#322 Wirecast, CrashPlan, Effective Focal Length

Are we losing touch with real people because of technology? Wirecast review from telestream.com. William Thompson Jr gives us a ScreenSteps testimonial and Allister Jenks explains how CrashPlan from crashplan.com provides a fabulous backup solution. In Chit Chat Across the Pond Bart explains Effective Focal Length in cameras vs. sensor size and the history behind it.



Hi this is Allison Sheridan of the NosillaCast Mac Podcast, hosted at Podfeet.com, a technology geek podcast with an EVER so slight Macintosh bias. Today is Sunday July 24th, 2011 and this is show number 322. Would you believe I’m not going to talk about Lion at all today? It’s not that I’m not playing with it and enjoying it, it’s because we just recorded the BEST episode of the Mac Roundtable all about Lion. We had a veritable food fight about Lion, or as John F. Braun is wont to say, “a spirited discussion”. We also had Bart and Don McAllister and Adam Christianson on the show. I think in an hour and twenty minutes we only agreed on the good/badness of ONE feature the entire time. It was a blast. Check out Episode #103 over at macroundtable.com

Are we losing touch with real people?

Last week I had a lunch with some girlfriends, and my friend Jackie voiced an interesting opinion about technology. She feels that we’re losing human interaction. She feels that we’re losing a lot of information about what people really think and feel because we can’t look in their eyes to understand them. She works with troubled children and has a great sense of people and is very empathetic.

I told her though that we aren’t losing the in depth human interaction, because she and I were still sitting there talking directly to each other, so it wasn’t lost at all. However, the onslaught of technology in which I live has actually added to my human interaction. Certainly it’s not as rich of an emotional experience to be in a text message as to sit across the table from that person, but without the internets I wouldn’t have that conversation at all. I think about all the fabulous conversations I’ve had with Bart over the four years I knew him before we ever met. I knew when we met in real life it would be different, but I also knew that we would be great friends for life. I knew his heart and his values and he’d taught me about the culture in Belgium and Ireland, I knew about his education, his friends and even what he liked to eat and drink. I knew him.

I think that we can get pretty darn rich experiences with people through the internet, but no matter what level of depth, it’s more than we had without the internet. Without it we wouldn’t know people from all over the world. I wouldn’t have friends in England, Ireland, Belgium, Japan, New Zealand, Australia, Peru and Iowa. I suppose if you stopped talking to people in real life and only played on the internet Jackie could be right, but I’ll stick with my mixture for all the fun I have with all of you.


You’ve heard me talk a lot about the live NosillaCast, but most of you have never gotten to enjoy the experience. It’s great fun, and I have made some very close friends in the NosillaCastaways, the überfans of the show. In order to pull off the live show I use some fairly sophisticated tools, with capabilities that would have cost tens of thousands years ago. When I first started the live show, I just pushed the button on ustream.tv that said broadcast. I agreed to allow it to use my camera and microphone and I was on the air. Usteam even has a live chat so I was able to type into the Flash interface on screen and chat with people watching. And that’s when the madness started.

You get started in something like this and before you know it you’re addicted! Luckily I don’t have it as bad as Mark Dalton of The Tech Lounge, but talking to him is like talking to a live video drug pusher! He’s a great deal of help but he’s sucking me into his world.

The first step was to figure out how to broadcast more than just my lovely face while I was talking. Seemed like it would be fun to add in video of what I was actually doing to produce the show, like showing GarageBand. I got the free utility Camtwist from camtwiststudio.com, which allows you to create a virtual video source of your desktop. I used that to grab both my video and video of GarageBand.

But then someone, I think it was Stu Helm of the International Mac Podcast, told me about IRC, or Internet Relay Chat. This is a very old technology circa 1998, well before AIM or any of that nonsense. Turns out the chat on the web was using IRC, but if you had any kind of sophistication at all you used a 3rd party client like Colloquy or LimeChat to do the chatting.

