One of the horrors of owning a DSLR and using multiple lenses is the dread of getting dust on the camera sensor. In small amounts it’s visible whenever you shoot using a small aperture like f/22 but if you leave it go too long you’ll see round smudges show up on your every day snaps at f/8 or f/4 too.
This video describes part of the process I go through when I clean my camera lens. A Nikon body is used in the video but the method is similar for Canon and other manufacturers. I only have a blower and soft brush but they have served me well over the course of the last decade.
Cleaning the sensor is risky. It’s a sensitive piece of electronics but there’s an infrared filter in front of it and that’s what you’re really cleaning. It’s sturdy and tough but if you pushed too hard on it you will scratch it. I’ve never scratched the sensors of any of my cameras though so I don’t worry too much about it as long as I’m careful.
After blowing and wiping the dust away you should do the same with the inside glass of your lens. It’s likely that’s where the dust came from in the first place.
Once I’ve rebooted my camera I’ll test the sensor by doing the following:
|Camera||Canon EOS 6D|
The usual way of taking long exposure photos is by leaving the shutter open for a long time. This requires either a dark location or ND filters of some sort on the end of your lens. There is another way and that’s called image stacking.
In a nutshell, you take a series of well exposed photos of short exposure for the same duration you’d use for a long exposure shot. Then in development you create a number of images files which are then merged together to create a final “averaged” image. You can use Photoshop, GIMP, Imagemagick or I presume many other apps to create this image. I used Imagemagick here as I don’t have Photoshop and didn’t want to load all those images into GIMP and I had read that “convert” would do a good job.
Here’s one I created earlier today in the slightly shady but bright gardens of Blarney Castle:
The images that went into creating that image all look like this. They were shot at f/4, mostly shot at 1/80 of a second and ISO 100. I wanted fast images with minimal noise and the scene is mostly flat so I wasn’t too worried about depth of field.
To make this image I took 27 photos of the scene. I imported them into Lightroom (didn’t do much apart from applying my default settings) and exported Jpeg files. In the directory where I exported them I ran the convert programme from ImageMagick like this:
convert *.jpg -average average.jpg
That command was used by Luis Argerich, the author of this post who created a simulated 4 hour exposure of the sky and went on to say:
Averaging can be used in static scenes to create a new photo with less noise. Noise is reduced in the function of the square root of the number of images. So if you average 25 shots you have 5 times less noise than in a single image.
Averaging can also be used in non-static scenes to simulate a long exposure.
Patrick David in this post suggests a slightly different command which I tried and it created a similar photo.
If your exposure somehow went wildly different with some images bright, some dark, use the “Match Total Exposures” feature in Lightroom to pull them back.
ImageMagick is fairly easy to install. If you are using Linux you probably already have it installed. You can download it from this site or if you use Mac OS X, install Homebrew and then it’s as simple as this to install:
brew install imagemagick
Here are a few more examples:
This one didn’t work out. I was trying to capture the swirling of the bubbles on the water.
This one works better. The source photos are all around 1/25th of a second which is certainly not fast enough to freeze the water.
Almost happy with this one. The source photos go from 1/60th to 1/100th of a second.
I like this. It was created from ten photos shot at f/4, 1/60th sec, ISO 100.
I didn’t try very hard to make the images here pretty. They’re purely experimental and done with minimal effort but I’m very happy with most of the results. In shaded daylight I was able to take the equivalent of five to ten second exposures without ND filters or reducing the size of the aperture. It would have been easier to make the aperture smaller and add an ND filter but that’s not the point of this exercise.
One issue that may bite you is the speed of your media. My camera quite often flashed a “busy” notice because it was writing to the SD card. Then again, I was shooting 20MP images and my card says it’s rated at 30MB/second which is a problem as each image is around 20MB. As they’ll only ever be viewed online that’s probably not really needed. I might try the half-size option next time.
One nice bonus to this method is that Google Photos will generate nice animated GIFs from your image stack. I posted mine here. I won’t embed them as the files are huge!
I’m definitely trying this out again!
|Camera||Canon EOS 6D|
Since I started posting photos online I’ve always created two images:
This has served me well as I have from time to time changed the software I use to develop photos. Otherwise, I might have the web version and not be able to recreate a full size version for printing or other uses.
Up until very recently after I worked on an image I would add it to an “inphotos” default collection (press B), then right-click and export twice. Once for web, once for full size. I had to do this for each image. Sometimes I could select a bunch of them and export if I knew I had a number of “keepers” from a shoot but otherwise it was tiresome.
I’m now experimenting with smart collections in a Hard Drive Publish Service. I still have an inphotos.org collection, but I added another one called, “Published inphotos”. That’s a smart folder that contains all the published photos that have already gone up on the site. That folder contains every image that comes from the inphotos.org collection and is labelled Yellow.
Aside: I also added a “Potential” smart folder for photos I’d like to work on. Labelling a photo RED will put it in this folder.
