WHILE BEING A PROFESSIONAL operator does seem to logically equate with working with a full frame camera, it’s really worth not closing your mind to other formats, and there are plenty of these to choose from. Demolishing the idea that crop-sensor cameras are in any way inferior to their larger full frame cousins, for example, the newly launched Arri Alexa 35 has at its heart a Super 35 chip, and yet this is without a doubt a very high performing model, which comes with a top-end professional price tag of around £75,000 to match.
Look closer and you’ll soon discover that sensors of all sizes offer individual sets of pros and cons and, by fully understanding what these happen to be, you can make a much more informed decision about which option to go for. Alongside full frame and Super 35, there are popular formats such as MFT and APS-C to consider and, for the uninitiated, it can all start to get a little confusing, and no-one wants to risk buying into a system that isn’t the right fit.
In particular, if you’re looking to go to the expense of investing in a full set of cinema lenses for your business then you need to be thinking carefully about which route to go down, and once you start to talk to experts, such as CVP’s Technical Marketing Manager Jake Ratcliffe, it soon becomes clear that there is way more flexibility built in than you might imagine, and some educated decisions need to be made regarding which way you might want to go.
“Investing into a set of cinema lenses is not a decision to be taken lightly,” says Jake, “especially given the cost involved, but with a variety of full frame and super 35 lenses available and a wide range of cameras with different sensor sizes and formats to consider, the question of what to invest in can be a difficult one to answer.
“The arrival of the Alexa 35 signifies that Super 35 is having somewhat of a renaissance right now, but to properly consider which format and cinema lens combination might work best for your operation it’s necessary for some of the myths that have grown up over the years to be dispelled. You also need to have an understanding of how lenses designed for different formats will still have the ability to work across the board, albeit with a few
compromises along the way.”
FULL FRAME FLEXIBILITY
It might come as a surprise to a few filmmakers to realise that a full frame lens can make an excellent partner for a crop frame camera, and can even offer serious advantages that lenses bespoke to that system will struggle to match.
“First off is the versatility that a larger image circle lens brings,” says Jake. “It means you can use them on your Super 35 camera, full frame and even smaller sensors like MFT. This ensures that you’ll be able to use and hold on to these lenses for years to come as your cameras change, or you might be able to rent them out to a bigger user base. The fact is that lenses with larger image circles will allow you to put them onto larger sensors and all other sensors smaller than that.
“You’ll also be using a smaller portion of a full frame lens’ image circle if you’re working with a Super 35 camera, or similar, which means that corner to corner performance should be better, as you’ll only be using the central portion of the lens. It all depends on what Super 35 lens you might be comparing it to, of course. Full frame cine lenses are also more readily available new than Super 35 ones, so they should be easier to find.”
Because you’re using a smaller portion of the image circle it will appear as though the focal length of your full frame lens has changed, but the perspective you achieve will remain exactly the same: check out our Box Out for a fuller explanation of what’s going on.
You do have the option, however, to fit an accessory known as a Speed Booster to get around the issue of the full frame lens you’ve fitted not covering as much field of view. “These are a great way to use full-frame lenses in conjunction with S35 or APS-C sensors,” says Jake. “The best way to think of a
focal reducer is essentially the opposite of a teleconverter. When using a teleconverter you’re essentially zooming in on the projected image circle of your lens, meaning that you’re losing light and image quality, but you’re zooming into the focal length. A focal reducer works in the opposite way, meaning you essentially zoom out, using more of the lens’ image circle, so you’re gaining light and can potentially achieve a better image quality.
“The big benefit of using a focal reducer is the ability to achieve part of the full-frame look on a super 35 sensor such as the one employed by the C70, while also achieving an extra stop of light to play with, which can be helpful. “When I talk about the full frame look, what I mean is that you’re achieving a wider field of view from a longer focal length lens. This isn’t taking sensor design into account, just the optical and sensor size side of things. You also hear people talk about improved or reduced
image quality when using focal reducers, and there are a few reasons for this. Of course, when you put more glass in front of your sensor you run the risk of introducing optical flaws, and you’ll also be working with an increased image circle, instead of just the centre of the lens.
“This could go either way: your image quality could be improved, as you are now using more of your lens’ image circle, thus reducing how noticeable optical flaws will be, but on the other hand you could also notice vignetting, reduced sharpness and increased aberrations out towards the edges of your lens’ imaging circle. How noticeable this might be will be down to how good a lens you’re working with, rather than the performance of the focal reducer.”
Another point to consider is that the more affordable full frame cine lens sets will have limited ultrawide options, so it might make sense to invest separately in a more specific wide angle lens that’s designed to partner your sensor’s format to complement a full frame cine set.
LITTLE AND LARGE
What then are the key advantages of working with lenses specifically designed for crop sensor cameras, rather than
investing in a full frame set and just using them for everything? “There are plenty of awesome Super 35 lenses available,” explains Jake, “and for people who know they’re going to be investing into a given Super 35 system and are not planning on getting a full frame camera, they can offer some key benefits. Lenses with smaller image circles are usually smaller, lighter and more affordable compared to their fullframe counterparts. There are also more versatile zoom lenses available for Super 35 than full frame which, for documentary, broadcast and wildlife work, could be a consideration that’s very important.”
It is also entirely possible to fit lenses designed for Super 35-sensored cameras to full frame models, and while again there will be a few compromises to consider along the way, there could also be solid reasons why such an approach might make sense.
“If you want to use lenses designed for Super 35 on a full frame camera you can do this in several ways,” says Jake. “You could simply crop the FF image down, so that the lenses you’re using will have a smaller portion of sensor to cover, and plenty of cinema cameras will allow you to do this. You’ll be sacrificing a certain amount of resolution, but results can still be very good.
“Another way to work with these lenses is to use an expander, otherwise known as a teleconverter, and these take the smaller image circle of your given lens and then spit a larger image circle out the back. Essentially, they’re doing the reverse of what focal reducers are doing, so you’ll lose light and can run into a degradation in performance depending on the quality of the expander you’re working with.”
Another option to consider is working with vintage stills lenses, and the quirky and unique effects these can provide have made their use increasingly popular in recent years. “These have become increasing viable on the back of the popularisation of short flange mounts, such as Sony’s E and Canon’s RF,” comments Jake. “These shallow mounts allow end users to get adapters for a massive range of lenses, which has led people to experiment more and to get some amazing results. It’s also a good way to get relatively affordable optics that have a different quality and feel to modern lenses for a special look.”
The more you look the more you realise that there is life beyond full frame and some incredible solutions that are worth considering. To get some expert guidance through what can sometimes be a confusing number of choices contact CVP at its Newman House address and fix up a no-commitment run through of the options that are available.
Focal Length Facts
IF YOU’RE WORKING WITH a lens that’s not been primarily designed for the sensor in your camera, then you’ll be working with more or less of the image circle, which will affect the field of view you’ll achieve. However, the focal length of the lens you’re working with won’t change, and if you were to take an image side by side with the same lens on cameras with different sized sensors, and then were to crop them to show the same area of the scene, you would find the perspective offered would be virtually identical. Head to the Share Grid Blog for a guide to different sensor sizes and formats.
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