What is the Image Quality tradeoff between primes and 2.8 zooms?

rmp

If we skip over the cost, size, weight, and range trade-offs between prime lenses and the 2.8 zooms, where is the image quality trade off today. From the "olden days," I remember that primes produced better quality prints than zooms. But, just how much better are the primes today. Is there some simple answer? I hope for something like "If I want to use a YY mm equivalent lens and print at size XXX or larger then I should use a prime lens."

PB_PM

The question today isn't so much which is better, so much as what fits your shooting style the best. Modern F2.8 zooms and fast primes both have strengths and weakness, just as in the past. Zooms have more distortion, but offer greater flexibility. Fast primes offer larger maximum apertures, but tend to have more vignetting and CA wide open.

In terms of resolution, the difference varies from lens to lens. Some primes are extremely good, others not so much. Treat each lens on it's own merits, not on whether one is a prime or a zoom.

TaoTeJared

This needs specifics and not generalities of zooms for this discussion.

There is a major difference between the class of zooms and when comparing them to primes.

Pro Zoom - i.e. 70-200vr 24-70, 14-24/ F2.8s
Pro-sumer Zoom - 70-200vr, 24-120vr, 16-35vr/ F4s 80-400vr
Advanced Consumer - 18-200vr, 16-85, 70-300vr
Consumer Zoom - 24-80, 18-55, 18-everything else, 55-200/300

Set aside the artistic abilities and subjective aspects that primes have over zooms. That is just beating a dead horse.

Pro & Pro-sumer zooms vs Primes there is not that much difference in the quality of images at equal F-stops. Mostly it is artistic or as PB_PM said correctly it is more of a shooting style or the need of the situation.

Advanced consumer zooms stopped down (2-stops, generally f8-11) there is a difference, but not too much on prints of a 8x10 print. Larger than that, you will see some difference. Software and post can usually make up for it. Wide open though, primes are visually much better.

Consumer zooms - Primes are better.

Macro prime are always better than zooms.

You also can get into Release time frames as a limiting factor as well. The 14-24 performs better than the 20mm f2.8. The 20mm is also about 15 years old (in design terms.) I have an old 50mm 1.4 from the 70's and any zoom is technically probably better than it. Flip that to the 50AF-G (either 1.8 or 1.4) and they are sharper than zooms at the same F-stops.

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The reason why many say "primes are better" is because of the artistic abilities and subjective aspects that primes have over zooms. Because of their larger apertures, it opens opportunities in those aspects that zooms can't provide.

rmp

Thank you. These answers are getting better and forcing me to think about the question more precisely.

How do you compare the image quality of a pro-zoom say the 70-200 f2.8 against the image quality of say a 135 f2.0 -- If you ignore the f-stop difference and the bokeh?

Msmoto

MTF Charts can tell a lot.

E.g., for the new Zeiss Otus…
http://www.zeiss.com/content/dam/Photography/new/pdf/en/downloadcenter/datasheets_otus/otus_1455.pdf
Nikon 400mm f/2.8:
http://www.nikonusa.com/en/Nikon-Products/Product/Camera-Lenses/2171/AF-S-NIKKOR-400mm-f%2F2.8G-ED-VR.html#!/media:image:2171_AF-S-NIKKOR-400mm-f2.8G-ED-VR_MTF.jpg

Nikon 135mm f/2
http://www.nikonusa.com/en/Nikon-Products/Product/Camera-Lenses/1935/AF-DC-Nikkor-135mm-f%2F2D.html#!/media:image:1935_AF-DC-NIKKOR-135mm-f2D_MTF.jpg

Sigma 35mm f/1.4
http://www.sigmaphoto.com/product/35mm-f14-dg-hsm-a (Click on Tech Specs)

Zeiss Distagon T 15mm f/2.8
http://www.zeiss.com/content/dam/Photography/new/pdf/en/downloadcenter/datasheets_slr/distagont2815.pdf

Or go to the Leica site and download technical data of the APO Summicron 50mm f/2
http://us.leica-camera.com/photography/m_system/lenses/available_light/8884.html

Now, the trick is to be able to compare these charts. Some use 10mm and 30mm lines, sagittal (from the center out) and meridonial (at right angle to the sagittal lines), Others use 5mm, 10mm, 20mm, and 40mm lines and variations. So, compare apples to apples and not ….. well, you know.

Also, on an MTF chart, the closer the lines for the meridonial and sagittal lines, the better the bokeh. And of course if one finds a lens which has the lines all clustered at the top of the graph, this is the very sharpest across the field. In general, telephoto lenses will look better on the MTF charts than do wide angle lenses.