Next someone told me it would be cooler if people watching could hear not just my voice as I created the recordings, but also GarageBand when I was playing back clips. Now I needed Audio Hijack Pro from Rogue Amoeba to take my microphone input and GarageBand and combine them together into one audio source using SoundSource also from Rogue Amoeba.

You know what would be cool though? What if people watching the video could see the chat when I saved the videos to Ustream? And then we decided we wanted high definition video to make it look a lot better. Well now it was time to get into the big time (or so I thought). Someone, probably my dealer, Mark Dalton. I ended up buying a product called Ustream Producer Pro that really took things up a notch. With Ustream Producer Pro I was able to pipe in two video sources at once, both video of my lovely face, and GarageBand. It also allowed me to pipe in the live chat to a third pane, all in beautiful high def!

This was nirvana – we had everything we needed. Well, except it was all in Flash, which meant people couldn’t play the live stream on their iPads and iPhones. Sheesh. They’re demanding, aren’t they??? Well I aim to serve. Luckily my other pusher, Stu suggested I add a pure audio stream to the live show that was iOS accessible. The good news is that he had a server handy that he said I could use, even though I was clearly abusing our friendship by saying yes, I went for it.

Ok, great – we have EVERYTHING now, right? Well…. right around then Ustream started really bumping up the ads. I know we’re getting the streaming service for free, so I think it’s perfectly reasonable for Ustream to have ads. Pre-roll ads, 30 seconds, that’s perfectly reasonable. pop-up ads in the bottom third from time to time, that’s cool. But Ustream started to put 30 second full frame ads in the middle of the show! I can tell you that the NosillaCastaways were not happy. They were missing what was going on. If I maybe knew they were going to do it, I could have just paused the show for 30 seconds, but every person got them at a different time. Basically someone was mad at all times.

Well, I got in touch with my pusher Mark, and he told me about yet another application. It turns out that Ustream Producer Pro was developed by Telestream, but marketed and sold through Ustream. Telestream is a fabulous company. They gave us Flip4Mac, that lets us play WMV files. They gave us Screenflow – my personal favorite screen capture video program. They used to make a great program called Drive-In that allowed us to make perfect duplicate copies of our DVDs (complete with DRM), but of course the Motion Picture Association killed it because it was so useful.

Well it turns out that Telestream makes a higher end version of Ustream Producer Pro called Wirecast, that could allow me to break free from Ustream and try out some other video streaming service. I was hesitant to jump to Wirecast because it costs $450. Now I know that compared to what this would have cost years ago, this is a bargain, but I’d already spent $200 on Ustream Producer Pro. I wrote to the folks at Telestream and asked if there was an upgrade path so my $200 would go to good use, and they said they could give me a coupon for $200 off, but if I wanted a copy to do a review, I could have one. This is one of those soul searching moments – and I decided to accept their offer after telling them I would be as tough as I normally am on a new tool. When I first into their site to download the application, I had to log in and I was perturbed to find a visually only CAPTCHA, so I shot off my usual email suggesting recaptcha.com as an alternative accessible CAPTCHA method and I have every confidence in this developer to get that sorted straight away.

wirecast imageryThe first thing I did on launching Wirecast was actually go through their tutorial. No, it wasn’t reading the manual, it was following along with a tutorial. They give you a file that opens Wirecast with some samples that work with the tutorial so they sorta spoon feed you, just the way I like it. I learned in the tutorial how to flip between sources, how to do a preview of what you’re about to show (that wasn’t available in Ustream Producer Pro), and even how to make that only happen when you’re ready to show something new by disabling AutoLive.

Layers were interesting – you can put different things on layers, like the lower thirds image I have with the name of the show and the podfeet logo. I’d done that in Ustream Producer Pro but it would never “stick”. Every single time I started the show, I had to add that effect, and I had to add audio. Oddly save, well, didn’t, in Ustream Producer Pro. I am already juggling so many balls and spinning so many plates that remembering to turn on the audio was something I often forgot (but the chat room was quick to remind me).

