There are always lots of opinions about specific new camera bodies and lenses. A perpetual stream of new equipment introductions directly fuels gear acquisition syndrome, and many folks get glandular as they read about the latest and greatest technology. “Where should you put your upgrade money?” is a question on a lot of photographers’ minds these days.

In the past this used to be a fairly simple question to answer as an investment in better quality glass would usually produce an increase in overall image quality. Today, the answer is not so clear-cut with the arrival of higher pixel density sensors, the abandoning of low pass filters in many cameras, and rapidly advancing and more complex lens technology.

Many newer lenses seem to be much more demanding on auto-focusing systems and some photographers are becoming frustrated with the AF performance of their new lenses when used on older camera bodies. For example, when I did my hands-on review of the Tamron 150-600 f/5-6.3 VC lens I noticed that there was noticeable focus lag when used on a Nikon D7000. When I used that lens with my D800 it was stellar…being both fast and accurate. Other reviewers had noticed AF issues when the lens was first introduced for Canon bodies.

When I purchased my personal copy of the Tamron 150-600 a number of months after I originally did my review, I found that the focus lag issue that used to be present with the D7000 was much improved…most likely due to Tamron firmware updates.

I’m not singling out the Tamron 150-600 as being especially bad or problematic – I actually loved using the lens when I owned a copy of it. This is just an example of what can happen when an older body with less robust auto-focusing capability is matched up with a modern and more demanding lens.

Many folks have asked me whether their older body will work with a specific new lens and I tend to answer all of those questions in the same manner… unless you have the opportunity to test your older camera body with the specific lens you are thinking about buying it can be a bit of a gamble.

An issue that doesn’t seem to get much discussion is the impact of higher pixel density sensors when matched up with older lenses, or the potential impact of cameras that utilize sensors that don’t have low pass filters when matched up with various lenses.

The basic underlying issue is how well will newer and older technologies work when bodies and lenses of differing vintages are coupled together. And, if you’re like me and don’t have unlimited funds to update your camera gear, the question we all want answered is whether we’ll actually see an improvement in image quality if we invest in some new gear and match it up with older stuff.

I appreciate that some folks are not fans of DxOMark or the testing that they do with camera sensors and lenses. I view their testing as an important source of impartial, third-party evaluations of cameras and lenses, and I visit their website on a regular basis.

Let’ s consider a few examples of how DxOMark test data can be used to help determine if a particular lens or camera body purchase makes logical sense from an image quality standpoint.

As photographers most of us are concerned about the dynamic range and colour depth performance of the sensor in our camera. Other than Fuji (which DxOMark no longer tests because of Fuji’s proprietary sensor design) DxO has a great database of tests on a wide range of camera makes and models… at least those with interchangeable lenses, or higher-end bridge cameras.

If you shoot a lot of landscape images where dynamic range is critical, or weddings and other types of people images where subtle colour differentiation is important in terms of colour depth, then spending some time looking at DxO test data can help you make a more informed choice in terms of a camera make/model.

Obviously a photographer’s individual skills with post-processing can help bring out the best in any RAW file, but there can still be a large difference in the starting point of image quality based on the performance of the sensor in a particular camera body. Low light performance is another concern shared by many photographers. Again, DxO provides independent test data on this dimension as well.

For example, when the Nikon 1 V3 was introduced I referred to DxO sensor testing to help assess whether an upgrade to that camera would make sense for my business in terms of image quality.

My V2’s score 20.2-bits on colour depth, 10.8 EV with dynamic range and are rated at 403 ISO in terms of low light performance. By comparison the V3 scores 20.8-bits on colour depth, 10.7 EV with dynamic range and low light performance comes in at 384 ISO.

Since a 1-bit difference is needed to be noticeable with colour depth and 0.5 EV for dynamic range, DxO’s independent testing helped me decide that from an image quality standpoint there was no point in upgrading to the V3.

Another key consideration for most photographers is image sharpness and an elite group of people will spend untold thousands of dollars trying to achieve the ultimate. Most of us have more practical and pragmatic expectations. We want better performance for the money we are prepared to invest – but we’re not expecting the ‘ultimate’.

Let’s have a look at one of the newer lenses… the Tamron 15-30 f/2.8 VC. It was recently tested by DxOMark and scored very well. In terms of sharpness it rivals the legendary Nikkor 14-24.

Let’s say that you already own a Nikon D800 along with a Nikkor 16-35 f/4 VR and you’ve been thinking about the Tamron 15-30 VC or the Nikkor 14-24 as potential upgrades. Does that mean that you should run out and buy the Tamron 15-30 today since it is much cheaper than the Nikkor 14-24 mm, has VC, and earned great test scores?  Not necessarily.