Obviously I haven’t added every published photo to it and I probably won’t. I don’t have time to, but I will fill in older photos when I have a spare moment.
If you’re not familiar with collections here are two videos from Adobe on ordinary collections and smart collections that are worth watching:
I then created two publish services. One for full size images, the other for web images.
The 00-inphotos and 00-Large smart folders initially contained every image that is in the inphotos.org collection. I soon realised I’d have a problem with the web sized 00-inphotos folder. If I published a photo how would I remember that event easily? In the past I moved the file into a different physical folder, but I wanted Lightroom to track this. To do this I decided to add a yellow label to every photo I published. I created a new “00-published” smart folder. This folder collects every image that is labelled Yellow from the inphotos.org collection.I modified the 00-inphotos smart folder so it contained every image except those labelled Yellow.
So, when I published an image I went into the inphotos.org collection in Lightroom and labelled the image yellow by pressing “7”. This would cause the 00-inphotos smart collection to delete the image, and the image would be added to the 00-published smart collection. I just had to hit Publish on each of them and the file would be “moved” from one physical folder to the other.
It’s early days yet and I’ve only posted a few photos using this method but it works well. Editing photos and adding them to the inphotos.org collection is a breeze but this is a process that’s not set in stone and will be refined with time. If it’s too awkward I’ll move on to something else.
I use the WordPress “new post” interface to make new posts, or if I have time to do so, I’ll schedule a number of posts using Postbot.
How do you use Lightroom to post to your blog or social media site?
I love shallow depth of field and the Brenizer Method (or bokeh panorama) is an intriguing way of achieving that in a wide angle shot.
Basically, with your lens zoomed in you take many overlapping photos of your scene like you would a panorama but you don’t go for the traditional 360 degree image. It’s more like 50-90 degrees, or what a “normal” lens would see. The beauty of the technique is achieving a very shallow depth of field because your lens is zoomed in and the DOF is shallower still than it would be wide open, or so I’ve read. I haven’t managed to take such a photo yet!
Here’s a great video showing how to do it with Photoshop, but you could use Hugin or Microsoft Ice as well.
I had no idea this existed, but then I’ve rarely had to match the exposures of multiple files. When I used the GIMP to edit photos I would play around with multiple exposures more often but Lightroom can extract so much information from RAW files it covers 99% of my image development.
tl;dr – fix the exposure of one image, select other relevant images and click on Settings->Match Total Exposures.
If you have an external flash (and this even applies to the onboard flash but that’s a lot weaker) for your DSLR try shooting with the camera in manual mode and let the flash light the scene for you.
Canon flash units use E-TTL to figure out what power to use, Nikon and other manufacturers use something similar. In the bad old days photographs had to figure out the right settings with a light meter but now the tiny computer in your flash does the job automatically. This means you have a lot more freedom with your camera.
Instead of shooting in Program or auto mode switch the dial to M and change the aperture to F8, and the speed of the shutter to match how wide your lens is (or faster if you’re hand holding, try 1/50th of a second to start). Try shooting an indoor scene with objects at various distances. Do the same in Program mode too. You’ll probably find that objects that are blurry in Program mode are in-focus in manual mode!
By shooting in manual mode you’ll have more control over the depth of field, that is the area of the scene that will be in focus. F4 means that only a narrow sliver of the scene will be in focus but F8 broadens that. This is why those family portraits you shot in Program mode had some blurry faces in the background!
Many lenses produce sharper and better looking images at a certain aperture setting. F8 is widely suggested as a good starting point but it depends on the lens in question.
Unfortunately changing the aperture means less light gets to the sensor but your flash will do a good job of compensating for that. It can’t cope with every aperture setting or scene so experiment and get to know your equipment.
On Canon cameras Manual mode is better than Aperture priority mode for simple flash photography. In Aperture priority mode the camera adjusts the shutter speed for the ambient light and doesn’t use the flash in this calculation. In a dim room this will result in a long exposure. The flash will illuminate the subject but the background will be exposed for too. This is of course a valid way of taking photos but you have to be prepared for some camera shake, or you can underexpose the image on purpose to reduce the shutter speed. Long exposure shots with a flash produce some great looking action shots too, but be sure to set the 2nd curtain sync correctly! Here’s a good comparision of 1st and 2nd curtain sync.
Here’s some good advice and tips on the subject for Canon EOS owners.
|Camera||Canon EOS 40D|
Version 2.8 of GIMP saves images as .xcf files by default when you hit CTRL-S. I remember a development version did this years ago but it was reversed before final release due to user feedback AFAIR.
I can understand the reasoning behind this decision but I hate it. It really, really bugs me. I don’t think it’s going to change in the future but if you must have your CTRL-S “save as a bloody jpeg because I said so” there is a way around it. You’ll use keyboard shortcuts.
Go to Edit->Keyboard Shortcuts and then search for export. Now change the shortcut to CTRL-S for either “Export…” or “Export to”. The former shows a save dialog, while the latter overwrites the file you have loaded. I prefer the save dialog.