Both versions have a shot editor, but the one in Wirecast is much more capable. let me first explain what it does – it lets me have a 3-up view, my lovely face in the upper left, GarageBand in the lower left, and the live chat in a pane on the right half of the screen. with Wirecast I can slide those views around and change their size to make them look just perfect on screen. Ustream Producer Pro wasted a lot of screen real estate and you couldn’t edit the views. One complaint I have with the editor though is that it seems to open partway below my screen on two monitors, so every single time I open it I have to pull it up where I can see the whole window.

wirecast 3-up setupWirecast and Ustream Producer Pro both let you change the aspect ratio and quality of the video you’re presenting. As of the time of this review, I’m having trouble where the display of my video isn’t the right aspect ratio. As I fiddle with the settings, I can get it where I’m squashed fat, or made real thin (which I prefer), but only sometimes does it come in at the right aspect ratio. Steve and I did some very controlled experiments, changing one thing at a time but we were unable to find a pattern and come out with the right view. I’m not sure if it’s a problem on Wirecast end, or if it’s a problem on Justin.tv’s end where we were experimenting. The good news is that with Justin.tv we had pre-roll ads of either 15 or 30 seconds, some mild-mannered popups, but NO interrupting ads in the middle of the show.

I had a little trouble figuring out one thing – but with the help of Mark Dalton and the folks at Telestream in parallel, they showed me how to stop my own mic from me hearing it. The worst thing in doing recording is hearing your own voice, especially if it’s delayed a little bit. I made a suggestion on how they could have made this control easier to find, just changing a default setting, and they said they’d make a change for the next release. I liked that, having an impact on the product.

I’m excited about the more advance options available in Wirecast that I haven’t gotten to play with yet. Wirecast allows you to create green screen recordings – so I could create the whole show where it looks like I’m sitting on a beach in Hawaii. They call this feature chromakey. I think it’s a bit advanced for me at this time, but I’m sure we’ll grow into it.

Wirecast isn’t limited to Flash streaming like Ustream Producer Pro, you can broadcast in Quicktime, or even Windows Media. I experimented with Quicktime streaming a ong time ago, might be time to see what I can do with that too.

I mentioned Justin.tv, Wirecast also lets you stream to LiveStream, Stickam, Sermon.net, Brightcove, Akamai, Limelight, BitGravity, Wowza and more… For now I think I’ll stick with Justin.tv because it worked well for us, but I love the idea that I have the freedom to move the show when and if a better solution comes along. Another awesome feature of Wirecast is that you can record to disk. This means that I could produce the live show, record it to disk, and then push it out as a podcast. I’m not sure there’s demand for that, but it might be fun to do.

Ustream Producer Pro uses an embedded tool called Desktop Presenter to capture the screen, but with Wirecast you get Desktop Presenter as a standalone tool. At first I was bummed because I couldn’t capture just a portion of the screen, but then I figured out that the standalone app allows you to capture a specific window, no matter how big or small you make it or if you move it around, and that was perfect for what I was trying to do. the other big advantage of the standalone version of Desktop Presenter is you can capture either screen if you have a second monitor. The built in one on Ustream Producer Pro doesn’t allow you to do that – it’s primary monitor or nothing (I actually think it’s a bug). Add that to the loooong list of things I needed to remember that I had to switch my primary monitor to the second screen. Using Wirecast the number of things I have to remember has dropped by 30%.

Wirecast releases us from Ustream, where the iPhone app simply doesn’t work. I applied for my show to be in the app, they accepted it, but every time we tried to use it, it might work for a little while, but it would always fail. We tested out the Justin.tv app for iPhone and it worked like a champ. There isn’t an iPad version which is unfortunate, but what’s more unfortunate is the app is TEN DOLLARS! That’s highway robbery in my book – I know you love me and all, but I can’t imagine you guys paying $10 to see the live show get created, but at least it worked.

