Hey Doc

(Test pattern)

All modern cameras are capable to perform auto focus. Regardless of which method the auto focus is based on, there will be some discrepancy. Commonly refers to as front-focus or back-focus. Front-focus means the auto-focus plane is in front (closer to the camera) of the intended point, Back-focus means its in the back. This discrepancy is within the lens used. Few professional digital cameras have the ability to manually make the adjustment for each lens used on that camera. I have learned a way to test for the lens. Here is how.
1. Open this test pattern on your monitor, make size adjustment that it fills the entire screen.
2. Place the monitor 45 degrees angle in the direction where the camera is pointing.

Camera ---------- \ (monitor)

3. Mount the camera on a tripod. Place the tripod at the location that the test pattern is filled the entire viewfinder. Set the camera to shutter priority.
4. Set the auto focus sensor at the center of the picture, where the "|" bar is located.
5. Select widest aperture on your camera (example f2.8) and activate the auto-focus by pressing halfway down the shutter button. Move the camera back or forth slightly then focus again and take the picture.
6. Follow the procedure for each setting if you are testing a zoom lens.
7. Upload the pictures to your computer and use the image viewing program to see the results.



Here is the result of my Sigma 70-200mm zoom lens at 100mm setting. Clearly the auto focus plane is between the center bar and the number 1 (it is front focus of one degree). If I want, I can make this adjustment in my Nikon camera so the auto focus will be compensated for this lens. Make sure all settings are tested and averaged. Since the offset is not that great for this lens, I will not make any adjustment because, remember, don't fix it if it ain't broken.

North Beach, Columbus + Vallejo, San Francisco

Balclutha is a square-rigger sailing ship. Permanent exhibit at the foot of the Hyde street, San Francisco. A little history of the ship follow the link.


Aquatic Park, San Francisco. Showing the Balclutha in the background. It is also the site for the Maritime Museum.



Imagine this is mid 1800's, tall ship like Balclutha filling the bay of San Francisco. Check out these historic photos of SF Bay.



Fog at the GGB

San Jose Henry's Hi-Life serving BBQ since 1960

The second print of my photo book is arrived. I have added 40 more pages to beef up the contents. I really like the quality of the book. I chose using the premium quality paper this time. It really made the difference on the feel of each page. There are few things I learned to ensure the photo quality for the final print. The images need to be saved in sRGB color profile. Most print shop uses sRGB in their printing machine. This way, the image color will stay the same as you see on your PC monitor. Keep the image resolution as high as possible between 240-300 dpi, and the JPEG compression at minimum. Downside of this is your final book file will be huge. My book file is 75Mb big. Since the file will be uploaded to the publisher, it took a little while on my ADSL line. For the hardcover 7"x7" was over $30 per book. If you want, Blurb will advertise and sell the book for you.

Blurb.COM is the publisher. Highly recommended !!

Picture window at Children's Discovery Museum

I use a prepaid cell phone only when I am visiting in US. Unlikely that my phone number was pasted all over the places. But, I have been receiving calls from a recorded message telling me that my car warranty is to be expired, by the way, I don't even own a car. Interestingly, the caller ID varies on every call. It can be from out of state to local. I ran a search on the numbers and found I am not the only one getting this type of calls. Some people indicated that they had replied to the call but got no further reactions, even asked to be removed from the call list. Obviously it is some kind of scam but for what purpose? other then wasted a minutes from your calling time. I stopped answering calls from numbers I don't know.

I think Google and Yahoo alike, gave us a tool to do the things we can't even imagine 10 years ago.
Thanks!!