What Is It?

“Crop Factor” is the idea that imagers smaller than a full 35mm stills frame effectively increase the focal length of any given lens.  Essentially they “crop in” on the image being transmitted from the lens onto the focal plane.  For example, the most common crop factor talked about is that of APS-C or Super35 sensors, which have crop factors of 1.5x or 1.6x depending on manufacturer.  This results in a 24mm lens on a APS-C/Super35 camera behaving like a 35mm lens would on a full frame camera.

There are many other sensor sizes out there, each with a different crop factor.  The most commonly referenced sensor size after APS-C/Super35 in terms of crop factor is the Four Thirds sensor.  This sensor is most often found in cameras like the Panasonic GH4 and GH5.  The crop factor of a Four Thirds sensor is roughly 2.0x when compared to a full frame camera.  So on a Four Thirds camera, our 24mm lens would behave like a 48mm lens on a full frame camera.  Most sensors of other sizes (1″, 2/3″, 1/3″, etc) are found in fixed lens cameras or broadcast cameras and don’t get brought up in discussions of crop factor too often.

But What About Crop Sensor Lenses?

There are tons of lenses that are designed to be used exclusively with smaller sensor cameras.  Sigma’s 18-35mm and 50-100mm f/1.8 Art lenses are a great example.  Surely the design of these lenses eliminates the crop factor of the smaller sensor?  So a 24mm crop sensor lens on a crop sensor camera will behave like a 24mm full frame lens on a full frame camera, right?

I hear this argument frequently, but it is incorrect.  Focal length is an expression of a physical measurement between the lens and the image sensor and does not change no matter what size image sensor the lens is designed for.  24mm is 24mm is 24mm no matter who made the lens and what camera or sensor its going to be paired with.  So what then is the difference between a crop sensor lens and a full frame lens?

The difference between full frame and crop sensor lenses is the size of the image circle created by the lens.  Lenses designed for smaller sensor cameras make smaller image circles than ones designed for full frame cameras.

What the crop sensor lens is projecting onto the crop sensor has the same scale as the full frame lens, but the extra “wasted” space of a larger image circle isn’t being transmitted.  They do this to make the lenses more affordable and lighter.  A smaller image circle means less glass, which means less materials, which means it’s cheaper and lighter.

Why I Think Crop Factor is a Mostly Useless Term

I hate it when people start talking about crop factor.  There, I said it.  Why?  Because it is a relative term that is a comparison of one camera with one type of sensor to another camera with another type of sensor.  It doesn’t tell you anything concrete about the camera that is right in front of you.  The information provided by the comparison is really only useful if you are familiar with the characteristics of one of the cameras.  For example, knowing that a 24mm lens on a crop sensor camera behaves like a 35mm lens on a full frame sensor doesn’t do you any good unless you know how a 35mm lens behaves on a full frame camera.  Personally I have spent much more time with crop sensor DSLR’s and Super35 camcorders than full frame cameras, so knowing the crop factor never really helped me out.  I can’t picture in my head what any given focal length looked like on a full frame camera because I don’t have the experience with that size of a sensor.

Why Angle of View is Better

Angle of view is an expression of how wide or narrow a field of view a given sensor has with a given lens.

There is an equation that is used to find the angle of view.

AoV = 2(ARCTAN(Sensor Width in mm/(2*Focal Length in mm)))

It’s not the easiest equation, at least for those of us that don’t do a lot of math all the time.  For example, based on my calculations, a 24mm lens on a Sony FS7 has a horizontal angle of view of 52.4 degrees.  And there it is.  I now know something about my camera and lens pair that is independent of any other camera system or lens.

But the good news is that once you figure out the angle of view for a camera, that’s it.  Or you could do what I did and make an Excel spreadsheet that has the equation programmed in so you can change focal lengths and sensor sizes as models change.  I also keep a copy on my Google drive so I can access it from anywhere.

The row in blue is the width of the sensors in mm, and the yellow column is a selection of different lens focal lengths.

In the chart you can see the difference between the sensor sizes and the affect they have on the angle of view.  You will also note that different camera manufacturers have slightly different specifications of Super35, with Canon being just slightly larger than Sony.

