Aking Litrato

Quick Tips are based on the knowledge and understanding of the contributors.  Tutorials would be mostly basic. Understanding the basics would be a strong foundation for those who want to take up advance photography.

If you find something that is confusing or if the topics need more explanation,  any comments or suggestion will be appreciated. Feel Free!

Enjoy!

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Study Guide
The Focusing Points
Image Sensors and Depth of Field: Quest 1
My RAW Workflow
Sigma DUAL FOCUS system: Quick Tips
Battery Guide for your Flash: NiCd or NiMh?

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(Archie Fresco 15 June 09)
(Photos and Graphics by Eugene S. Lim)

 A common error of having a blurred or out of focus subject is due to not understanding how the black square (boxes) inside the viewfinder works. Basically, most camera users have an idea that it is the point where they should place the subject so that it would be in focus. The little black squares are called Focusing Points (FP) that serves as a guide on focusing which are very helpful. Figure 1 and 2 shows modern SLRs having three, seven, or more focusing points. For easier explanation we will use only three FPs.

 

        

Figure 1: 3 Focusing Points and 7 Focusing Points (the circle shown is called Partial Metering Circle, not covered in this topic)

Looking at the graphic example below

Figure 2

 

 

Figure 3

FP-1 is pointed at subject Man-A

FP-2 is pointed at subject Man-B

FP-3 is pointed at subject Man-C

 

Figure 4

 

Changing to top view (Figure 4), we can see that the subjects are 5 feet distant from each other. Man-A is 5 feet away from the camera, Man-B 10 feet, and Man-C 15 feet. Man-B and Man-C are 5 feet away from Man-A.

Usually when we half press the shutter button and aim the camera towards the subject, one of the FPs would blink (lit) generally in color red to indicate that it has achieved focus. The common error is ignoring which of the FP blinked. Often as a beginner when we hear the camera beep, we immediately press the shutter button. The camera beep feature is a way of telling the photographer that the subject is in focus, but which is the subject? The camera does not know that unless we manually select a FP.

If Man-B is your main subject but the FP blinked at Man-A at the same time after hearing the camera beep you quickly pressed the shutter button, the result is Man-B will end up being out of focus (blurred) because you did not verify which FP blinked. Would you say that the lens have a problem? "My lens front/back focuses!" No it's not. Most probably it was your fault. There is a method on testing if a lens has focusing issues which we won't discuss here. Going back to the topic, if you checked first the FPs then Man-B would have been in focus.

Focus Points could be selected Manually by the photographer or Automatically by the camera.

In Automatic or Auto FP mode, the camera makes the decision for you. Like in the example, Man-B was your main subject but Man-A was the one detected by the camera. Using Auto FP is quite unpredictable, especially on most compact cameras (Point and Shoot), for the automatic FP selection based some of its calculation on scene contrast and subject distance. Often the closest focusable subject is selected automatically. This mode is a bit useable for snapshots.

In Manual or Manual FP selection mode you select any FP. You are commanding the camera to use that FP for it where your subject is. In this mode the photographer has total control and ensures that the camera will focus correctly on the subject. Again, if you used FP-2 then Man-B would be properly in focus.

When I practice or shoot, I usually turn off the camera beep so that I would be able to train my eye to verify first the scene in the viewfinder before triggering the shutter button. Also, I often use the center FP when shooting handheld while I use the other FPs when my camera is mounted on a tripod. I find the center FP more flexible to use on my style of shooting. I rarely turn on the camera beep, mostly during snapshots.

Figures 5 and 6 are examples of using focusing points

 

Figure 5: FP blinked (red dot) at left box.

Main interest is the subject's expression.

 

 

Figure 6: FP blinked (red dot) at center box.

 

The Focusing Point selection and camera beep are very handy tools. There is nothing wrong using the camera beep but it is a good practice to check first the scene to ensure that your subject is focused before taking the shot. Learning how to use these tools properly can help us create better photographs. I also recommend that during your first year in photography, try to turn off the camera beep and use only the center FP to train yourself not to be too dependent on Automatic features and for Check First Before Shooting to become a habit. Another important advice is to read and understand your camera manual. If you do these things your confidence in photography will boost up.

 

In future topics, we will discuss more basic techniques on using Focus Points on SLRs and compact cameras.

