Sensitivity or Megapixels?

You can have both at a low cost nowadays.

I say forget megapixels, and quite frankly, forget high ISO. Most can do ISO 3200 quite reasonably, and I don't see any particular low or mid-level camera performing far better than another at ISO 1600 or 3200. They all produce "decent" images. So basically, what I'm trying to tell you is that neither factor is incredibly important to me. You may think they are until you actually start taking photos. Then you may also find that neither setting is that important to you, and that you rarely need to take photos at anything beyond ISO 800. Even then, the ISO performance between different camera brands is all quite comparable, so why worry?

Some people will tell you to look at the lens line-up of the brand you're interested in, and see if what you need is available. It's true, but only if you already know what type of photos you want to shoot, and I'm welling to bet a couple of gonads that most beginners want to shoot a bit of everything. The advice is good, but not for the person who wants to shoot a bit of everything, because every camera lineup has many lenses available, and if you don't plan on owning more than 3, 4, or maybe even 5 lenses, then pretty much every company will have the lenses you need. It's rare to meet someone who needs a lens offered only by one company. Also, 3rd party companies like Sigma, Tamron, and Tokina sometimes offer great lenses available for every DSLR brand, or most of them.

Take my friend for example. Yesterday, he was playing with my Nikon D300 with Sigma 30 mm lens attached. He owns a Pentax and the 18-55 mm kit lens that he clearly doesn't know how to use. He likes taking photos of people, and he LOVED the results from my camera, and said my camera is better than his. It's true, but my camera has NOTHING to do with the results. It's the lens. The lens is fantastic for taking people photos, particularly since we were in a restaurant with rather low lighting.

He loves taking photos of people, but I'm certain he also likes taking landscape photos when he travels. After he took photos of our (20 other) friends, he tries to take a macro shot of a glass of coconut juice. He couldn't with my lens. Why did he try? I don't know. My lens wasn't really designed well for close-focusing macro photography. It turns out that he also loves macro photographs of random objects, rather than the traditional insects and flowers. He couldn't take the photos he wanted with my $1800 US dollar, 12 MP DSLR. Why? Because it had the wrong lens.

He likes portrait shots, landscape, and macros. That's a huge chunk of the photography field right there! He was able to do it better with his Pentax K100D + kit lens (6 MP, around $500 worth of equipment) than with my D300 + Sigma 30 mm (around $2200 USD). Why? Because the basic kit lenses are usually quite capable of close-focusing, which would give him greater ability to take the random macro shots that he enjoys.

The camera didn't matter, but the lens did.

The funny (and confusing thing) is that the Sigma 30 mm f/1.4 lens is available for Nikon/Fuji, and also Canon, Pentax/Samsung, Sony/Konica Minolta, Olympus/Panasonic/Leica/Four-thirds cameras, and Sigma's own DSLRs. It's available for pretty much every brand. If he owned that lens for his Pentax, he would have stopped blaming his camera and praising mine.


So basically, while lenses are what matters, every brand has great lenses available. So for most people, the brand doesn't really matter, whether you're talking about camera or lenses!! Most people are very satisfied with any brand they choose. Just choose the camera you like most, and at the price you are willing to pay. Buy the camera you like, and get the lenses you want as you discover them.

A good lens is of course the backbone of photography, and prior to digital imaging, i used to always tell people who asked to buy the lens they liked, then work out a body to go with it, rather than a $2,000 body and a $200 lens. Also - a prime [fixed] lens is far superior to a zoom lens.

But there is more to it now - pixel count is a real concern if you want big images, sensor size is a real concern if you want high quality images, and camera algorithms are crucial for good tone and colour separation etc. Then there is speed of processing as well. The size of the photo diode cells in the CCD or CMOS are also really important.

Anyways, i like the Canon 400D / 450D - good price, can get amazing optics, and it considers most of the things i mentioned. Also, there are lots of second hand lenses around, lots of good lenses [and crap ones] that you can use, including Sigma of course.

The real choice that you will be making when you purchase a camera is the brand (i.e. Canon, Nikon, Sony). This will most likely tie you to that brand due to the high cost of glass.

dxpx said:

Hello all. I'll keep this short and sweet. Im seriously looking into the digital SLR world in hopes to purchase a remarkable machine at a relatively decent cost. [Note: i realize "decent" is quite the arbitrary term associated with finance these days. ><]


Anyways, my question for you is this - which do you think is ultimately key in deciding on an epic photo device: higher sensitivity [ISO] or larger scale Megapixel? Again, lets assume we cant have both - in hopes to lower expenditures.


Please. Enlighten me!

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Higher megapixels are, in general, not better for image quality. Ever since we hit about 6MP, the detriments of more megapixels are more signficant.

1. Given the same sensor size/generation, smaller photosites for high-MP cameras cause softness due to diffraction sooner (at larger apertures) than larger photosites.

2. Given the same sensor size/generation, smaller photosites for high-MP cameras produce more noise than larger photosites.

3. Given the same sensor size/generation, smaller photosites for high-MP cameras require better technique or more stabilization as movement effects mroe photosites.

Smaller photosites have advantages- if they offset the disadvantages depend a lot on the photographer:

1. Smaller photosites in the same sensor size allow more detail. (generalization)

2. Smaller photosites in the same sensor size allow better cropping.

3. Smaller photosites may allow more enlargement.


So, if you're sure you'll often print Super A3+ or larger, a higher megapixel camera may be an advantage. If you're sure you'll often have the wrong lens and need to crop, more megapixels may be an advantage. If you want about a stop less noise in every image, less megapixels are the way to go, if you want to shoot with a large depth of field, less megapixels are the way to go and if you don't own a tripod or a camera with stabilized sensor or lenses, less megapixels are probably the way to go.