The beauty of angle of view is that once you know the angle for the camera and lens set you’re using, you can do away with a lot of the guess work around camera placement and lens choices.  You will be able to frame things up reasonably well without even turning the camera on.  For me this makes the process of choosing a camera placement and lens needed to create the shot I want much quicker and easier and I very rarely pick a lens and then decide I need to change it, because I am able to use the angle of view to get a good approximation of the shot ahead of time.

Don’t Completely Forget About Crop Factor

Crop factor CAN be useful information to have in some situations.  It will come in exceedingly handy when trying to match cameras with different sensor sizes.  For example, trying to match a Sony a7Sii with a Sony FS7.  Crop factor actually goes way beyond just affecting the focal length, it also applies to aperture, and can be used to set ISO numbers to achieve similar noise profiles.  It’s a quite complex subject, and I’ll let Chris Rule from ShinyEye Studio explain it in this video.  Jump back to the beginning if you want a really great explanation of depth of field, or watch from the 20 minute mark to see how to match cameras.

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Cinema lenses are lenses that all share certain characteristics.  They all have gears for follow focus and iris control, they have smooth or “declicked” apertures, they have uniform front diameters, and they are typically very fast.

We tested a full set of Canon CN-E lenses, a full set of Rokinon XEEN lenses, a selection of Zeiss CP.2 lenses, 6 Leica-R still lenses that have been converted into Cinema lenses by Duclos Lenses, and 3 Sony SLC lenses.

The Video

WHAT WE WANTED TO TEST

• Contrast
• Color
• Rack Focus
• Lens flare

The Results

For the most part, all of the lenses performed about the same in all categories.  The four modern cinema lenses all behaved similarly for contrast, with the Leica-R’s being a little bit more contrasty, which is not unexpected from vintage lenses.  We were slightly surprised at how little difference we saw in the color between the different brands.  We expected to see more of the “character” of each manufacturer in evidence, but saw little actual variation.  The focus rack tests yielded only one interesting difference between the lenses.  The Sony SLC lenses showed no breathing at all when focusing between the subject and the color chart, all the others had some amount of breathing, although it was very small compared to non-cinema lenses.  The lens flare test yielded the greatest variety of results from the lens, with each set having a different color cast to the flare and different artifacts and bleed amounts.

These tests were done mostly just to see the different lenses side by side in a controlled environment, not to rate or grade them against eachother to determine which is the best.  All of them produce excellent images at a reasonable price.

WHAT WE DID NOT TEST

• Bokeh
• Minimal focus
• Maximum aperture

We felt that to perform these tests would have required too many additional setups with each lens and ballooned an already long test beyond what most people are willing to invest in.  We may come back in the future and run these tests on our selection of lenses.

You can find videos for each set of lenses, and a video for just the side by side comparisons by following the links below.

• Canon CN-E
• Rokinon XEEN
• Zeiss CP.2
• Sony SLC
• Leica-R
• Side by Sides

ABOUT EACH SET OF LENSES

Canon CN-E

Pretty standard as far as cinema lenses go.  The set includes; 14mm T3.1, 24mm T1.5, 35mm T1.5, 50mm T1.3, 85mm T1.3, and 135mm T2.2 lenses.  They range in price from $4,950-$5,220 each before any rebates or discounts.  Z Systems rental price is $65/day each or $325/day for the full set.

Pros:

• Speed
• Uniform gears
• Color matched coatings
• Minimal breathing
• Full frame coverage

Cons:

• EF-mount only
• Price

Uniques:

• Hyper accurate focus marks

Rokinon XEEN

Another standard set of cinema lenses.  The set includes; 14mm T3.1, 24mm T1.5, 35mm T1.5, 50mm T1.5, 85mm T1.5, and 135mm T2.2 lenses.  The lenses are all $2,495 each.  Z Systems rental price is $45/day each or $225/day for the full set.

Pros:

• Speed
• Uniform gears
• Color matched coatings
• Minimal Breathing
• Full frame coverage
• Uniform length (except 14mm)
• Price
• Available in a wide variety of mounts

Cons:

• None

Uniques:

• None

Zeiss CP.2

Another fairly standard set of cinema lenses.  The set we tested includes; 21mm T2.9, 35mm T1.5, 50mm T1.5, 85mm T1.5, and 135mm T2.1 lenses.  The lenses range in price from $3,990-$5700 each.  Z Systems rental price is $65/day each or $300/day for the set of 5.

