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07
Apr
2014

Do you really need that expensive lens?

Posted by Todd Sisson

 

 

 

It is tempting to believe that owning jazzy lenses like Nikon's top of the line Nikon 70-200mm f/2.8G zoom will result in significantly superior image quality.  We put this idea (that we have hitherto subscribed to) through the testing mill here at sisson.co.nz with surprising results...

Lens Lust 

Lens-lust is not an addiction, it's an illness.  We photographers are shouldn't be chastised for our wallet-incinerating lens purchasing proclivities - we deserve support groups with uncomfortable chairs, scaldingly hot instant beverages and bland biscuits in every major town and city.  

Instead, all we get are camera club meetings featuring uncomfortable chairs, scaldingly hot instant beverages and bland biscuits. Sending a lens lustee into an environment full of camera gear and similarly weak individiuals is akin to cleaning up a coke fiend by sending them to Columbia.  Gear-head photographers are powerless once in the cruel clutches of lens-lust and nothing brings on the sweats like expensive, top of the line lenses. 

I can't offer you a twelve step re-hab plan, but I can help you to (hopefully) make some informed decisions if you are looking to purchase lenses primarily for landscape photography - this may just help you kick that expensive-lens-lust into touch.

 What are the advantages of expensive lenses?

  • Speed. Fancy pants lenses are usually faster than cheaper lenses i.e. they have a larger maximum aperture which lets more light through to the lens when shot wide open.  Probably the most common example of a fast lens is the 70-200mm f/2.8 zoom lens which is two stops faster than most kit 70-200mm zooms which have an f/5.6 maximum aperture. Larger apertures result in faster shutter speeds - handy for freezing motion or handholding. Very few landscape photographs are made at f/2.8 due to the narrow depth of field (DOF) that results.
  • Optical quality. Snazzy lenses should produce usably sharp results even wide open at their maximum apertures. Cheap lenses usually produce crappy images when shot wide open.  Again, we are rarely find ourselves shooting wide open when making landscape images as we are usually seeking maximal DOF.
  • Build Quality. Exotic lenses generally include a lot more metal in their construction, have more switches for controlling auto-focus (AF) and are better weather-sealed than their cheaper cousins from Shelbyville. Flagship lenses will usually be the first to include new AF technologies, lens coatings and other doo-dads that help marketing departments 'shift units'. These features are of use to war correspondents and sports photographers but are largely redundant in the slow paced, AK47-free world of landscape photography.
  • Status. Massive lenses emblazoned with gold lettering make a statement.  Whether anyone correctly reads that statement as desired is debatable.

What are the disadvantages of expensive lenses?

  • Weight. All that metal and glass adds lots of weight to your camera bag. For example the Nikon 70-200mm f/2.8G zoom weighs a whopping 1.5kg compared to a mere 0.85kg for the optically identical Nikon 70-200mm f/4G Zoom lens. Carrying that weight makes no sense unless you really need that extra stop of light gathering.
  • Bulk.  Expensive, fast lenses have to be physically larger to gather all of that extra light - this results in bigger, bulkier camera bags.
  • Expense.  Expensive lenses are expensive - this does have the advantage of lightening your wallet somewhat.
  • Status.  Few things say 'I possess limited social skills' better than gratuitous and inappropriate use of enormous lenses in everyday situations - think long and hard before unleashing that 600mm f/4 lens at your pre-schooler's Teddy Bear's picnic...

Are expensive lenses better than cheap lenses?

Yes. Expensive lenses should be better than cheap lenses in almost every way. But just because an expensive lens is better than a cheap(er) lens doesn't mean that it is the appropriate choice for landscape photography.  Let's compare two lenses:    

 

Our 'cheap' lens is the *Nikon 18-200mm f/3.5-5.6 G ED-IF AF-S VR DX zoom  which retails on Amazon for $650 US approx.  On our gear page I describe this lens as a 'steaming pile of Bakerlite' - I hate this lens and it is only in our possession as it is used by our seven year old son.   
Our expensive lens is the top-of-the-line Nikon 70-200mm f/2.8G ED VR II AF-S zoom which goes for $2,400 USD. I love everything about this lens apart from its price, weight and bulk.  

 

One would reasonably expect the f/2.8  lens to absolutely trounce the ($1,800 cheaper) zoom when shot side by side at the DX zoom's maximum aperture of f/5.6. Let us see whether one might be correct... 

 

Nikon 18-200mm f/3.5-5.6 DX VR (left) vs Nikon 70-200mm f/2.8 VRii cheap vs expensive lens comparison. Centre of frame at f/5.6.

As one would hope, the USD $2,400 zoom is noticably sharper in the centre of frame compared to the obsolete consumer DX shot wide open (just remember that the 70-200mm is already stopped down 2 stops at f/5.6).  This is not to say that the DX zoom is performing badly in the centre of frame - a little sharpening would have the zoom looking great at centre of frame and it is definitely of usable quality.  Let's see how it fares out on the edges though...

 

Nikon 18-200mm f/3.5-5.6 DX VR (left) vs Nikon 70-200mm f/2.8 VRii cheap vs expensive lens comparison. Corner of frame at f/5.6.

