Thoughts on Photography

What is my Ideal F-Stop?

Last year I decided to use the URL "idealfstop.com" to set up my website.  So I guess its time to start talking about "what is an ideal f-stop?"  There are at least two answers to this question.  From the creative perspective, the ideal f-stop is whatever you think is best.  But I'm not interested in that discussion.  Rather, I think its useful to understand the technical answer to the question.

Every lens we have in our bag has a "sweet spot" - the point at which the lens is the sharpest.  It almost never occurs with the lens aperture wide open, but rather when it is stopped down a bit.  For each lens, this will be a different setting.  Some lenses are incredibly sharp at f2.8, while others need to go to f8.0 to reach their peak.  Wouldn't it be useful to know this information about each of your lenses?

As a fairly lazy photographer, I just don't feel like doing the complex lens tests to figure all of this out.  Maybe someday and when I'm old, fat and unemployed I will do this; but right now.  I just want some quick answers.  So I visited one of the better websites for lens reviews, took their data and made a short list of my lenses and their ideal f-stops.  If you are interested in doing the same, I highly encourage a visit to www.photozone.de. 

Here are the results for the lenses in my bag:

                       

Lens	Ideal f-stop
Sigma 20mm/f 1.8	8
Canon 24-105mm IS / f4.0	5.6
Canon 50mm / f1.4	2.8 - 4.0
Canon 85mm / f1.2	2.8 - 5.6
Canon   200mm / f2.8	5.6

Two cool & affordable things to add to your camera bag

I've purchased a couple of items recently that I've been happy with and thought I would share.  Both are under $40 and worth the money. 

First is the UPstrap camera strap.  I'm late to the party here, but if you haven't heard of this yet, just go out and get one.  There isn't a better no-slip, sling it over your shoulder camera strap on the market.  I love this thing.  You will find them at www.upstrap-pro.com.  I bought the "SLR-Classic" for $32 + shipping.  For a more in-depth third party review, check out this Luminous-Landscape Article.  This thing doesn't even come close to slipping off your shoulder.  I've walked the dogs while using it and not once did I feel like I had to reset the strap back on my shoulder to avoid having the camera fall...it just won't. 

Second is a cool new item that is necessary in today's digital age:  A depth of field calculator.  In the old film days, there used to be no need for these things because the scales were available right on the lens. All you had to do was look at the marks on the scale that corresponded to your f-stop and immediately, you knew how much of the scene would be in focus. 

But with digital, each sensor crop factor (1.3x, 1.6x, etc.) requires a different scale.  That's why we no longer have scales on our lenses (a sacrifice for us full-frame 5D users who could have used the old scales).   Well the makers of the Expodisc have provided a flexible and pocket sized solution.  You definitely need to check this out.  It's called the ExpoAperture2 Depth-of-Field Guide.  I picked up one at my local camera shop (listed as a dealer on the Expodisc website) for $29.99.  I can see where a portrait photograph would find this tool to be indispensable.  After just two days with this little tool, I find I'm thinking much harder about my choice of aperture and the impact of distance-to-subject & lens focal length will have on my finished image.  I could go on, but you just have to sit and play with this thing awhile to see how it starts the creative juices flowing. 

Circular Polarizers - Part 1

So I had an eye opening experience last weekend.  I'm out walking with my faithful photo assistant Abby (my Jack Russell Terrier) and I decided the day was going to be a worthless photo-outing since the sun was out and there was not a cloud in the sky.  Instead of wasting the day, I decided to have some fun experimenting with my circular polarizer.  One of the functions of a circular polarizer is to make skies more blue when it is rotated just the right way.  Another function is to reduce/eliminate reflections on glass/water/foliage.   On this day, my intent was just to see what I could do with these big blue skies that were ruining the potential for getting a good "melancholy" image.   So I shot off a couple of frames with the polarizer turned a bit each time. Turning a circular polarizer changes the intensity of it's effect on the scene. 

Here are my results:

Wow! What a difference.  This little circular polarizer works some kind of magic.  It has made the colors more saturated.  But it has also done something else, which I consider even more valuable.  Let me explain.

When I look at the two images above, one seems to have a higher dynamic range.  How can image two seem to have a higher dynamic range?  If you look at it, the trees and power lines are less of a silhouette and have more color than in the first image.  The bricks on the house are showing detail that is lost in the shadows of the first image.  You see much less blocked up (blacked out) shadow area in the second image.  Just look at the tree on the right side of the image to see what I mean. 

