Tuesday, February 16, 2021

A few thoughts for the landscape photographer

In this post I wish to say a few more words about focusing for landscape photography, with and without Magic Lantern; when we are trying to achieve 'deep focus' capture, ie everything from infinity to a point of interest in the near field.

As a 5D3 Canon (Magic Lantern) user, I wrote my Depth Of Field Information Script (DOFIS) to give me all the info I need for focusing, either on the LV screen or on the Quick Shooting screen. For example, the latest version of DOFIS’s QS screen display, on my 5D3, looks like this:

Here we see DOFIS providing us all the information we require:

  • Where we are focused (65cm from the sensor's plane);
  • What the diffraction aware defocus blur is (30um above, as diffraction aware is switched off), ie the one we will use as the focus bracketing overlap criterion;
  • The infinity blurs, ie defocus, diffraction, and total (49, 13 and 51 um);
  • How many brackets we will need to take to get to the hyperfocal, ie 2 above;
  • Plus, some helpful, additional information, eg: the focal length we are at (16mm), and, as a warning, whether Dual-ISO or Silent Picture is switch on (SP and/or DI showing, as above).

So, in the above example, I would switch off SP and DI, as I don’t need them to be on; and use DOFIS to guide my focus bracketing, until I had captured an appropriate infinity shot, ie at a low defocus blur, accepting that, even at infinity, I will still have around a 13um diffraction blur, ie from the f/10 aperture.

But what if you are not a Magic Lantern shooter?

The first guidance I would give is to focus on the nearest object of interest that you wish to see in focus, ie don't worry about depths of field at the moment. Choose your near field focus point, as you know what your far field focus is going to be: infinity!

Knowing/using the Rule of Ten (RoT) comes in handy now, and is especially suited for focal lengths around and less than the CoC of the camera format, eg 30um or 30mm on a full frame, or 20um or 20mm on a crop sensor: whether you shoot Sony, Nikon or whatever. Noting, that you can adjust the RoT hyperfocal to any CoC you wish to use.

If you need to be reminded of the RoT approach, then have a look here.

In the above scenario, ie at 16mm at f/10, we know, using the RoT, that the,16um CoC, hyperfocal is at 1.6m, ie focal-length/10, Plus, a 16um CoC is a pretty good quality to use, ie for printing, thus I won't need to adjust the RoT hyperfocal in this case.

Of course, knowing the hyperfocal is at 1.6m, tells me that the near depth of field, when focused at 1.6m, is 0.8m; which is not going to cover my current focus at 65cm (0.65m), using a CoC of 16um.

Of course, if I had used a CoC of nearer 30um, then the hyperfocal would be less than 1.6m. For example, if we double the RoT based hyperfocal CoC, from 16um to 32um, the hyperfocal distance is simply halved, ie to 0.8m. Plus we know that the near depth of field at 0.8m is simply h/2 or 0.4m. So, in this case, one shot at around 0.8m should cover my needs.

But let's assume we wish to work with a RoT CoC, ie of 16um.

Using the odds hyperfocal based bracketing rule, as we are starting at the hyperfocal, I know that my 'perfect' focus brackets are at h/3, h/5, h/7 etc; and that the near or far depth of field, either side of the point of focus, are the even values, eg focused at h/3, the depths of field are at h/2 and h/4. 

With h being 1.6m, h/3 is just over 0.5m, ie less than nearest point of interest at 65cm, thus, in my head, I've now worked out my optimum focusing strategy:

  • Take a focus bracket where I am, ie at 65cm;
  • Take another around the hyperfocal, ie 1.6m.

By using the point of focus for the nearest feature of interest, rather than attempt to work out whether the near depth of field is covering it, we guarantee our closest near field feature is tack sharp. Noting that we will also have a little focus insurance as well, ie out to the near depth of field at our point of focus.

As usual, pragmatism should guide you, especially if you are poor at judging distances. So an alternative to the 'perfect' two image example capture above is to:

  • Take a focus bracket at my nearest point of interest, ie 65cm
  • Take another focus bracket at my RoT estimate of h, but biased towards the camera, ie get to know/visualise your height ;-)
  • Take a final image at 2-3 times h, ie for infinity.

So, even if you are not a Magic Lantern shooter, by knowing/using the Rule of Ten and the Odds/Evens rule, you can always pre-plan focus brackets in your head.

As usual I welcome any feedback on this post or on any of my posts. 

 

Sunday, February 14, 2021

DOFIS: Minor update

Just a quick post to discuss a couple of tweaks to DOFIS and how to use the information it displays in the non-LV, Quick Shooting screen.

DOFIS now alerts you to switch to M mode, as DOFIS works best in this mode:

I've also tweaked what DOFIS shows in the Quick Shooting screen:


Here we see an additional blur being shown in brackets, before the usual blurs that show the infinity defocus blur, the diffraction blur and the total blur at infinity.

