[stevebrot]

as i mentioned in another thread in the general forum

this self portait http://fork.zenfolio.com/img/v4/p704833906.jpg

image was taken using live view on the K20d, while it was upside down at nearly ground level. This should would have been very difficult to take if i actualy had to snake my way down to the ground over the rusty rails, and i'm a flexible guy, some people here are not as mobile due to various reasons.

now imagine that my LCD had a 360* swirl/tilt function and was 4X4 or 4X5", it would open up a door to many more options.

you are too dismissive of the capabilities of LCD screens and live view, esp on a tripod.

the biggest problem right now is the refresh rate, its too slow, once they get the refresh rates of photocamera LCD's to levels higher than your vision, it will be much more pleasant to use.

I have a Canon G2 with swing out, reversible LCD. The display is a nice tool for self-portraits, ground-level shooting, and over-crowd shots. On the other hand, using the manual focus is a joke! And in bright light, I use the (fortunately) very good optical viewfinder. In fact, I usually use the optical finder since I find it easier to avoid camera motion with the body plastered against my face.

Now, I understand that the technology has advanced significantly since my G2 was made, but it still is not that great.

Steve

(Oh...I forgot to mention that for those of us with old eyes, even arms-length with a live-view display is often not far enough...)

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Last edited by stevebrot; 10-30-2008 at 12:12 PM.

[Gooshin]

I'm pretty sure the XSi does. And look at Canon's site, many current EF-S lenses are screw drive, the 18-200 for example.

this is an image of an XSI mount

http://images.digitalcamerainfo.com/images/upload/reviews/Canon/Digital%20Re...-mount_375.jpg

this is an image of the 18-200 lens

http://a.img-dpreview.com/lensreviews/canon_18-200_3p5-5p6_is_c16/Images/allroundview.jpg

there is no in-body motor drive coupling.

please, prove me wrong, but i am under 100% certainty that no current canon body has in-body focusing.

that is why their lenses, even regular ones like 50mm's are much larger than the pentax ones (atleast the ones without HSM/SDM)

[RBellavance]

there is no in-body motor drive coupling.

That is correct. The Canon EF and EF-S mount are fully electronic, with no mechanical coupling between the lens and body. Ref: Canon EF lens mount - Wikipedia, the free encyclopedia

[kristoffon]

OK. Now please someone enlighten me. Have a look at Canon's website specifications for the NEW 18-200 lens.

EF-S 18-200mm f/3.5-5.6 IS

First, not it's not tagged with USM.

Second, click on specifications and look where it says: "Focus Adjustment: Gear-driven by DC monitor". An USM lens says "Focus Adjustment: Inner focusing system, with focusing cam"

Third, its compatibility list is "For EOS 50D, 40D, 30D, 20D, 20Da, Rebel XSi/XS, Digital Rebel XTi/XT and Digital Rebel."

Also the Wikipedia page just posted has many lenses marked as not having USM.

Also the lens I mentioned has a Wikipedia page just for it, which states it doesn't have USM: http://en.wikipedia.org/wiki/Canon_EF-S_18-200mm_lens

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Last edited by kristoffon; 10-30-2008 at 01:00 PM.

[Gooshin]

OK. Now please someone enlighten me. Have a look at Canon's website specifications for the NEW 18-200 lens.

EF-S 18-200mm f/3.5-5.6 IS

First, not it's not tagged with USM.

Second, click on specifications and look where it says: "Focus Adjustment: Gear-driven by DC monitor". An USM lens says "Focus Adjustment: Inner focusing system, with focusing cam"

Third, its compatibility list is "For EOS 50D, 40D, 30D, 20D, 20Da, Rebel XSi/XS, Digital Rebel XTi/XT and Digital Rebel."

they are refering to an inferior, non ultra sonic (USM) design, but it is is still built into the lens.

from DPREVIEW:

Autofocus

Autofocus is driven via a micro motor system, which is louder and feels less refined than the ring-type ultrasonic focusing motors used in many other mid-range zooms. To be fair it is one of the better examples of its type, similar in focusing speed and noise level to Canon's ubiquitous EF-S 18-55mm F3.5-5.6 (IS) kit lenses (and much faster and quieter than some other micro motor lenses we've tested recently). The design does however mean that the focus ring spins around during autofocus, and manual focus can only be engaged by flicking the AF/M switch. This is a little disappointing for a lens of this level, but does help keep size, weight and cost down a bit.
In normal use the autofocus is fast and positive (tested mainly using the EOS 50D body), although with the usual tendency of slow maximum aperture zooms to hunt in low light. Its focus tracking abilities are reasonable, but not outstanding, and naturally no match for a fast, internal focusing USM lens. As always it must be noted that focus speed and accuracy is dependent upon a number of variables, including the camera body used, subject contrast, and light levels.

