA filter the same strength, and the lens is the same sharpness, then all the photos will also have the same detail,

...the exact same lens is used and the sensors are of the exact same design with the exact same size pixels, AA filter, CFA, and processing...


It is possible to have same noise characteristics if the pixel size and sensor tech is the same, irrespective of total sensor size.


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