Bottom line time. If you want to step up your game on video streaming to the web, and you want to have the freedom to choose your streaming provider (or even provide the streaming services yourself), you might really like Wirecast. It’s very capable, and very stable. While I do have some issues with it like the edit window not being on screen properly and the aspect ratio being hinky, I’m confident enough in this vendor that I know they’ll get these things sorted.

If you haven’t done this kind of thing before, the whole structure will be very unfamiliar to you, but their great spoon-feeding tutorial will help you get the hang of it. $450 is a lot of money, but again if you step back and think about what you’re actually able to do with it, it’s an amazing price. I would say that if you’re stepping into this whole arena, I wouldn’t spend the money on Ustream Producer Pro, I’d bite the bullet and go straight to Wirecast. they have a free trial so you can mess around with it and learn how it works, appears to be full featured and it puts a watermark across your video until you buy it. That’s a great way to let people learn the tool in my opinion. If you don’t have the money (or don’t want to shell out $450) for Wirecast, there are stepping stones as I described that will get you about 50% of the functionality for a lot less money. Just don’t talk to Mark Dalton.

I put a link in the shownotes to the page where they compare Ustream Producer Pro to Wirecast in all the features, and you’ll be dismayed to find out that there’s also a Wirecast Pro tool…but until Mark tells me I need it, I’ll be sticking with Wirecast.


This week’s ScreenSteps ad comes in the form of a real life testimony from William Thompson Junior. I swear this was not solicited, he voluntarily sent this in – I think you’ll like his sense of humor about it.

Hi Allison. For years I have been listening to your show during my long weekly commute from NY to LA. Thanks so much for helping the long flight seem to pass more quickly. Invariably, there is always a spot in the show where you discuss the wonderful benefits of ScreenSteps from Blue Mango. I have to admit that I usually tune this section out, much like the flight attendant’s ubiquitous description of the proper way to fasten a seat belt. However, this past week I needed to document a piece of new software for 200 auditors, and timing was critical. I thought of your show and ScreenSteps. Now, I work for a large public accounting firm and nothing remotely close to ScreenSteps is supported by our IT. The old “Print Screen”, paste to MS Paint, edit, paste to MS Word, add text … method is usually used. I wanted an easier way. I thought, doesn’t The Nosillacast podcaster always promote a documentation solution.

So, I downloaded the free 14 day ScreenSteps trial at BlueMangoLearning.com. It took me about 15 minutes to comprehend the workflow and to watch the wonderful tutorial videos. Within 2 hours I had created a beautiful 30 page manual with a TOC, headers, footers, chapters, annotated pictures and instructions. I plunked down the money for the pro registration key and exported to PDF. After a quick final review, I sent it out to my team.

About 15 minutes later I started receiving emails from coworkers with statements like:
How did you do this so fast?
When did you have time to do this?
This is a lot of work. Thanks a lot.
Wow, so detailed.
This is exactly what we need.
Great job!

Thank you for your show and for pointing me to ScreenSteps. Having the right tool to solve a problem made all the difference. I feel like a hero. Now I have to decide if I should tell the team how I did it, or continue to let them think I am a documentation SUPER STAAHHR!!!

I love this letter William – maybe people will believe me now? Head on over to ScreenSteps.com and check out their free trial of ScreenSteps, tell them Allison sent you!

Crashplan by Allister

Hello Allison and the NosillaCastaways. Allister here again from the wintry shores of New Zealand. I’m here to give you a review of CrashPlan, a backup and recovery application and service from crashplan.com. But as always, there must be a problem to solve. This one’s easy. I don’t want to lose my data. For any reason. Ever.

crashplan logoCrashPlan feels to me like Time Machine on steroids. Let me first say that Time Machine has operated flawlessly for me from the day I installed Snow Leopard. I’ve not pushed the envelope, just plugged in a drive and said yes.

It’s like Time Machine because once I set it all up I need to do pretty much nothing. I have a couple of bare drives which I store at my office. I bring one home periodically and insert it into a USB dock. The next morning I eject the drive and take it back to the office. That’s it! But getting to that point takes a little effort.