[kristoffon]

Hmmmm... I was under the impression that non-USM meant the screw type system. And let me say that it looks to me as a retarded system. If it's made to be cheap, better to have the motor in body anyways. But I don't care for USM either.

[jeffkrol]

Hmmmm... I was under the impression that non-USM meant the screw type system. And let me say that it looks to me as a retarded system. If it's made to be cheap, better to have the motor in body anyways. But I don't care for USM either.

Canon motors........ 4 types, all in lens.
Canon EOS Lens Motors - photo.net

what?

Not sure what your "what" is for but here goes:

With the crop factor you have to enlarge the image more than FF to get the same output size.
If you shoot an image in FF and APS, let's just say oh I don't know, 2 rulers, one vertical one horizontal. The shot captures the vertical ruler to 5" the horizontal to 4". If you enlarge it to 8 x 10 the FF will be enlarged (the amount of magnification) less that the APS image. In FF you are starting with a larger image and you are using the lens' zoom or your distance from the subject to get the same image as the APS

Now here is one of 2 places I misspoke. The next sentence should read:

Your lens still projects the same size image in APS it just cuts off part of it. Not bad for tele but sucks for WA.

Here is the second place:

The more you enlarge something the more noise, the more imperfections are visible.
What I actually meant was whatever flaws are in the image they are magnified to a greater extent from the smaller sensor. Not that there is more noise/garbage it's just larger.

[RBellavance]

Hmmmm... I was under the impression that non-USM meant the screw type system. And let me say that it looks to me as a retarded system. If it's made to be cheap, better to have the motor in body anyways. But I don't care for USM either.

That retarded system (micro-motor) is what Pentax SDM is

[Class A]

The inability will of course lead to unwillingness.

That's your view and you are entitled to it. The truth may be different.

With a fixed pixel count, the smaller the sensor size, the smaller the pixel size will be

Exactly, sensor size matters. Whether the pixel count stays the same or not is immaterial since pixel density doesn't matter (a lot).

Nope. Adding up and averaging out two or even more *noisy* pixels will not give you a noiseless pixel data. The Physics is only one larger pixel, with more area and full well capacity in receiving light and store more charge, will have less noise, i.e., a higher S/N ratio.

Rice High, this goes against anything reasonable I've read.
Have a look at falconeye's posting:

• In the first order, noise is a function of sensor surface only.
  
• Second order effect in favor of a high pixel count is: The read-out noise is minimized.
  
• Second order effect in favor of a low pixel count is: The area sensitive to light is maximized.

What is it that stops you from acknowledging this?

I think your error is in assuming that the noise combined from four pixels will be higher than the noise from a single pixel four times as large. This is not the case (outside extreme size ranges). Whether the summing up of the photons happens through the large pixel (think of it as being composed of four sub-areas) or in the digital domain by summing up the individual small pixel results does not matter. In theory, that is. There are of course always practical considerations and in real life things don't always work that well, but I haven't heard of any substantial explanation as to why current sensors would deviate from the above logic. Please see falconeye's posting again.

I've have also read that larger pixels also have a higher noise floor so they do not automatically feature a higher DR. Anyhow, I'm no expert in this matter and I do not have the time to make myself one. My common sense and physics background tell me that the arguments regarding pixel density being a secondary issue are correct and that there is no reason to believe that a sensor with larger pixels is automatically superior to one that has the same size but smaller (and correspondingly more) pixels.

Not exactly. In-camera processing is required to filter out those colour noise. Noise are random and the RGB channel will not behave the same for different shooting conditions! The best thing is STILL there is LESS noise from the sensor.

I don't understand what you are trying to get at. Obviously less noise from the sensor is preferable. But larger pixels don't give you less noise, a larger sensor area does.

The Physics is CCD/CMOS is a light sensitive charge up device. ...

I was referring to your statement regarding "3d feel" and questioned how you wanted to substantiate this.

[stevebrot]

That retarded system (micro-motor) is what Pentax SDM is

I don't think so. Pentax does not make any micro-motor lenses. The Pentax Supersonic Drive Motor (SDM) is similar to the Sigma HSM, Nikon SWM, and Canon USM technologies.

