What is a Sweet Spot, and How Do I Find It? (11/9/11)
f/3.5
f/5.6
f/8
f/11
You have probably heard the term before. “The lens’ sweet spot is…” Almost every lens has one. The sweet spot is the aperture setting
or range of aperture settings at which your images are sharpest. For most lenses, it is somewhere in the
middle range of aperture settings for a given lens.
For example, with my Nikon 105mm f/2.8 macro, the sweet spot
for me is from f/8 to f/11. Now I
do love the wonderful soft focus that f/2.8 gives, but my images are not their
sharpest at this aperture setting.
As I go above f/11, once again the image quality is not to my liking. This is not to say that I cannot get
perfectly fine images at other aperture settings, and I very often use other
settings for a particular effect, but there is a certain change in the sharpness
as I move away from the f/8 - f/11 range.
So, how do you find the sweet spot of your lens? It’s really quite simple.
First, choose your lens (in my example here, I am using my
Nikon 105mm, f/2.8), and mount your camera on a tripod, or place it on a steady
surface to minimize camera shake.
If you do not edit in a program that will reveal your EXIF
data (aperture setting, shutter speed, ISO, etc), then be sure to have a piece
of paper handy to write down your aperture setting for each shot.
Set your camera on Aperture Priority (this allows you to
choose the aperture, and your camera will choose the required shutter speed),
and open the aperture as wide as possible for your particular lens. If you are not sure what your widest
setting is, you can usually find it right on the lens. I started with mine at f/3.5. Its widest is f/2.8, but I wanted to
minimize the number of photo you need to look at here. Now go ahead and take your shot.
Without moving the camera or recomposing your subject, close
the aperture a bit, and take another shot. Continue in this way closing down a bit with each successive
shot (f/5.6, f/8, f/11, etc.). Go
as far as you would like. For the
lenses I have, I usually don’t go much beyond f/16, but I encourage you to go
beyond that if you can, to see the results.
Now all you have left to do is review your images. Although not absolutely necessary, if
you can view your images at 100% resolution, it will be easier for you to note
the changes. You should be able to
see at which settings your lens is sharpest, and at which settings this
sharpness seems to change. Once
you’ve determined these settings, you’ve found the sweet spot for your
particular lens!
Notes:
The Iens I reference here is a prime lens (having one focal
length). If you are using a zoom,
you will need to set it to one focal length and leave it there as you increase
or decrease your aperture settings.
Once you find the sweet spot for a particular focal length, it will
usually be for that focal length only.
To find the sweet spot for other focal lengths just repeat the process
using your choice of focal length.
To keep from showing a long series of photos here, I have
posted only four, which I felt was the minimum number to give you the basic
idea.
The Rule of Thirds and The Golden Rectangle (9/26/11)
At the risk of scaring you away, today we are having a little math lesson.
Now hold on!!! Come back here! There, now that's better. I'll wait for your breathing to slow down.
Google Images
But did you know that The Rule of Thirds is based on an ancient mathematical concept? It is, and that concept is called The Golden Rectangle. The Golden Rectangle is a rectangle whose sides are in a specific proportion to one another. Architects, artists, photographers, and many others use it. The Golden Rectangle creates what is referred to as symmetrical beauty. A perfectly rational concept, yes?
Enter mathematics. In mathematics, an irrational number is a number whose decimal form does not have a pattern, and goes on indefinitely. A very popular irrational number in mathematics is Phi. The decimal form of Phi is 1.6180339887... The sides of a Golden Rectangle are based on Phi.
In other words, if when you divide the length of a long side of a rectangle by the length of a short side, the result is 1.6180339887… then you have a Golden Rectangle!
So that little grid you see in your viewfinder? Just a series of 9 Golden Rectangles!
There you have it! A perfectly rational concept (The Rule of Thirds), based on a completely irrational number (Phi)! Kinda cool huh? It's okay, you can say no!!! :-)
Tripods (7/6/11)
Last week I received a comment from the lovely Anna from Alchemy of Art. She asked if I might do a post on tripods, as she is in the process of purchasing a new one. Now I do not have a vast amount of knowledge on tripods, but I can tell you about mine, and my experience in purchasing it.
From the time I became seriously interested in photography (about 6 years ago), through my trip to Vermont this winter, I was using a tripod that I picked up in a small camera store just outside of NYC. I really did not know what to look for at the time I bought it; I just knew my camera needed a “stand!” I also did not want to spend much money on one, so I saw one that seemed to look okay, and bought it. Now since I rarely used it, it worked just fine for me!
Well, things changed A LOT. Long story short, in Vermont I found that it was easily blown over by the wind, and I also seriously bent a leg on it while attempting to slam it into a snow bank to photograph a covered bridge. I had also realized that as much as I did not like (still do not like) using one, it really is quite necessary a lot of the time.
