Using Speedboosters on Fullframe Cameras


This post is by BastianK from phillipreeve.net

Introduction

Zhong Yi LensTurboII and Nikon AF 85mm 1.4D via Pixco Speedbooster on Sony A7rII

Speedboosters are still somewhat popular among videographers, but since these days used fullframe cameras are very affordable, this is not really the case for still photographers anymore. They can be used for some creative shallow depth of field photography on fullframe cameras though, and that is what we will have a look at here.

Sample Pictures

Sony A7r | Zhong Yi LensTurbo II | Canon nFD 85mm 1.2L | ©Simeon Kolev

Sony A7r | Zhong Yi LensTurbo II | Samyang 35mm 1.4 | ©Simeon Kolev
Sony A7r | Zhong Yi LensTurbo II | Zenitar 50mm 1.7 | ©Simeon Kolev
Sony A7r | Zhong Yi LensTurbo II | Zenitar 50mm 1.7 | ©Simeon Kolev

What is a Speedbooster?

A Speedbooster is the opposite of a Teleconverter. Teleconverters have a factor bigger than one (most common are 1.4 and 2.0). They give you more reach at the cost of speed and they also degrade the lens’ image quality, as they will magnify the image, they also magnify all the aberrations.

Speedbosters on the other hand have a factor smaller than one (for example 0.71 or 0.73). They give you a wider field of view and at the same time they improve the lens’ maximum aperture. As the image will be compressed, the image quality of the lens theoretically even improves. Sounds too good to be true? Yes, because there is one more thing: as the image will be compressed, it will not cover the same area as before anymore. Therefore Speedboosters have originally been developed to negate the crop factor of APS-C sensors, so that fullframe (D)SLR lenses can be used on APS-C mirrorless cameras to their full extent.

This was very useful before we had affordable fullframe mirrorless cameras. Nowadays these Speedboosters are not really needed anymore for still photography – unless you are a Fuji X user and stuck with APS-C sensors.

Nikon AF 85mm 1.4D

The Nikon AF 85mm 1.4D is a fullframe lens. Used on a Sony APS-C camera it will give the same field of view and depth of field as a 128mm f/2.1 lens – thanks to the 1.5x crop factor. Using the Zhong Yi Lensturbo II (factor 0.73x) turns this 85mm 1.4 into a 62mm f/1.0 lens. Used on an APS-C camera with 1.5x crop factor we end up with a fullframe equivalent of a 93mm f/1.5 lens. Not exactly the same as an 85mm 1.4, but pretty close.

Why use it on a fullframe camera?

Now what happens when using Speedboosters on a fullframe camera? Generally neither the Speedbooster nor the fullframe lenses have an image circle big enough for that compressed image to still be big enough to cover the whole fullframe area, so you end up with black corners like here:

Nikon AF 85mm 1.4D

However, when cropping out the black corners – depending on the lens used – you may still end up with a wider framing. If you are a fan of wide formats (like I am), the gain in field of view is very small. However, if you often find yourself cropping to 4:3, 5:3 or even 1:1, the situation might be different:

Pixco Speedboosster | Nikon AF 85mm 1.4D

As you can see above, using the lens together with a Speedbooster and then cropping to 1:1 actually gives a much wider field of view compared to using the lens alone and cropping that to 1:1.

Sony A7r | Zhong Yi LensTurbo II | Canon nFD 50mm 1.2L | ©Simeon Kolev

I bought a Nikon-F to Sony-E Zhong Yi Lensturbo II and a Pixco Speedbooster and tried a bunch of F-mount lenses with them and noted in the following tables how much wider the coverage is for different aspect ratios. As you can see, this is highly dependant on the lenses used. I also wrote down what fictional fullframe lens you would need to get the same field of view and depth of field without a Speedbooster.

Sony A7III | Zhong Yi LensTurbo II | Nikon AF 85mm 1.4D

Zhong Yi Lens Turbo II

Zhong Yi LensTurboII

The Zhong Yi LensTurbo II has in my opinion the better image quality of the two adapters tested here. It gives a flatter field and better off center sharpness than the Pixco.

However, its mechanical design is “interesting”. The APS-C E-mount cameras feature some light baffles around the sensor, that combined with the protruding rear element of this adapter leads to the E-mount version having an interestingly cut rear element.

These cut outs don’t really lead to a smaller image circle compared to the Pixco, but bokeh highlights might be cut at the top or bottom by this.

Because of that unusual shape of the rear element the locking mechanism is also a bit weird, as you have to rotate a ring to lock the adapter on camera. Interestingly the adapter didn’t properly fit on my A7rII, but did on the A7III…

I also tried this adapter with the Nikon AF 180mm 2.8D and the Nikon 200mm 2.0 IF-ED. With these stronger lenses there was almost no additional field of view, therefore I did not include them in the tables.

Pixco Speedbooster

Pixco Speedbooster

This Pixco does not have any mechanical oddities, it works just like a normal adapter.

As you can see the Pixco Speedbooster gives a slightly wider field of view, it does create more distortion and also adds unfavourable field curvature though.

The 44x33mm “medium format” digital sensors have a vertical crop factor of 0.73 compared to fullframe (horizontally it is less, only 0.82). So some of these lenses in combination with a Speedbooster do come close to that, so if you fancy a 4:3 aspect ratio to begin with, one of these Speedboosters might be something for you.

Conclusion

Now obviously using these Speedboosters with (D)SLR fullframe lenses on fullframe mirrorless cameras is not something for everyone, but rather for the tinkerers among you.

When you are a portrait photographer and you often find yourself cropping to less wide aspect ratios, this solution might be worth a closer look though. Turning an 85mm 1.4 into a 70mm 1.1 equivalent gives a pretty cool look, that can otherwise not be easily achieved.

Sony A7r | Zhong Yi LensTurbo II | Canon nFD 85mm 1.2L | ©Simeon Kolev

Also keep in mind I only had a look at a fraction of the possibilities here. I wonder what a Sigma 50mm 1.4 EX would look like in combination with a Speedbooster. Or a Sigma 40mm 1.4 Art or Zeiss Otus 55mm 1.4, which are said to cover a bigger image circle to begin with. And then these adapters are available for plenty of different camera systems.

My friend Simeon has taken some amazing pictures with the Canon nFD 85mm 1.2L on a modified Zhong Yi Lensturbo II. His pictures are the main reason I decided to have a closer look at this option and to share it with you. He allowed me to use some of his pictures which you can find throughout this article.

Zhong Yi Lens Turbo II
buy from ebay.com | ebay.de | B&H (affiliate links) 

Pixco Speedbooster
buy from ebay.com | ebay.de | amazon.com | amazon.de (affiliate links)

Metabones Speedbooster
buy from ebay.com | ebay.de | amazon.com | amazon.de | B&H (affiliate links)

Sample Images

Sony A7r | Zhong Yi LensTurbo II | Samyang 35mm 1.4 | ©Simeon Kolev
Sony A7r | Zhong Yi LensTurbo II | Canon nFD 85mm 1.2L | ©Simeon Kolev
Sony A7r | Zhong Yi LensTurbo II | Canon nFD 85mm 1.2L | ©Simeon Kolev
Sony A7r | Zhong Yi LensTurbo II | Samyang 35mm 1.4 | ©Simeon Kolev
Sony A7III | Zhong Yi LensTurbo II | Nikon AF 85mm 1.4D

Further Reading

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