Sunday, July 5, 2020

Quick update on Deep Focus Photography

As I'm still shielding, because of C19, and am also recovering from a broken leg and surgey, I thought I would take a quick relook at my auto deep photography experiments.

Currently I have auto deep focus capture running on the following cameras:
  • Canon G1X - via a CHDK script
  • Canon G5X - via a CHDK script
  • Canon G7X - via a CHDK script
  • Canon EOSM3 - via a CHDK script
  • OMD EM5II - via the in-camera functionality
I'm going to ignore the OMD in this post,  as it relies on a propriety solution, and is not optimised for landscape deep focus capture.

The G5X and G7X have the smallest sensors, both using a "1 inch" format sensor, with the G1X upping the size to "1.5 inch" format.

This leaves my EOSM3 camera as the only APS-C format that runs one of my CHDK auto focus bracketing scripts. The latest version of the script can be downloaded from the link on the right: M3 Brackets. 

Once you have CHDK running on the M3, the script is simple to use, with the following UI:
  • Select the focus bracketing logic, ie OFF allows you to 'just' exposure bracket; X2INF focus brackets from the current position to infinity; and Min2INF covers to entire focus of the lens, irrespective of where you are focused;
  • Select what ETTR-based exposure bracketing logic you wish to use at each focus bracket. The options are: none or +4Ev or +3Ev or +2Ev or +2/+4Ev or ISO1600;
  • Select your infinity focus, ie the last shot in the bracket sequence, at the overlap defocus blur divided by either 2, 3 or 4;
  • Select the overlap defocus blur in microns, between 5 and 20, with 15 being a reasonable number to use on an APS-C sensor;
  • Select if you wish to use a start delay time in seconds;
  • Select whether you delineate the bracket sequence with dark frame 'bookends';
  • Select whether the LCD is off during capture;
  • Select a so-called nudge distance to ensure the script doesn't freeze at the macro end. The default is 10mm;
  • Select a lens thickness to be used, in the split thin lens model, if you haven't explicitly coded a lens into the script. The script has the 11-22mm lens encoded, but you can add other lenses. Unless you know what you are doing, leave the lens thickness at zero and use a thin lens model;
  • Select 'Get Lens Name' to allow you to programme your own lens thickness.
As to some test results, I set the 11-22mm to 11mm, F/7.1 and ISO100, at an exposure of 0.5s. I used the Min2INF option and the script took 13 images, which I post processed in Lightroom, with a round trip to Helicon Focus.

Using Jeffrey Friedl's Lightroom “Metadata Viewer” Plugin, it was easy to extract the following (lower) focus distances from the EXIF data:
  • 0.15m
  • 0.16m
  • 0.17m
  • 0.18m
  • 0.19m
  • 0.21m
  • 0.24m
  • 0.25m
  • 0.33m
  • 0.45m
  • 0.71m
  • 1.54m
  • 3.84m
The resultant, deep focus, 'post processed' image looks like this:


Hopefully this short post has illustrated the power of CHDK to automatically create deep focus images on an APS-C cropped sensor, ie the EOSM3.

As usual I welcome feedback on this post.

Thursday, June 11, 2020

Hyperfocal Informed Bracketing Strategy

If you have been following my previous posts on using the Rule of Ten to inform your (non macro) focusing, you should now have a good understanding on how to:
  • calculate the hyperfocal using the Rule of Ten;
  • set a specific infinity blur and maximise the near depth of field for a single shot;
  • select the overlap blur using the equivalence rule;
  • carry our focus bracketing using the odds or evens rule.
In this post I'm introducing a pragmatic focus bracketing strategy, designed to be easy to use and robust enough to handle deep focus situations.

The Hyperfocal Informed Bracketing (HIB) strategy is based on knowing/calculating a single number. Namely the hyperfocal distance; either explicitly knowing it, estimating it from the DoF scale of your lens, or using the RoT to estimate it.

The HIB approach assumes you are focused on the nearest point of interest (POI) in your scene and you want the scene out to infinity to be in high quality focus.

