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.

Augmented Reality Depth of Field

The current Depth of Field Info script (DOFI) was written to be as un-intrusive as possible, whilst displaying the maximum (blur) info associated with focus, for example when undertaking manual focus bracketing or setting the infinity focus.

The latest version of ML DOFI, as usual downloadable from the link on the right, now includes an augmented reality (AR) option, that shows the focus and various key distances (3*hyperfocal (3*H), H, H/3, H/5, H/7) on the ground plane. That is at the optimum focus positions for focus stacking.

Of course, because the script doesn’t know the camera’s full orientation, this version assumes that the ground plane’s height is specified by the user and that the ground plane is parallel to the axis of the lens. In most cases the AR mode will be used with the camera on a tripod.

The AR mode can be switched on and off in DOFI’s menu.

To use the AR mode, first ensure you have the correct info set in the menu, ie tripod height and camera format.

After that, all you need to do is centre the display on the infinity horizon, ie level the camera. The AR mode shows infinity as a black dot.

To illustrate DOFI’s AR mode, this screen capture shows what the AR display looks like if you are focused short of the ground plane’s intersection with the lens field of view, ie the point of focus is hidden. 


Here we see the hyperfocal shown by the yellow dot with a green bar, and the 3*H distance. For infinity focusing, the sweet spot is between H and 3H, that is infinity blurs between the ML set Circle of Confusion and a third on this. Going less than a third of the CoC is not likely to gain you anything, as your defocus blur will be less than two sensor pixels.


In this next screen capture we have refocused towards infinity and the point of focus, as projected on the ground plane, is shown as a red dot, indicating it is less than the hyperfocal.


Finally, this screen capture shows the focus dot has turned green, indicating we are focused at greater than the hyperfocal. We also see we are focused less than 3*H.


As is the case with all DoF info, the AR mode is there to aid/inform focus setting. DOFI’s DoF and FoV calculations are based on a thin lens model and are a reasonable approximation away from the macro end, say, at H/7 or greater.

Finally, I welcome feedback, especially ideas that could make DOFI better.

Monday, February 17, 2020

First thoughts on ‘switching’ to MFT

For British readers, saying that Micro Four Thirds cameras are like Marmite will be well understood, ie they divide opinion.

As a Canon-guy, and a Canon-guy that only uses Magic Lantern or CHDK augmented cameras (5D3, EOSM(Vis), EOSM(IR), EOSM3, G1X, G5X, G7X, S95) I have been reluctant to explore other camera manufactures; although I did‘play around’ with the Sony S6000 a couple of years ago; but sold it on.

However, a recent travel experience has led me to explore the Medium Format sensor option, with a crop of 2; and,specifically, the Olympus brand.

My recent experience pivoted around having to carrying all my 5D3-based infrastructure with me on a tour of Scotland, iein and out of hotels and out shooting day and night. A lot of heavy ‘stuff’, when you factor in the camera, the lenses, the (large) tripod, the gear head, the laptop etc etc etc.

I was drawn to the Olympus MFT cameras for five reasons: their size, relative to the 5D3; their mirrorless advantage that allows me to use ‘specialist’ lens adapters, such as the ND Throttle; their ‘button re-programmability’, but I won’t say much about their menus; their focus bracketing; and their Live Time feature, that allows one to see the exposure (and histogram) evolving in real time.

As this is an experiment for me, I decided to ‘go cheap, and buy into a ‘last gen’ Olympus. Thus, I bought a second-hand OM-D M5 Mk II, rather than get a MkIII. I also ‘went cheap’ on dedicated lenses and decided to buy at the ‘kit end’ rather than the ‘pro end’: Olympus 14-42mm, 40-150mm, plus a Samyang 7.5mm Fish Eye.

In addition to the (dumb) ND Throttle, which is there for Long Exposure capture, I purchased a basic ‘dumb’ adapter for my Canon EOS lenses; as the OM-D M5-II has great focus peaking, I think this will be OK for my type of photography. I don’t do sports or bird photography, that would require fast acting AF tracking; ‘all’ I do is put a camera on a tripod and try and slow down.

To complete my ‘new’, lightweight travel set up, I will likely throw in my CHDK G7X or G5X, and, of course, my newly acquired Peak Design Travel Tripod: an incredible piece of engineering design.

Finally, to complete the downsizing, no more laptops for me when I’m on the road. In future I’ll simply use my existingiPad Pro 10.5, loaded with Lightroom and Affinity Photo (£16, one off purchase), as my Photoshop substitute, as Adobe need to do a lot more with the iPad-based Photoshop before I consider it useable.

I’m looking forward to trying out my new, old stuff, and will write about my ‘on the road’ MFT experiences in future posts.

Saturday, February 1, 2020

Wecome to the DOFI family

In the last month I've completely overhauled my Depth of Field scripts.

I have done this for two reasons. First, I've refined my use of output-based focusing, eg knowing the infinity blurs; and second, I've now ported these ideas from my EOS Magic Lantern cameras (5D3 and various EOSMs) , over to my CHDK Powershot cameras (G1X, G7X, G5X and S95).

My approach is to use my Depth of Field Information (DOFI) scripts to constantly tell me:
  • The optical, defocus blur at infinity in microns;
  • The diffraction blur through the scene in microns;
  • The total blur at infinity in microns;
  • An estimate of how many focus brackets will be required to seamlessly focus stack from the current position to the hyperfocal;
  • Where I am relative to the hyperfocal
  • Whether the current position has a positive or negative overlap with the last image captured.
More information on the Magic Lantern version of DOFI, simply called DOFI, can be found here: https://www.magiclantern.fm/forum/index.php?topic=24762.msg224057#msg224057

More information on the CHDK version of DOFI, called DOFIC, may be found here: https://chdk.fandom.com/wiki/Depth_Of_Field_Info_-_Chdk_version

The third member of the DOFI family is called DOFIZ, which adds exposure bracketing control to DOFIC. More information on DOFIZ may be found here: https://chdk.fandom.com/wiki/DOFIZ:_DOFIC_with_Exposure_Bracketing

The latest version of the scripts will always be available from the script download list on the right.

Bottom line: for those that want optimum focus, you likely will not do better than using either DOFI or DOFIC; and for the lucky Powershot photographers, DOFIZ gives you full control over your exposure bracketing, including as you are focus stacking. 

As usual, I welcome feedback on the DOFI scripts.