The new blur field, 30um above, is simply a reminder of the overlap blur that is being used when focus bracketing: noting that this overlap blur gets adjusted if you switch on diffraction aware in DOFIS. The 30um shown above indicates that I've switched diffraction aware off, ie the blur being shown is my ML CoC setting of 30um.

On a Full Frame sensor I recommend the base overlap, ie before diffraction is accounted for, be set to 30um and on an APS-C format sensor to 20um. You can certainly use a smaller overlap criterion, however, the cost is more focus brackets.

As an illustration, the following landscape workflow is one way to use DOFIS, ie from near to far:

  • Compose and set the aperture/exposure you wish to use, ie to minimise diffraction, but maximise image quality, and ensure the best photon capture, eg ETTR with/without Dual-ISO
  • Focus on the closest part of the near field object that you wish to see in focus and review the DOFIS feedback and decide if one image is acceptable, ie are you are focused at/beyond the hyperfocal.
  • In the above we see we are focused at 80cm and that the infinity defocus and total blurs are much bigger than the overlap (CoC) blur, as we are focused at less than the hyperfocal (the overlap/CoC value). All we need to do is take an image (or an exposure bracket set) and follow DOFIS's advice, ie look at how many focus brackets it is telling us we need to take and using the colours (green and red: see the last post) to set the next focus until we have captured our focus bracket set, including, if you wish, a zero defocus blur shot at the 'measured infinity', ie where Canon is still measuring distance and the defocus blur reporting is at/near zero.
As usual I welcome any feedback on DOFIS, either here or on DOFIS's Magic Lantern forum page.

Friday, February 12, 2021

DOFIS: 2021 Uplift

I wrote my Depth Of Field Information Script (DOFIS) as I wished to know about focus on my 5D3.

I believe the DOFIS lens model is the best you can have, without having access to lens CAD design details, ie it uses a split/thick lens model and accounts for pupil magnification.

DOFIS will give you information on: where you are focused; what the infinity blurs are at that focus (defocus, diffraction and total blurs); the depths of field (either relative to the focus or as an absolute from the sensor plane); how many brackets you will need to take to get to the hyperfocal; if you are beyond the hyperfocal; and where to focus next when focus bracketing.

So what more I could I need out of DOFIS?

Up until now DOFIS only provided you all the above information if you are in LV. If you wished to use the view finder, then you needed to come out of LV.

So, I'm pleased to say that DOFIS now works outside of LV, albeit restricted to M mode for now.

Like ML, which enhances the non-LV Quick Shooting (QS) screen with additional info, eg see the battery info and colour temperature below, DOFIS now displays focus information in the Canon QS screen eg:


In the above screen capture we see DOFIS at start up, with the DOFIS info bar being black with white text, showing the point of focus and the defocus/diffraction/total blurs in microns.

In this release of DOFIS I've restricted the information to focus position and infinity blurs, ie not depth of field information.

Whenever DOFIS doesn't have a point of focus reference, eg a 'base' image hasn't been taken, or the aperture or focal length changes, you will see the above presentation, ie white on black.

As soon as you take an image the QS screen will change to look something like this:


Here we see the same focus position (35cm) and the same infinity blur information, but enhanced by DOFIS info area turning yellow, showing the current focus is the same as that of the last captured image, and with an additional piece of information that gives you an estimate of the number of focus brackets to get to the hyperfocal.

If you now start to refocus, the information displayed reflecting your focus position (either moving away or towards infinity), the infinity blurs, and the number of brackets required to get to the hyperfocal will change, as will the colour of the bar according to whether you have a positive (green) or negative (red) focus overlap with the last image you took eg:





You can return to the last image's focus position at anytime, ie refocus until the bar is yellow.

Thus, all you need to do is refocus until you see a red bar, then back off to a green bar.

Once you go beyond the hyperfocal, you can then use DOFIS to inform your infinity focusing, eg:


Here we see that in this bracketing sequence I took a final image at 4.25m, which DOFIS tells us is beyond the hyperfocal, giving me a infinity defocus blur of 3 microns, which, with an F/10 diffraction blur of 13, gave me a total (convolved) blur at infinity of just over 13um.

Finally you can switch off the DOFIS QS display by switching the Focus Bracketing off in the DOFIS menu.

As usual I welcome any feedback on DOFIS, especially being used on cameras other than the 5D3; and any ideas about making DOFIS better.

The latest version of DOFIS, which has been developed on a 5D3, may be downloaded from the right, but the QS feature may not work in a non-DSLR, eg an EOSM appears to not report focus when the QS screen is showing. Finally, if things don’t seem to work with your ML camera, then feel free to tweak the script, eg the position of the DOFIS box on the QS screen. 

