New lens testing

 I asked ChatGPT4o this question:

How do I test the new lens against manufacturing faults? Suggest practical methods I can try. 

ChatGPT4o answered:

Testing your new lens for manufacturing faults involves a series of practical steps to ensure its optical and mechanical performance is up to standard. Here are some methods you can try:

1. Visual Inspection

- Inspect the Glass: Look for any scratches, dust, or defects on the lens elements. Check both the front and rear elements.

- Aperture Blades: Ensure the aperture blades move smoothly and are free from oil or irregularities.

- Mount: Check the lens mount for any signs of damage or wear.

2. Mechanical Functionality

- Focus Ring: Rotate the focus ring through its entire range. It should move smoothly without any sticking or unusual resistance.

- Aperture Ring: Check that the aperture ring clicks at each stop and moves smoothly.

3. Optical Tests

- Sharpness and Resolution:

  - Infinity Focus: Take a series of test shots of distant objects at different apertures, including wide open (f/1.5) and stopped down. The images should be sharp, especially in the center, and stopping down should improve edge sharpness.

  - Close Focus: Test the minimum focusing distance and ensure the images are sharp at various apertures.

- Distortion and Vignetting: 

  - Distortion: Photograph a brick wall or a grid pattern to check for any barrel or pincushion distortion.

  - Vignetting: Take images of a blank wall or sky at different apertures to see if there is any noticeable light falloff towards the edges.

- Chromatic Aberrations: 

  - Take high-contrast images, such as tree branches against a bright sky, and check for any color fringing (purple or green edges) along the boundaries.

- Bokeh Quality: 

  - Shoot images with out-of-focus backgrounds (e.g., portraits) to evaluate the quality of the bokeh. The out-of-focus areas should be smooth and pleasing to the eye.

- Flare and Ghosting:

  - Point the lens towards a bright light source, like the sun or a strong artificial light, to see how well the lens handles flare and ghosting. Check for any significant artifacts or loss of contrast.

4. Real-World Shooting

- Daily Usage: Use the lens in various real-world scenarios (e.g., landscapes, portraits, low-light conditions) to ensure it performs well across different situations.

- Check Consistency: Review your images for consistent sharpness and exposure across different settings and lighting conditions.

5. Comparative Analysis

- Comparison: If possible, compare the new lens with another similar lens that you know is defect-free. Look for differences in image quality, sharpness, and performance.

6. Software Tools

- Focus Charts and Test Patterns: Use printed focus charts and test patterns to evaluate sharpness and focus accuracy.

- Image Analysis Software: Programs like Adobe Lightroom, DxO Optics, or even free tools like RawTherapee can help analyze sharpness, chromatic aberrations, and distortion.

Focusing Summicron-M 35mm f/2 on Leica CL (part 1)

Leica CL is a compact, and lightweight camera with APC-S sensor that you can mount interchangeable lenses. The camera produces 24 MP images. 

In this post I will share the result of focusing experiments I have recently run using a Summicron-M 35mm f/2 ASPH lens mounted on Leica CL. 

Camera configuration:

• Leica CL, 24MP with APS-C sensor 
• LEICA Summicron-M 35mm F/2 ASPH lens 
• Film Style: Monochrome or Monochrome HC
• Photo File Format: DNG
• Focus method: manual assisted by focus peaking
• Shooting:
• Light: overcast
• Distance: 15-20m 
• Shutter speed: 1/1000s
• ISO: 100
• Aperture: f/2
• Focus: Number plate of the white car
• Post-processing: 
• Color (no processing or no presets applied)
• Color (Adobe Lightroom Auto preset applied) 
• BW (no processing, or presets applied)
• Exported using Adobe Lightroom Export as:
• 24MP JPEG loss-less output, 300dpi, sharpened for matte print paper

Because the CL has a crop sensor the effective focal length becomes 50 mm. This was the focal length used by legendary Henri Cartier-Bresson.

Shooting notes:

• I chose Monochrome HC film style that comes with the CL. Note, the term Film Style is just a name referring to Leica CL emulating film photography. The CL is a digital camera.
• 💡Using one of Monochrome film styles I can easily see focus peaking red dots while manually zooming. 
• The HC film style works really well under mid-day overcast lighting conditions. I could choose Natural Monochrome style (without HC) in the case of darker overcast lighting, such as late-evening.
• Thanks to M-ADAPTER L, when the lens is mounted on the CL camera, it automatically reads lens metadata and configures the right wheel to zoom on the image for focus assist. The zoom is crucial for precision focusing using focus peaking.
• While I zoomed in the number plate of the white car, I maximised number of red dots on that plate by adjusting the focus ring back and forth. This way the resultant focus was spot on the white car.

Download the following images to inspect. 

Simply click the image. That will enlarge it in on your browser. Then right-click and select Save Image As from the context menu to download the high resolution image on your device or computer.

Inspect them using your favourite editing/preview tool. 

Zoom to enlarge the number plate of the white car which I focused on during shooting.

24MP Images (free to download): 

• Color (no processing)

• Color (auto processing)

• BW (no processing)

A mood of joy

 A photon is a quanta of light. Light is absorbed and emitted one photon at a time - Michigan State University.