Hope this helps... :-B :-B :-B :-B :-B

TaoTeJared

You can't really decouple the 135 f2.0 from the bokeh. It is a specialty lens and that is the main design feature of it. From what I have seen it is sharper but that alone doesn't make it any better on the surface. The defocus controol (if used properly) is what makes it much better and why one would buy it.

That is comparing two Pro level lenses. The actual, measurable quality will basically be equal between all pro level glass.

A better comparison would be the new 35mm 1.8 (FX) vs 24-70 (which no one really knows that answer yet. And I would like to see that.) There have been many reviews of the 70-200 vs 85mm 1.4 (S/G) which most put the two about the same but subjectively the bokeh & resolution is slightly better on the 85. Same with the 105vr & 105DC.

Personally I believe the better questions are;
How much quality do you need? Mostly Facebook posts or many 24x48 inch prints?
What are you trying to achieve & what lens would work best to accomplish the look?
Then what are the other options and their drawbacks?
Finally, what is the best cost vs. budget vs. trade-offs to achieve it.

Just because one lens is tested better than another means squat when creating an image. Better test scores don't = good images. Having the right lens for the task along with the skill to use it does.

If you are one that always shoots at F8-16, almost any lens will do and I have seen commercial photographers actually shoot with consumer glass but always at their optimum settings. The key is, they know why they have made that choice and it is post processed to the extreme. That does not mean though a 18-55 or 24-85 kit lens will create the same "pop" or resolution that a pro zoom or prime will.

Keep this in mind, right now the fad in commercial photography is to find really young (under 21 yrs old) photographers with an artistic look. (Actually I believe it is driven by the fact they charge a million times less than an Annie Leibovitz and magazines are all going broke.) Technically their images are usually poor - Miss focused, composition muddy, lower resolutions, and a whole slew of other things. Their gear is seriously uninspiring - Dx with kit lenses, Holga, Diana, basic kits. But they have created their own "instagram", photoshoped, current generational grunge look that people want. Basically the camera is just the tool that captures a basic image. The creativity of it comes together in post processing. To me, (and not taking anything away from their abilities) they are not photographers, they are post processors. For that type of work, the lens "tests" means very little so a kit zoom isn't any better than a prime.

They and many pros who have this approach get away with minimal cost with gear. Then you have someone like Annie Leibovitz who regularly shoots with a $40k Hasselblad, $6k lenses, and lighting kits that are in the 10s of thousands of dollars. (for Game of Thrones lovers)

I buy primes for the Bokeh and character they give an image, f/4 zooms for convenience and speed, and Holga's to remind me they suck. I look at sharpness tests to tell me where their optimal resolution starts and ends (almost always 5.6-11 on every lens) for when I desire the sharpest image I can get.

rmp

I agree that the equipment does not make a good photo.

I hate the thought, but I guess I must learn to love MTF charts or create my own interpretation -- maybe a new test facility? (WOW, that 400mm has some MTF chart.)

Maybe a comparison would be the new 35mm 1.8 (FX) vs 24-70 (which no one really knows that answer yet.)

How would or could we test/compare the 35mm 1.8 vs the 24-70 with just two pictures (one from each lens)?

What would the test facility/pictures need to show?

TaoTeJared

MTFs are very good although they are not easily learned. Once you do though, then they make sense. What finely made since to me is to pull the MTF charts for all the lenses I own and test shoot them to match the lines on the image to find CAs, sharpness location, etc.

My rule of thumb is to have the top line number above .8 though the first 25% of the chart with the dashed line no more .05 fluctuating from the main line through 75% of the graph.

The second lines usually line up with telling micro contrast (very close <.2 away from top line) and strong CAs, > .2 with dashed line spreading far away from solid line.

Those are the main things I pull out of them or look for.

sevencrossing

If we skip over the cost, size, weight,

They are pretty big things to ignore

From the "olden days," I remember that primes produced better quality prints than zooms.

Things have changed dramatically. Nikons latest's zooms, are probably better than many Primes from the "olden days"

rmp

Thanks TaoTeJared. I liked your description of your interpretation of the MTF charts. And I give up, I will finally listen to you and Msmoto and learn to read MTF charts.

I think you are correct sevencrossing, the latest zooms are really good. That is what is making it hard for me to consider and/or buy new primes.

Since I have the holly trinity of zooms, what characteristic of the new 35 mm f1.8 would make me buy it? Would it be the additional f-stop? The better bokeh? Or something else?