What has happened here is that by darkening the blue sky which is dominating the frame, the polarizer forced me to use a slower shutter speed.  On the first image I think I was at 1/180 second and the second image, closer to 1/60 second.  By darkening just the sky, the polarizer is working much like a Graduated Neutral Density filter would do.  Except with a GND filter, you are usually just darkening a general area of an overall image.  The Polarizer is selectively choosing to darken just the sky in this image.  What that then allows me to do is use a slower shutter speed and give more exposure to the shadow areas resulting in more detail and color in the image.

It's like using HDR software without the hassle and artificial effects that the software produces.  All of a sudden, I'm very curious about how this circular polarizer may change my attitude toward sunny days.  I plan to do a more controlled study, with and without the polarizer (the two images here both had the polarizer on the lens) and also compare the results to something I might be able to do using software after the fact.  In addition, I plan to do some work on how the polarizer reduces reflections, but that seems less important to me at the moment than the possibility of creating HDR in-camera with just one image. 

Bokeh for Dummies

"Bokeh":
- a Japanese word - the transliteration of a Japanese word for "blur" - describing the subjective aesthetic quality of out-of-focus areas of an image projected by a camera lens.  (I stole this from Wikipedia) 

"Bokeh for Dummies":
- a layman's interpretation - concerning the out-of-focus area of an image - How silky smooth is it?  How pleasing is it to the eye?    How seamlessly does it seem to transition from the in-focus area of the image?  (I stole this from one of my own brain cells)

My definition is technically not correct.  But art isn't always about the technicalities.  So if you are so inclined to learn all the technical aspects of bokeh, read this or this or this or even this.   At the end of the day, I'm really not very interested in the technical aspects of bokeh.  However, I'm greatly interested in the subjective aspects of bokeh.  Because art really is subjective in the end, isn't it?

Just for fun, I decided to try a very unscientific experiment with a couple of my own lenses to explore this subjective side of the whole bokeh concept.   I used the Canon 85mm f1.2 prime lens and the Canon 24-105IS f4.0 zoom lens set at approximately 85mm.  I set the same shutter speed for each comparison image and used an f4.0 aperture on both lenses.  Below is a sample from the test (click thumbnail for a larger image).   

All of the images can be seen in the Bokeh Test Gallery

The results were predictable from the standpoint that the 85 prime lens seems to offer a smoother transition from in-focus to out-of-focus areas in the image.  It also seems to have a softer, silkier bokeh versus the zoom lens.  The comparison images are a good way to look at the details, but what I find more enlightening is to flip back and forth between the full sized images in the Bokeh Test Gallery and get an overall experience of the difference.  For me, the 85 prime's bokeh just feels easier on the eyes. 

Something interesting to note is that even though each comparison photo was shot with the same shutter speed and aperture settings, the zoom lens produced a noticeably darker, more contrasty image.  In this way, it's not helping itself in the bokeh contest. 

I'm not sure if these results will hold true with all of my primes versus my zooms, but I intend to explore this further. 

Buying Camera Equipment - where to put the money

As a person who has spent way more money on photo equipment in the last three years than I thought I would in a lifetime, I've come to appreciate where my invested dollar is treated best.  I entered the digital age of photography three generations ago (or about 3 years ago) with my purchase of the Canon 10D.  Since then I've owned a Canon 1dMKII, which I eventually sold to buy my current camera, the Canon 5D.

My advice...INVEST IN LENSES.  They hardly become obsolete and are compatible each time you upgrade your camera body with the same manufacturer (with the exception of Canon's -s series lenses).  The lens is the key component for unlocking creativity with your photography.  In general, I prefer primes over zooms with the largest f-stop I can afford.  Primes are usually more affordable, give superb image quality and generally offer larger f-stops, giving you a world of creative possibilities.   

But here's the real key...if you ever decided to sell a lens, you can get up to 90% of what you paid for it when you resell it (assuming you've taken good care of it).  For example,  I recently sold my 17-40mm lens after owning it for three years.  I got 85% of my original purchase price.  In contrast, my three year old Canon 10D (which I bought at the same time as the 17-40mm lens) won't even bring $500 on the resale market, 1/3 of what I paid for it new.   

As PMA approaches, one thing is for sure, camera bodies (or more specifically, camera sensors) will continue to evolve at a rapid pace.  This cycle makes the camera body the worst place to "trade up" due to the severe depreciation.  Lenses are like money in the bank.  You can't rent a lens for three years as cheaply as you can own it and then resell it. 

That's my two cents.