Pros:

• Uniform gears
• Color matched coatings
• Minimal Breathing
• Full frame coverage
• Available in a wide variety of mounts

Cons:

• Price
• Not uniform length

Uniques:

• Customer changeable lens mounts

Sony SLC

These lenses were originally offered in a kit with the Sony PMW-F3 camera.  They have since been replaced by a more complete line of Sony Cine Alta lenses with improved housings.  The set we tested includes; 35mm T2, 50mm T2, 85mm T2.  The lenses we tested are no longer available for purchase, but the new Cine Alta lenses are available as a set of 6 for $12,499.  Z Systems rental price on the lenses we tested is $65/day each or $150/day for the set of 3.

Pros:

• Uniform gears
• Color matched coatings
• No focus breathing
• Uniform speed

Cons:

• Super35 Coverage
• Size
• Only available as a set

Uniques:

• None

Leica-R Duclos Conversions

These lenses are a bit different than the others we tested.  They were originally still lenses for Leica cameras that have been converted for cinema use.  The conversion includes the addition of cinema gears to the focus rings of the declicking of the iris’.  The set we tested also has uniform filter thread adapters and has been permanently converted to EF mount.  We tested 6 of the 9 lenses in our set, the ones we tested were; 19mm f/2.8, 21mm f/4, 35mm f/1.4, 50mm f/1.4, 80mm f/1.4, and 100mm f/2.8.  As these are custom converted lenses there is no purchase price available.  Z Systems rental price on the lenses is $30-$35/day each or $275/day for the set of 9 lenses.

Pros:

• Large number of lenses
• Vintage character
• Full frame coverage
• Size
• Weight

Cons:

• Little uniformity
• Not color matched
• Purchase/Conversion price

Uniques:

• None

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Canon COMPACT-SERVO 18-80 observations

1. We liked it – it is lightweight and the images looked very good.  Breathing was almost zero.
2. It shares the optical coatings of Canon’s higher end Cine zoom and prime lenses, so it looks ‘warmer’ than the DSLR lenses.  It is meant to match the other Cine lens’ look.
3. It gets power just fine via the appropriate Metabones adapter – no extra cables required.
4. Any control of the iris from the camera body does not work – you have to use the iris ring on the lens.
5. Iris metadata reported back to the cameras is inaccurate.
6. The start/stop button on the optional servo zoom controller did not trigger recording on any of the cameras.
7. With the FS5 and the FS7, it is a little awkward and weird to have two servo handgrip controllers – the one that comes with the camera, and the one for the lens.  The servo controller on the camera did not control the zoom on the lens.
8. The servo zoom rocker is a little ‘heavy handed’ – not as precise of a feel as the servo zoom rocker on the more expensive lenses.
9. The rosette mounting of the optional servo zoom controller was a nice touch – it is very easy to relocate it to a handle on a rig or even to the camera.

Other details

Canon said that while the lens is based on the 18-80 DSLR lens, it is rather reworked – inside and out:

• external geared barrels
• extra optical elements in the rear to get it from full frame to Super 35 mm footprint
• Cine optical coatings to match their Cine lens line – hence the telltale red mounting ring in the back.

Photos of the lens in action

More features and specifications

Accessory hand grip

	Canon COMPACT-SERVO 18-80mm T4.4 EF-mount lens $5,225.00
	Canon ZSG-C10 Zoom Grip for COMPACT-SERVO Lens $474.05

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ZEISS has announced that they will be reintroducing their 0% financing program for all Compact Prime, Compact Zoom, and Otus lens bundles.

Here is the official announcement from Zeiss:

We are delighted to reintroduce our ZEISS Cine Lens Finance Program giving you access to our entire range of ZEISS Compact Prime CP.2, CZ.2 Zooms and Otus Lens Bundles.

Finance the purchase at 0% over 12-months with no money down for a 3, 4, 5, 6 or 7 lens ZEISS Compact Prime CP.2 set, the ZEISS Compact Zoom CZ.2 lenses or Otus 2 or 3 set lens bundles. This program is available to you when purchasing from an authorized and qualified ZEISS Dealer. Qualifying CP.2 and CZ.2 lenses include the PL, EF, F, MFT and E mount versions as well as applicable accessories.

