Monday, November 12, 2018

Focus bracketing using the Rule of 10

In the last post I introduced the ‘Rule of 10 (ROT)’ for those that are looking to manage focus from infinity to a near field subject, eg landscape photographers. The ROT is simply hyperfocal focusing without Apps or look-up tables, ie all in your head.

The ROT simply says that at an aperture of F/10, if you focus as one tenth of the focal length of the lens (in meters), your infinity blur (ie the circle of confusion, CoC) will be the focal length in microns. That is the ROT focus point is the hyperfocal focus point for a CoC of FL in microns.

Focusing at the ROT focus points gives a depth of field between ROT/2 to infinity.

Further, to adjust the quality, to smaller or greater infinity blurs, all one need do is adjust the focus distance by the ratio of the required blur to the (ROT) FL-based blur.

Finally, to move away from using F/10, all one need do is adjust the focus distance by the ratio of the required aperture to F/10. That is, if you wish to use F/5.6 (half of F/10) you would simply refocus at double the F/10 ROT distance.

As an example, with a 10mm lens at F/10, one would focus at 10/10 or 1m, giving an infinity blur of 10 microns and a depth of field from 0.5m (1.0/2) to infinity.

If one wished to relax the blur criterion to, say, an OK 30 microns (triple the high quality 10 microns ROT figure), all one would need do is simply refocus at one third of the basic ROT number, ie 1.0/3 or around 0.34 m. Thus, giving a depth of field of 0.17 m (0.34/2) to infinity, at an infinity blur (CoC) of 30 microns, ie still an OK number for a full frame sensor.

The previous post also, pragmatically, suggested that infinity blurs between 10 and 30 microns is where one should be seeking focus solutions using a full frame (say, 20-10 microns on a crop sensor). Noting that for on-screen viewing one could relax the blur beyond 30, but in doing so one would eliminate the ability to print to a satisfactory quality. Thus, I suggest one sticks with the 10-30 micron blur (or CoC) criterion unless you really will only project on screen.

In other posts I also introduced a simple procedure for focus stacking, once again based on what this post calls the ROT focus point, ie the FL/10 focus. See 
http://photography.grayheron.net/2017/09/unlocking-power-of-hyperfocal-distance.html

Thus, if we call our ROT focus point, R, if one wished to achieve a greater near field focus cover, ie better that the R/2 near field point; all one needed to do, to ensure each focus bracket touches the last one, is to focus at the odd number fractional values or R, ie R/3, R/5, R/7 etc.

The depth of field would then, following focus stacking in post, become R/(x+1) to infinity. Where x is the final focus bracket denominator. For example, if one took four focus brackets, at R (ie R/1), R/3, R/5 and R/7, the depth of field coverage would extend from R/8 to infinity. We also see how the focus coverage narrows rather quickly once you focus short of the ROT (hyperfocal) point (eg at R/5 the depth of field is R/4 to R/6) and therefore, one needs to really need the extra focus coverage to go past one of two additional focus brackets.

As an example, let’s assume we are shooting with a 24mm lens. The ROT focus point, at F/10, is 2.4m, at an infinity blur (CoC) of 24 microns. Giving a depth of field of 1.2 m (2.4/2) to infinity. Let’s further assume that 24 micron blur quality is an acceptable one, but that we need to do better in the near field (as the focus falls off rather fast here, compared to the far field). That is, say, we have a feature of interest at 0.5 m we wish to bring into focus.


Without focus stacking the focus field looks like this, where a unity blur is 24 microns. This plot also shows the usual defocus characteristics: the far field asymptotically going to the infinity blur (24 microns here) and the near field quickly going towards infinity. We can also see that a single image won't meet our goal of covering a feature of interest at 0.5m.


Using our focus stacking rule, we know the first focus bracket should be set to ROT/3, or 2.4/3 = 0.8 m, giving a depth of field of ROT/4 to ROT/2 = 0.6 to 1.2 m (that is ROT/( x +/- 1). This gives us two focus brackets looking like this:

[BTW the above two plots are screen captures from online version of cBlur: http://cblur.org/en/. To set unity to specific blurs you need to do the following: put cBlur's d
esired image resolution into sensor resolution mode and use the following Mpixel number: 3333/(FL*FL). Thus at 24mm focal length the Mpixel you should use is: 3333/(24*24) = 5.786. Doing this the unity blur in cBlur becomes the 24 micron in this case.]