This is where the wheels fall off cheaper lenses - out at the edges when shot wide open. The 18-200mm zoom (left) is almost devoid of detail compared to the superb detail presented by the 70-200mm lens .  The Zoom would still make a great portrait image at f/5.6 (with the subject in centre of frame) but I wouldn't use it at these settings for landscape due to the edge softness.  Think about it though, how often would you shoot a landscape image at f/5.6? Let's compare the two lenses at a more landscape friendly f/11 aperture setting...

  

Nikon 18-200mm f/3.5-5.6 DX VR (left) vs Nikon 70-200mm f/2.8 VRii cheap vs expensive lens comparison. Centre of frame at f/11. 

The 70-200mm f/2.8 lens certainly shows its class at f/11, displaying more detail, better contrast and superior color rendition. But remember that we are viewing these files at 100% - the 18-200mm is actually looking incredibly good, especially given that it is USD $1,800 cheaper!  Let's see if the cheap lens has narrowed the performance gap in the corners now that it is stopped down to f/11...

 

Nikon 18-200mm f/3.5-5.6 DX VR (left) vs Nikon 70-200mm f/2.8 VRii cheap vs expensive lens comparison. Corner of frame at f/11. 

Man! The cheap lens has improved dramatically out in the corners now that it is stopped down to f/11.  Sure, it's hoity-toity cousin is looking sharper but this is the far edge of frame and is the difference actually that ($1,800) meaningful?  Let's see if we can narrow the gap by adding a little sharpening to the cheap zoom image...

 

Nikon 18-200mm f/3.5-5.6 DX VR (left) vs Nikon 70-200mm f/2.8 VRii cheap vs expensive lens comparison. Corner of frame at f/11 after some post-processing. 

With sharpening, clarity and vibrance applied the Cheap DX zoom is suddenly looking as good as the (unprocessed) file from the flagship 70-200mm f/2.8 zoom!   

Nikon 18-200mm f/3.5-5.6 DX VR (left) vs Nikon 70-200mm f/2.8 VRii cheap vs expensive lens comparison. Centre of frame at f/11 after post-processing.

The story is repeated in the centre of frame where the cheaper lens is now looking virtually indistinguishable from the wallet busting f/2.8.  Sure, the 70-200mm f/2.8's file will always look superior after post-processing but this will only be visible once the file is enlarged to ridiculous proportions. Let's compare the two files when viewed at 50% (which gives a rough approximation of finished 300 DPI print size).

 

 Nikon 18-200mm f/3.5-5.6 DX VR (left) vs Nikon 70-200mm f/2.8 VRii cheap vs expensive lens comparison. Centre of frame at f/11 (print preview at 50%).

Spot the $1,600 difference? Nope, neither can I.  In fact the DX lens has delivered superior DOF at f/11 due to the fact that crop sensors produce more DOF at any given field of view compared to full frame cameras. This is one reason why we love DX for landscape (that and lower price, lighter gear and less bulk - remind me again why we use the D800?).  Finally, let's see what's happening out wide at this view.

 Nikon 18-200mm f/3.5-5.6 DX VR (left) vs Nikon 70-200mm f/2.8 VRii cheap vs expensive lens comparison. Corner of frame at f/11 (print preview at 50%).

 Once again the two images are virtually identical when viewed at 'print-preview' size.

 

My conclusion:

There is definitely a difference in image quality produced by these two lenses but I was surprised at how close I  could get the two files with a minute's work in Lightroom. Would I willingly ditch the 70-200mm for the 18-200mm DX? Hell no, but remember, this is comparing Nikon's best 200mm zoom with the crappiest lens that we still own and the real world difference in performance at 'landscape settings' is neglible.  The flagship lens will always produce better results but I don't see USD $1,800 difference in usable image quality in between these lenses and the gap is eliminated altogether when comparing the 70-200mm f/2.8 VRii to Nikon's newer Nikon 70-200mm f/4G ED VR zoom.  

Ultimate image quality is nice to have, but good enough is good enough for all but the most demanding (and well heeled) photographers. I used to obsess over this stuff, but after making hundreds of beautiful prints from cheaper lenses I have come to the conclusion that you are better off carrying less weight, spending less money and buying high quality 'mid-range' lenses such as the aforementioned Nikon 70-200mm f/4G ED VR zoom (which Sarah owns and I don't!).

 

Test Methodology

I am not a lens tester and testing a crop sensor optimized DX lens against a full frame FX lens is like comparing an apple with a banana - only a bit harder.  Because I needed to test the results at the corners of each lens' image circle the DX was shot in DX mode and the FX was shot in FX mode on a Nikon D800E FX-Format DSLR .  This resulted in a larger file for the FX (70-200mm) image and I opted to down-rez this file rather than up-rez the DX file - seemed fairer that way.  Nit pickers will note that this will have understated the acuity of the f/2.8 lens, but trust me the difference is neglible and I am happy that the results are representative of the real story here - how good crappy lenses actually are when stopped down.

Camera settings:

  • ISO 100
  • Aperture priority
  • 3 second mirror lockup shutter delay
  • Tripod mounted (VR off)
  • Focus was set on the tree in the left corner using Liveview zooming and manual focus.
  • The DX lens was shot at 133mm (200mm FX equivalent) to give a near identical field of view and place the corner details at the edge of frame.

 

Check out Sarah's Lightroom Presets! 

 

 

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