In general, according to where your (nearest) POI is, relative to the hyperfocal, all you need to do to focus bracket for the near field, is to keep doubling the distance, until you are beyond H at which point you should select your final infinity shot.

If your POI is positioned beyond H, then all you need to do is take a single image at your selected infinity position, eg from, say, 2H to infinity.

If your POI is positioned between H/2 and H, then all you need to do is take the POI image and an infinity shot.

If your POI is positioned between H/4 and H/2, then all you need to do is take the POI image, refocus to double the POI and take a second shot, before adding a third infinity shot.

Finally, if your POI is less than H/4, then take three near field images at the POI, double the POI distance and four times the POI, ie double the second shot's distance, before taking a fourth infinity image.

Note that when the POI is less than H/4, the HIB strategy is strictly not fully optimum, but it is close enough That is pragmatism rather than mathematical purity.

To help you understand and practice HIB based focusing bracketing, I have created another eClass, which you can access on the right.

The following partial screen grab shows the HIB strategy in action. The (overlap) defocus CoC was put at 12 micron, ie double the 24mm RoT H. The POI is less than H/4, thus we take focus brackets at the POI, at twice the POI and at 4 times the POI, as well as an infinity shot at twice H.


I hope you have found this post of some value. As usual I welcome feedback of any kind.

Sunday, June 7, 2020

Hyperfocal Bracketing Simulator (HBS)

In the previous post I talked about two eClasses I have created, both accessible through the eClasses links on the right: Getting more out of Focus :-) and Getting even more out of Focus :-)

These two classes lay out the foundation of an integrated focusing methodology, for both tilted and non-tilted lenses, based on simply knowing the hyperfocal distance.

In addition, the classes show that you can calculate the hyperfocal in your head, using the Rule of Ten (RoT). No apps; no tables; just simple arithmetic, eg doubling or halving.

Each of these two classes includes a specific simulator, that allows you to explore the ideas presented in each class.

In this post I'm pleased to introduce a third simulator, specifically directed at helping you understand hyperfocal bracketing.

Access to HBS is from the link on the right: under eClasses.

The simulator has sufficient instruction built in, so I won't duplicate that here.

The simulator allows you to independently select your infinity shot and up to four hyperfocal brackets, ie at H/2, H/4, H/6, H/8 or H/3, H/5, H/7, H/9 according to whether you are using the Evens or Odds rule.

The simulator looks like this, where we see that diffraction is switched on; That we have an infinity shot at 2H and that we have two (evens) focus brackets to cover the near field, ie at H/2 and H/4.


As usual I welcome feedback on HBS, especially ideas to make it better.

Wednesday, May 20, 2020

Getting (even) more out of Focus :-)

Anyone looking back and reading this post in future years, or anyone’s post created in the first half of 2020, needs to be reminded that most of the planet was in ‘lock down’ for months, thanks to COVID-19.

Of course, in the greater scheme of things, the COVID-19 story is ‘just’ another footnote in the Earth’s history. We will prevail, and many of us hope the COVID-19 lessons will be used by those who try and govern us, to make a better world: only time will tell.

One positive that has come out of the COVID-19 times, if you forgive me saying that, is the time that has been created, albeit restricted within our homes, to reflect and reenergise ourselves, without the ‘distractions’ of our ‘normal’ lives.

For me, I have taken the opportunity to create a two-part ‘photography class’ on non-macro focusing, that I gave to my Camera Club in two webinars.

I titled the classes ‘Getting (even) more our of Focus :-)” and their purpose was to help dispel a few myths about focusing and introduce a few (science-based) ‘rules of thumb’ to help photographers with their focusing, eg the ‘the Rule of Ten (RoT)’ to calculate the hyperfocal in your head and ‘the Odds & Evens Rule’ to assist your manual focus bracketing.

The classes were recorded, but only club members can access these recordings. However, when I created the classes, I had it in my mind to provide a (free) learning resource for all, hence I made use of the Desmos environment to create two standalone, web-accessible e-classes.

Desmos is well known to school maths, science and engineering teachers. It is rich in functionality, especially when it comes to graphing.