Looking back at our example, as a single extra focus bracket is not enough, we need to take one more at the next position, ie ROT/5 or 0.48 m, giving an additional focus cover between ROT/4 and ROT/6 or 0.6 to 0.4 m.

Thus we end up shooting the following focus brackets, using a blur (CoC) of 24 microns:

  • Bracket 1 @ 2.4 m, covering infinity to 1.2 m
  • Bracket 2 @ 0.8 m, covering 1.2 m to 0.6 m
  • Bracket 3 @ 0.48 m, covering 0.6 to 0.4 m
For those looking for a two-image focus strategy, I would recommend the following:
  • Take the first image as twice the ROT value
  • Take the second one at half the ROT value
In the 24mm example above that means, one image focused at 4.8m and one at 1.2m, giving the following result, ie a higher quality background, plus some extended near field:


Finally, we need to recognise that knowing the ROT doesn’t do the focusing for us! The ROT information simply informs you where you need to focus. You will still need to focus your lens at the indicated ROT distances, eg using auto focus and pointing to an area on the scene that you believe to be at the required distance or using Live View and focus peaking at the required distance.

What the ROT does is give you the best information to inform your focusing, eg better than assuming one third into the image is (always) OK.

In this post we have seen that, by using the Rule of 10, we can estimate all our focus information in our head using simple arithmetic, whether we wish to focus bracket or not. In future posts I will carry on exploring the ROT focusing strategy and its power. 


As usual I welcome any feedback on my posts.

Saturday, November 10, 2018

Infinity focusing in your head: The rule of 10.

For those that just want the answer, you can safety skip to the bottom of this post.

If you are a landscape photographer, you tend to have a dominant focusing need: namely getting everything from a sensible near field feature to infinity ‘in focus’.

You will also know that the ‘out of focusness’ is a blurring in your image, mainly composed of two components: the defocus that the lens creates and diffraction.

The lens defocus varies through the scene, whereas we can assume the diffraction blur remains constant.

As a landscape photographer you will also know that the lens defocus blur is only zero at the point, or plane, of focus. Falling off rapidly, and approaching infinity, in the near field; and collapsing to a value at infinity, which we call the circle of confusion (coc).

Then, of course, we have the hyperfocal distance (for example see http://photography.grayheron.net/2017/04/getting-best-out-of-hyperfocal-focusing.html) which is where the infinity defocus blur is just acceptable for our needs.

Our needs will vary according to how we are presenting our image, for instance to judges in a print competition or online. Without regurgitating well-known things: for a full frame format, an infinity blur (coc) of, say, 30 microns, is considered OK. But for higher scrutiny, blurs lower than this should be used, recognizing that blurs below about 2 sensors pitches is likely not to help that much more, so this is a pragmatic lower blur limit.

The above ignores the addition of diffraction blur, which most people add in through a little bit of (root mean square) math, which in this article we will be seeking to dispense with.

But, for completeness the diffraction blur is directly proportional to the aperture number, eg F/5.6 or F/16. At visual, ie not IR, frequencies the constant is about 1.3. That is the diffraction blur due to diffraction, which we assume doesn’t vary with distance, is some 1.3*N (in microns). 


If we now make use of the simplified hyperfocal equation, where we assume a simple lens arrangement and drop a few insignificant terms, we can estimate the hyperfocal distance (H), that is just due to lens defocus blur, as H = FL*FL/(N*C).

Where FL is the focal length in mm; N the aperture number; and C the circle of confusion also in mm, ie the defocus blur that meets our focus quality criterion.

Many who are reading this will have attempted to calculate the above themselves, or use one of the many Apps or look-up tables that are available, to estimate H. Some may have also fallen into the ‘trap’ of thinking that focusing a ‘third into the scene’ is a good place to go.

Whatever approach you have used to date, is mainly because the arithmetic can, at times, get non-trivial to do in your head.

So let’s make focusing trivial!

To do this all we need to do is make C (the coc in microns), our defocus blur criterion, equal to the FL (in mm) and focus at F/10. If we do this H simply becomes FL/10 in meters.

So now we have the Rule of 10 for landscape focusing.