So how do we decide what gets backed up where? A ‘backup set’ is a selection of folders and files which you choose to be backed up together. Each backup set can then be sent to multiple ‘destinations’. Destinations can include another folder on your drive, an external hard drive, a network drive, another computer on your LAN that’s running CrashPlan, a friend’s computer on the internet that’s running CrashPlan or the CrashPlan+ online backup service. Any backup set can be sent to any or all of these locations. Want 10 copies of that data all over the world? No problem for CrashPlan!

So now we know what’s being backed up and to where, when does this happen? Whenever you want! Each backup set has a backup frequency which can be as often as every minute or any time greater than that. You can also set a daily window in which a backup set is allowed to be backed up. Say, between midnight and 6am.

So if these backups are running every minute, should you be worried about it being a resource hog? Nope. You can control CrashPlan’s CPU use both for when you’re active on your machine and when you’re away. You can also control the bandwidth it uses, when you’re active and when you’re away, and separately for LAN traffic and internet traffic.

So, what about files changing over time or being deleted? By default CrashPlan will never delete a file it has backed up. But you can tell it to clear those out after a certain time. You can also tell it how many versions to keep depending on the age. This can be specified for very recent files, files in the last 90 days, in the last year and in forever.
Is that ALL? Nope. You can fine tune your backup sets by excluding files by filename including regular expression support. You can have CrashPlan watch the file system in real time, turn compression on or off, decide how it encrypts the data and whether it should back up open files.

So my data is safe, how do I get it back when I need it? Easy peasy! It’s like writing a story. You tell CrashPlan where the files originally came from – from which computer and backup set. You tell it from which destination to retrieve them. You then filter by filename or select from a full list. You tell it which version to get, where you now want to put them and what to do about overwriting files already present. Then push the button and let CrashPlan do the work.

You can imagine there’s a lot going on with CrashPlan. How on earth do you keep up? Well, you can just keep an eye on the emails and tweets it sends you. You can get backup summaries and alerts for backups that have not been able to run in a while. Or, if you really want the nitty gritty, check out the history log which shows you all the detail of what, when, how much, how fast and what went wrong.

So with all this power, I’m sure you’re wondering by now – how much? Well, if you can make do with only one backup set (like just your home folder) and you don’t need to use the online backup service – it’s FREE. However the real power comes with CrashPlan+. this is essentially the online backup service, but also allows you to specify multiple backup sets – which is where I think the real power of CrashPlan is. Even then, it’s hardly going to break the bank. Three bucks a month for umlimited backups from one computer or six bucks for unlimited backups from your whole household. And when they say ‘unlimited’ they mean it. When another online backup service recently dropped their unlimited plans, CrashPlan got a LOT of new customers and were at pains to point out that ‘unlimited’ is a key selling point for them.

So, that’s CrashPlan. Download it and have a look around. Run a backup and see how it works. They’ll even give you 30 days free to try CrashPlan+.

My setup now includes backing up some data from my internal hard drive to a LAN drive, some data from the LAN drive to CrashPlan+ and most of my data from various locations onto external portable hard drives which then go offsite. I’ve just started setting up other Macs in the house to backup to my external hard drives. It really is the ease of Time Machine for operation, but backed by a superbly capable and flexible engine that will help you put your data exactly where you want it.


Today when we were recording the Mac Roundtable podcast, Adam Christianson was mentioning how in OSX, there are ways to actually create custom dictionaries so you can type in a word and get a different word or phrase. There was this pause, and then he said, “of course I use TextExpander for that.” There was a sigh of relief as all of us said, “of course, that’s what we all use!” I then confessed to Bart that I actually created a TextExpander snippet to spell Bart Busschots! He laughed and said he thought that was a brilliant use of TextExpander. Do you have hard things to write like that? Maybe a company name or an organization name? Or a team name someone thought clever at the time but it’s 28 characters long? I have one like that. TextExpander makes it so easy to type these giant names, long phrases you write all the time, the tool is a lifesaver. if you haven’t got TextExpander yet, go over to smilesoftware.com and download the free trial. I promise you will love this tool, and if I’m wrong, Smile will put their money where my mouth is and give you your money back with their 90 day guarantee. Be sure to tell them you heard about it on the NosillaCast, it REALLY helps the show!