Steve

[jeffkrol]

Nope. Adding up and averaging out two or even more *noisy* pixels will not give you a noiseless pixel data. The Physics is only one larger pixel, with more area and full well capacity in receiving light and store more charge, will have less noise, i.e., a higher S/N ratio.

I think you should think about Eric Fossum's words....
Re: Pixel Density: when Moore is less: News Discussion Forum: Digital Photography Review
I don't disagree with your analysis, but there are two factors that you may not be considering.

First, as pixel sizes shrink, light gathering technology (microlenses) and quantum efficiency both are typically improved. So, while mathematically there may be no improvement in SNR as pixels sizes are shrunk (incl. spatial averaging), in fact due to QE improvements etc., there is an apparent improvement with pixel shrink.

If you care to argue w/ the inventor of the active pixel sensor go ahead.

Also an interesting paper:
http://www.imagesensors.org/Past%20Workshops/2007%20Workshop/2007%20Papers/0...%20et%20al.pdf

All of which stemmed from this thesis presented by Emil J. Martinec and not refuted by Mr. Fossum.


If we look at the numbers for middle grey, which are largely due to photon noise, we find that the D40X noise figures are uniformly about 30% higher than those of the D40 up through ISO 1600.

So one would be led to believe that the 'terrible tradeoff' is that the D40x gets more resolution than the D40, but at the expense of being a rather noisier camera. Indeed, the casual visitor to DPReview considering the purchase of one of these cameras would be faced with a real dilemma -- do they go for the extra resolution, but then what about the extra noise that comes with it?

Of course, this is a false choice. The point is that the noise is measured in these reviews at the pixel level, without any context as to the spatial frequency at which it's being measured (it's always measured at the pixel level, also known as the Nyquist frequency) which of course varies with the pixel density. If one does the math, photon noise scales in inverse proportion to the pixel pitch (the number of photons captured scales with the area, the photon noise is the square root of the number of photons, so scales with the square root of area, ie the linear dimension of the sensor real estate). So with 67% more pixels, the D40x pixel pitch is 30% smaller than the D40 pixel pitch, and there's the explanation of the 30% noise difference at the pixel level.

But this is also entirely misleading. Since noise scales with the linear dimension of the region of sensor considered, what would happen if one resampled the D40x image to 6MP? Well, one would combine the data from 1.67 D40x pixels to make the pixels of the resampled image, and the noise would reduce by about 30% at the pixel level of the resampled image (assuming the resampling is done properly). In other words, viewed at the same image size, the D40x and the D40 have the SAME amount of noise. The only difference is that the D40x need not be resampled to deliver this same level of noise, it merely needs to be viewed at equal size. Oh yes, there is one additional difference -- the D40x has 30% higher resolution while having that same level of noise.

So, I can imagine the route by which arrives to the conclusion that the megapixel race is a bad thing, it is a viewpoint entirely reinforced by this site's testing methodology which concentrates on pixel-level noise without (say) rescaling it to noise as a percentage of frame height. And it can lead the consumer to make bad choices, for instance by not realizing that the D40x and D40 have the same level of image noise, if they are noise-averse they may decide to go for the D40 when there is absolutely no reason to do so.
Re: Pixel Density: when Moore is less: News Discussion Forum: Digital Photography Review
apparently physics says one thing, engineering says another.......

[RBellavance]

I don't think so. Pentax does not make any micro-motor lenses. The Pentax Supersonic Drive Motor (SDM) is similar to the Sigma HSM, Nikon SWM, and Canon USM technologies.

According to Richard Day, SDM is implemented with micro-motors (at least in the DA*16-50 and DA*50-135): SDM v USM & SWM - An explanation: Pentax SLR Talk Forum: Digital Photography Review

[Gooshin]

According to Richard Day, SDM is implemented with micro-motors (at least in the DA*16-50 and DA*50-135): SDM v USM & SWM - An explanation: Pentax SLR Talk Forum: Digital Photography Review

maybe thats why people are reporting less than stellar focusing speeds.. har har har

[egordon99]

Nope, the EF (and EF-S) mount is COMPLETELY electrical. There are no mechanical connections between an EOS body and an EF(-S) lens. No aperture actuator lever, and NO screw shaft for focusing. EVERY EF(-S) autofocus lens has a motor in the lens. NO EOS body has an autofocus motor in it (and if it did, it wouldn't be able to connect to anything on the lens )

I'm pretty sure the XSi does. And look at Canon's site, many current EF-S lenses are screw drive, the 18-200 for example.