Before you say that’s stupid. Let’s go through what we have done in order to make calculating H a trival matter of dividing the lens focal length by 10.

As we know our lens quality varies as we change aperture, with a pragmatic sweet spot often being accepted as 2 stops down from being wide open. We also know that if we stop down too much, then diffraction blur counteracts against the increase in depth of field. That is there is another, depth of field, sweet spot that most recognize as being around F/10, without complicating things with format changes, ie full frame compared with crop.

Thus, an aperture of F/10 is a good starting point for a landscape photographer seeking to achieve focus from infinity to near, and balance out lens defocus with diffraction softening

As for choosing C to be FL, really FL/1000 to account for the fact that we speak of C in microns, that is simply a way of making in-head calculations trivial.

Hence we have H, in meters, as FL*FL/(10*FL) = FL/10.

To bring this all together, without proof, we also should note that having defocus blurs, ie ignoring the diffraction component for now, of between 30 microns (OK quality) and 10 microns (high quality) is where we need to be.

So, let’s look at a few examples using the Rule of 10.

Case 1

Full frame camera at a focal length of 30mm, shooting to achieve OK defocus quality. Where should we focus?

Our rule of 10 tells us that we should focus at 3m into the scene, at which point the infinity (defocus) blur will be FL in microns, ie 30 microns, which is our OK criterion.

We also know, from the full hyperfocal equations, that the depth of field in the near field extends, from the focus point (H), back to H/2, where the defocus blur at that point is the same as at infinity, ie in this case 30 microns.

Thus the depth of field extends from 1.5m to infinity.

Well this looks too simple to be true: as we haven’t used an App or a look-up table, and have calculated things in out head. But that’s the beauty of the F/10 rule.
 

So, in this example, at a focal length of 30mm and at an aperture of F/10, our hyperfocal distance is at 3m, where we will realize a circle of confusion, ie an infinity blur, of 30 microns.

Case 2

Let’s extend case 1, before looking at other cases. Let’s say that a CoC, or infinity blur, needs to be higher quality, say double the quality at 15 microns.

Well our rule of 10 tells us that the blur we are using is 30 microns, ie FL in microns. So to achieve a blur of 15 microns, half of our FL (in microns), all we need to do is double the focusing distance. That is, instead of focusing at 3m, we focus at 6m into the scene.

Of course, now the depth of field, using our 15 micron criterion, extends from 6m, ie H/2, to infinity.

Case 3 – FL < 30mm

Let’s assume a focal length of, say, 16mm. What does our rule of 10 tell us?

Simply that if we focus at 1.6m (FL/10), at an aperture of F/10, we will achieve a depth of field from 0.8m (H/2 = 1.6/2) to infinity with a circle of confusion (defocus) blur of 16 microns (FL in microns).

Well a defocus blur of 16 microns is pretty good quality, ie it falls towards the high quality end of our CoC range of 10-30 microns.

But let’s assume we are ‘only’ shooting for Facebook and that we need to maximise the focus in the near field as much as possible, ie there is a feature of interest. Because we are uploading the image on line, we can tolerate shooing with an infinity blur at the low end, say, around 30 microns: in fact we could go higher than this, but for now we will assume 30ish microns.

Once again, all we need to do is note the difference between where we are, ie at 16 microns (FL in microns) and where we wish to be, ie 30ish microns: which is about a doubling. Thus, we can now refocus at half of where we are. Instead of at FL/10, ie 1.6m, we can refocus to 0.8m. Of course, now we are at 0.8m, we know that the depth of field (noting we are now using a coc of 32 microns) extends from 0.4m (H/2) to infinity.

Case 4 – FL > 30mm

Although as landscape photographers we tend to shoot wide, what if we need to shoot longer. Say at 50mm. What does our rule of 10 tells us?

Simply that, if we focus at 5m (ie FL/10 giving H = 5m) at an aperture of F/10, we will achieve a depth of field from 2.5m to infinity but (sic) with a coc of 50 microns.

As it is unlikely a CoC of 50 microns will be acceptable we need to adjust the focus. But by how much?

The F/10 rule tells us that to reduce the coc by X, we simple adjust the focus by X. That is, if we wish to achieve a coc of around 16 microns, that is about a third of 50 microns (FL in microns), then we need to refocus at 3 times from where we are using the F/10 rule, ie at 5*3, or 15m.