So the search was on, and these are some of the things I learned.
Like any good piece of photographic equipment, a tripod costs money, and for the most part, you get what you pay for. The most expensive tripods are usually constructed from carbon fiber. Why? It is extremely light (relative to other materials), and is really quite indestructible.
You want to pay very close attention to the weight limit. If you are shooting wildlife with an 800mm lens, you don’t buy a tripod that is meant to support 4 lbs. maximum.
Once you open the tripod, is that it, or can you adjust the angles of the legs?
What about the height of the tripod? When fully extended, will you still have to bend to look through the viewfinder of your camera? This can get mighty uncomfortable very quickly.
How quickly can you go from folded to set-up? A few seconds, or several minutes?
Now some tripods come with attached heads, but many do not. If you will be purchasing your head separately, you need to think about that also. For example, do you do a lot of panning shots? If so, then you will want some type of panning lever on the head in order to be able to pan more easily.
Are you okay with unscrewing your camera from the tripod each time you do not want to use the tripod, or would you like to be able to just flip a lever to disconnect it from the tripod (quick release)?
Don’t forget that the head adds weight, and sometimes a substantial amount.
I know this may sound like a lot, but once you decide on and purchase the tripod, you will probably have it for a very long time. I somewhat liken the purchase of a tripod to buying a pair of shoes. You can do so online because you like the way they look, but you hope for the best once they arrive. Why? Even though the size may be your size, not all shoes fit the same. So the one best tip I can offer you is that if you are at all able to do so, go to a good camera store, and try some out. Be sure to take your camera with you with your heaviest lens attached to it. If you are unable to do this, check into some of the online companies that allow you to borrow photographic equipment. If all else fails, be sure that you order from a company that has a “return if you don’t like it” policy. Many larger online photographic stores are quite understanding about this.
Now, what do I use? I have a Manfrotto 055XPROB tripod. It is aluminum which means it is not light. Because I do mostly macro, it has a center column that can be flipped into a horizontal position, and legs that can be opened to a 23-degree angle from the ground.
The head I use is a Manfrotto 498RC2 quick release ball head. On top of the head is mounted a macro rail. If you are wondering what a macro rail is, it is a set up that allows you to move your camera backward, forward, left and right, by just the tiniest, tiniest amount. If you’ve done any macro photography, you know how important this is, since at times the difference between in-focus and out-of-focus is miniscule at best.
Bottom line? I am working with a relatively heavy set-up, but for me it works. I love the set-up I have and the only real “complaint” I have is the weight, but only carbon fiber would have alleviated that, and I did not want to spend that kind of money. I’d rather save it for a new lens, and hey, if I’m walking long distances with it, I’m getting a workout at the same time!!!
Macro Lens Alternative, Part 2 of 2 (6/2/11)
So maybe you’ve decided that reversal rings are not for you. Do you have other alternatives? You do, and one very good one is the extension tube. As I mentioned in Part 1, this option will cost a bit more. I have a set of Kenko extension tubes. They come in a set of 3 (12mm, 20mm, and 36mm). The current cost is about $179.00 for the set. There are a host of other manufacturers, but be careful when looking to buy them. You want to be sure that the ones you purchase are for your particular camera (Nikon mount, Canon mount, etc.) and that once the tubes are mounted, you will still have use of your camera’s metering system. There are many out there that when mounted, render your cameras metering system quite useless. They are simply tubes with no electrical components. Some people even make their own out of cardboard tubes. I don’t suggest this!
Extension tubes are just what they sound like. Tubes. They look similar to a lens, but there is no glass. The tube or tubes mount to your camera just like a lens would, and then your lens is mounted to the extension tube, again, just as if you were mounting a lens on your camera. It really does not take much more time than changing lenses. Once you’ve done this, you are ready to go!
The set-up I use is my Nikon 50mm, f/1.8 with one or more (you can use one or stack all 3) of the extension tubes, depending on how up-close and personal I want to get. What the extension tubes give you the ability to do is to get closer to your subject. For example, with my 50mm, the minimum focusing distance is 1.5 feet. Depending on my choice of extension tubes, I can almost touch my subject with the lens when using them, and still be able to focus. Again, as I mentioned previously, I do not use the focusing ring, but move in and out on my subject to focus. I have found that this is almost a necessity with the extension tubes.
Now are there any downsides to extension tubes? There are some, but I can honestly say that none of them have been even the smallest issue for me, and I absolutely love using them. Of course, they will not replace a dedicated macro lens, but you’d be amazed at what you can do with them, and just how close you can get.
So here are some downsides for you:
You will lose some light, and you will lose more light when using all 3, than you will when just using one. Of course, this means a slower shutter, and more chance of introducing “camera shake” because of that.
