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View Full Version : 4mpx and 4x zoom or 5mpx and 3x zoom? And which camera?



jessie25
04-13-2005, 08:28 PM
Which do you think is better? 4 megapixels with 4x optical zoom? Or 5 megapixels with 3x optical zoom?

What I mean is, does the extra megapixel compensate for the lesser zoom by allowing more cropping? Or would the extra zoom range more than make up for the lower megapixel?

I can't seem to do the math. Can anyone help?

Once I've covered that, I'm considering the following cameras:

5mpx, 3x zoom: Canon PowerShot A95, Nikon Coolpix 5100, Kodak EasyShare CX7530.

4mpx, 4x zoom: Canon PowerShot A520, Kodak EasyShare DX7440.

Keeping in mind that I don't care the least bit about manual controls, I just want a simple point-and-shoot that will take fast pictures, focus well indoors in low light and with flash photos, and use AA batteries... which do you recommend?

EAP
04-13-2005, 10:22 PM
I don't think the extra megapixel will make much difference, whereas the extra zoom capability is definitely a plus. That said, numerous posters on this forum greatly prefer the Canon A95 over the A520, picture quality-wise.

John_Reed
04-13-2005, 11:06 PM
Which do you think is better? 4 megapixels with 4x optical zoom? Or 5 megapixels with 3x optical zoom?

What I mean is, does the extra megapixel compensate for the lesser zoom by allowing more cropping? Or would the extra zoom range more than make up for the lower megapixel?

I can't seem to do the math. Can anyone help?

Once I've covered that, I'm considering the following cameras:

5mpx, 3x zoom: Canon PowerShot A95, Nikon Coolpix 5100, Kodak EasyShare CX7530.

4mpx, 4x zoom: Canon PowerShot A520, Kodak EasyShare DX7440.

Keeping in mind that I don't care the least bit about manual controls, I just want a simple point-and-shoot that will take fast pictures, focus well indoors in low light and with flash photos, and use AA batteries... which do you recommend?It's not enough to compare the "X" power. You also have to figure in the maximum equivalent zoom length, if by "better" you mean more zoom. Given that, here's the math for the Canon A520 (140mm max zoom) vs. the A95 (114mm max zoom):

Take a full-zoom shot with the A95 (2592X1944 pixels) of some particular subject, take the same shot with the A520 (2272X1704 pixels) at full zoom. So the question is, how much of a crop would you need from the A95 shot to encompass the full-zoom photo of the A520? Answer: Width = 2592 X 114/140 = 2111 pixels wide, which is ~160 pixels narrower than the same image shot with the A520 at full zoom. Repeat the process in the vertical dimension, your cropped image is now 1583 pixels high. So, your crop of the A95 image to equal the 4 megapixels collected by the A520 contains 2111 X 1583 pixels, or 3.34 megapixels. So the longer optical zoom wins the race by a nose. Just for kicks, try this same exercise with a 36mm to 432mm FZ5 sometime. More optical zoom will nearly always win this comparison.

Starscream
04-14-2005, 12:15 AM
You simply can not go wrong with the A95.
The difference between 3x and 4x is negligable and you get the very handy rotating screen which i could not miss anymore (you don't think you need it until you have used it).

jessie25
04-14-2005, 06:00 AM
Thanks for helping out with the math, John - that's exactly the calculation I was stumped on. I appreciate it.

As for the comparison between specific cameras, I admit the rotating LCD is tempting on the A95, but that alone won't make the decision for me - it's really not that big a deal to me.

Canon A520 versus Kodak DX7440? Either of those versus the Kodak CX6445, which doesn't seem to exist on this website but is also 4mpx, 4x optical zoom and a bunch of other tempting features? Any thoughts?

Causeway
04-14-2005, 06:30 AM
There is also the Panasonic Lumix DMC-LZ2. 5MP Digital Camera with 6x Image Stabilized Optical Zoom.

Thalas'shaya
04-14-2005, 06:30 AM
the reason i picked the A95 over the A520 for myself was that the A95 had better in-camera red-eye reduction and better low-light focus than the A520. also, image quality was better across the board on the A95. finally, the A520 was too small and didn't feel as nice in the hand as the A95 did. for me, it was three parts image-quality considerations and one part touchy-feely. i figure if i ever need the extra zoom, i'll buy a lens. :)

sarah12334
04-14-2005, 07:40 AM
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gary_hendricks
04-14-2005, 07:41 AM
I'd certainly recommend the Canon A95 (http://www.basic-digital-photography.com/canon-powershot-a95-review.html) as your camera of choice.

jessie25
04-14-2005, 07:45 AM
Is the A95 really that much better than the 3 Kodak models or the Nikon 5100?

The Kodaks are looking tempting, I admit; only 2xAA instead of 4xAA, less expensive, seemingly good features and quality. I like the feature that allows you to snap another photo even while in review mode. What is really so much better about the A95, besides the rotating LCD?

Also, I can pick up the Nikon 5100 for over $130 cheaper than the A95. I'm having a near-impossible time finding reviews on it because I think it was only released in Canada, not in the US. But it's got 5 megapixels, a 3x optical zoom, has an AF-assist lamp, scene modes, is very compact, and comes with rechargeable batteries and a 2-year warranty.

