the last word

Photography meets digital computer technology. Photography wins -- most of the time.

  • site home
  • blog home
  • galleries
  • contact
  • underwater
  • the bleeding edge
You are here: Home / The Last Word / EFCS and atmospheric effects

EFCS and atmospheric effects

May 16, 2015 JimK Leave a Comment

I’ve been making images like this lately:

[Group 1]-_DSC3473__DSC3493-20 images_0000-Edit

This is a 20-image stitch made with a Sony a7II and a Leica 280mm f/4 Apo-Telyt-R.

I decided that I wanted to try a zoom lens, so that, when I’m not stitching, I could frame by zooming. Many people say you should “zoom with your feet” but that’s problematical when your subject is several miles away.

I have a Nikon 200-400mm f/4 zoom. I thought I’d give it a try. But first I wanted to do some tests to see if the lens was up to the task. I’d used it before with success, but never in situations like this kind of landscape, where sharpness is important.

I put the lens on a Nikon D810, the combination on a sturdy tripod with a Arca Swiss D4 head (the more I use geared heads, the less patient I am with ball heads), zoomed it out to 400mm, and aimed it at this scene:

_8105640

As I focused using live view, I noticed that there was a fair amount of image motion due to thermal effects in the several miles of atmosphere between me and the trees on the ridgeline. It was midday, which is a bad time for thermal agitation of the air.  I made an aperture series with EFCS on, and one with it off.

I noticed that there wasn’t much difference between the two series. Here’s f/8 at 1/125 with EFCS on blown up to 200%:

_8105625-2

And f/8 at 1/100 with EFCS off:

_8105630-2

Is the lens that bad, or is the air that bad?

The next day, in the mid afternoon, I put a Nikon 400mm f/2.8 AF-S (non-VR) lens on the camera, and aimed it across the valley:

_8105680

I did another set of aperture series with and without EFCS. Here they are:

 

f/2.8, 1/1600, EFCS on
f/2.8, 1/1600, EFCS on
f/2.8, 1/1600, EFCS off
f/2.8, 1/1600, EFCS off

Pretty darned blurry, and not a lot to choose between the two images. Either the lens isn’t that sharp wide open — not its reputation — or I wasn’t able to focus accurately. I will say that focusing was very difficult due to the combination of atmosperic thermal effects and vibration. I’ve recently begun turning on image stabilization on long lenses to focus, even when the lenses are on tripods. I find my accuracy is greatly improved. Most of the time I remember to turn stabilization off before I take the shot.

 

f/4, 1/800, EFCS on
f/4, 1/800, EFCS on
f/4, 1/800, EFCS off
f/4, 1/800, EFCS off

Still not much difference.

f/5.6, 1/400, EFCS on
f/5.6, 1/400, EFCS on
f/5.6, 1/400, EFCS off
f/5.6, 1/400, EFCS off

Now the EFCS image is noticeably sharper, but the difference is not dramatic.

f/8, 1/200, EFCS on
f/8, 1/200, EFCS on
f/8, 1/200, EFCS off
f/8, 1/200, EFCS off

Now there’s quite a difference. The lens is getting sharper, and the EFCS can make a difference.

f/11, 1/100, EFCS on
f/11, 1/100, EFCS on
f/11, 1/100, EFCS off
f/11, 1/100, EFCS off

Now the EFCS image isn’t looking any better, and it might even be worse. What’s happening here? I think that, as the shutter speed goes down, the atmospheric turbulence has a greater effect, rendering the image formed by the lens so blurry that any sharpness improvement that EFCS brings is not visible.

I’m going to have to try some shots in still morning air and see what the effects are. And the zoom sharpness? I still don’t know, because the zoom shots I was looking at where the lens is its sharpest were at a shutter speed of around 1/100, where the motion of a few miles of air just kills the clarity.

The Last Word

← A book report: LensWork publishing services EFCS without atmospheric effects →

Leave a Reply Cancel reply

Your email address will not be published. Required fields are marked *

March 2023
S M T W T F S
 1234
567891011
12131415161718
19202122232425
262728293031  
« Jan    

Articles

  • About
    • Patents and papers about color
    • Who am I?
  • Good 35-70 MF lens
  • How to…
    • Backing up photographic images
    • How to change email providers
  • Lens screening testing
    • Equipment and Software
    • Examples
      • Bad and OK 200-600 at 600
      • Excellent 180-400 zoom
      • Fair 14-30mm zoom
      • Good 100-200 mm MF zoom
      • Good 100-400 zoom
      • Good 100mm lens on P1 P45+
      • Good 120mm MF lens
      • Good 18mm FF lens
      • Good 24-105 mm FF lens
      • Good 24-70 FF zoom
      • Good 35 mm FF lens
      • Good 60 mm lens on IQ3-100
      • Good 63 mm MF lens
      • Good 65 mm FF lens
      • Good 85 mm FF lens
      • Good and bad 25mm FF lenses
      • Good zoom at 24 mm
      • Marginal 18mm lens
      • Marginal 35mm FF lens
      • Mildly problematic 55 mm FF lens
      • OK 16-35mm zoom
      • OK 60mm lens on P1 P45+
      • OK Sony 600mm f/4
      • Pretty good 16-35 FF zoom
      • Pretty good 90mm FF lens
      • Problematic 400 mm FF lens
      • Tilted 20 mm f/1.8 FF lens
      • Tilted 30 mm MF lens
      • Tilted 50 mm FF lens
      • Two 15mm FF lenses
    • Found a problem – now what?
    • Goals for this test
    • Minimum target distances
      • MFT
      • APS-C
      • Full frame
      • Small medium format
    • Printable Siemens Star targets
    • Target size on sensor
      • MFT
      • APS-C
      • Full frame
      • Small medium format
    • Test instructions — postproduction
    • Test instructions — reading the images
    • Test instructions – capture
    • Theory of the test
    • What’s wrong with conventional lens screening?
  • Previsualization heresy
  • Privacy Policy
  • Recommended photographic web sites
  • Using in-camera histograms for ETTR
    • Acknowledgments
    • Why ETTR?
    • Normal in-camera histograms
    • Image processing for in-camera histograms
    • Making the in-camera histogram closely represent the raw histogram
    • Shortcuts to UniWB
    • Preparing for monitor-based UniWB
    • A one-step UniWB procedure
    • The math behind the one-step method
    • Iteration using Newton’s Method

Category List

Recent Comments

  • Mal Paso on Christmas tree light bokeh with the XCD 38V on the X2D
  • Sebastian on More on tilted adapters
  • JimK on On microlens size in the GFX 100 and GFX 50R/S
  • Kyle Krug on On microlens size in the GFX 100 and GFX 50R/S
  • JimK on Hasselblad X2D electronic shutter scan time
  • Jake on Hasselblad X2D electronic shutter scan time
  • Piotr Chylarecki on Who am I?
  • JimK on Who am I?
  • Piotr Chylarecki on Who am I?
  • Stefan on Swebo TC-1 OOBE

Archives

Copyright © 2023 · Daily Dish Pro On Genesis Framework · WordPress · Log in

Unless otherwise noted, all images copyright Jim Kasson.