 

(Archie Fresco 07 April 2009)

 

When I first heard about the Depth of Field (DOF), literary I thought of the physical "depth" like a cliff. What is really Depth of Field? In photography it relates to focus, sharpness, and blurriness. An image that has acceptable overall sharpness from foreground to background is said to have a great DOF while an image that has a sharp subject and blurred background is said to have a shallow DOF.

 

What are the factors that influence the Depth of Field?

 

1. Aperture size (f-stop) - The smaller the lens opening the greater the DOF. The larger the lens opening the shallower the DOF.

 

2. Focal Length (FL) - The shorter the lens FL the greater the DOF. The longer the lens FL the shallower the DOF.

 

3. Distance from the subject - The farther you are to the subject you are focusing the greater the DOF. The closer you are to the subject you are focusing the shallower the DOF.

 

Any changes made from the said factors will affect the quality of the DOF.

 

Example: The wider the aperture, the shorter the FL, and the closer to the subject being the focused the shallower the DOF.

 

Now, how does the image sensor or film size influence the DOF? This is actually a question that I asked myself and turned out to be a QUEST for answers.

With today's technology, digital cameras offered different sizes of image sensors ranging from about 4 x 3 mm to 36 x 24 mm size format. Having two digital cameras, a bridge and a DSLR, I noticed that they don't give the same DOF even at the same f-stop and same FL. To find out why and how, I made comparisons and experiments.

Experiment 1: Digital vs. Digital

 

Fuji S6000fd - image sensor size 1/1.7" (7.6 x 5.7 mm)

Sigma SD14 - image sensor size 20.7 x 13.8 mm (APS-C)

S6000fd Fujinon Lens f/4 ISO 100 FL 10.8mm approx. 49mm (35mm format) Aspect Ratio 4:3

Examining the photos it is obvious there is a difference in DOF. S6000fd at f/4 has a greater DOF compared with Sigma SD14 plus 28mm lens at f/4 which appear to have less sharpness (appears blurred) at the background. Cameras were placed at the same height and distance about 3 feet away from the subject. Both photos were shot in RAW format converted to JPEG without any manipulation.

 

Mathematically, a change in image sensor size affects a lens focal length. A 30mm lens (35mm format) will be equivalent to a 51mm lens when used on a camera with a 1.7 multiplying factor which is also called as a crop factor. Does the lens physically change in FL? Actually, is does NOT. A 30mm lens (35mm format) is still 30mm whether it is used on an APS size image sensor. A small sensor does not make the FL longer it just crops the image when used with a lens with a larger image circle. Small sensors technically have lenses that uses small image circle (click here).

Yellow - Full Frame Size, Red - APS Size, Blue - Image circle

 

Before everything gets confusing, as said FL is a factor that influenced DOF.

 

Analyzing the f-stop formula

 

f-stop = Focal Length / Aperture Diameter

 

f/8 @ 28mm lens is not the same with f/8 @ 50mm lens though they have the same f-stop value, the actual diameter is different. The longer FL will have a shallower DOF. At f/8 the actual diameter at 50mm will be bigger than that of the 28mm.

 

This leaves me a theoretical answer that a lens FL should be proportional to the image sensor or film size to attain the same DOF with other format size. Again, a 35mm full frame f/16 DOF is not same with APS f/16 DOF even if both uses 50mm lens (35mm format). This I will search and discover in Quest 2.

 

Maybe you could help me quest for the answer.

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(Archie Fresco 30 March 2009)

 

When using JPEG the camera's computer edits the RAW image and do the adjustments automatically; exposure, contrast, color, brightness, sharpening, white balance, and then converts-compresses the RAW file to JPEG making it a smaller in terms of bytes. Using this file format, the photographer has only 50% control over the image (composition & exposure) the remaining 50% is done by the camera (editing). JPEG in-camera processing is analogous to color film negative process; the photographer exposes the film and brings it to photo lab which does the film processing and printing.

 

Note: All digital cameras captures RAW file but most compact cameras does not save RAW files.

 

For high quality images, shoot in RAW.

 

My RAW WORKFLOW

 

RAW ---> TIFF ---> JPEG

 

Software

 

Sigma Photo Pro 2.5

Adobe Photoshop Lightroom 2.0

Nero Photosnap Viewer

Microsoft Photo Editor

Nero Smart Essentials

 

RAW File Adjustments

Sigma Photo Pro 2.5; Basic adjustments like exposure, contrast, shadow, highlights, saturation, sharpness, fill light, and color wheel (White balance).