Does anyone know how the Nikon 5100 would compare to the Canon A95 in terms of shutter lag, low-light focusing and performance and overall image quality? Is the A95 really worth $130 more?

And how do either of these compare to the Kodak DX7440, CX6445, or CX7530, two of which I can't seem to find reviewed either?

John_Reed
04-14-2005, 12:09 PM
dgjdfklgjdfklgjdflgjdfklgjdfklgdfjkljHow long have you had decode?

Rhys
06-16-2005, 01:23 PM
It's not enough to compare the "X" power. You also have to figure in the maximum equivalent zoom length, if by "better" you mean more zoom. Given that, here's the math for the Canon A520 (140mm max zoom) vs. the A95 (114mm max zoom):

Take a full-zoom shot with the A95 (2592X1944 pixels) of some particular subject, take the same shot with the A520 (2272X1704 pixels) at full zoom. So the question is, how much of a crop would you need from the A95 shot to encompass the full-zoom photo of the A520? Answer: Width = 2592 X 114/140 = 2111 pixels wide, which is ~160 pixels narrower than the same image shot with the A520 at full zoom. Repeat the process in the vertical dimension, your cropped image is now 1583 pixels high. So, your crop of the A95 image to equal the 4 megapixels collected by the A520 contains 2111 X 1583 pixels, or 3.34 megapixels. So the longer optical zoom wins the race by a nose. Just for kicks, try this same exercise with a 36mm to 432mm FZ5 sometime. More optical zoom will nearly always win this comparison.


There's a simpler way of doing this, I think...

If we have a camera with a fixed focal length lens that takes a 3 megapixel image then all we need is the horizontal length of the image. Mostly that will be given but I'll include the calculations required if it's not...

Take the number of pixels (3,000,000 for our 3 megapixel example) and divide by aspect ratio factor (this is either 4:3 in the case of compact digitals or 2:3 in the case of digital SLRs). Assuming we're using a compact digital then this will be 4:3 which becomes 4x3 which is 12. This gives us 250,000. Now we take a square root of that, giving us 500.

I know - square roots are a bit technical but don't worry - the rest is simple multiplication and division that any schoolchild can do. In fact - it's dead easy on any calculator such as the free calculator that came in my cereal box last week.

So we multiply the 500 by 3 giving us 1500 and by 4 giving us 2000. This is the width and height of the 3 megapixel image. Ok, so you don't believe me - multiply 1500 by 2000 and we have 3,000,000 again. Happy? Ok - now we know the width of the image we need.

Next we take a camera that has an 8 megapixel image and do the same thing. We already know the calculations so I won't repeat them.
Given 8,000,000 pixels, we have an image in 4:3 format of 2449 x 3265 (again truncating at the decimal point).

So... how much zoom equals the difference between 3 megapixels and 8? Well, let's divide 2000 into 3265 and find out... Wow! It's a mere 1.6 times zoom.

Out of curiosity, let's try to calculate it the other way around. Let's take a 3 megapixel image out of John's Panasonic's focal length and see how big his sensor needs to be in order not to need a zoom...

His Panasonic has a 12x zoom. Let's multiply our 2000 and 1500 by 12... This gives us 24000 and 18000. Now let's calculate megapixalage... Wow - John really needs a 432 megapixel camera in order to do a digital zoom of 12 times in order to get a 3 megapixel image.

I hope people can understand my calculations.

Newbie
06-16-2005, 02:13 PM
Gah stupid bug made me lose my post...

basicly what I said is that Rhys is right, more optical zoom is always(almost) better than more megapixels.

Many people have suggested you the A95 and I agree its a great camera(I have it), but I don't think it suits your needs, here is why:
"I don't care the least bit about manual controls"
"I just want a simple point-and-shoot"
"that will take fast pictures"

The A95 is an awesome camera with full manual controls and although you can go into Auto or P mode, when you do, you use only a small part of the camera. It is far from being a fast camera.

I don't know why you prefer AA batteries, I mean sure they are nice, but why limit yourself to that ?

Anyway, I looked up for some other cameras which use AA batteries and I have found many Sony, they are known for focusing well in low light.
W1, W5, S40, S60, S90...

I made a little comparison of speed between the S90 and the A95(I based myself on the review of both cameras at dpreview.com)
Full press shutter lag
A95 ~0.9s vs S90 ~0.3s
half press lag
wide angle: A95 ~0.8s vs S90 ~0.3s
telephoto: A95 ~1.5s vs S90 ~0.4s
Those are the places where the difference is the biggest.
The A95 does considerably better than the S90 in burst mode.

I have no experience with the S90, so, have a look at it, but I can't clearly recommend it. On dpreview.com they also have comparison between the S90 and the A520(in the review of the S90).

jessie25
06-16-2005, 04:44 PM
Sorry, this is an old thread that got bumped up because someone in another thread had a question about optical zoom versus megapixels. I bought my camera months ago (A520) and I'm very happy with it. Thanks for the tips though.