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Click here to to PRE-ORDER the Canon COMPACT-SERVO 18-80mm T4.4 EF-mount lens

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Zeiss has recently started shipping the third lens in its Loxia series, the Loxia 2.8/21. It’s a compact, super-wide angle MF lens designed for the Sony FE camera system. The lens introduces a new optical design specially developed for high resolution, full-frame sensors such as the one used in the Sony Alpha A7S II. Like the Loxia 35 and Loxia 50, the new lens is also well suited for video applications using cameras like the Sony PXW-FS5 and PXW-FS7.

The latest member of the ZEISS Loxia family is called ZEISS Loxia 2.8/21. It is a super wide angle, developed for compact full-frame cameras with E-mount and with a new optical design based on the ZEISS Distagon. The ZEISS Loxia 2.8/21 supplements the ZEISS Loxia 2/35 and ZEISS Loxia 2/50 lenses, which were presented last year at photokina. Especially practical for cinematographers, the ZEISS Loxia 2.8/21 has the mechanical aperture setting and the de-activation of the aperture click stop, both found on all ZEISS Loxia lenses.

“Since the Sony α7 series came out, the market has been waiting for a powerful super wide-angle lens for compact full-frame cameras. For many photographers such a lens was the missing tool in their gear. ZEISS is now meeting that demand with the ZEISS Loxia 2.8/21,” said Christophe Casenave, Product Manager at ZEISS Camera Lenses.

As the latest member in the compact, light-weight family of ZEISS Loxia lenses, the ZEISS Loxia 2.8/21 offers trusted features that combine traditional photography and modern technology. The electronic interface transmits lens data (EXIF) as well as the focus movements and – if desired by the photographer – activates the magnifying function of the camera. For the sophisticated photographer who does not want to leave all the work to the camera, there are many opportunities to compose thanks to the lens’s precise manual focusing with end stop and the mechanical setting of the aperture (a perture priority mode for the working aperture). As a result, photographers can take advantage of all the possibilities offered by modern compact system cameras with an electronic viewfinder.

Optimal for different types of use

With an angular field exceeding 91 degrees (diagonal) on a full-frame camera, the ZEISS Loxia 2.8/21 is well suited for nature, landscape and architectural photography. In landscape photography in particular, an exact infinity setting is a critical factor. Here, the precise manual focusing of the ZEISS Loxia 2.8/21 supports the user enormously. Furthermore, the lens enables creative, naturally proportioned images with a low minimum object distance of just 0.25 meters (9.84”). The ZEISS Loxia 2.8/21 is extremely compact and light, making it the perfect choice for travel and street photography.

ZEISS Loxia lenses for video

Ambitious videographers will also discover once again that the ZEISS Loxia 2.8/21 is a tool that offers optimum creative potential. The mechanical deactivation of the aperture click stop for infinite aperture settings (de-click), which already came with the ZEISS Loxia 2/35 and ZEISS Loxia 2/50, is also found in the new ZEISS Loxia super wide angle. The smooth focus operation with a rotation angle of 90 degrees of the ZEISS Loxia 2.8/21 allows for the finest variations when focusing video cameras with E-mount, such as the Sony PXW-FS7 or PXW-FS5. “In addition, the identical external diameter of the ZEISS Loxia lenses across all focal lengths simplifies the changing of lenses during shoots, so accessories like a follow focus don’t need to be readjusted,” added Casenave.

Newest optical design with robust construction

The ZEISS Loxia 2.8/21 has been specially developed for digital sensors. The newly calculated lenses consist of 11 lens elements in nine groups. The underlying optical design is a ZEISS Distagon. High resolution along the entire image field, low distortion and color fringing, and an appealing bokeh – especially at the maximum aperture of f/2.8 – round out the exceptional features of this lens. “It’s a small jewel offering outstanding optical performance,” said Casenave, summarizing the optical qualities of the ZEISS Loxia 2.8/21. Other qualities include its impressive mechanical quality and robust barrel. Made entirely of metal, the barrel protects the lens and can withstand the rugged everyday situations that professional photographers face, thereby ensuring a long product life. Like the other ZEISS Loxia lenses, the filter diameter is 52 mm. Finally, a special weather protection on the lens mount protects the lens from spray getting between the camera and lens.

Product Overview

Technical Specifications

Click here to download/view the brochure (PDF)

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