How big could I make a print with the 24-70 f2.8 at 35 mm? How big could I make a print with the new 35 mm f1.8?

sevencrossing

How big could I make a print with the 24-70 f2.8 at 35 mm? How big could I make a print with the new 35 mm f1.8?

unless you have a very big room and deep pocked I would keep them under five feet wide

ptrmcky

In terms of image quality, I can't really see much difference. I've had the D800 and 24-70 for about 2 months now and I'm still amazed how the files look at 100%.

Nikon's top lenses are so sharp you will be more limited by your pixel count than how much the lens can resolve if you want to print big.

henrik1963

Just to add to what others have said - some lenses gives you warmer colors than others. Some have a dreamy look where others have that razor sharp look to them.

If we made a "guess a Nikon lens" quiz with 100 pictures - most of us would have a hard time picking the right lens most of the time :-) Sure close ups shot at 1.4 on a FF camera would be a dead give away. But for pictures shot at F 4 most of us would have a hard time telling the prime from the Pro zoom.

Golf007sd

Some very good, thoughtful input on the topic...well done.

Personally, I find the need for both these types of lens. However, I totally agree with sevencrossing: cost, size and weight are truly big factors when one is considering getting either of these type of lenses.

I think you should get yourself (or rent) a 35 or 50mm modern prime lens and have it for yourself and see first hand what they have to offer vs the great zoom lenses you already own. My recommendation would be the Sigma 35 1.4 Art.

rmp

Thanks everyone. I think I have my answer.

Msmoto

Not yet….the idea of purchasing a 35mm f/1.8 when the Sigma f/1.4 is such a stunning lens….. I will be happy to let you test the Sigma, "rmp"….. When I return from the get together…...

rmp

OK, but all you other readers, I need your help. You can help by defining the "test". I assume Nikon 24-70 mm f2.8 and a Sigma 35mm 1.8 on a D800e. I assume one, and only one, picture with each lens. I assume an eyeball comparison of the two pictures.

Now just what do we include in this test picture?
I assume some kind of
focus test chart such as http://regex.info/blog/photo-tech/focus-chart
resolution test chart such as http://www.graphics.cornell.edu/~westin/misc/res-chart.html
color test chart such as http://www.digitalimageflow.com/DGKChrome/DGK-ChromeHD_ebay1s.jpg

What else? Depth-of-field? Bokeh?

Ironheart

There are two quantitative reasons to consider a (nikon) prime over a (nikon) zoom. First is light gathering ability, there are some shots that just require the f1.8 (or 1.4) in order to get the shot at any reasonable ISO. Second is DoF, the larger apertures will give you more of it. The sigma 18-35mm f1.8 dc hsm seems to break this rule, haven't seen any photos yet.

As others have mentioned there are numerous qualitative reasons to consider primes over zooms. These would be the ones I would be looking to put into your test rig. Usually a mannequin or at least a head bust with real hair, clothes, backdrop, etc... Is used for the "je ne sais quoi" set. You should have some standardized color charts, or a least the 64 crayons box as well.

I agree with seven that skipping size, weight and cost is kinda missing the point. There are places I just won't take a zoom due to some combination of these three.

Vipmediastar_JZ

My recommendation would be the Sigma 35 1.4 Art.

+infinity
It is a 35 in FX and 50 in DX.
It is just painfully sharp and im getting good success with it. The bench photo that I put on yesterdays PAD was shot at f/1.4

now at 35mm the 24-70 2.8 still has some distortion which is annoying to me just in case this hasn't been covered yet.
The zooms are indeed convenient but the primes are very engaging in bokeh, dof, and weight.
my 26 pesos ( 2 cents)

Golf007sd

@rmp: You might want to follow this topic that TTJ is working on. May bear some fruit in addressing your questions.

tcole1983

I really don't know my opinion. I say this because I went from my 18-200 to now having the 17-55 and 3 primes....all of which have a different purpose. However I hardly find a use for my 35 f1.8....my 17-55 covers it and is sharp at f2.8 so I don't have a problem with it. I do notice when I correct my 17-55 vs 105 there is a big difference, the 105 hardly seems to do anything but I can always tell when I hit the correction button for my 17-55. It doesn't bug me though and I won't give up at least having one zoom in a range I use most often.

I do think primes win for bokeh. My 105 and 300 knock the socks off anything my 18-200 produced, but maybe the 70-200 would be more comparable. I still think my primes have a different look and feel. I always feel better about portraits with my 105 than with my 17-55.

