Hardware Review: Sigma 18-250

Lens reviews are at the heart of any photography-themed blog, and today is the review of the Sigma 18-250…with it’s wide focal range, this is a key lens to have in your bag if you want your SLR to reach it’s best potential.  While Point and Shoot and camera phones may be great for some scenarios, it’s the bigger sensor size of the SLR that will garner you better photos…yet these photos are only as good as the glass they’re captured through!  So, without further ado, let’s take a look at the Sigma 18-250! Read more

Hardware review Sigma 85mm f1.4

Low Light - Hand held fire light

For today, I am happy to bring to you the latest hardware gear review – from none other than the folks at Sigma, with their 85mm f1.4 lens.  Let’s just jump right in:

1.  Focal Length – I’ve talked at length on the blog before about fixed focal length versus variable length zooms.  Their differences, both pros and cons of each are duly noted, and for the most part, I think we can skip the formalities of the technical explanations.  It’s an 85mm lens.  This means you are not going to be able to zoom with the lens, rather with your feet.  It also means that you will gain pros in IQ (See #8 below).  Normally I am shooting with either a 10-22 for wide angle landscapes or a 70-200 for portrait work, so this took a bit of adjusting.

When I did shoot portrait work, I kept on having to step further back to bring more of the subjects face into the scene, and with landscapes, I found myself rotating into portrait position (vertical) and instead of trying to get everything in one shot, rather capturing several shots, with the acceptance that I would have to stitch together in post production.

It’s not perfect for either, but a good compromise in focal length to try and meet the needs of both ends as much as possible.  If I had to choose my favorite focal length, it probably would not be an 85mm, but there are very subjective reasons for that, which probably aren’t as relevant here, so I will defer that for another post.  The focal length is what it is.  You either like the length or you do not.  I was middle of the road on it – sometimes I liked it, sometimes I didn’t.

In the end, I think the focal length was fine for most purposes.  Even

2.  F-Stop Range – This is the reason I want this lens.  Stopping all the way open to an f1.4 gives you amazing results from two key perspectives:

  • Depth of Field – When you shoot with a low depth of field, the subject is very easily separated from the background.  This also brings up the subject of bokeh quality, and here I was quite impressed as I didn’t see any evidence of jagged lines or aperture opening sizes, which is often characteristic of cheaper lens builds.
  • Low Light photography – Low light photography to me means shooting at or near dusk, or in an incandescent environment where you don’t want to introduce flash.  You don’t want to be a part of the scene.  The photographer wants to blend into the background and be as unobtrusive as possible.  Lenses with low f-stop ranges allow you to do this, and the Sigma 85mm f1.4 is no exception!

3.  Noise – The motor on this lens is as quiet as one would expect for current technology – whisper!  I never heard anything that would cause a distraction, and at this point I am actually considering upgrading the Sigma Macro for this reason – the quieter the operation, the easier it is to concentrate on what you are shooting!

4.  Size/weight – About what would would expect for this focal length and aperture.  Remember, the lower the aperture (f1.4) the beefier a lens will have to be, because elements will need to be thicker in order to have any sort of stability.  It made for near perfect balance in conjunction with the 40D.  On a larger camera like the 5D or 1Ds Mark IV, I could see where you might not have as much a balance, but for my purposes, it works!

5.  Build – Patented and as expected, the water resistant housing, and non-slip grip that is now almost a trademark feature of Sigma was present so no surprises there.  I always enjoy shooting with Sigma gear because the heft of it just feels solid in my hands.

6.  OS/IS/VR – There is no built in motion correction here, which is what I collectively use to refer to the proprietary features of Sigma, Canon’s and Nikon’s camera shake correction technologies.  ALthough I should probably share that OS = Optical Stabilization (Sigma), IS = Image Stabilization (Canon), and VR = Vibration Reduction (Nikon).  Since this lens doesn’t have this motion correction feature, there’s really not much to discuss here.

The one note I would have is that when shooting with this lens, the benefit is primarily in that you can shoot at f1.4 which lets in a lot of light.  To that end, the need for motion correction is probably not as needed, except for the most exceeding low light scenarios, but you’ll see in a minute, that’d have to be pretty darn low!

7.  Cost – For the benefit of shooting at f1.4, the price of admission is hefty indeed.  B&H Photo prices it out at $969.  Since this is a new lens in their lineup, you likely will not find it for much less than this, as there is no aftermarket yet to speak of.

8.  Image Quality – Here, as always, I like to let the images speak for themselves.  I’ve tried to include a few samples that demonstrate both the depth of field capabilities and the low light performance.  Keep in mind – every image here was shot hand held!

Shallow DOF on Sigma 85mm f1.4

Shallow DOF #2 on Sigma 85mm f1.4

Selective Focus on the 85mm

Low Light - Handheld Sunset

Low Light - Hand held fire light

Fishing with shallow DOF

*Editor Note*  This review was done back in 2011, but still holds today after another rental session with this lens.  My review still stands!

