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andrew_certain

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Posts posted by andrew_certain

    Can't find JPGs on card (Shooting RAW + JPG)

    in Canon EOS Mount

    Posted

    The droplet listed above takes the RAW file and converts it with Photoshop. If you want to

    just extract the JPG that was saved by the camera (and you know how to compile software),

    you can get the parse.c file from http://www.cybercom.net/~dcoffin/dcraw/, and compile

    it. It will extract the JPG from the RAW file.

     

    My guess is that Google could find you somebody who has already built something for

    your system. If it's OSX, let me know and I can send you what I have built (and a script for

    automatically rotating them to the right orientation).

     

    Andrew

    20D: CF Accidentally Reformatted

    in Canon EOS Mount

    Posted

    If you're on a PC: <a href="http://www.heidi.ie/eraser/">http://www.heidi.ie/eraser/

    </a><p>

     

    On a Mac/Linux, you can try <a href="http://www.thefreecountry.com/security/

    securedelete.shtml">http://www.thefreecountry.com/security/securedelete.shtml</a>, or

    write your own (<a href="http://www.linuxgazette.com/issue63/nielsen2.html">here's

    </a> one in Perl).

    <p>

    If you want to Google search, try including "secure erase" in your search terms.

    <p>

    Andrew

    Attention iView users - Please advise

    in The Digital Darkroom: Process, Technique & Printing

    Posted

    I imported all my photos into iView about a year ago and have been using it ever since to

    manage my photos. At first it is a little daunting to catalog all the old images, but I found

    I got into a groove and it didn't take me as long as I thought it would.

     

    One thing you can try is to work in batches from the same shoot. If you go into slideshow

    mode (I have it set up to start a slideshow when you double-click on an image), you can

    use the number keys to sort the pictures. I would go through the images and assign #1,

    say, to the set of people in the first image. If the same people were in the second, I'd

    assign it to #1 as well. If they were a different set, I would assign it to #2. After I got

    through all the pictures, I'd sort by label, select all the images with the same people and

    enter the people's names. If there were more combinations of people than available

    labels, I repeated the process with the left-over pictures.

     

    Assuming your EXIF information is correct, the first thing I always do is run the "Make

    Event Date from Capture Date" script in the scripts menu. I also set it up so that when I'm

    looking at the pictures in a catalog, it shows the filename, the event date and the people.

     

    After I have all the people information entered, I reset the labels and go through each

    image again, tagging my favorites. I then select them all and enter a keyword indicating

    that they are best. Finally, I enter "Checked" in the Status field so that I can search for

    images without that Status to find ones I still need to annotate.

     

    To organize the files, I put new downloaded files in a directory named for the download

    date. The directory structure doesn't really matter all that much since you can pull images

    up by any field in iView. It only matters if you have filenames that might conflict (e.g. you

    have two cameras or you've rolled over the counter).

     

    There are also forums at the iView website where you can ask questions.

     

    Hope this helps.

     

    Andrew

    Will flash photography always come out with 400 speed film?

    in Canon EOS Mount

    Posted

    You may ask, "If the flash is so brief (1/1000 of a second or less), why is the shutter speed

    so relatively long (1/60 - 1/125)?"

     

    The answer is that the shutter works sort of like a curtain at a theater, except that the

    shutter starts out with the curtain closed by having the right curtain cover the whole

    shutter and the left curtain all the way to one side. When the shutter opens, the right

    curtain starts opening. The left curtain then starts closing after the duration of the shutter

    speed. If the shutter speed is shorter than the time it takes the right curtain to fully open,

    the sensor or film will be exposed by the slit between the curtains moving across the

    sensor or film.

    The problem with that and flash is that since the flash duration is so short, the flash would

    only illuminate through that slit. For most cameras, the shutter sync speed (i.e. the time

    for the right curtain to totally open, or the shortest shutter speed in which the whole

    sensor or film is exposed to light at the same time) is between 1/125 and 1/250 of a

    second. This is the shortest exposure that you can use without a special flash.

     

    Andrew

     

    PS. Of course, the shutter may go left-to-right, top-to-bottom or whatever, and there are

    other simplifying assumptions in my explanation, but if you knew that, you didn't need my

    explanation.

    Lens for portraits - confused!

    in Canon EOS Mount

    Posted

    With all due respect to the other fine information Brian has included, the DOF calculations

    in his last post are not correct. The page he referred to uses meters,

    not feet, so that could explain some of the error, though he would have had to enter the

    subject distance without converting from feet to meters (i.e. typed 14 for the 85mm lens)

    and then converted from meters to feet on the other end.

    <p>

    <a href="http://www.dofmaster.com/dofjs.html">This page</a> has a much more

    flexible DOF calculator (except that it doesn't do f1.2). At f1.4, which has a broader DOF

    than f1.2, shows that at 14 ft with a 85mm lens, your DOF is .69 ft.

    <p>

    Andrew

    85mm f/1.2L on 20D - need advise

    in Canon EOS Mount

    Posted

    I rented the 85 1.2 to shoot at my sister's wedding and the assorted parties around it.

    What I can tell you is that that time was not long enough for me to get used to the lens.