My main body is a D2x, it's got really, really, really tiny photosites (12.4MP on APS-C) and it works for most of my types of photography but diffraction sets in around f/11 so for landscapes I'd be happier with a D70.

Finally, in terms of economics- buy the cheapest camera that meets your requirements because in 2-4 years you'll be buying a newer camera with better results for about the same price.

Zeiss said:

Also - a prime [fixed] lens is far superior to a zoom lens.

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This is generally, but not always true. Some zooms are close to or exceed the quality of some primes. Newer optical designs tend to be done on zooms, where prime designs tend to be relatively static with perhaps some increased performance due to new elements and coatings. For instance, I've got a 20-35mm zoom that handily trounces a 24mm prime at 24mm.

dxpx said:

Hello all. I'll keep this short and sweet. Im seriously looking into the digital SLR world in hopes to purchase a remarkable machine at a relatively decent cost. [Note: i realize "decent" is quite the arbitrary term associated with finance these days. ><]


Anyways, my question for you is this - which do you think is ultimately key in deciding on an epic photo device: higher sensitivity [ISO] or larger scale Megapixel? Again, lets assume we cant have both - in hopes to lower expenditures.


Please. Enlighten me!

Click to expand...

What you want is "enough" pixels. After you have enough having more is no use. How many is "enough" depends on how you will use the photos. If you are making small prints up to 8x10 or viewing them on some kind of screen then even a 6MP camera is enough. If you have more pixels then you have enough so that you can loose some when you make a crop or make slightly larger prints

When think about "sensitivity", think in terms of the entire system. An f/1.4 lens is sixteen times more sensitive than an f/5.6 lens on the same SLR body. If your goal is low light photography, lenses really do matter more then anything else.

An "SLR System" is composed of a DSLR body, a few lenses and maybe a flash and some other misc. 'stuff". If you have a budget don't spend more then half of it on the body. Reserve the other half for the lens

Larger photosites are the key in this game I'm perfectly happy with the 12.8MP the 5D spits out and I have no problems taking it to 1600 and getting away with it where as in contrast I cringe at 1600 on my 1D Mk IIN. Sure higher resolutions are great and more MP is always welcome but for me its about sensitivity what good is having 20 billion MP lets say but the pictures crap because of noise?

Not only are smaller photosites not as good at collecting light as larger ones, requiring a certain amount of "gain" to be dialed in which is what causes the noise, but they can exacerbate the problem of light fall-off on the edges/corners of the image with less-than-ideal lenses or older lenses not designed for digital originally. Since the sensors are perfectly flat and reflective issues of flare and fall-off require lenses to be designed to eliminate as much as possible the bending of the light painting the edges. The straighter the light hits the photosite, the more efficient it is at responding to the light. Smaller sites make this issue more critical.

The issue of photosite density/resolution vs. noise requires a compromise

You'd be fine for the most part even with a 6mp dSLR, which is in some ways an ideal trade-off for APS sized sensors between image quality and noise. Even moving up to 8mp isn't too bad, but larger megapixel counts on the same sized sensor start requiring advanced electronic/computer circuitry to offset the disadvantages.

In the end, you should be just fine with most modern dSLRs, but all this is just stuff to get you started on the fun subject of digital photography.

^^^ Yeah. In fact, if I were working for a company like Nikon, I'd try to bring a 6 MP camera APS-C sensor camera to market. A new 6 MP sensor released with todays sensor technology would be amazing for those who want the ultimate low light camera. Just advertise it as the ultimate low light camera, and produce them in smaller quantities. It may produce the cleanest images yet.
Or if a full frame 8 MP camera were to be released, think about the large number of people who may buy this over other cameras (ie: the Nikon D3) simply because they could take CLEAN images at ISO 12800. There may be a market for this, and that market may willing to pay something like $4000 for it. Who knows. Not many people need a 12 MP sensor. I would have been equally satisfied if Nikon released the D300 with a 10 MP sensor.

Abstract said:

^^^ Yeah. In fact, if I were working for a company like Nikon, I'd try to bring a 6 MP camera APS-C sensor camera to market. A new 6 MP sensor released with todays sensor technology would be amazing for those who want the ultimate low light camera. Just advertise it as the ultimate low light camera, and produce them in smaller quantities. It may produce the cleanest images yet.
Or if a full frame 8 MP camera were to be released, think about the large number of people who may buy this over other cameras (ie: the Nikon D3) simply because they could take CLEAN images at ISO 12800. There may be a market for this, and that market may willing to pay something like $4000 for it. Who knows. Not many people need a 12 MP sensor. I would have been equally satisfied if Nikon released the D300 with a 10 MP sensor.

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Speak to Sigma, their DP-1 seems to be moving in that direction if they can make a version maybe like you said.

compuwar said:

This is generally, but not always true. Some zooms are close to or exceed the quality of some primes. Newer optical designs tend to be done on zooms, where prime designs tend to be relatively static with perhaps some increased performance due to new elements and coatings. For instance, I've got a 20-35mm zoom that handily trounces a 24mm prime at 24mm.

Click to expand...

In addition to what you said, Olympus are going to bring out a 28-70mm with a constant F2. Thats very fast for a zoom when making comparisons to primes.