Tuesday, 18 March 2008

Canon 5D and 'Hot' Pixels

So I've just got this brand-spanking new 5D, right. And I've taken it out on its first landscape shoot to a favourite spot of mine where I 'test' a lot of my gear and put it through its paces.

I'd heard, and read, a lot about the 5D's low noise - especially with long exposures, so I was very keen to experience this for myself. I enabled the custom function that extends the camera's ISO capabilities, and set the camera to 50. I also put long exposure noise reduction to 'on', and set my tripod up for some long exposures.

The previous night I had been reading a few commentaries on the internet - in particularly one from Ken Rockwell - that claimed there is little to no benefit in shooting RAW. I had been surfing on this topic because, to my horror, I discovered that shooting RAW with the 5D only gives me about 220 images on a 4 Gig card! Whereas turned to high quality jpeg nets upwards of 1000 images. That's more like it, I thought.

So anyway, the high quality jpegs were in the bag (so the speak), and I headed home to marvel at them in Lightroom. And marvel at them I did. Wow, the sensor on the 5D is incredibly noiseless at ISO 50 - even with 30 second exposures. I was impressed.

But hang on a minute. What are those little spots through the images? They seem to be in exactly the same place all the time. Don't tell me I've got dust on the sensor already? I haven't even changed the lens on it - ever. A closer look was called for.

A 'Hot' pixel from the 5D - at 300% enlargement, from a 15 second exposure.

On closer inspection it turned out that dust wasn't the problem at all. My brand spanking 5D has 'hot pixels' - about 6 of them, that show themselves during long exposures (of about 2 seconds or more).

I was gutted, crushed, inconsolable. How could this be? I'd never had this happen on any of the dozen or so camera bodies that I've used or tested over the years. Yet here it was, on the supposed 'King" of them all, the 'noiseless' 5D. My initial thought was to send the camera straight back to Canon and complain bitterly. Luckily, I slept on it over night and decided to do a little more investigating.

Internet discussion on similar problems with the 5D (and other cameras) shows mixed views. About half who responded to another disgruntled 5D owner with hot pixels said 'send it back and complain bitterly'. My thoughts exactly.

But there were others who claimed that hot pixels were to be expected from all camera sensors, and a 'few' hot pixels out of 12.8 million isn't too bad. And anyway, they said, there is a difference between 'stuck', 'dead' and 'hot' pixels. Dead pixels are just that - dead, and won't show any information no matter what settings the camera is on. They always appear as black spots, beause no information is reaching them at all. Stuck pixels are the opposite - the always appear as bright white, because the are 'stuck' and blow out the information they receive. Whereas hot pixels only show up when the exposures are longer (typically over 1 second) and function perfectly normally on speeds below this.

Further testing with my 5D showed that the sensor was indeed fine under 'normal' shooting conditions. No bright or 'stuck' pixels at all. It was something of a relief. But I still wasn't happy.

Then I hit upon a site that claimed cameras could be 'cured' of hot pixels. Apparently all sensors do indeed have them, but they are 'mapped out' before leaving the factory. By activating 'sensor cleaning' from the menu with the lens still on, the camera 're-maps' those pixels, and viola - no more hot pixels. Trouble is, it didn't work.

Lots of people claim it does fix hot pixels, (or maybe it fixes 'stuck' pixels) and I have no cause to doubt them. Maybe I did something wrong? But whatever the case, it didn't fix my hot pixel problem. So I'm sending my 5D back - right?

Well no, actually, because I followed the final solution to the whole 'hot' pixel problem and it worked a treat. Shoot RAW. That's it. Just shoot RAW. That was my problem all along (thanks for nothing Rockwell). I ALWAYS shoot RAW, that's why I've never come across this problem before. I can practically guarantee my other cameras have also had a few hot pixels, but the RAW processing 'maps' these out so they don't appear in the final image. Works great.

So now I have a perfectly functioning 5D, and yet another reason to shoot in RAW. And the solution to the 200 odd images I can store on a 4 Gig card? That one's easy. I've just purchased an 8 Gig card as well.

Confessions of a True Gear-Head!

Doesn't seem that long ago I was writing on this blog about my new Canon 30D - how much I loved it, and how it would see me right for quite some time with my photography. Oh the subtle (and maybe not so subtle?) irony of it all!

Truth is I 'was' happy (notice the use of the past tense) with the 30D, and it is a great camera. The 17-55mm f2.8 and 10-22mm Canon EF-S lenses I paired it up with are some of the best glass I've ever owned, and it was/is truly a great setup.

So why am I using the past tense in all of this?

Well, yeah, I've gone and changed cameras (but not systems), and now - finally - have the 5D as my weapon of choice.

I say 'finally' because really that's the case. I've lusted after the 5D since it came out, and always wanted to own one since I reviewed it for D-Photo. But at $5000NZ for the body, it was a little out of my price range. So I opted for the next best thing - the 30D with its reduced sensor size (and reduced weight/size/specs/price).

So how come I have the 5D now? Well partly it's a change in my financial circumstances (at least I think I can afford one), and partly it's due to the great deals that are out now with the 5D.

Yes, we all know that Canon are about to 'upgrade' the 5D. It has served Canon well over the past 4 years as the camera of choice for those who wanted/needed a full frame sensor but didn't want to (or couldn't afford to) - make the leap to the 1D series (there's some SERIOUS $$$$). And although four years is a long time in the digital technology business, the 'need' to upgrade doesn't make the 5D obsolete. It makes it a bargain.

I'm sure the 'new' 5D (or 7D or 9D or whatever they'll call it) will have live view (don't want it), 16MP (not even sure I need all 12.8 of the 5D's), in-built sensor cleaning (now that would be handy), Digic III processing (what - the 5D's not fast enough?), and a few other tweaks and cosmetic changes. Hey, I know it will be a nice camera.

But I'm a landscape photographer (largely), and what the 5D doesn't have, I don't need. At ISO 50, with a 30sec exposure, this thing is NOISELESS! I don't know what I can happily blow up the 12.8MP sensor images to - haven't tried yet. But I'm willing to bet it's BIG. As big as I'll need anyways.

My 'kit' came with a Canon 24-105mm f4 'L' IS lens - and oh my lordy, what a lens! It's solid, beautifully made, balances well on the 5D (haven't decided whether I need the 5D's vertical grip yet), and makes crisp, clear, contrasty, colourful images.

It also means that my 17-55mm EF-S f2.8 and 10-22mm EF-S f3.4-4.5 won't work on the 5D with its full-frame sensor, so out they go. That's kinda sad - but not too sad when you consider what I've replaced them with. The aforementioned 24-105mm f4 'L', and a 17-40mm f4 'L', to go with my earlier purchase of a 70-200 mm f4 'L' - and my f4 'L' lens trinity is complete! Yeeehaaa!

I believe the saying is "Happier than a pig in mud"?

"West Coast Realtor" - Canon 5D and 24-105mm f4 'L' lens.