You’ll still get the “close without saving” dialog. If it really bugs you (and I think it will) there’s a checkbox in the preferences asking you to, “confirm closing of unsaved images”.
*sigh* what a mess.
Bibble 5 and Aftershot Pro have a useful lens correction function that will fix the distortion created by a camera lens when a photo is taken. You won’t even recognise the distortion unless you’re looking for it but quite often it can look like straight lines are slightly bent or bulging.
The animated gif above shows you what that distortion looks like in my favourite zoom lens, the Sigma 18-200mm DC. The middle of the image is clearly bulging out. The bottom of the sign isn’t straight but after correction it’s much better.
Unfortunately not every lens is supported. In the lens correction widget of Aftershot Pro you’ll see an “Uncalibrated Lens” message if your lens isn’t there.
Bibble 4 supported this lens and I only realised today that a bug in Bibble 5 and Aftershot identified the lens incorrectly and led me on a merry dance across the Internet. Bibble 5 and Aftershot Pro think my lens is the “Sigma 18-200mm DC OS” but my lens doesn’t have an Optical Stabilizer! Bibble 4 probably detected the lens correctly.
Unfortunately for me there’s no mention of “Sigma 18-200mm DC” in the “Canon Lens Table” or profile_canonlenstable.txt. Only the OS lens is mentioned and I presume the non OS lens was removed in Bibble 5 by error. Once I added an entry for my lens and added settings for the OS lens everything worked ok again.
Anyway, thanks to this ASP forum post and this Bibble forum post I was able to add my lens to Aftershot Pro. The nice thing about the lens database is that it is composed of text files that are easy to edit. I found a basic uncalibrated entry for the non OS lens. Unfortunately I didn’t search further or I’d have found the “Sigma 18-200mm DC” settings I wanted and saved myself some time! I created a new file called profile_mylenses.txt and added that filename to profile.txt.
First of all, I had to find the lens correction parameters that would fix things. The Bibble 5 post above links to sites that will help you figure out the correct a, b and c coefficients but thankfully I didn’t have far to look to find working figures.
I checked out PTLens first. It’s a programme that corrects lots of different lens distortions and it’s reasonably priced at US$25 per license. The author has shrewdly kept his lens distortion database in a secret format so I had to continue looking.
I then found LensFun, an open source tool to do much the same thing but using an older version of the PTLens database. The source is available so I went digging and found this interesting file! All the info I needed in one XML file!
All that remained to do was edit profile_mylenses.txt. In Windows and Linux the file can be placed in the following locations respectively. Mac OS X is probably in “Application Support” or somewhere obvious like that. In Windows you’ll want to use WordPad as the other profile files don’t have Windows line endings. You’ll also have to open it as an administrator to edit it.
C:\Program Files (x86)\Corel\Corel AfterShot Pro\supportfiles\Profiles\LensProfiles\
After some editing and experimenting I found that these settings worked well:
menu_lens: Sigma 18-200mm f/3.5-6.3 DC OS
cal_abc: 18 0.018238 -0.045992 0.000000
cal_abc: 21 0.013683 -0.026594 0.000000
cal_abc: 24 0.007113 -0.008911 0.000000
cal_abc: 33 0.000000 0.010791 0.000000
cal_abc: 59 0.000000 0.012006 0.000000
cal_abc: 88 0.000000 0.010958 0.000000
cal_abc: 144 0.000000 0.008752 0.000000
cal_abc: 200 0.000000 0.007390 0.000000
I had to restart Aftershot Pro to test new settings each time.
If editing files like that puts you off you can create a preset to apply the lens correction. Click on the Manual tab in the Lens Correction widget where you can enter the a, b and c coefficients. Now go to the Presets widget and follow the instructions in my HOWTO: Add a copyright notice in Aftershot Pro tutorial except you’ll want the Lens Correction function to be active.
I suspect that these changes will be overwritten whenever I upgrade Aftershot Pro but maybe Corel will notice this little post of mine and they’ll fix the detection, or duplicate the settings in the next version..
While writing this post I found entries for the “Sigma 18-200mm f/3.5-6.3 DC” lens in profile_genericSLR.txt. Because the programme misidentified my lens it never used those settings. The 1.5 multiplier settings have the same settings as above, the 1.6 multiplier one is slightly different but there’s not much difference when applied to my test image.
Let that be a lesson to you if you’re trying to get this work. Look harder for an existing profile and make sure your lens is identified correctly! Argh!
Martin, over at Photoakademie.eu created a workflow video showing how a photo was processed and eventually turned into a black and white image using Aftershot Pro.
Coming from a GIMP background I used layers and layer masks but never used adjustment layers to keep changes separate. Quite an eye opener for me!
Plus another demonstration of Aftershot Pro and a Google Plus account dedicated to sharing presets.
You can download a 30 day trial of Aftershot Pro here (I should be on commission for this..)
|Camera||Canon EOS 40D|