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Bill ONeil
Focal length doubling
on Oct 4, 2011 at 2:37:44 pm

Is there a workaround to the focal length doubling that occurs when attaching 35mm lenses to the Micro 4/3" mount? Someone told me that the new NovoFlex adaptor moves the lens further from the camera allowing it to maintain its focal length. I have a bunch of fast Nikon primes and am looking at purchasing the AF-100, but doubling the focal lengths would be a deal-breaker. Thanks!

Bill O'Neil


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John Fishback
Re: Focal length doubling
on Oct 4, 2011 at 10:32:20 pm

Our NovoFlex Nikon adaptor "doubles the focal length"as expected. We've had it about 6 months, so maybe there's a new version. BTW, old Nikon glass looks great connected to the AF100.

John

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Erik Naso
Re: Focal length doubling
on Oct 5, 2011 at 5:51:14 pm

The MFT sensor is smaller than a full frame 35mm DSLR sensor by about half, so all lenses that are 35mm will have a smaller field of view. The AF100 sensor only sees the center of a 35mm lens thus making a 25mm more like a 50mm. Remember is not magnified. It just a smaller sensor. I don't know of any adapters that can change the field of view. This is the same for Canon 7D and Nikon DSLR's that have smaller sensors than a full frame 35mm like the Canon 5D.

Make sense?

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Bill ONeil
Re: Focal length doubling
on Oct 5, 2011 at 6:14:11 pm

Yes, I understand all of this. I had just heard from a guy that the new adaptor moves the lens further from the sensor, thus making it more true to the original focal length. He must have erred in his claim or he was mistakenly referring to a Micro 4/3 lenses.


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Jason Jenkins
Re: Focal length doubling
on Oct 6, 2011 at 4:28:07 am

[Bill ONeil] "I had just heard from a guy that the new adaptor moves the lens further from the sensor, thus making it more true to the original focal length."

That can't be right. If the distance between the lens and the sensor isn't exactly right, the barrel markings will be off and you'll lose the ability to focus at infinity.

Jason Jenkins
Flowmotion Media
Video production... with style!


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Guy McLoughlin
Re: Focal length doubling
on Oct 6, 2011 at 2:54:15 pm

...You have to STOP thinking about lenses in terms of a 35mm Full Frame Still Photo camera, because it makes no sense for other formats, especially when looking at film and video formats.

A 165mm Super-Angulon Lens is an Ultra-Wide lens on an 8x10 inch large format camera, and a medium telephoto on a 35mm Full Frame camera.

The Micro 4/3 format is very close to the size of the standard 35mm Motion Picture format, so you should be thinking of Micro 4/3 lenses the same way you would when using a 35mm Motion Picture camera.

AbelCine has a very good interactive FOV tool that helps to understand the relationship between lens focal lengths and camera formats.

Abel Cine FOV Tool


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Noah Kadner
Re: Focal length doubling
on Oct 10, 2011 at 5:26:05 am

Yeah I mean it's a crop. Sure you don't get the same FOV as you would on the same lens with a full frame sensor or 35mm film. But that's simple physics. All it means is if you want a specific perspective you need to recalibrate mentally which lens can deliver it than you might be used to coming from 35mm. But there's no way to trick around it.

Noah

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Featuring the Panasonic GH2 and GoPro HD Hero.


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Bill ONeil
Re: Focal length doubling
on Oct 10, 2011 at 12:43:06 pm

The widest Nikon I have is 28mm so I would have to purchase a micro 4/3" wide lens to be covered.

Hmmm, Maybe I'll just purchase the new AG-HPX250 10 bit P2 camera and use my brevis 35mm adaptor for the shallow DOF stuff.

I wish Panasonic would create a 10 bit, 35mm large sensor camera that records to P2.


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Guy McLoughlin
Re: Focal length doubling
on Oct 10, 2011 at 4:38:28 pm

>>>The widest Nikon I have is 28mm so I would have to purchase a micro 4/3" wide lens to be covered.

A Nikon 28mm on the AF100 will produce a FOV that is very similar to a 55mm lens on a Full Frame Still Photo camera, so this focal length is more of a "normal" lens for the AF100 camera. If you want something wide, then you would be looking for a lens in the range of 17mm - 7mm. ( Olympus and Panasonic have a few lenses in this range )

>>>Maybe I'll just purchase the new AG-HPX250 10 bit P2 camera and use my brevis 35mm adaptor for the shallow DOF stuff.