Saturday, February 6, 2021

MUSIC: Camera/user specific settings

A relatively minor tweak to MUSIC, that brings in the functionality to change a few settings on the fly. 

The 'home' menu in MUSIC, ie use case 1, now looks like this:


Here we see a new menu item, that only appears under the UC1 menu, that allow you to change a few settings, to reflect your camera and your user preferences.

If you elect to change, the menu switches to looking like this:

In this release of MUSIC you can now choose the long press time, for quick access (QA) to repeatedly running the selected use case. You still need to explicitly select the QA key in the script, ie to match your camera's buttons and de-conflict from your other 'trigger keys', ie for AETTR etc.

You can also set the ISOless trigger value, that gets used for handheld bracketing. The choices being ISO 800, 1600 or 3200.

For more information on choosing the right ISOless trigger point, a few good reads are:  

http://dslr-astrophotography.com/iso-values-canon-cameras/  

https://www.photonstophotos.net/Charts/PDR.htm 

https://clarkvision.com/imagedetail/iso/

Finally, as a safety feature, I personally value, MUSIC will switch off Dual-ISO, advanced bracketing and FRSP at camera start up, ie if they are on.

As usual I welcome any feedback on MUSIC or any of my posts.


Friday, February 5, 2021

MUSIC: Use Case 6 - Handheld optimum exposure bracketing

In this post I'll discuss MUSIC's use case 6: the handheld (HH) exposure bracketing option.

Unlike 'normal' exposure bracketing, where we are likely to be on a tripod and adjusting exposure time, in HH exposure bracketing we need to account for the fact we are, obviously, hand holding.

I wrote use case 6 for those times I can not use a tripod or stabilise my camera, and I'm forced to handhold, albeit, maybe, using a string tripod to 'eliminate' at least one degree of freedom of potential motion blur. UC6 is well suited for wide angle captures.

I've also tweaked MUSIC’s UC6 (download the latest version on the right) and included a shutter-triggered option, ie in addition to the other two triggering modes: via the script run feature or via the LV quick access feature.

Before looking at the new UC6 functionality a quick reminder about HH bracketing, that assumes your base exposure is an ETTR set one, based on the lowest ISO value you can use, which covers the highlights. UC6 then takes two other images:

  • The second image is taken at your base ISO and with the slowest shutter you set in MUSIC: this gives you the maximum photon capture;
  • The third image, for the shadows, is then taken at the second image's shutter, ie your slowest, but at an ISO value that you set in the script as the start of your camera's ISO invariance zone. There is no point increasing the ISO beyond the start of this ISO value, which, for example, I define as ISO 1600, or even 3200, on my 5D3, and 800 on my M. One of these two links should help you find your ISO value:
  • http://dslr-astrophotography.com/iso-values-canon-cameras/
  • https://www.photonstophotos.net/Charts/PDR.htm

The UC6 menu now looks like this:


Here we see two new menu items: HH Shutter and Shutter triggered?

The HH Shutter allows you to specify your minimum hand holding shutter speed: 1/30s shown above. With the Shutter triggered option set to no, UC6 can be used in LV mode, run from the script or by turning on quick access and doing a long press of your selected triggering key, eg the SET button on my 5D3 or a 1-finger long press on mu EOSM.

With Shutter triggered set to yes, the UC6 menu switches to looking like this - note there is no bookend option if using UC6 in shutter triggered mode:

Having set UC6 triggering to the shutter, all I need to do now is leave the ML menu and use the camera’s shutter, either in LV or looking through the VF: in each case, UC6 bracketing will take place, giving me the 'perfect' handheld bracket set, ie from a low ISO ETTR base exposure.

My personal capture technique being to allocate auto ETTR to the double half shutter press on my 5D3, thus allowing me to compose and set the base exposure, before doing a full shutter press, all the time looking through the VF and using the camera against my face to help stabilise the camera.

Post processing is as normal, eg:

  • Ingest into Lightroom
  • Set and sync the WB across the bracket set
  • Look at the ISO 1600 capture and consider extending the bracket set with a virtual copy and 2-3 Ev uplift of the ISOless captured image
  • Process in LR's HDR Merge
  • Finish post processing on your floating point TIFF, ie you will have +/- 10Ev range to play with, either in LR or in Photoshop, but, of course, there may not be data everywhere ;-)

Bottom line: Use Case 6 gives you a optimum bracketing feature when hand holding. It also allows you to trigger this from the MUSIC script, the LV, via MUSIC's quick access feature, or via the normal shutter.

As usual I welcome any comments on this post or any of my posts.


Wednesday, February 3, 2021

MUSIC: Use Case 9 - Auto bracketing from a metered shadow exposure

A quick post to say I've added another use case (UC9) to MUSIC. This one will auto capture an optimum exposure set from a metered shadow exposure.