Which will give us a near field depth of field distance (at a coc of 50/3 microns) of 7.5m (15/2).

As the intention of this post was to just introduce the Rule of 10 for (landscape) focusing, I’ll sum up the main points:

  • Assuming you wish to achieve near to infinity focus, ie for landscapes, you should set the aperture to F/10 and focus at FL/10 in meters.
  • At this focus the circle of confusion, ie lens defocus at infinity, will be FL in microns.
  • If you wish to achieve a lower or higher coc, ie infinity defocus, all you need to do is refocus by the ratio of FL to your final coc criterion.
In future posts I’ll look further into the ‘Rule of 10’, but for now I hope you get some benefit out of the rule. At least you will now be able to leave your look up tables and Apps at home, and achieve a more informed focus than hoping 1/3 into the frame is OK. All in your head!

Tuesday, November 6, 2018

Wirelessly Control your camera and Magic Lantern states

I thought I would share an experiment I’ve just successfully completed, whereby I can now wirelessly control Magic Lantern states, for example setting combinations of Dual ISO, Advanced Bracketing and Auto ETTR, as well as taking images: all without touching the camera.

To achieve this I’m making use of the Foolography Unleashed dongle for my 5D3: https://www.foolography.com/products/unleashed/




The dongle is permanently plugged into the side my 5D3 and requires no batteries. The dongle’s functionality allows me to control various, but not exhaustive, camera functions, via an app (I have mine running on my iPhone, iPad and iPod).

The App’s screen looks like this (this is an actual screen capture fro my iPad):



As a proof of principle, I decided to make use of the metering mode and the white balance. The WB has 9 different settings, so in theory I could set 9 different ML states. For now I’ve coded four, namely:

  • State 1 (WB AWB): Dual ISO OFF, Auto ETTR OFF, (Auto) Advanced Bracketing OFF
  • State 2 (WB Sunshine): Dual ISO ON
  • State 3 (WB Shady): Get/set ETTR exposure
  • State 4 (WB cloudy): Take an (auto) Advanced Bracket set
Once you have selected a state, by choosing the WB value that corresponds to that state, you then use the app to simply toggle between the two (metering mode) extremes, swiping down, top to bottom. The Lua script then does the rest.

For now I simply switch between the various states to achieve what I want. For instance, I might use the app like this:

  1. Set state 1 (WB AWB) to ensure everything off
  2. Go to Sunshine WB and set my Dual ISO (100/800)
  3. Go to Shady WB and set my exposure via ETTR
  4. Press the shutter, via the app, and review the (low quality) image in the app
Alternatively, I could:
  1. Set state 1 (WB AWB) to ensure everything off
  2. Go to Cloudy WB and set Advanced Bracketing
  3. Press the shutter, via the app, and let ML get the brackets, and review the (low quality) image in the app
Obviously, this is a simple demo or proof of principle. If I progress the idea I will tidy things up.

Also, there are some limitations: the biggest being you need a look up table (written down or remember) to convert WBs into ML states. Nevertheless, once again, ML and Lua shows what can be done.

For those interested, here is the (crude) script.

wb_value = -1
change = false
previous_meter_value = 0

function property.WB_MODE_LV:handler(value)
wb_value = value
end

function property.METERING_MODE:handler(value)
if (previous_meter_value == 3 and value == 5) then -- if previous metering value was 3 and the current one is 5
change = true
previous_meter_value = 0 -- clear variable
else
change = false
previous_meter_value = value -- remember current metering value
end
end

function watch(arg)
if change == true then
change = false
if wb_value == 0 then -- set all states to off
menu.set("Expo","Dual ISO",0)
menu.set("Expo","Auto ETTR",0)
menu.set("Shoot","Advanced Bracket",0)
elseif wb_value == 1 then -- switch Dual ISO on
menu.set("Expo","Dual ISO",1)
elseif wb_value == 8 then -- set ETTR exposure (make sure you set ETTR for your needs)
menu.set("Expo","Dual ISO",0)
menu.set("Expo","Auto ETTR",1)
menu.set("Shoot","Advanced Bracket",0)
key.press(KEY.SET) -- ETTR must be configured for SET trigger
elseif wb_value == 2 then -- Do Auto bracketing
menu.set("Expo","Dual ISO",0)
menu.set("Expo","Auto ETTR",0)
menu.set("Shoot","Advanced Bracket",1)
end
wb_value = -1 -- clear variable
end
return true
end

event.shoot_task = watch

Saturday, October 20, 2018

EOSM Medium Format Photography

Following from my last post, I thought I would show what a full 645 image looks like using the Fotodiox 645 Adapter and an EOSM.