Chit Chat Across the Pond

=========insert part 1 and 2 ========

Correction from Last Week – Clam XAV

Bart miss-read the check boxes in the default ClamXav setup – it does NOT default to having the sample rules on – mixed up the labels on the columns.

Security Light

Main Topic 1 – What on earth is EFL, and what does it mean to have a cropped sensor?

There are two variables that affect the field of view of a photograph – they are the focal length of your lens, and the size of the piece of film or sensor that’s recording the image.

A lens casts a circular image, or which we only record a rectangular subset, the bigger the subset the bigger our field of view, the small the subset, the smaller the field of view.

The focal length of the lens determines how much the projected image by the lens is zoomed relative to reality. Smaller numbers if mm means more zoomed out, bigger numbers of mm means more zoomed in.

In the early days of photography it was impossible to magnify and image, so you had to use a negative the same size as you wanted your final print. If you wanted a 20″ x 20″ print, you needed a VERY big camera and a 20″ by 20″ sheet of glass to use as your negative.

Even when faster photographic papers made magnification of the negative possible during development, there was no single size of film in use, so photographers were used to the idea that a 20mm lens would behave completely differently on different cameras.

Then, by a pure accident of history, the small compact camera that used movie film mounted sideways invented by Oskar Barnack took off. The Leica camera was the first 35mm film camera, and it became a revolution. At first ‘real’ photographers scoffed at those little toy cameras, but pioneers likeHenri Cartier-Bresson soon started to change people’s minds.

By the second half of the 20th century there was no doubt at all about what the standard size of film was, 35mm! There were still a few eccentrics using the much bigger medium and large format films, but SLR cameras were 55mm, and they were the main-stay in photojournalism, professional photography, and amateur photograph. This meant that film size was no longer seen as flexible so the only factor that determined the field of view of your shots was the focal length of your lens – so 50mm became synonymous with no zoom, i.e. a natural view, anything less was a wide angle lens, and anything more a telephoto lens.

BTW – the reason the ‘nifty-50’ is such a desired lens is that it’s neutral and doesn’t distort perspectives because it neither zooms in nor out.

The digital age has shattered the dominance of 35mm film, and digital sensors are NOT all the same size, even the two big DSLR companies, Nikon & Canon, do not share a standard size, and you have many other sizes making their way forward like the modern 4/3 standard in compact digital cameras.

However, we still need a standard way of talking about things, and we still need a common standard, so we’ve taken the idea of 35mm as a standard unit with us into the digital age. We describe digital cameras by their ‘crop factor’ which is a way of expressing the ratio between the size of the sensor in a camera and the ‘standard’ 35mm frame. This ‘crop factor’ is also called a Focal Length Multiplies or FLM, and Nikon have a crop factor of 1.5, while Canon use 1.6.

Another term you hear a lot now is “Full Frame Sensor”, what that means is a digital camera with a crop factor of 1, i.e. it has a 35mm chip!

The important concept to get is the so-called Effective Focal Length, or EFL, which tells you how a lens will behave on your camera, relative to a lens on a 35mm film camera. You do this using a simple formula:

actualFocalLength = cropFactor * EFL

So, to get a lens for a Nikon D40 that behaves like a 50mm lens, i.e. a ‘nifty 50’ we have the following math:

D40mm = 1.5 * 50mm


on a Nikon D40, we need a 33.3mm lens if we want a Nifty 50 – the closet you can get at a reasonable price is 30mm, so that’s what myself & Allison use

Or, to put it another way, on a Nikon D40, a 33.3mm lens has an EFL of 50mm, and a 30mm lens has an EFL of approximately 50mm, so it’s our equivalent of a nifty fifity

Main Topic 2 – Don’t Cripple Your Lenses!

