If you were using photoshop, simply create two layers. One with the photo, the other with he black frame. I believe you set the layer blend mode to "difference".

If the colors for each layer are the same the result is black.
So if you have a hot or dead pixel, its color will be the same for all shots with an exposure of a certain time.

Normally noise will cause the pixel to be a bit different color.
For any given tie, the pixel will be off by that amount consistently.

So take a blank black frame with he same exposure time of the photo in question. Subtract the pixel noise, and you have a fairly decent result approximating the pixel color without the noise.

A lot effects the quality of the results, but its is good enough that your camera has this functionality built in.
So you'll notice if you take a frame with a five second exposure, the camera will take about another five seconds before the image is saved.
It is during this time that the black subtraction frame is being taken.


So... to make a rather long story short...
For lightning you generally take very long exposures. (15-30 seconds or longer.).
If you allow the subtraction frame to be taken (as part of noise reduction), you need to wait 15-30 seconds or longer before you can think about taking your next photo.

The alternative is to turn off noise reduction and to always use a specific exposure time. (This will result in a more noisy image)
Then later take one black frame with the lens cap on for the same time.
You can then apply this same black frame to all of your images in Photoshop and probably save your self a lot of time.
(you'll only have a few good shots, shy waste 30 seconds on several hundred attempts?



OK, don't know if I made that any better or worse, but Google for noise reduction or subtraction frame and you should get some pretty good technical answers.

Slight dampness, probably OK. I've even heard of people having no problems in slight rain with something like the kit 18-55, but I would not risk it.

When traveling I take old plastic grocery bags. Bag the camera & lens, clip the hood over the lens, and tear out a hole for the front element.
Doesn't do much for your fashion reputation. But if you can shrug off the silly remarks, it works well for rain.

When at Niagara Falls, I simply punched a hole in the rain slicker (basically a full body length grocery bag) again using the lens hood to hold the plastic around the lens and tore the hole out. With that I was on the Maid of the Mist at the base of the falls -- lets say it was very, very wet!
But the camera and lens was just fine.

No luck. Unlike the hard disk, there was no option to delete the partition and I couldn't find another way.

But that is a good idea. I may have some DOS tools that should allow me to remove the partition info.

Thanks

OK not Pentax related, but I think I destroyed one of th SD cards I generally use for my Pentax...

I took one of my 2G SD cards that I've been using on my SLR for over a year and stuck it into a point and shoot.. The damned thing formatted the card down to 1G.
I cannot find any way to reformat it back to 2G. Everything I use to format only sees the card as 1G capacity.

Any ideas how to recover the capacity?

Personally it looks a bit like lens flare. Is the glass in good shape or could there be some deterioration or other nastiness with regard to the glass and/or their coatings?

Not sure if it is a good example, but 1/20s, f1.4, iso100, K10D, Pentax 50mm 1.4 lens.

Differences: it is still dark outside here so the light is artificial.
Also, it is the SMC Pentax FA 1:1.4 50mm lens.

I'll try when I get home from work today and see if there is a difference, but I don't suspect one. I've taken some pretty dark photos with the lens (one reason why I bought it originally) and have not see dramatic color casts that were not seen with other lenses.




(FYI, the image tagging looks like this:
[ img ]http://moringello-east.no-ip.com:8080/start/public/080313_IGP1129.jpg[ /img ]
I put extra spaces in the tag so they show up.)

I was mainly concentrating on the "Obviously it is at night mostly..." comment as a basis for my initial response., but good question. Never done daylight lightning shots. I'm guessing add a number of "luck" filters and good timing.

Trying to click the shutter once you see the lightning won't work, so you'd need some way to leave the shutter open for a reasonable length of time.
If F22 (or higher) won't get you there, I would try to throw on enough ND filters to bring the exposure down.

What sort of daylight? At some point the lightning may not significantly outweigh the ambient light, so aperture and filters won't help much.
At that point I'm lost.

Easy as pie...

Exposure is variable. I generally use 30 seconds at a time. For the K10D and RAW, this works well without too much noise and without turning on the noise cancellation -- which requires a thirty second dark frame to be shot. Thus you can are waiting doing nothing until that noise canceling frame is done.
Don't know if that makes sense for you but in short, be sure to turn off noise reduction.

Unless there is something closer that I want to see clearly, I try to focus on infinity (not necessarily the focus stop at the end where the 8 mark is. It is usually slightly less than where the focus ring stops moving).
If you can see anything at all, focus on the most distant object you can see. If not, try to find the actual infinity focus spot before hand, and note that for later.
If it is so dark you cannot focus, it may not make much difference anyway since you'll probably get silhouettes anyway.

As for aperture, I usually try F8. Depends on the lens and focal length.
Also depends on the amount of ambient light you want to show up.
If I want it dark I close down to a smaller aperture like 8-16.
If I want the foreground to show up I may open up a bit.

The ISO, you may have to play with. I tend to stay at 100 or 200 just to keep the noise down to a minimum. But if the lightning is dim or if you want the ambient lighting to show up more, you may have to go up higher.

Shoot RAW. The RAW converter does a wonderful job at removing noise. Once it is written as JPEG, the noise may not go away too easily.


One thing to note... if you have the K10D, the Remote Assistant software is rubbish for continual shooting.
You can set it up to take a repeated 30 second exposure... which works well for about five images. Then it all goes to hll and you spend your entire evening trying to make it work.
Save yourself the trouble, just set up bulb mode, and hold the release yourself. (or set to 30 second exposure.)


Google probably will lead you to sites that explain in more detail. But I found a lot that make it out to be more difficult than it has to be.

In short, just keep your exposure to 15-30 seconds (more or less).

Mine is rather stiff at one point and not smooth all the way through the range.

The SDM on that lens is now making a squeaking noise. Sounds like an old rusty gate swinging inside.

The 50-135 is built very well. In fact I've actually dropped it from about three feet six months ago and it is is working flawlessly with almost every day use.

The 16-50 on the other hand is, lets say, not the highest quality product I've bought.

Cherry blossoms at downtown Washington DC is something not to be missed this time of year. Photo from a year or two ago, but they should be waking up in a week or two.