I am interested in doing close-up photography at 4 feet because I cannot kneel on the ground to get close to a subject near the ground level.
I have determined that I can get 1:2 photos with the Nikon D500 camera and Nikkor 300mm f/4E PF lens with either the Nikon 14E III or Nikon 20E III teleconverters at 4 feet. Now I want to determine how good the photos will be with this combination, by using my resolving power chart I made which is described in my June 9th post. If the photos are sharp enough, I can use Photoshop to get closer than 1:2 by cropping and re-sizing.
I am going to show the resolving power of the Nikkor 300mm f/4E PF lens on the Nikon D500 camera without attachments to establish a base point before using the teleconverters. The following photos of the resolution chart were taken at a 4 foot working distance.
Bear with me for the following explanation.
I printed the computer generated resolution chart with an Epson R3000 printer on Epson glossy photo paper. This print is what I used for this post, and will use for future posts, to determine the resolving power of my photographic gear. As you will soon see, the print does not present as nice a chart as I showed in the June 9th post. In that post, I posted computer generated photos of the chart. In my first photographs of the print with the 300mm f/4E PF lens, I observed that the photograph of the chart was so good, that it showed the ink spots laid down by the printer. That the nice sharp edges of the bars (as shown in the computer generated screen shots), were actually jagged "rugged coast lines" of ink spots. At first I thought that that's not good, that I should probably photograph the chart shown on the computer screen to show the straight lines of the bar edges. Then I realized that it is more informative to show the actual print, jagged bars and ink spots.
I am going to describe in detail, the photography setup for taking the photographs, and the method for processing the photos, so I do not have to repeat myself in future posts.
I pinned the resolution chart on a black paper hard board, and illuminated it with an OTT Lamp which gave a near 4800 degrees Kelvin white balance.
I mounted the Nikon D500 camera on a tripod and moved it until the front of the Nikkor 300mm f/4E PF lens was 48 inches from the chart. I used live view to manually focus the lens using the lens focus ring. I used a Nikon MC-36 cable release to fire the shutter. I waited several seconds after removing my fingers off the focus ring before releasing the shutter to reduce vibration. The camera was set at ISO 100.
I took 5 photos at following lens apertures: f/4 at 1/125 sec., f/5.6 at 1/80 sec., f/8 at 1/40 sec., f/16 at 1/10 sec., and f/22 at 1/5 sec.
Once I focused on the chart at f/4, I did not touch the focus ring again, so that the focus did not change between aperture settings. Thereafter, the only time I touched the camera was to rotate the camera front command dial to change the aperture setting.
I processed the Raw Nef files as follows. I opened the raw Nef files with DxO Optics Pro. I did zero processing in DxO, especially no sharpening, no contrast nor clarity type of processing, that would change what came out of the camera. I only used DxO to open the Nef files and export them as Dng files. Note - I use DxO because Camera Raw CS6 will not open D500 Nef files, thanks to Adobe and their cloud.
I opened the Dng files in Camera Raw CS6. The only processing I did in Camera Raw was to raise the exposure slider by +2.0 ev, and decreased the Black and Shadow slides. I did no other changes, especially no sharpening, no contrast changes, and no clarity changes.
I then opened the PSD files in Photoshop CS6. I did zero processing in Photoshop. I only used Photoshop to "save for web", to size the Jpg files to the posting requirements.
By doing zero changes to the structure of the files, except for boosting the exposure to brighten the photo, what you see is what the camera recorded.
Here is the photo of the resolution chart taken at f/4:
The photo measures 3.8 inches by 2.6 inches for a 4.15 to 1 photo (4.15 times larger than the D500 sensor).
The D500 camera photo pixel size is 5624px by 3754px. For posting, I took slices of the photo to show the center area more closely. I did no changes to the pixels, just showing proportions of the photo. Note - I took slices that were in proportion to the 1024px by 1024px max. size for posting. Here is a 512px by 512px portion of the photo:
This portion of the photo shows the center most part of the chart. This photo clearly shows the ink pattern laid down by the Epson R3000 printer on glossy photo paper on the edges of the bars. To see closer, here is a 256px by 256px portion of the photo:
Since it is too small, I am going to change the pixels somewhat by re-sizing this 256x256px photo to 1024px by 1024px in Photoshop, using bicubic smoother, here is the resulting photo:
Now you see what I meant by "jagged edges".
The smallest set of bars, bars no. 6, in the computer file that made this printout, measured 0.02 inches long and 0.004 inches wide, and the white spaces between the bars are 0.004 inches wide. Obviously, the Epson R3000 printer, as good as it is, cannot hold to these dimensions on the glossy printer paper. The ink spreads unevenly on the paper at these small dimensions.
However, what you see can be used to observe changes in appreance as I change the aperture from f/4 to f/22. To continue on.
Here is the photo taken at f/5.6:
Here is a 256px by 256px slice of the f/5.6 photo:
And here is the f/5.6 256x256px slice resized to 1024px by 1024px:
The f/5.6 photo shows the ink pattern of the 0.004 inch wide bars a little more clearly, and some what sharper, than the f/4 photo.
Here is the photo taken at f/8:
Here is a 256px by 256px slice of the f/8 photo:
And here is the f/8 256x256px slice resized to 1024x1024px:
The f/8 photo shows the ink pattern on the edges of the bars a little more clearly, and some what sharper, than the f/4 and f/5.6 photos.
Here is the photo taken at f/16:
And here is a 225px by 225px slice of the f/16 photo:
And here is the f/16 256x256px slice resized to 1024x1024px:
Compared to the f/8 photo, the f/16 photo is starting to show diffraction; the bar edges are not as clear and sharp.
Here is the photo taken at f/22:
And here is a 256px by 256px slice of the f/22 photo:
And here is the f/22 256x256px slice resized to 1024x1024px:
The f/22 photo is definitely showing the affects of diffaction caused by the small aperture.
In conclusion, the sharpest photo taken with the Nikkor 300mm f/4E PF lens on the Nikon D500 camera is produced at an aperture of f/8. Also, this combination of lens and camera takes fairly detailed photos at 48 inches working distance. The smallest bars have a width equal to the average human hair diameter, approximately 0.004 inches. That's pretty good for a 4 foot working distance.
Before I move on to use the Nikon teleconverters with the Nikkor 300mm lens, Lou Jost requested that I determine the resolving power of the Sigma APO MACRO 180mm f/2.8EX lens mounted on the Nikon D500 Camera. And to photograph the chart at several magnification values from 1 to 1/5, each at a few aperture values. So that is my next post or posts. I have several photographs to take. Just as well, it is windy and cold outside here in Sequim, Washington.
Leon