The first class, ‘Getting more out of Focus’, includes a focus simulator that allows the ‘student’ to explore the blur field created by the lens defocus and the aperture diffraction, as well as exploring focus bracketing. It also introduces: the ‘Rule of Ten’; the odds part of hyperfocal bracketing for focus bracketing; and how to control infinity focusing. All in your head, without any apps or look up tables.

The second class, ‘Getting even more out of Focus :-)’, introduced a refinement to the first class and consolidated the RoT and infinity focusing, and used the evens part of the Odss & Evens Rule. It also provides a Tilt & Shift simulator to allow the student to explore and practice using the ultimate focus control lens, the Tilt/Shift lens. Finally, it demonstrated how to post process focus brackets using various tools (but this is only accessible to my photography club’s members).

Although the class mentions Magic Lantern, and discusses how Lua scripts can help in focusing, the two classes are not Canon specific.

The classes are free to access and can be found via the following two links:

Class 1:

https://student.desmos.com/activitybuilder/student-greeting/5ea8857d202c250d0167a208

Class 2:

https://student.desmos.com/activitybuilder/student-greeting/5ec439936236cb760b9af4b9

To access the classes simply use the links above and enter your name (real or not).

I hope you get some value out of the above. Creating these classes greatly helped me get through the COVID-19 crisis. As usual I welcome feedback: either here or via the feedback pages in the classes.

Saturday, April 4, 2020

One slider post processing...nearly

For those reading this post in future years you will need to first remember that the global pandemic of 2020 is fully underway, and yours truly, like everyone else, is locked down.

One benefit of the situation is that we all find ourselves with a lot of time on our hands and, for me, that means I have spent many hours refining my post processing workflow.

I have not, however, done this on my own. Over the years I’ve been informed by many web teaches: through free education and paid. Some names I could mention are: Sean Bagshaw; Mark Metternich; Matt Kloskowski. I thank them for passing on their knowledge.

The other thank you must go to Adobe, for evolving Lightroom into a really good post processor. Factor in Photoshop and you have a really first class duo.

So what I have done is compress/merge/fuse my ideas with all those mentioned above, and others, into a single preset, that I call ‘Garry’s Magic Preset’.

To use the preset, once you have ingested the image into Lighroom, is a simple twostep process.

  • Go to the develop module and select Garry’s Magic Preset. 
  • Adjust the exposure slider and WB until the image looks OK for further processing.
That’s it.

To illustrate the power of the preset, let’s look at an image I captured, handheld, in Quebec in 2013. As usual for me, ETTRed.


This is the image having pressed my preset. Yes, I know, it looks worse!


However, this is the image after simply adjusting one slider, the exposure slider.


Of course, this is only the start of the post processing. From here, I would adjust colour, possibly via Lightroom LUT profiles, and do local adjustments in Lightroom, including using the ‘quasi-luminosity’ masking that is now in LR. None of which I’m doing in this post.

I hope you have enjoyed this short post and, as usual, I welcome feedback of any kind.

Sunday, March 8, 2020

Near-Far, Zero-Noise Bracketing

It’s a rather windy and wet Sunday, so an ideal opportunity to carry out some indoors photography experiments: this time ‘perfecting’ what I call the Near-Far, Zero-Noise Bracketing technique.

I’ve evolved this technique mainly for use with my manual lenses, to ensure I capture the ‘optimum’ 4-image, focus and exposure bracket set.

In this post I’m using my OM-D M5II, with my manual, Laowa 15mm f/4 Wide Angle Macro, which means I can focus ‘anywhere’, ie (really) near to (far) infinity.