We need to remember that many of the reviews and test articles on new lenses were shot with the latest and most advanced camera bodies. How well a particular lens performs can be impacted to a considerable degree by the camera to which it is mounted.

DxO has come up with a measurement for sharpness that they call “Perceptual MPix”. They basically define this as “the number of P-Mpix of a camera/lens combination is equal to the pixel count of a sensor that would give the same sharpness if tested with a perfect theoretical optics, as the camera/lens combination under test.” Basically the higher the number of MPix that a particular camera/lens combination scores, the better the perceived resolution.

Based on DxO testing, on average, about 45% of megapixels are lost due to lens or sensor defects.

OK…so what does this mean in the real world? In a nutshell, the same lens can perform differently when mounted on various camera bodies and can result in more, or fewer, lost megapixels in terms of sharpness. Let’s get back to our Nikon D800 example.

The Tamron 15-30 f/2.8 when mounted on a D800 delivers 15 MPix…a sharpness loss of about 58% – which is much worse than the average camera/lens combination tested by DxO.

What about the Nikkor 16-35 f/4 that is theoretically owned in the example? It delivers 14 MPix, or a sharpness loss of 61%.

And the Nikkor 14-24? On a D800 it delivers 17 MPix, or a sharpness loss of 53%… which is still worse than the average camera/lens combination tested by DxO.

So…for most D800 owners it likely would not make much sense to ‘upgrade’ to the Tamron 15-30 or the Nikkor 14-24 as the gain in sharpness is fairly small when compared to the Nikkor 16-35 f/4 that they already own.

Hmmm…let’s change camera bodies so our pretend owner now has a D800E/ D810. Would an upgrade make sense then? Quite possibly. Let’s look at the DxO test data to find out why.

On a D800E or D810 the Nikkor 16-35 f/4 delivers 19 MPix, or a sharpness loss of 47% – still a bit worse than the average combination tested by DxO but better than the performance of the D800 by a fair degree.

If we replace the Nikkor 16-35 f/4 with the Tamron 15-30 a D800E/D810 would deliver 24 MPix, or a sharpness loss of about 33%. This is well above the average camera/lens combination tested by DxO and also much better than the Nikkor 16-35 f/4. On a D800E the Nikkor 14-24 delivers the same MPix performance as the Tamron 15-30. On a D810 it is very slightly less.

It is also interesting to note that when using the Tamron 15-30 the D600 (15 MPix – 37% loss), D610 (16 MPix – 33% loss), and D750 (19 MPix – 21% loss) all outperform the D800 (15 MPix – 58% loss) in terms of the percentage of sharpness loss.

So what about an old lens on a newer body? Say you own a Nikon D7000 and a Nikkor DX 16-85 lens. That combination delivers 6 Mpix, or a sharpness loss of almost 63%. So, let’s say you decide to upgrade your DX body to a D7100 (sorry DxO test data is not yet available for the D7200) thinking that it will improve sharpness since the sensor has more megapixels and no longer has a low pass filter.

Well…if you mount the Nikkor 16-85 on a D7100 that combination will deliver 8 MPix, which obviously is better than the 6 MPix performance of the D7000…but there is still a sharpness loss of almost 67%. Hmmm…the increased number of mega-pixels and the absence of a low pass filter had very little impact on sharpness when using the 16-85 lens. In effect you would have paid for more megapixels with the D7100 but they did very little for you from a sharpness perspective.

Perhaps the issue is the older lens technology of the 16-85?

To investigate that possibility I looked at the Nikkor DX 18-140 which was introduced in 2013. On a D7000 that combination delivers 8 MPix, or a sharpness loss of 50%. That’s still a bit below average but a considerable improvement over the 16-85.

Mounting the 18-140 on a D7100 produced 11 MPix. Obviously that’s better than the 8 MPix on the D7000, but it still represents a sharpness loss of 54% on the D7100 – well below average and a somewhat larger percentage loss of sharpness when compared to that same lens on a D7000.

Obviously there are a range of other factors that come into play when selecting a lens, but sharpness is typically a key consideration for most photographers.

As I’ve been looking at this type of data over the past number of years it drove home an important point for me. Reading about new camera bodies and lenses gets my adrenaline going and causes me to suffer from gear acquisition syndrome. It’s critical that I temper that gear lust with the reality that the actual, measurable improvement in performance in terms of dynamic range, colour depth, low light performance and sharpness may not actually be worth the price to upgrade my gear. To know if it is or not I need to use my head, not my heart. Sometimes the best place to keep our upgrade money is in our wallets until an upgrade has truly earned its release.

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