Understanding Focus

Canon USM Feature Explained

A friend recently asked me why his camera was so slow to focus.  The answer naturally started with (as do most answers in photography) my standard phrase, “It depends…”  I realized after my conversation with him that this would be an excellent topic for exploring here on the blog.  So, today, we’ll be taking a look at focusing concepts in your camera gear.  To start off, it probably makes the most sense to identify that there are focusing features both on your camera, and on your lens.  On cameras, it’s most often referred to as the “auto-focusing system” or AF.

AF Systems

Canon 7D AF System

The above AF system comes from the Canon 7D, but generally speaking, newer cameras will have better AF systems than older cameras.  What makes them better is the presence of more AF points.  The more points the sensor has, the easier it is to identify a point to focus on.  The AF system identifies these points based on contrast between light and dark, so reflected light does matter to a degree as well. The bottom line though is that with more focusing points, more focus detection, better contrast algorithms, etc. and better sensitivity to light will allow a camera to find a subject quicker than its older counterpart with fewer AF points.  Of course, the AF system is only as good as the lens that it connects to, and the lighting conditions you are in.  If you have a great AF system (camera body) and a slower lens (an aperture in the range of f4 or f5.6), you will still be limited by light.

The upshot:  More AF points = Better Camera (in general)

While there are always exceptions and nuances or unique scenarios for specialty gear, focusing speed is really more a function of the lens than the camera body.  What you will find in bodies though, is that you get better target acqusition and tracking on the higher end bodies than the entry-level models (say an Xsi versus a 1DMark II).   The camera basically does the job of saying “here’s the point to focus on”, and then transfers the job to the lens of actually making that point the sharpest one in the picture.

One question that I often hear though is “So, what defines how fast the focus locks – the AF system or the lens?”  The answer is that the AF system does the focus lock – the “lock” is really just defining the point to focus on…it’s just a fancier way of saying it.  If you have no point locked in, even the fastest lens will just search and search and not bring anything sharp because it doesn’t know what to make sharp.

I would be remiss though if I didn’t acknowledge that newer cameras do work better in lower light too though, because they do.  Here’s why:  you will get better low light performance on a higher end body, simply because the sensor is larger, and more sensitive to light.  But when we start talking about light, we have to actually give more of a nod to the lens.

Lens Focusing

Where camera bodies pull their weight in target acquisition and tracking, lenses pull their weight when it comes to operation in lower lighting conditions.  The larger your aperture (the smaller number actually means a wider open aperture, remember?), the better it will perform in low light because you are simply letting more light get to the sensor.  That lens that opens to f2.8 will let more light in regardless of the body it is connected to!  This is why expensive lenses that can open t f2.8, f2.0 or even wider are referred to as “fast glass” because they let such a large amount of light onto any sensor.

The other part of what really gives a nod to lenses over bodies is that lenses are what actually does the focusing.  Adjusting the focus to something that is “sharp” is done by the lens.  Where the camera said “Hey, cool, I’ve found the point to focus on”, here, the lens uses the AF points from the camera body and basically says “okay, I am going to focus in on this point that you’ve defined.”

The last point to bring up here is to mention the focusing motor of the lens.  Terms that are often bandied about include USM, HSM, and other similar terms.  This is where it can get really confusing because each vendor uses unique terms, and even within a specific vendor, the same letters can mean different things.  Here’s (since it’s the CanonBlogger site), I am going to stick to the Canon nomenclature for now, which is the USM.  In the Canon family, USM is seen in many lenses and has quite a history.  It started in the body before the digital camera revolution.  When Canon introduced the EF lens mount in 1987, the technology was available to put the USM on the lens, which allowed it to operate even faster.  They never looked back!

Nowadays, USM is bandied about within the Canon family, and you have to be careful now, because one is used to identify a lens feature, while the other is more marketing and hype (in my opinion anyway).  The one that really matters are the ones that refer to the Ring USM.  These lenses are more expensive, heavier than their counterparts, are much quieter, and also tend to bring the subject into focus faster.

Canon USM Feature Explained

The alternate motor or Micromotor Ultrasonic Drives are the ones used in cheaper lenses, which by comparison are lighter, noisier, and focus more slowly on the subject.  Most kit lenses are of these variety.


What did we learn here?  First off, hopefully you’ve come away with a better understanding of body AF systems versus lens focusing.  On the most simple of explanations – a camera AF system says where to focus, and the lens is what actually does the focusing.  It should come as no surprise though, that both tie in very tightly to light.  In the body, better sensitivity to light allows for better contrast in the AF points, while in the lens, the wider aperture can bring more light in under conditions where a narrower opening would not suffice.  So, higher sensitivity and wider openings can impact contrast and focusing speed in bodies and lenses respectively.

The bottom line:  neither does this task independently, but when  it comes to speed – most of this comes from your lens, not your body!


Got questions, comments, or additional thoughts to share?  Sound off in the comments!  Have a great weekend, and we’ll see you back here on Monday!