I own a Nikon D200, a Nikon 70-200 VR zoom, and a Tamron 90 prime used in this test.
Using a tripod, mirrorup, and cable release I have taken the same picture, a shot of San Francisco with pine needles showing on the upper three sides of the image. With the prime a f22, and the zoom at f22 and 95mm, the overall clarity at 100% in Lightroom is better with the prime.
The trees are probably 40 feet in front of the lense, and the city is several miles across the bay.
A simple question: why? Should the zoom at 95mm with the same aperture be indestinguishable from the prime? Apparently not. Why not?
There are no pictures attached to your post, but I would expect to see much better results from a prime lens specifically designed for macro work when stopped down beyond f11 - f13. Read up on diffraction limits for lenses - in particular with respect to digital sensors.
Another thing to watch out for is the VR setting on the Nikor and realizing each company creates glass differently which will impact the overall colour of the image.
There are several factors here. Firstly a macro lens is optimised for close up shooting, and it is not unusual for a macro lens to be good but not stellar at large distance. Secondly you are stopping down to F22 where the dominant aberration is diffraction. It could be that the zoom is stopping down to a bit less than F22, and that could account for the differences seen. Or something else is at play at such a small aperture. Thirdly the zoom you have is known to be first rate, and if it is anything like the older 80-200 zoom, it performs best at large distance, and at the short end of the focal length range.
Quite why you want to use such good lenses at F22 on a D200 is beyond me. On a FF camera they might be acceptable at F22 on an A4 print, if a bit soft.
There are no pictures attached to your post, but I would expect to see much better results from a prime lens specifically designed for macro work when stopped down beyond f11 - f13. Read up on diffraction limits for lenses - in particular with respect to digital sensors.
Marc
So even though it is used for macro work, you would see the better image? I mean it is not a macro image in that scenario..
For the Tamron 90, yes, you will see a better image at normal distances as it is a very sharp lens at any distance. There are some macros that do not work so well when focused at non-macro distances, but these are usually older ones. I think all modern macros are generally excellent at macro distances and at least very good (if not excellent) at normal distances too.
Palmer, just a small note: along with Mark's diffraction explanation, bear in mind that macro lenses are generally some of the sharpest lenses you can buy. The Tamron 90 and Nikon 105VR are two of the sharpest lenses you can buy and are as good as it gets at that focal length, regardless of macro/non-macro distances.
Thanks for your reply. I gather that I made a mistake using the zoom at 200mm at f22.
I systematically tested each stop from 2.8 in sequence. I was trying to get the pine needles framing the image into sharp focus. To amplify my prior explanation a bit: I was set up on a roadside on a hillside. Large long needle pine trees were filtering the view of the city which was lit with horizontal afternoon sun and overall blue sky. The tree branches were 40-50 feet in front of the lens, and the city was several miles away.
At 200 mm and f8 the city was crisp, but the needles still soft and fuzzy. At about f13 the needles became much better. Then without much change, I went onward to f22.
Then I backed the zoom off to 95mm to attempt to get a shot which I thought would be comparable to the prime. Finally, I switched to the Tamron 90 prime, and shot at f22. When I got the two f22 images side by side in Lightroom I was surprised that the Tamron looked better.
Because the pine needles are around the edge of the image (where the zoom could be expected to be softer) perhaps I should have expected the prime to be better.
Perhaps I need to be more discipline in the testing. I also shot one picture with my 1.4 Nikon 50mm. It is splendid for overall clarity, the composition is weak because the city is so far away.
Thanks for any advice, including a proper testing protocol.
phinsdale wrote:
Unexpected results in an experiment
I own a Nikon D200, a Nikon 70-200 VR zoom, and a Tamron 90 prime used in this test.
Using a tripod, mirrorup, and cable release I have taken the same picture, a shot of San Francisco with pine needles showing on the upper three sides of the image. With the prime a f22, and the zoom at f22 and 95mm, the overall clarity at 100% in Lightroom is better with the prime.
The trees are probably 40 feet in front of the lense, and the city is several miles across the bay.
A simple question: why? Should the zoom at 95mm with the same aperture be indestinguishable from the prime? Apparently not. Why not?
First of all. Primes are generally sharper than Zooms. Zooms are a compromize between several optical needs. However really brilliant zooms like the AF-S 70-200/2,8 VR, are getting close.
Primes are much simpler built, than Zooms Thats why, they generally have the avantage.
Sekond. Macrolenses like the Tamron is special constructed to avoid diffraction at high f. values like F:/22. The zoom is not.Your zoom peaks in sharpness around f:/5,6. At higher F-stops sharpness will gradually deteriate.
Third: VR in the earler versions does not go well with tripods.
Typical sharpness will decline with VR on a tripod.
Thanks for helpful explanation. Also, I failed to turn off the VR even though I was using the tripod, and taking all precautions EG mirrorup, and cable. I gather that the VR creates its own motion blur when it is trying to compensate for (hopefully) non-existent motion.
On a FF camera they might be acceptable at F22 on an A4 print, if a bit soft.