TaoTeJared

...Since I have the holly trinity of zooms, what characteristic of the new 35 mm f1.8 would make me buy it? Would it be the additional f-stop? The better bokeh? Or something else?
How big could I make a print with the 24-70 f2.8 at 35 mm? How big could I make a print with the new 35 mm f1.8?

That is a question that can only be answered by you and what you are trying to achieve. Shallower depth of field, Low light shooting adding about a stop, some primes have more "character" than zooms, and many other subjective qualities. All of these are a personal preference. Then there is also the convenience of a zoom or/and the convenience of a smaller, lighter prime. But again, these are subjective qualities.

OK, but all you other readers, I need your help. You can help by defining the "test". I assume Nikon 24-70 mm f2.8 and a Sigma 35mm 1.8 on a D800e. I assume one, and only one, picture with each lens. I assume an eyeball comparison of the two pictures.

Various companies test lenses - DXO, Imatest, MTF charts and a few others do quantifiable tests on field curvature, contrast, resolution, CAs, and various other items. That is the "tests" that I referred too. Many do tests that show many of the subjective qualities of lenses - that is what I'm more personally interested in. In subjectively terms, Zooms are generally referred to as "flat" lacking character where many prime lens designs have "character" designed into them. (Zeiss and Leica are well known for this.)

An extreme example of character would be a Petzval Lens.

It is not a super sharp lens, and by many "tests" it scores quite low, but it is still a desired look many like.

tektrader

I have the Trinity and they are very good. BUT where they lose out is that current cameras don't allow microfocus adjust at more than 1 point. ALL my zooms need different micro focus adjust at the extents of the zoom.

Critical focus isn't always achieved because of this.

This is where Primes can be better. Also many fast primes have really bad LOCA which I hate. LOCA in the trinity doesn't seem to be an issue. They are very good

donaldejose

Certainly primes are better in that they offer an additional f-stop (or more) and also tend to score higher in sharpness and contrast when testing with a test chart. They also can offer better bokeh such as the 85mm f1.4 vs 85mm on the 70-200 f2.8 zoom. If you are shooting a certain limited type of photo, such as fashion or portrait, where you want the characteristics primes offer and zooms don't, primes are better. However, I have been impressed with how many pros seem to carry only zooms in their pack.

http://www.moosepeterson.com/blog/about/whats-in-mooses-camera-bag/mooses-wildlife-gear/

http://www.moosepeterson.com/blog/about/whats-in-mooses-camera-bag/mooses-landscape-gear/

http://blog.artwolfe.com/2009/01/equipment/

http://blog.artwolfe.com/tag/gear/

http://www.dslrbodies.com/essays/in-thoms-bag.html

My conclusion is that if the "pro" zooms are good enough for the work pros do then whatever weakness they have compared to primes is not sufficient to stop you and me from achieving great images.

ads

On top of the outright quality I'll throw in another factor to consider, which is the environment.

I usually shoot primes, but I have a trip planned to shoot in slot canyons which are notoriously dusty so frequently changing lenses can be a bad idea. So for the trip to the south west I'll use a wide angle zoom rather than swapping primes.

Obviously that isn't a factor if you are shooting somewhere more civilised.

haroldp

Nikon's 14-24 / 2.8 is perfect in the slot canyons, clean it carefully when you are done.

For most pro's, getting the shot with acceptable (to the customer) IQ is what matters, in many cases this means a zoom.

The Nikon pro zooms meet those requirements in any conditions where they are likely to be used by people who understand them.

Theoretical increments of IQ in a shot you missed because the wrong lens was mounted does not get you paid (or re-hired). This of course does not apply to controlled conditions like fashion shoots which is why MF still dominates those.

Before zooms became practical, the image of PJ's with 3 or 4 cameras (usually Leica) around their neck was common (I was one of them). They had different lenses mounted on each.

For myself, most of the time the 70-200, 24-70, 80-400 G, or 24-120 (for events and touring) are mounted.

I also use the 24 / 1.4 (always at f1.4) and the 400 / 2.8 VRII (usually with 1.7 extender) under circumstances calling for them.

The 105 f2 DC is still my favorite Nikon portrait lens.

The only one of those cases where IQ is the determinate is the 400 / 2.8 with 1.7 extender. No other combination (that I own) provides this reach with acceptable IQ.

'Better' does not really apply, the question is which lens is most likely to help me get the image that I want under a particular set of circumstances.

Regards ... H