First, let's remind ourselves what the basic features of the EOSM are:
  • Sensor photo detectors (Mpix) 18.63 
  • Resolution is 5280 x 3528  
  • Sensor size is 14.9 x 22.3 (mm)
  • (Crop) Multiplier relative to a 35mm FF camera is 1.6 
  • Aspect ratio is 3:2 
If printing at 300 dpi quality, this equates to a print that (changing units) would be a 17.6x11. inch print.

If we now use the EOSM-645 Adapter in full 645 mode, ie 8 images, taken in two rows, with the EOSM in portrait mode we end up with essentially a 4:3 aspect ratio and with an image with a 120+ Mpix image, ie 12400 x 9820 pixels, or some 41x32 inches at 300 dpi

As for setting up the shot, an acceptable 645 hyperfocal distance (for now ignoring diffraction and using  George Douvos's excellent TrueDoF-Pro App) is to use a (defocus) Circle of Confusion of 47 microns at F/20-22, is just under 2m. Note we can use such small apertures as we are shooting medium format, albeit via 'sensor bracketing'.

However, we wish to do better than an infinity defocus blur of 47 microns, so we will half that to, say, 23 microns, giving a focus point at about 4-5m.

So what does a medium format image looks like if taken with an EOSM? Well here is the test image I just took, with the help of Magic Lantern, ie ETTR and Dual-ISO. OK, it's not meant to be submitted for a competition: by it does show off the format, ie it's a 4:3 image and has 12400x9820 pixels (albeit scaled here)




Thursday, October 18, 2018

Taking the EOSM to new heights

A lot has happened since my last post, so it may take me a few blog entries to catch up with things.

From a photography perspective I have been fortunate enough to travel to Ireland and France with my camera(s): so, I have a great set of ‘data’ from the field.

Gear wise I still suffer from GAS, ie Gear Acquisition Syndrome; so I have some stories to tell :-)

To kick things off, let me share with you some things I’ve been doing with my trusty Canon EOSMs. I have three of these, with one having been converted to Infrared capture.

For me the EOSM, coupled with Magic Lantern, eg RAW-ETTR, Dual-ISO and Auto-Bracketing, represents the ‘ultimate’ cropped format companion, despite the EOSM now being some 6 years old.

I have augmented two of EOSMs with a cage and handle set-up, which gives me something to hold and to bolt on to!


To further enhance my EOSM family, I also use the following ‘add ons’:

A Swivi S5 loupe, which is great for low level photography:

A Really Right Stuff TFA-01 Ultra Pocket Pod and BC-18 Microball:


A Really Right Stuff Safari Clamp, which works with the BC-18:



A Platypod Ultra:


…and this week some new stuff turned up!

The latest addition to my EOSM toolkit arrived in the form of a Medium Format adapter! Yes that’s right I now can shoot (quasi) Medium Format images with my EOSMs (visible and IR bands).

Let me first clarify what I mean by a Medium Format EOSM.

Although I’m not (yet) using a technical camera, with front and rear standards, (but I hope to in time), I am using a Mamiya Sekor 645 lens (I have a 45mm FL F/2.8 N at the moment) and coupling this to a Fotodiox adater (link), to create a ‘virtual’ medium format sensor back (my EOSM) through, what I call, ‘sensor bracketing’.

The limitation of the approach is you require time to capture the medium format data, thus the technique is best suited for images where objects are not moving (by much) and/or you can tolerate movement, eg LE work. Also, the EOSM sensor pixel size is a little bit smaller than one typically found in a digital medium format camera.

The Fotodiox adapter looks like this.
 


As I say, the lens is a 645 45mm one, which I already had for use with my Fotodiox ND Throttle on my 5D3 (or EOSM via an adapter). A variable ND that sits behind the lens, thus eliminating the 'dark X effect' when using a wide angle lens.

So why bother?