In this photograph we see a tunnel made by jets of water coming out of regularly placed nozzles along the long edge of a shallow pool. A child is running through the tunnel, enjoying the thrill of his play. I captured him in the last 1600th of a second before the shutter was closed.

During evolution of my photographic style I have increasingly become attracted to taking moody photographs.

For me what matters is the emotive content of a photograph. Everything else is an accessory. What I mean by that is the mood, a general sense of what is going on. I like it when I leave blanks in a puzzle and the viewer participates the discovery process. Facing sun is one way of creating such opportunities, allowing me to use darkness eliminating what is not essential for the mood. 

When we face the sun during sunrise or sunset or other times during winter when the light rays have stronger horizontal vectors, longer shadows and occasionally glitters expose a different world. Maybe this is so primordial for humans. We seem to feel differently at those times. 

You might ask why using a dark silhouette? Wouldn't it be better if the subject (child) was exposed even slightly so? Wouldn’t knowing his facial features or his outfit enhance the mood?

I have technical and philosophical arguments against using higher exposure.

Technically I had to reduce the exposure compensation before taking the picture. Facing the sun, that is the only way to eliminate burn outs. Drastic negative exposure compensation kept the child in dark, apart from leaving a lovely outline. That is exactly what I saw in the viewfinder.

Philosophically what interested me was depicting the water tunnel and the running child, the only necessary elements to reflect a mood of joy. I wanted to hide everything else, including clutters on the upper right side where people with prams, another child and a seagull are. Those were distractions for my story.

I tried exposing the running child using a subject mask in Adobe Lightroom. It worked, but the resulting image looked a bit fake, and worse, it ruined the mood.

The moral of the story is you need to know your place, your philosophy, your artistic stance before taking a picture. 

For me slowing down, having a strong sense of intent and being picky works. Often I return from my photo walks empty handed. That is ok. That is part of the process. But once in a while you will capture something beautiful, then you will realise why it was worth all the trouble.

AI has come

My computer has just had its 10th birthday, a MacBook Pro (Retina, 13-inch, Mid 2014.) Its operating system was stuck at MacOS Big Sur.

A few months ago my Adobe Creative Cloud subscription refused to upgrade Lightroom, as the new version required new hardware and new OS. 

Adobe has recently added generative AI into Photoshop. You can now use prompts and talk to it. 

AI tools demand ample horsepower. My computer has Intel i7 processor and Intel Iris graphics card, relics from not so distant past. 

Despite the hype, I approach using AI cautiously. There is a danger of losing our creativity if we offload too much of our skillset to AI. Being creative is what keeps me going, it is the fuel of my spirit, it is what makes me human. 

Realising the distinction between fixing photographs and making photographs is important. Soon AI will be able to do both.

Getting help from AI to do tedious tasks, for example, culling hundreds of similar images is interesting. Currently editing is the most boring and time-consuming aspect of digital photography. I would welcome AI if it could be trained to keep what I think as the best, an agent that understands my taste.

I am not even remotely interested in getting AI to create fake images. For me photography is about capturing reality. There is camera and there is photographer. The photographer is the sole agent who makes the decision to frame and shoot the picture. If AI makes that decision, an entirely plausible prospect, then AI becomes the photographer, not me. Where is the fun in that?

Moody pictures

What is so special about moody pictures? 

As a photographer I’ve always been attracted to gentle light. It is the feeble presence of light that works its magic, offering us an alternative reality.

Copyright © 2015-2024 Ergun Coruh. All rights reserved. 

In this picture we see a bunch of youngsters, sitting on an old stone platform at the Sydney Harbour. Their gaze wanders around sails on the water and the skyline far ahead while golden lights of a dying day are casting intricate shades from behind the Harbour Bridge. They might be reflecting on life, perhaps big questions that they don’t think about during the hustles of a day. 

When I photograph sunsets I photograph everything else but the sunset. For me it is pointless to target a beautiful sunset alone if there is no meaningful story attached to it. Without people this would have been just another Sydney Harbour picture.

How do I shoot a picture at sunset

My camera is a Leica Q-P. It has 24MP full frame sensor with a fix 28mm Summilux f/1.7 ASPH lens. 

I always use Aperture priority mode, AE (auto-focus) set to spot metering, and AF (auto-focus) set to single point. I use the thumb lock button as the AE lock, and half-pressed shutter release button as the AF lock.

I begin by setting the exposure compensation in the middle. I set aperture using the aperture ring, trying to stay between f/4.0 and f/5.6, with ISO not exceeding 100. My goal is to get my subjects definitely into focus and most of the stuff beyond them too. 

I point middle of the lens to a darker mid-tone spot to increase exposure lightly, exposing sufficient details on and around the subject(s), eliminating underexposed areas as much as possible without blowing highlights too much. I press the thumb lock button with my thumb and keep it pressed to lock the exposure. 

I compose the frame my moving my lens around, cutting out distractions at the same time. If there are too much exposure in white areas, I unlock by releasing my thumb, halve the exposure compensation using the thumb wheel, and re-sample the exposure and re-lock it. 

I check the shutter speed to stay at 1/250s or faster. I half-press the shutter release button with my index finger to focus somewhere on the subject(s) or somewhere near, I check the histogram, if necessary I repeat everything from scratch. 

I check the subject(s) one last time to see if there is any awkwardness I wouldn’t want in the frame. Finally when the decisive moment comes I press the shutter.