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Old Nov 4, 2003, 3:06 PM   #1
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Default Shutter Speed and Focust Assist questions....

Two questions I have always had regarding my digital cameras.
Just found this forum (although I have read "Steve's" reviews for years!) and I thought I'd ask them here.

Some background, I have always owned Olympus digital cameras. Currently I'm on a C3030Z and am thinking of upgrading to a C750. Everytime I think I'll try another brand I just really like the reviews I read re. the Olympus image quality. Since I do print and frame a lot of images, I'm big on the quality of the natural light photography. So anyway...

1) Why is there such a long shutter lag with digital cameras? Every one I have used (non-Olympus as well) has this and it is very annoying. I can get rid of the auto-focus lag easy enough, but it is still very difficult to time an action photo. If I see a digital image on my screen, why can it not be captured the instant I push the button?

I guess the obvious followup, are there any cameras that do get rid of this shutter lag?


2) With my 3030, even more than the 2020 before that, I notice poor focusing in low light or specifically night conditions. This may be obvious to some, but I thought it would bounce a beam out and be able to focus no matter what the light condition. I find that my night photographs of people are 50% out of focus. Any way to remedy this? Are there any digital cameras that do have a "focus assist" feature as mentioned in the 750 review.



3) (I know, I only said 2 things) what is your pick for a small durable camera with great image quality? I would like something I can ski with as I do a lot of West Coast skiing and the scenes are beautiful. If they were easy to ski with, I'd get an SLR digital, but as it is I can just fit the 3030 in a pocket, but even that is too big. I considered the Olympus stylus, but really like the specs on the 750. I obviously looked at the Canon Elphs, am impressed with their size, but have found their pictures to be grainy in marginal light conditions and I guess have been spoiled by my 3030.

Thanks in advance for any feedback,

-todd
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Old Nov 4, 2003, 4:42 PM   #2
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You may want to read the reviews at http://www.dpreview.com and http://www.imaging-resource.com

Dave Etchells (owner/editor of imaging-resource.com) shows a camera's performance in the "Picky Details" section of his reviews.

Phil Askey (owner/editor of dpreview.com) shows a camera's performance in the "Performance and File Sizes" section of his reviews. Phil also tests low light focus ability.

Unfortunately, most consumer (non SLR) based digital cameras use a contrast detection focus system, which is not as fast or reliable as the phase detection focus systems used in SLR's.

Although, some consumer cameras are including "hybrid" focus systems now (passive external sensors + contrast detection). The new Minolta DiMAGE G400 is an example of a camera using both focus types.

Autofocus Lag, cycle times, low light focus ability, etc., can vary dramatically between camera models.
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Old Nov 4, 2003, 8:53 PM   #3
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Thanks Jim, appreciate the links, I'll definitely look at those sites. I also caught a link in the Olympus group (below) about the focusing. That's too bad, I didn't know that is how it was done.


Anyone know why the shutter lag exists in digital cameras?
Seems to me they'd be able to design one without.


Thanks,
-todd
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Old Nov 4, 2003, 9:18 PM   #4
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Maybe it just does take its time to process the image, that's why the shutter lag is that long. I know there's a longer and more scientific(mechanical) explanation to this!
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Old Nov 4, 2003, 9:36 PM   #5
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First, here's how the contrast detection works:
http://www.howstuffworks.com/autofocus3.htm

The reason why it's slow is because the camera first has to focus out and see what happens, and then focus in and see what happens, then out and in again until it sees the contrast at its greatest.

Some newer ultra zoom cameras are faster now (the Oly 750 is a generation behind these because it was released earlier), but after trying many UZ camera brands at a camera show, I still like the C-7x0 best (but I'm waiting to see what the 770 will be before I think about replacing my C-700).

You can personally avoid 95% of the shutter lag by focusing manually and setting the exposure yourself. I assume you know about the trick about half-pressing the shutter button to prefocus and set exposure ahead of time.

Here's an example where I did that with the C-700, and got a shot of a railway crossing on a fast moving train:
http://www.photobucket.com/albums/08.../defeatlag.jpg
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Old Nov 5, 2003, 10:36 PM   #6
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Quote:
Originally Posted by Mike_PEAT
First, here's how the contrast detection works:
http://www.howstuffworks.com/autofocus3.htm

...

Some newer ultra zoom cameras are faster now (the Oly 750 is a generation behind these because it was released earlier), ...

Thanks. I understand that i can save time by prefocusing.

I'm wondering why after doing that, there is still a lag at all?
(or else, a noticeable lag). Even a second or half second can
have an effect on moving images...you have to lead your subject
or follow and hope you catch it. What is the design reason
why it doesn't capture whatever it is looking at the instant I hit the button! (after a prefocus, of course.)


Followup, what is the new UltraZoom design that makes it focus faster? I did see that referenced in another post but I guess I didn't know what ultrazoom was (other than 10X for the 750).


Thanks,

-todd
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Old Nov 6, 2003, 9:51 AM   #7
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Quote:
Originally Posted by JimC
You may want to read the reviews at http://www.dpreview.com and http://www.imaging-resource.com

Dave Etchells (owner/editor of imaging-resource.com) shows a camera's performance in the "Picky Details" section of his reviews.

Phil Askey (owner/editor of dpreview.com) shows a camera's performance in the "Performance and File Sizes" section of his reviews. Phil also tests low light focus ability.
Some cameras still can have lag, even when prefocused . Most don't have much lag. Again, check out the reviews for the models you are considering. Both Dave Etchells and Phil Askey measure these times (even the lag after a camera is prefocused).

For example: here is the "picky details" section for the Olympus C-750UZ from Dave Etchell's review (very fast when prefocused):

http://www.imaging-resource.com/PRODS/C750/C75A7.HTM
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Old Nov 6, 2003, 12:58 PM   #8
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A nice feature is continuous or tracking focus that focuses right up to taking the photo. It makes pre-focus a lot more reliable if something moves between half pressing the button and taking the picture. It is especially handy for getting candids of kids or people at gatherings etc. It takes extra battery power. The Minolta A1 only runs the continuous focus when you grip the handgrip. Steve reports 1/5 second delay with pre-focus and a half second without it on the A1.
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