The answer, of course, is easy: why not, it looks like fun :-)

On a more serious note this approach allows one to capture images for large prints, either ‘full’ 645 format (8 EOSM captures) or high resolution panos (6 EOSM captures), for high quality and/or large printing, ie competitions/exhibits etc. Unlike other approaches, eg pano heads etc, there is no distortion with this approach, as the lens remains fixed. The closest I currently have to the approach is to use my 24mm TSE lens in shift mode: which I do with my 5D3.

Before looking at an example, let’s talk about ‘scaling’.

When going from a full frame EOS to an APS-C, like the EOSM, we make use of the relative size of the sensor and talk about the ‘crop’, ie 1.6 in the case of the EOSM. Thus, a 10mm lens on my EOSM will have a similar field of view to a 10*1.6 lens on my 5D3, ie a 16mm focal length lens.

Similarly, we can talk about the crop of a medium format lens systems, where the sensor comparatively looks like this. Plus for fun we see what an iPhone sensor looks like.


In the case of the Fotodiox-EOSM set up, the crop is about 0.625 relative to my 5D3, ie 1.6 the other way from a full frame 35mm. Thus, a 645 45mm Medium Format lens has an equivalent field of view as a 28mm lens on my 5D3; or just under 18mm on my EOSM. That is rather wide, but not too wide to introduce ‘WA distortions’.

As for depth of field, as I’m mainly interested in infinity focus, ie for landscapes, once again such things scale with the crop rather nicely. Thus the Circle of Confusion I use for, say, my 5D3 or EOSM work can be scaled by the crop. For example, the CoC range I would use with my new 'medium format' EOSM, with a sensor pixel size of 4.3 microns, is in the range (high to acceptable quality) of (4.3micronsx2x1.6*1.6 = 0.022mm) to (0.019 x 1.6 x 1.6 = 0.048mm).

If I’m interested in using the EOSM-Fotodiox Medium Format set up for high quality work, I would therefore use a CoC of, say, 22 microns, giving an approximate focus requirement at F/16 of 45X45/(0.022*16), ie just under 6m.

BTW it is useful to remember, that to calculate the approximate focus point for any infinity blur of C (ignoring diffraction), you simply focus at f*f/(N*C). Where f is the focal length and N the aperture. With f and C in the same units, eg mm. Remembering that Cs less than two sensor pixels are rather meaningless, ie you should 'never' focus at infinity, but short of it, ie at f*f/(N*sensor-pixel^2).

So let’s cut to the chase. How does one use the Fotodiox 645 adapter? Plus, how does one post process the captured (sensor) bracket set?

First it is worth noting that in the last week Adobe updated both Lightroom and Photoshop CC, so they now can automatically stitch an exposure bracketed, pano set. Thus, in addition to the sensor brackets, one can factor in exposure brackets at each sensor bracket point, and, in post, push one button to process the bracket set.

Plus, to really give you a headache, you could also focus bracket as well! Thus one, full, 645 image, using the EOSM Fotodiox set up and, say, three exposure brackets, and two focus points, one final image would be composed of 8 (for a full 645 sensor bracketing) x 3 (for the exposure bracketing) x 2 (say, for two focus bracketing sets) images: that is 48 images! As I say, fun stuff.

But let’s keep things simple for now and ‘just’ take a 645 pano image using the Fotodiox adapter, ie 6 sensor brackets.

I composed the image, upside down, so this really feels like ‘old photography’ [:-)], using the adapter’s viewing ‘screen’, then moved the EOSM to the first capture location. Here I estimated 6m into the field and focused the lens at that point; then set the aperture on the lens to F/16. I then ETTRed using Magic Lantern and took the required ‘sensor brackets’ and three exposure brackets, ie 18 images.

I then ingested the captured brackets into LR and processed them: in later posts I’ll talk about how one can use Photoshop to further process such images. Plus, of course, how to do sensor, exposure and focus bracketing together!

As an example, here is an image I just took: in all its 12368* 5501 pixel glory, ie just over a 68 M pixel pano, with no distortion!

Here is the image (obviously greatly reduced).


Finally, there are obviously limitations one needs to accept. For a start you can't really shoot with movement in the scene. In future posts I'll explore ways to maximise the value of the approach, eg using ND filters and shooting LE bracket sets.