The technique, on my OM-D M5II, using an infinity blur criterion of 15 microns, is rather simple, but I constantly find it works. It goes like this: 

  • In manual mode, put the lens at the widest aperture, ie F/4 in this case, and focus on the nearest object you wish to see in focus, typically for this technique to work this object will typically be greater than, say, 0.5m away. If it's closer than this, you may need to inject intermediate focus-exposure brackets;
  • Set the lens aperture to F/7.1 to F/8, but on my MFT camera, no more, as diffraction will begin to get the better of you;  
  • Using the OM-D LV, with exposure blinkies on and the LV histogram to guide you, set the exposure for the highlights and take your first image;  
  • Take note of the exposure compensation and adjust the exposure by 4 stops, and take your second image;  
  • Reset focus for the background, eg I have set my lens infinity at the lens hard stop, using the fotodiox dlx stretch adapter, so all I need to do is set the focus to the hard stop point on the lens, where I know I will have optimum infinity focus;  
  • Take the third image at the current exposure;  
  • Finally, change the exposure by -4Ev and take the fourth and last image.
Ingest the four images into Lightroom, and use LR’s HDR capability to process the two exposure brackets. Then, in my case, I do a round trip with these two processed images to Helicon Focus. Once I’m back in LR, I process for a look.

As an example, here are the four captured zero-noise images, just taken in my kitchen. Note the focus difference between the tap and the chairs:






Here are the two LR HDR merged images, ie covering near and far, merged exposure brackets:



Here is the final ‘Near-Far, Zero-Noise’ image. BTW it was a windy day outside, so some tree movement can be seen:

I hope some found this post of value/interest; and, as usual, I welcome feedback on this or any previous post.


Saturday, March 7, 2020

In-field Manual Lens Calibration

I have several manual lenses that I’ve acquired for my EOS cameras, for example: a rather unusual Venus Optics wide-angle lens, the Laowa 15mm f/4 Macro Lens; and a Rokinon 14mm f/2.8.

Like others, I try and get the maximum value out of these lenses by using then with adapters on mirrorless cameras, eg the Canon EOSM.

Recently I made the decision to down size my travel gear and introduce a Micro Four Thirds (MFT) format camera: choosing to buy a second hand Olympus OM-D M5 Mk 2.

I was drawn to the OMDM5II because it was small and light weight, and it had so many features, eg non-macro focus stacking.

My first adapter was a relatively cheap K&F Concept adapter. However, either this was a badly made one, or the manufacturer had the relative flange distances wrong; as infinity focus was way out. For example, the 14mm Rokinon’s infinity focus was at about 0.3m on the lens.

Some lenses can be manually calibrated by partially disassembling them, but not all. Plus, I had an idea that I wished to try out, namely, realizing an infield calibration approach, whereby I would decide the infinity I needed for that shoot.

For example, the first useful 'infinity' would be at the ‘classical’ hyperfocal (H), eg giving an infinity blur of 30/crop microns. The second infinity would be where the infinity blur was around two sensor pixels, eg around H/2-H/3, according to your camera. With the third infinity at the 'visible' infinity. As you move from H to the visible infinity, your blur at infinity will, of course, reduce, but so will your near depth of field, moving from H/2 to H.

So I purchased a Fotodiox DLX Stretch Lens Mount Adapter, obviously for the Canon EOS  EF/EF-S Lens to Micro Four Thirds (MFT) version, which comes with a Macro Focusing Helicoid and Magnetic Drop-In Filters, ie rear NDs. https://fotodioxpro.com/products/eos-mft-dlx-stretch 



It was a bit of a gamble, as I didn’t know how the adapter, which is designed to work as a macro bellows, would handle the infinity correction.

Having now tried it on both manual lenses, I am pleased to report that the Stretch Adapter works fantastically well.

Once fitted to the OMD M5II, all I do is: decide where I wish to calibrate, eg H, 3H or ‘visible infinity’;
set my aperture to the widest it will go; set my lens focus ring to the infinity mark or even the infinity hard stop; and adjust the adapter until things look tack sharp on the zoomed in LV.

For landscape photography this is great. But what about portrait photography? Once again, the adapter shows its utility. In this case I set the lens to sensible distance which is also registered on the lens, eg 1m, say, and go through the same process as above.

Bottom line: if you have EOS lenses and a mirrorless camera, but, sadly, not an EOSM, then you may be interested in acquiring the Fotodiox DLX Stretch Lens Mount Adapter, which will give you in-field, micro calibration of your manual lenses.