    I'm just warning you that after renting it, you might conclude that it's too difficult to work

    with, which might not be the case if you owned it and used it for months. The difference

    in DOF for portraits is substantial. If you or the subject moves at all between when you

    focus and when you release the shutter (even 5mm), you can be disappointed.

     

    I'm not saying it isn't a great lens. I just want you to be prepared for a longer learning

    curve than with other lenses.

     

    On the other hand, you might be much more skilled than I and adapt in days.

     

    Andrew

    Improper autofocusing on 300D...

    in Canon EOS Mount

    Posted

    The problem with autofocus is that it blindly (err... naively?) tries to maximize contrast

    under the sensor. If there are several focus distances that have roughly the same contrast,

    it will usually choose the nearer one. So far, so good. Unfortunately, if you have a

    naturally low-contrast object (say, like a face or solid-color clothing) in front of a high-

    contrast object (say, like a brick wall), the AF system sees that the best contrast position is

    to focus on the wall. As Steve remarks, choosing an AF point (can you do that with a

    300D?) that has no background nearby is a good option.

     

    My guess is that the reason you see this on the 135 and not the 70-200 is that you are

    using them for different subjects. If you used the 70-200 for the shot you posted, my

    guess is you'd be likely to have the same problem.

     

    Finally, Steve mentioned that you might try a different focal-length lens, but before you go

    out and spend money on another lens, plug some numbers into a DOF calculator. As you

    get closer to your subjects, the effect of lens length on DOF decreases. It's true that when

    using a long lens, the DOF is shallower for a given object distance, but if you want to get

    the same composition in the plane of focus with a short lens, you have to reduce the

    object distance, which has the effect of reducing the DOF. The closer the focusing

    distance, the more these two things cancel out and yield the same DOF.

     

    See http://www.vanwalree.com/optics/dofderivation.html for some math.

     

    Andrew

    Improper autofocusing on 300D...

    in Canon EOS Mount

    Posted

    At f2.0, if you have someone's face basically filling the frame, the DOF is going to be less

    than an inch. In other words, the eye might be in focus, but the tip of the nose will not.

    That's using dofmaster.com's .019mm CoC for the 300D. Now, if you expect the image to

    be "sharp" when you view it at 100% resolution on your

    monitor, you should probably use a CoC of 7.5 microns, which is the pixel size on the

    300D sensor. That would give you a DOF of around a quarter inch. This is just due to the

    laws of physics, and there is no way to take a close-up of a person at f2.0 and have both

    the eyes and the tip of the nose in focus.

    <p>

    Even if you're willing to have the tip of the nose blurry, if you are shooting handheld, the

    amount of camera movement between focusing and

    exposure may be enough to throw off the focus from what you want. If you focus and

    then recompose, <a

    href="http://visual-vacations.com/Photography/focus-recompose_sucks.htm">you're

    dead</a>.<p>

     

    My experience with lenses faster than f2.8 on my 10D is that I have to indeed take a lot of

    them to get ones that are focused the way I want them to. I don't think you're going to

    find any equipment that helps you much here (other than maybe a tripod), as it's a matter

    of optics, not technology.<p>

     

    Andrew

    Google Ad Disclaimer

    in PhotoNet Site Help

    Posted

    I've read several postings in the other forums where people question how Photo.net could

    be " supporting" a scam website that appears in the Google ad bar. To preserve

    photo.net's reputation, you might want to consider putting a simple disclaimer under the

    ad explaining that these websites are not chosen or endorsed by photo.net.

     

    Andrew

    Color Theory Question

    in The Digital Darkroom: Process, Technique & Printing

    Posted

    Chris, Mac's traditionally used a gamma of 1.8, but (at least under OSX) you can set them

    anywhere you want. I'm still not sure how what you wrote would explain needing a

    gamma of 1.6. Thanks for the gif; what gamma is it supposed to represent?

     

    Craig, at least with mine, I get equivalent shadow detail (about every other level up to

    about 20) with 1.8 or 2.2.

     

    Ellis, thanks for the hint. I had no idea that the intensity perception in different color

    channels would be so different (though I guess had I studied the RGB -> HSV conversion

    equations more closely, it may have been obvious). Using a white/black checkerboard and

    128 grey gives a required gamma of 2.3. Still not quite what I expect, but interesting.

     

    Andrew

    Color Theory Question

    in The Digital Darkroom: Process, Technique & Printing

    Posted

    I'm trying to understand the math behind calibration (I'm a geek), so I've been performing

    some experiments in Photoshop. I have an Apple Cinema Display calibrated with Eye-One

    to a gamma of 2.2, so I'm pretty confident in the fidelity of the display (I also had two of

    my images printed by a pro lab and they matched the screen).

     

    Anyway, I created a red/black checkerboard and surrounded it by a field of solid red. The

    red in the checkerboard was 255 and the solid red was 128. I then used levels to adjust

    the gamma until the tones matched. I'm not sure what I expected, but it wasn't what I got.

    They matched at a gamma of 1.6 (a resulting value of 165).

     

    Can anybody point me to a good (hopefully online) explanation of how this stuff works?

     

    Thanks.

     

    Andrew

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