Wednesday, August 15, 2018

First Cut from Ireland


This is my first post from my photography trip to Ireland, with Peter Cox (https://www.petercox.ie/), who I can not recommend enough: knowledge + skill + humour. It was also my first trip to Ireland! We were there for 10 days and I was blessed with a great crowd: all Americans plus one Australian.

I intend to write about my Irish photography experiences in a few posts over the coming months. Today’s story is about how my 24mm TSE performed with the Rogeti TSE frame. The what I hear you say!

The TSE is a great landscape lens as it allows me to shift 12mm away from the base image, thus instead of taking an image at 24x36mm, I can take one with a ‘pseudo sensor’ size of, say, 48x36mm or 24x50mm. In addition, the quality of the glass in the TSE is high. 

But, of course, if I fix my camera on the tripod and shift the lens, I change perspective. That’s where the TSE Frame comes in, as the lens is fixed to the tripod and when I shift, the camera moves, not the lens.

Here is a picture of the TSE Frame with the 24mm TSE lens and you can read about it here: http://www.rogeti.com/en/tseframe/


Having established my composition I used Magic Lantern via the LCD.

Focusing was assisted by my Magic Lantern Focus Bar Lua script, but I also zoomed x10 to confirm focus, using my Swivi S5 LCD Loupe, as using the LCD in bright conditions is a challenge.


As for exposure, I shifted to the sky frame and used the Magic Lantern Raw ETTR functionality, to nail the highlights. I had already decided to use Dual-ISO to gain nearly 3Ev lift in the shadows: thus there was no need to exposure bracket for this scene.

For those that are not used to Dual-ISO ETTRed images; here are the three RAW captures after I shifted 12mm up and down from the base image.




And to illustrate the extreme ETTR nature of the sky image: here is the Lightroom histogram of the sky image above:



After ingesting into Lightroom, the first task was to ‘develop’ the Dual-ISO RAWs, arriving at these new RAW DNGs: each Auto Toned here to illustrate the final capture detail.





Once again to illustrate the Dual-ISO ETTRed 'development', here is the histogram of the sky shot, showing zero blown out pixels, thanks to ML.



It was then a simple matter of post processing in Lightroom. First, stitching with the LR pano feature; then completing the ‘final’ (for now) edit in Lightroom, giving this final, 5414x6767 209MB TIFF image. 



In future posts I'll explore other images from my trip to Ireland and further post processing in Photoshop.

Sunday, May 27, 2018

Infrared Post Processing in Lightroom

In a previous post I discussed the latest Lightroom release's new profile feature, and how it is a boon to those shooting in the infrared bands.

In this post I'll show a few examples, all processed in LR, and discuss how I approached my post processing.

The first thing to mention is the lens I was using, as the Kolari Vision data base (https://kolarivision.com/articles/lens-hotspot-list/) indicated that my 18-55mm EOSM lens was a good performer at F/10 or wider: that is it should have a minimum IR hotspot.

From my shots today I clearly had a central hotspot, and a left to right colour shift: although I can't yet say that is down to the lens. However, as we will see in this post, these 'features' can be dealt with in LR.

Before discussing the post processing, it is worth mentioning my (EOSM) in-camera approach:
  • Obviously I had Magic Lantern running (I used the latest Lua experimental fix build)
  • I had my Focus Bar script on, and the IR correction set in the FB script's menu
  • I had ETTR on, with a min shutter set to 1/30s, as I was handholding
  • I had the aperture  set to F/7, but I may widen this next time, ie to reduce the hotspot
  • I used SET to trigger the ETTR solution
  • As I was shooting landscapes, with not much in the near field, I used the FB script to find a focus solution beyond the hyperfocal
After ingesting into LR I applied my IR profile, corrected for the lens and carried out an Auto Tone correction. These simple steps take the image from the horrible to the OK:


The final step, as I was not doing a round trip to Photoshop to correct pixels, was to use the LR sliders, the radial filter (to sort out any hotspots or off-colour 'patches') and LR's HSL sliders to 'tidy up' the look.

I like to get a blue sky (obtained by the using the channel swapping profile), and slightly desaturated look to the foliage. The final image looked like this:

Here are four more images from today's walk:





I hope this short post has convinced IR shooters that you don't need Photoshop to achieve a false colour look: Lightroom is your IR friend - as is Magic Lantern, of course!