I’m sorry if this is a little bit ranty, but this is something that really gets my blood boiling!

Lens makes spend AGES doing really hard math and lots of testing to make lenses that are corrected for a million different kinds of imperfection that the universe tries to throw at you when you try to focus light. They correct for chromatic aberration, they correct for many forms of distortion, they try to stay sharp out to the very edge of the field of view, and they try to keep the lighting even right out to the edge so you get no vignetting like you used to get on older poorer lenses.

The lenses have many optical parts that have been carefully engineered to cancel out the bad properties of each, and the optics have very complex chemical coatings.

So what do people to do destroy all this hard work put in by lens designers and manufacturers?

1) they don’t use the lens hoods provided!

Every lens cap that comes with a lens hood comes with it for a reason. You’ll notice they all have different shapes, and the shape is mathematically determined by the lens, so if your lens came with one, USE IT, and never use the wrong lens hood on a lens.

The shape is carefully engineered to prevent internal reflections that cause either a loss of local contrast, or an out-right lens flare.

2) Don’t put cheap filters in front of them!

If you put a plastic filter over a carefully engineered lens you are distorting the light before it even gets to the lens, all the hard work by the lens makers is for nothing! You may as well take a brillo-pad to the lens!

Now that you’ve made it through the NosillaCast, be sure to go listen to the Mac Roundtable – what a blast that was! That’s going to wind this up for this week, many thanks to our sponsors for helping to pay the bills: ScreenSteps, and Smile. Don’t forget to send in your Dumb Questions, comments and suggestions by emailing me at allison@podfeet.com, follow me on twitter at twitter.com/podfeet. If you want to join in the fun of the live show, head on over to podfeet.com/live on Sunday nights at 5pm Pacific Time, and don’t forget that will direct you to Justin.tv for now. Thanks for listening, and stay subscribed.

5 thoughts on “#322 Wirecast, CrashPlan, Effective Focal Length

  1. Allister - July 24, 2011

    Pentax! The K-5 to be specific.

    I also have the easy 1.5 crop factor on a 16 megapixel sensor (which handles noise VERY well). I am *seriously* thinking about taking my $30 filter off now. My concern has not so much been breaking the lens as letting ANY foreign matter come into contact with it. That lens cap in the left pocket picks up lint and dust and that often ends up on my filter. Wipe that wrong one time and you have a scratch. I may have to do the high noon test. Errr. I may have to wait 6 months to do that here.

    I do have one question about the ‘natural’ focal length of a lens for a particular sensor. We know that the optics of a 50mm lens do not change, regardless of which camera you mount it on. I had considered that it is the optics of the lens, only, that determines the perspective effect. I understand that the sensor being smaller than the 35mm film frame means my field of view is smaller (as if I were using a greater focal length), but surely the perspective effect of the 50mm lens is the same regardless of the sensor size? Granted the perspective warping happens more toward the edges of the frame and therefore a smaller frame will not see as much, but if the deviation from ‘square’ begins from the centre of the frame, it would suggest that a 30mm lens on a Nikon DSLR would give the same amount of distortion as it does on the middle 2/3rds of a 35mm negative.

    This understanding aligns with the term ‘crop factor’. I.e. all the smaller sensor is doing is cropping the original image. As a thought experiment, if you take a range of photos using different focal lengths on 35mm film, print them, and then cut the 6 x 4 prints down to 4 x 2.666 in the middle of the prints – is that not the same result as just using the digital sensor? If that’s the case, how can the perspective or natural angles possibly have been altered simply by cutting up the prints?