As with all MUSIC use cases, once set up, you can trigger the new use case outside of the MUSIC menu by using your selected trigger button, eg I use a long SET press on my 5D3 and a long 1-finger press on my EOSM.

The UC9 menu looks like this:


Here we see you can: set a delay at the start, which isn't needed if using bookends; set quick access on, so you can keep repeating UC9 by doing a long press of your trigger key; and set the delta Ev between images (1-4 Ev).

As a demo (home) example of UC9's use, I composed my 5D3, set the aperture; used DOFIS to set the infinity blur I wished to use and confirmed the DoFs were ok, once again through the DOFIS LV feedback; set a delta Ev of 2; and switched on bookends and QA.

Then, in LV, I used the ML (RAW) spotmeter to set the shutter for the selected shadow area where I wish to ensure a captured detail.

I then simply did a long press of the SET button, to initiate UC9.

Note that UC9 uses ML's advanced bracketing, but you do not need to have this switched on and UC9 always leaves AB off.

The captured bracket set, without bookends, looked like this in Lightroom:


I then decided to use LR/Enfuse to bring the bracket set together in LR, then tweaked a few sliders, to get this final image:


Bottom line: I find this new MUSIC use case fits well with my needs and will ensure I capture a perfect exposure bracket set each time I need to: once set up in MUSIC, without touching Magic Lantern's menu, ie simply metering with ML’s spotmeter on the shadow area of interest and doing a long press to capture my bracket set. 

As usual I welcome any feedback on this post or any of my posts.



Tuesday, February 2, 2021

Composing wirelessly on the 5D3

Over the years I've evolved an approach to image capture that is heavily/totally dependent on Magic Lantern. In this post I will be discussing infield wireless connectivity.

As my main camera is a 5D3, this has been the main focus of my experiments, where I'm looking to be able to read the 5D3's fixed LV screen in bright sunshine and/or when the camera is in an unusual position, eg close to the ground when doing a WA shot, so it is difficult to see.

I've tried various LCD hoods and loupes, ie to shield the screen from bright lights, and currently use the Swivi 5, as it gives me straight through and 90 degree viewing:

Also I now have all my cameras 'caged'. Although a cage is usually associated with video capture, I find it a useful addition for photography, as it adds robustness to the camera, extra means of picking it up, and attachment points for 'stuff'; thus, in the case of smaller cameras, such as the EOS M, it allows me to add on a handle.

Recently Hollyland, who are known for their wireless Tx/Rx units for video, released a new product that got my attention: the Mars X.

The device is mechanically robust, 'affordable', and operates stably at a long range over 5GHz (300ft LOS). 

The unit's interface is (very) simple and takes the HDMI output from your camera (note it must be p not interlaced) and wirelessly transmits it to an (IOS or Android) phone or tablet, that becomes your wireless monitor. Interestingly, you can transmit to three devices at the same time.

There is a very good app that allows you to look at the HDMI out, be it the LV feed, ie for composing, looking at one of the Canon menus or carrying out a Canon image review, or, importantly for me, looking at the ML menus and the ML LV overlays.

The main use case for me is to use the Mars X when I need to set the camera up and/or compose, and I can't readily see the LV screen. 

As an example, if I was in a cathedral and placed my camera on a Platypod on the ground and wish to use DOFIS to set my focus and MUSIC to capture a silent bracket set. Using the Mars X I can easily see the LV on my iPhone/iPad, whilst operating the buttons on the camera. I could even attach the iPhone to my cage or handhold the iPhone.

To demonstrate what the Mars X can do, I set my 5D3 up on the Platypod and placed it on my dinning table:

Here we see the Mars X (antennae closed) attached, via a cold shoe, to my 5D3 cage. The Mars X has a self contained battery, which the manufacturer says is good for an hour. There is a USB-C charging port, thus I could, if required, add a power bank to the cage as well.

Finally, to give some insight into what the Mars X can do, I've placed my iPad on the table and videoed it whilst I fiddle with various settings on the camera. 

Two things worth noting: the latency is quoted at around 70ms and is OK for my use. The screen goes blank if the camera isn't feeding the HDMI out (obviously), ie when the camera is switching between screens or an image is being captured.

The video was captured by the Mars X app, which can also capture screen images. Note in this experiment, there is no sound. 

The video shows the Mars X interface and tools, plus, towards the end, me interacting with ML and my two scripts (DOFIS and MUSIC) and using DOFIS to provide focus feedback as I focus bracket, ie DOFIS feedback telling me where to focus next:

 

Bottom line: I think the Hollyland Mars X unit is an affordable alternative to buying a Swivi 5 loupe and, via the Hollyview app, it gives you great access to your camera's LV, plus the app has several additional tools (some of which are redundant if you have ML), eg histogram, waveform and focus peaking.

So, it's a thumbs up from this simple photographer!