GH5 What exactly does the Extra Tele Conversion do when used on a GH5?

A

analogs

Well-known member
Does anyone know exactly how it adds more reach to your lenses?

Is there a quality difference?

How much extension does it add? eg. 1.4 X 400mm when a 70-200mm is used set at 200mm end on a GH5?

Is it comparable to a native lens at that focal length or is the quality loss bad?

Thanks.
 
If you are in a 1080p mode, it usually uses a downscaled 20MP image to output 1080p. With the Extended Tele Converter enabled, it goes to 1:1 pixel mode to effectively zoom in to your image. There is a loss in quality, as you now lose down-sampling. I don't own the GH5, so I can't comment on how much the quality is affected, but I have used it on my GH5S, but the tele-focal effect is minimal since it's only a 10MP sensor to begin with.
 
The Extra Tele Conversion (ETC) mode is a sensor crop. Since the GH5 has a 5K sensor, 4K recording is done by downsampling the full sensor area. In ETC mode, the camera instead does a crop of a 4K region of the center of the sensor. This allows for a 1.4x extender in terms of angle of view (so a 200mm lens would give you the angle of view of a 280mm lens). If shooting HD, you can crop an even smaller region from the center of the sensor allowing a 2.7x extender in terms of angle of view.

In terms of image quality, with a sensor crop using a 1-to-1 pixel readout, you lose the benefits of downsampling. So taking a 5K image and scaling it down to 4K usually improves the sharpness and reduces noise (if the scaling is done well). Which means that in ETC mode, the image may be a bit noisier and softer than it would from the full sensor output. In 4K ETC mode, the difference may not be that significant, but probably becomes more noticeable in HD ETC mode which has a more significant crop.

One other thing to be aware of, is that since the ETC mode effectively decreases the sensor size, it also has an effect on the apparent depth of field (compared to changing lenses). So in 4K ETC mode, instead of shooting on a Micro 4/3 sensor, now it's more like you are shooting on a 1-inch sensor. So while the field of view of of a 200mm lens in 4K ETC mode would be similar to a 280mm lens, the depth of field will not be as shallow as if you had an actual 280mm lens (of the same aperture) shooting the full Micro 4/3 sensor area.

This article may also be useful as it compares the image quality of the different ETC modes:
https://www.newsshooter.com/2017/03/28/gh5-extra-tele-conversion/
 
davedv said:
The Extra Tele Conversion (ETC) mode is a sensor crop. Since the GH5 has a 5K sensor, 4K recording is done by downsampling the full sensor area. In ETC mode, the camera instead does a crop of a 4K region of the center of the sensor. This allows for a 1.4x extender in terms of angle of view (so a 200mm lens would give you the angle of view of a 280mm lens). If shooting HD, you can crop an even smaller region from the center of the sensor allowing a 2.7x extender in terms of angle of view.

In terms of image quality, with a sensor crop using a 1-to-1 pixel readout, you lose the benefits of downsampling. So taking a 5K image and scaling it down to 4K usually improves the sharpness and reduces noise (if the scaling is done well). Which means that in ETC mode, the image may be a bit noisier and softer than it would from the full sensor output. In 4K ETC mode, the difference may not be that significant, but probably becomes more noticeable in HD ETC mode which has a more significant crop.

One other thing to be aware of, is that since the ETC mode effectively decreases the sensor size, it also has an effect on the apparent depth of field (compared to changing lenses). So in 4K ETC mode, instead of shooting on a Micro 4/3 sensor, now it's more like you are shooting on a 1-inch sensor. So while the field of view of of a 200mm lens in 4K ETC mode would be similar to a 280mm lens, the depth of field will not be as shallow as if you had an actual 280mm lens (of the same aperture) shooting the full Micro 4/3 sensor area.

This article may also be useful as it compares the image quality of the different ETC modes:
https://www.newsshooter.com/2017/03/28/gh5-extra-tele-conversion/
Click to expand...

Thanks for the reply everyone.

So, a 200mm lens with a dumb adaptor would make it 400mm, so with ECT, that would make it 560mm(1.4 ext) but in HD would make it 1080mm?
If I was to use a 0.71 focal reducer, my 200mm would become 280mm, so with ECT(2.7 ext), that would make it 756mm if shooting in HD?

Is that right??
 
flinty said:
Well i use Etc most of the time on my GH5 for wildlife and find no quality loss,even 2x digital with a good lens is useable.The longest shot here 3360mm 35mm equivalent.
Click to expand...

I'm the same way. I use ETC all the time for wildlife shots and I can't tell the difference between being in and out of ETC mode. When I really need reach, I go to HD resolution and take advantage of the greater magnification. I upload to a couple stock sites, so it's better to have an HD close-up of a bird bathing in a stream than a 4K medium shot of a bird bathing in a stream.

Bob
 
BobKo said:
I'm the same way. I use ETC all the time for wildlife shots and I can't tell the difference between being in and out of ETC mode. When I really need reach, I go to HD resolution and take advantage of the greater magnification. I upload to a couple stock sites, so it's better to have an HD close-up of a bird bathing in a stream than a 4K medium shot of a bird bathing in a stream.

Bob
Click to expand...
Yes 100% agree,i dont use HD though as the 3000mm plus my kit gives is enough for me,its why i have stayed with the micro four third format.
https://www.youtube.com/watch?v=fpNr82s2lR0
 
I use the GH5 and ETC on a 75-300mm lens for wildlife. I can't see any degradation other than atmospheric induced from working with such a long lens. Here is a sample.

 
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What adaptor are you all using by the way? Metabones, Viltrox...

Is it a smart adaptor or focal reducer?

Thanks.
 
analogs said:
What adaptor are you all using by the way? Metabones, Viltrox...
Click to expand...

I'm not using any adapter... just straight Panasonic lenses. The lens I use most often is Panasonic's 14-140, the Type-II version. For really long reach, I have Panasonic's 100-300 lens. With ETC turned on, that is the equivalent of a 780mm lens in 4K and a 1620mm lens in HD. Again, all used without adapters.

Bob
 
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