  2. Donald Burr - July 25, 2011

    I LOVE Wirecast. I bought it on a whim earlier this year thinking I might use it to do some fancy streaming at anime conventions or whatnot, but I actually ended up using it during SCaLE during our streams of the keynotes. I was able to get a feed off the presenter’s laptop (using the free Wirecast Desktop Presenter software – it has a Windows version that works fine using Wine on Linux), and so I was able to inter-cut shots of the presenter with her slides (which solves the problem of “arrrgh! I can’t read the slides!”)

    Bear in mind that this was being broadcast to Ustream live during the actual event, but also was being simultaneously recorded to disk so I could post it to Vimeo later.

    (also please don’t criticize the camera handling, I didn’t have any assistants and since I was busy running wirecast, I couldn’t always frame the shot properly)

    BTW, combine Wirecast with a iPad app called Air Display and you have yourself a really neat control surface. I”ll have to make a video showing how this works.)

  3. Josh Owens - July 25, 2011

    I shot for many years with a UV filter on. Back in the 90’s I studied photography at Columbia College in Chicago and it was my main source of income for a few years after school. My professors and fellow students were fairly split on the subject whether to use a UV filter or not. I decided to use one for extra protection. Which it afforded me on many occasions. I ended up going through three filters. It does affect the image. I did a test when I first got one. This was done on film though before digital was affordable. When shooting with the filter I had to increase the development time of the film to achieve the same quality of negative and ultimately final print. Currently I do not find myself photographing under the same conditions I was then and mainly shoot for recreation so I choose not to use a UV filter. But if I ever plan to shoot a hardcore concert form the pit again or attach a camera to mountain bike as I follow some cyclists through rough trails you bet it’s going back on.

  4. Donald Burr - July 25, 2011

    I’ve always been afraid of busting or scratching my front element…until I read this:

    The practical upshot is:
    (1) A couple of scratches on the front lens element basically have ZERO effect on your picture.
    (2) Repairing a front element is probably one of the less expensive of lens repairs to make.

    So yeah, I don’t do the whole UV filter thing.

    I saved up for months for a really good circular polarizer, and it’s totally worth it. You can get a pretty decent one for around $150-200.

    There is one other kind of filter that is useful in certain situations: a Neutral Density filter. Think of them as “sunglasses for your camera.” It basically cuts the amount of light that enters your camera. This may sound silly and totally useless, but it has its uses. Let’s say you were attempting to take a photograph of a waterfall and you wanted that silky smooth water look. For that you’ll need to lengthen your exposure time, something on the order of several seconds or more. The problem with this is that it lets too much light into the camera, and if it’s a bright sunny day, that means you’ll get a badly overexposed picture. You can either wait until just before sunrise (or just after sunset) to take the picture, when there’s comparatively less light; or you can stop down your lens (pick a larger f/stop). But sometimes even that isn’t enough. So you pop an ND filter on (they are available in different “strengths”) and that cuts the amount of light coming into the camera for you, so that you can take a long exposure and still have everything come out right.

    Fortunately ND filters aren’t that expensive; you can get a decent set of several different “strengths” of ND filters for well under $100.

    There are also graduated neutral density filters, where basically the top part of the filter is dark and the bottom part is clear, and there is a gradient between the two. This is useful if you’re trying to take a picture of something that has two different exposure levels in it — like, if you’re trying to take a picture of a field or nature scene, but when you try and expose the picture so that the ground comes out perfect, the sky is totally overblown; whereas if you make your exposure so that the sky comes out just right, then the ground is too dark. In this case you rotate the ND filter so that the “dark” part covers the sky, and then you choose your exposure so that the ground comes out right, then because the ND filter “darkened” the sky, everything comes out perfectly.

  5. Donald Burr - July 25, 2011

    One other thing about filters: you may notice that if you have several different lenses, they have different diameters, which means ordinarily you’d need to buy one filter for each diameter lens you own. This can get prohibitively expensive. Instead, what you do is buy your filters to fit the largest lens that you own, and then get a set of step-down rings (which are fortunately quite cheap). Think of these as “adapters” that let you screw a larger filter into a smaller lens. That way you only have to save up for one really nice circular polarizing filter, etc.

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