You will be unable to focus at a distance when the tubes are attached.
You will quickly notice how narrow the field of focus is, and you will have to be very patient with yourself until you get a feel for using them. You will get something into focus, hold your breath, get ready to press the shutter, and in that split second…poof, it’s gone! Out of focus! But hey, you did not get where you are today without practice right?
Okay, so now we’ve discussed two alternatives to a macro lens; reversal rings and extension tubes, and you may be wondering, what is my personal preference? Definitely the extension tubes, although it will only take a minute on Google or another search engine to find those who swear by reversal rings. It’s simply a matter of preference and cost, and it’s always a good idea to do a lot of reading before making a decision.
The photographs here were done with the 50mm lens and a single 36mm extension tube. The Columbine bud is a good example of just how narrow the field of focus can be.
Macro Lens Alternative, Part 1 of 2 (6/15/11)
For those of you who have been visiting here for a while, you know that most of my work is done with a macro lens. The macro lens I use is a Nikon 105mm, f/2.8, and this like most other dedicated macro lenses, is not inexpensive. So what if you simply have an interest in trying macro photography? That is, if you’re not sure it’s something you truly want to pursue but would like to try it without the rather large expense?
One way to do this would be to borrow a lens. There are a few online stores that allow you to do this. As a matter of fact right now I am borrowing a Nikon 24-70, f/2.8. This is a hugely expensive lens that I am considering, and I want to be very sure before I make the decision to actually buy it. I have had it for two days, and I can say that it will more than likely “need” to join my lens family! It’s an amazing lens!
Okay, so you could borrow a macro lens or you could use something called a reversal ring with a lens you already have. The setup that I use is a Nikon 18-105mm f/3.5-5.6 with the reversal ring, but I have also used a very inexpensive yet wonderful Nikon 50mm f/1.8 with excellent results. The reversal rings cost about $15.00 online from B&H Photo, or other online photo stores, and they can also be purchased on E-Bay for about $5.00 (from Hong Kong).
So how does it work? It’s really quite simple, but first, be very sure to purchase the correct size reversal ring for your lens, and of course the correct mount for your particular make of camera (Nikon, Canon, etc.). The reversal ring is mounted to your camera, and your lens is mounted backward onto the reversal ring. Now you need to be very careful here because once your lens is mounted this way, all of the electrical connectors on the lens are now exposed, and you don’t want those to be damaged.
Now you are ready to try it out! This means LOTS of test shots. Begin by using the largest aperture possible for your lens (for me with the 18-105mm lens, f/3.5), then play with different shutter speeds, keeping in mind that using the reversal ring means you lose some light. When using a reversal ring, focusing is also different. The field of focus is very, very narrow. To focus, move in and out on your subject until you see what you like in your viewfinder. This is my choice of focusing for macro shots whether or not I am using a reversal ring. I rarely, if ever use the focusing ring on my lens, and auto focus is almost out of the question for me in macro photography. As with all macro photography, there is the tiniest difference between in and out of focus, so patience is key! Of course, a tripod will help with this, but unless I am being really particular, most of mine are done hand held.
There you have it! A much less expensive journey into macro photography. Of course, if you know that you are seriously into learning macro photography, then a dedicated macro lens is the way to go, but to just check it out, this might be a possibility for you.
At some point next week (I’ll try for Wednesday again), I’ll do a post on another alternative to a dedicated macro lens. It’s slightly more expensive, but if you are uncomfortable about reverse mounting a lens (I sure was!!), then this may be something more comfortable for you.
Now about the photos here. The first one was taken with the 18-105mm, at about 50mm and is SOOC. The selection in the black box was the flower I intended to focus on once the reversal ring was attached. The second one is of that particular flower taken with the same lens reverse mounted. I did a crop (because I did not like the way I composed it) and added a slight blur (because you KNOW I like that!) in CS5. Not too bad huh?
Barely There
Depending on the equipment you use (Nikon, Canon, and a host of others), your camera or the lenses you use may have built-in image stabilization. For example, Sony DSLRs have image stabilization built into many of their cameras, while Nikon offers many VR (vibration reduction) lenses.
Now for the most part we all want sharp images, and we all know that to get this, a tripod or a very fast shutter speed is usually necessary to minimize the effect of camera shake on your photographs. So, if you have some sort of image stabilization either built into your camera or lens, AND you use a tripod, you must be doubly insured of getting those tack sharp images, right? Maybe not.
To understand why, you need a basic understanding of how image stabilization works. Image stabilization is meant to seek out and reverse camera shake. The process of determining this shake is carried out though a series of very tiny vibrations within the camera or the lens. When camera shake is detected, the vibrations stop, and your image stabilization system reverses the shake as much as possible, given the current technology.