Files are saved to RAW folders.

 

RAW File Conversion

Sigma Photo Pro 2.5; After doing the adjustments, RAW files are converted to 16-bit TIFF. TIFF is not compressed.

Converted files are saved to TIFF folders.

 

TIFF File Adjustments

Adobe Photoshop Lightroom 2.0; cropping, exposure, contrast, shadow, highlights, saturation, sharpness, fill light, noise reduction, color, spot removal, chromatic aberration correction, dodging, burning, and curves.

 

Lightroom has an easier workflow than Photoshop Elements and CS versions. All the necessary tools for photo enhancements are included but no advance features like layers. Lightroom is basically resembles a Darkroom.  The software is intended only for photographers who are more into shooting than editing.

 

TIFF File Conversion

Adobe Photoshop Lightroom 2.0; 16 Bit TIFF is converted to the highest quality JPEG. Photo Labs only accepts JPEG for printing. TIFF files are initially reviewed at slide show feature of Lightroom before exporting into JPEG.

Converted files are saved to JPEG folders.

 

File Review

Nero Photosnap Viewer; After converting to JPEG, files are reviewed if further adjustments are needed. Files are reviewed 1-3 days. Viewed at morning, afternoon, night, lights off, and lights on. This is to ensure that colors look pleasing when viewed at different lighting conditions. Files are viewed 2 feet away and also 10-15 away from the monitor to ensure that the photo looks attractive. A photo that does not catch attention from that distance is deleted or adjusted. High Quality is a MUST. Reviewing photos is editing and quality control. If no more adjustments, files from JPEG folders are copied to TO BURN folders for back up.

 

Back Up

Nero Smart Essentials; Photos in JPEG are saved in to two DVD disc.

Disc A for frequent use, Disc B for safe keeping in case the other one fails.

 

Web

Microsoft Photo Editor; JPEG files are converted to smaller size for web posting.

 

Files Sizes

 

RAW - 10MB to 20MB; untouched

TIFF - 25MB to 100MB; processed

JPEG - 1MB to 15MB or more depending on image dimensions (sampling) and compression.

 

RAW processing can take 1-7 days depending on the number of files. One RAW File editing takes about 15 to 120 minutes.

 

Sample Photo

(Archie Fresco 15 January 2009)

Here is a short guide that you may find helpful.

Materials Used

Sunpak 383 Auto Super . Tested its recycling time on NiCd and NiMh batteries.
Fully charged batteries (Note: properly drained and charged based on manufacturers recommended charging time and charger specs)

4pcs - Powerbase NiMh 1800mAh 1.2Volts
4pcs - Powerbase NiMh 2100mAh 1.2Volts
4pcs - Powerbase NiMh 2600mAh 1.2Volts
4pcs - Powerbase NiCd 900mAh 1.2Volts

How I Tested it?

I fired 3 initial Flashes on full power before I measured the recycling time. This is to warm up the flash. After firing the fourth flash, about half a second I press the clock timer.
I did this up to eight flash burst but not consecutive. I stop 5-10 seconds after every flash burst.

Results

On the 3 sets of NiMh (1800, 2100, 2600), the recyling time of the Sunpak 383 goes up to 8-10 seconds
On the NiCd 900mAh, the recycling time goes up to 4-5 seconds. A very big difference.

Explanation

I read in most websites that NiCd has a lower internal resistance than NiMh batteries. Resistance in electrical terms means it limits the flow the current. Though both type of batteries has the same voltage rating of 1.2Volts, NiCd's rate of current flow is faster but when it comes to hours of usage, example both NiCd and NiMh are 1000mAh, NiMh wins.

Conclusion

Old Manual Flash users would benefit from the faster flash recycling time using NiCd.
Some flash units that can use NiCd based on manufacturers specs

Sunpak - all models
Vivitar - all models
Sigma - all models including their latest the EF530 DG ST/Super
Old model Canon, Nikon, Pentax, etc

Latest Canon, Nikon, Pentax flashes. Check manufacturers specs and recommendations. Using NiCd won't harm your flash unit but it is a good practice to check manufacturer's data. Read the Manual. Anyway these flash units uses NiMh and has recycling time of 1-5 seconds at full power which is enough for your daily needs.

I checked every hardware shops near my workplace and home but Powerbase NiCd is only brand that I found. Cost only 99 pesos (approx. US$ 2) a pair, cheap? YES!

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