A Great Resource To Use Before Purchasing A Camera Body Or Lens

While researching and deciding on what camera or lens to buy next, there can be a lot of banter, back and forth, and noise on opinions on what camera or lens is right for you. It is possible that some websites, influencers, or average Joe’s can hold slanted biases that may play a role in your purchasing decision, and we don’t want that. So what if I told you that there was a more objective resource to help aid your purchasing decisions? Well, I have a site to share with you: DxOMark.

Purchasing a new camera or lens may not only be an exciting process, but also a crucial one. With the selection out there, there are more options than ever before which can be quite overwhelming. I’m going to assume you may also want to make sure that you spend your hard earned dough in the right places to avoid a blunder buy or having to a cut a loss. Luckily there is a source out there that is objective, accurate, and up-to-date that can play a crucial role in purchasing decisions.

As I stated earlier in my introduction, DxOMark can be a useful resource that uses more objective data to render results on what lens or camera performs better than the other or among all products. The site uses lab testing and analyzation to give you results on how cameras or lens perform on a wide-array of important features, including: sharpness, noise, vignetting, chromatic abberration, ISO performance, and several more nuggets of information. I am not being coined to say this, DxoMark is a resource use every time when I’m looking to decide on one lens or opposed to the other. 

While it may be a confusing site to visit upon first glance, Tony Northrup put together a great video for everyone that breaks down how to browse through DxOMark, how it works, and what tests are the most useful in making an informed decision on your next lens or body purchase.

​A DxOMark Demonstration

Now that I've gone through what makes DxoMark a great resource and tool. I'll go through a mock example of DxOMark can help you when comparing lenses. For demonstration purposes, lets say I am a portrait photographer using a Nikon D750, I'm looking to add a 50-58mm prime lens to my collection.

I've narrowed my search down to a couple of lenses, the Nikon 58mm f/1.4 ($1,596) & the Sigma Art 50mm f/1.4 ($949). Let's run a few tests to compare key factors to help aid my purchasing decision. 

Nikon Nikkor 58mm f/1.4 vs Sigma Art 50mm f/1.4

Lens' First Impressions

Now before I completely dive in, I would like to also add that DxOMark performs tests for each combination of lenses on every camera body possible. While lens tests may vary from camera sensor to sensor, your results will be catered to what you're looking for. So for this I'll be selecting a Nikon D750 for all tests. After selecting both the camera body and the specific lens, an overall first impression will be displayed with a few scores. Lets compare the overall first impressions:

Nikon 58mm f/1.4

vs. Sigma Art 50mm f/1.4

Right off the bat you can see an overall score shown, in Northrup's video he explains that this piece of information isn't totally useful since it is an overall score that DxO decides opposed to what is most important you. So we need to rather dissect individual tests in order to find out what is most important to use, which is portraits in this case. So lets look into more importantly the 'Lens Metric Scores' shown:

1. Sharpness - We can all agree sharpness is vital to selecting the right lens. Here we can see right away that the Sigma is better in that department. DxOMark uses a measure of perceptual mega pixels. To put it simply, the Nikon 58mm can only effectively retain 18 megapixels of sharpness for the 24.3 megapixel camera, opposed to the Sigma 58mm that retains most of the sharpness with a score of 24 P-Mpix. The Sigma is a sharp lens coupled with a sharp sensor in this case. Winner: Sigma 50mm
2. Transmission - T-stops which are very similar to f-stops, are actually the measurement of the amount of light that reaches the sensor. Opposed to f-stops that measure the amount light the reaches the front element. In this category, both lenses perform well with the Nikon 58mm having the slight edge in this category. This especially important for photographers who use a wide-open aperture. Winner: Nikon 58mm
3. Distortion - This is simply the distortion the lens gives out. This can be fixed in post production so it is a little to no factor. Both give out for very minimal distortion with the Sigma winning with a slight edge. Winner: Sigma 50mm
4. Vignetting - Just like distortion this also can fixed in post. To explain the data, both come in around -1.2 EV, which means that the image's exposure on the edge will be -1.2 stop(s) below the center of the image. Both lenses check out similarly in this category. Winner: Draw
5. Chromatic Aberration - Measured in micrometers. The Nikon and Sigma have 2 and 9 µm respectively. Which means that the Sigma has more chromatic aberration than the Nikon. Winner: Nikon 58mm

For overall first impressions, the Sigma has the edge considering that the Sigma beats out the Nikon by 25% in the sharpness category which is significant. In the other data categories they both come out comparable. 

DxO Score Map & Field

Score Map

The score map is a basic representation of sharpness of the lens at certain focal lengths and f-stops. Since these are both prime lenses, we will focus on the sharpness of the perceptual megapixels at certain f-stops. The spectrum is set from red (not sharp) to green (sharpest). As you can see in the chart above, the sharpness quality for the Nikon 58mm is awful at wide-open f-stops (f/1.4-f/2). In this case the Sigma Art 50mm blows the Nikon lens out of the water showing strong sharpness of perceptual megapixels all the way up to f/16. Winner: Sigma 50mm

Score Field

​Now an even more interesting depiction on sharpness is represented through the DxOMark field map, which shows you how sharp the image will be at the center and edges of your image. Same as the score map, the spectrum is set from red (not sharp) to green (sharpest). Let's take a look:

This data above is rendered with both prime lenses shot at f/1.4 (wide-open). It is almost shocking to see how the performance of the cheaper lens blows the $1,600 lens out of the water. The Nikon lens has virtually no sharpness at wide-open apertures, while the Sigma Art performs almost perfectly tack sharp at f/1.4. Let's take a look at both lenses at f/2:

The Sigma 50mm is perfectly green which represents a perfectly tack sharp image at f/2, while the Nikon 58mm still lags behind substantiality with most of the image being unsharp at f/2. In fact, the Nikon lens doesn't have respectable performance until it reaches f/5.6 shown below:

With that being said, the Sigma 50mm @ f/1.4 still outperforms the sharpness of the Nikon 58mm @ f/5.6 which is very significant. 

Conclusion

Winner: Sigma Art 50mm ($949)

After reviewing a few of the features it is quite clear the Sigma 50mm outshines the Nikon 58mm, especially for portrait photographers who like to shoot wide-open. While both lenses are comparable when it comes to transmission, distortion, vignetting, and chromatic aberration, the Sigma Art 50mm overtakes the Nikon 58mm easily with its sharpness performance. It's also worth mentioning that the Sigma Art is over $600 cheaper. 

This is a perfect example of how researching can save you potentially hundreds of dollars when splitting hairs between bodies and lenses. It is also a great idea to try out the lenses for yourself by renting or borrowing lenses from a friend. If that isn't an option this is a great aid when putting in the time to research when making a decision on a lens. Again, this is simply an aid to use and is just a piece of the puzzle when deciding on a lens or body to purchase, do your due diligence. 

And for the those who may claim that DxO is full of it, I'll side with Northrup on this one and say, "Prove it."