It looks like a great camera, but DOF adapters are a huge step backwards from a technology / production perspective. The are very "slow" exposure wise ( you lose 1-2 stops right off the bat ), you have be be very careful about back-focus issues ( or your image is not sharp ), they weigh more than your camera package does ( very clunky to work with ), and you have to keep them juiced up with power to use them. ( more batteries to take care of )

>>>I wish Panasonic would create a 10 bit, 35mm large sensor camera that records to P2.

I expect to see a 10-bit 4:2:2 version of the AF-100 next year, but you will never see Panasonic produce a camera with the 35mm Still Photo Format, as it's not a good format for video. 35mm FF is too large, which means it's too shallow DOF, which means you have to stop down 2 extra stops to achieve the same DOF as a Micro 4/3 camera. Not a problem outdoors during the day, but it's a big issue when shooting indoors. With a Micro 4/3 camera you might light a set with a total of 4,000 watts of light, with a 35mm FF camera you would need 16,000 watts of light to achieve the same DOF.


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Bill ONeil
Re: Focal length doubling
on Oct 10, 2011 at 7:39:25 pm

Thanks Guy. That's good information. Actually, the Brevis 35mm adaptor only loses about a 1/2 stop with the flip module, plus the charge will last all day for the oscillating image plate. It is a bit of a hassle but it's almost second nature to me after using it for the past few years on my HVX-200.


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Guy McLoughlin
Re: Focal length doubling
on Oct 11, 2011 at 1:05:08 pm

>>>Actually, the Brevis 35mm adaptor only loses about a 1/2 stop with the flip module

Sounds like DOF adapters have improved a lot. 1/2 a stop is hardly noticeable.

...But if the ground glass image is still Full Frame 35mm Photo format ( which is the reason why you would use a DOF adapter ), then you still have to stop down 2 additional F-stops to equal the DOF of the Micro 4/3 format. ( so you have the same 4,000 watts of light versus 16,000 watts of light issue that Full Frame 35mm photo cameras like the Canon 5DMk2 face )


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Bill ONeil
Re: Focal length doubling
on Oct 11, 2011 at 3:14:19 pm

I had never heard of the Micro 4/3 lens format until the AF-100 arrived. 35mm lenses have always been a standard and I have acquired a nice collection of Nikons over the years . I also own a Canon 17-55mm 2.8 and a 50mm 1.4 for my Canon 7D.

It sounds like it's best to just purchase some fast Micro 4/3 lenses to get the most out of the AF-100 while requiring less light.


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Guy McLoughlin
Re: Focal length doubling
on Oct 11, 2011 at 5:14:38 pm

The 4/3 format and later the Micro 4/3 format was originally created by Olympus and Kodak almost 10 years ago.

The 35mm Still Photo format has been around since the first Leica cameras, but people need to realize that the 35mm Still Photo format is very different than the 35mm Motion Picture formats.

There aren't many great Micro 4/3 lenses around, but the are slowly trickling in with very big deal lenses coming next year. ( the 12-35mm Panasonic Fast Zoom is the one I am watching )

Nikon AI-S manual lenses are the ones I would recommend for AF-100 / GH-2 video production, as they are cheap, have manual apertures, and smooth focusing.

The Nikon 17-55mm AF Zoom is currently one of the best lenses for the AF-100, but it requires a special Nikon G mount adapter in order to control the aperture.

And for wide angles lenses, you have to go Micro 4/3 because regular 35mm still photo lenses don't have very short focal lengths. ( the Olympus 12mm f/2.0 and the Panasonic 7-14mm f/4.0 zoom are two top choices )


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Guy McLoughlin
Re: Focal length doubling
on Oct 10, 2011 at 4:22:43 pm

>>>Yeah I mean it's a crop. Sure you don't get the same FOV as you would on the same lens with a full frame sensor or 35mm film.

...But then every format is either a crop or enlargement compared to a different format. The 35mm Full Frame Still Photo format is a huge crop when compared to a 4x5 inch large format camera.

People coming from still photo background tend to get brainwashed on the 35mm Full Frame Still Photo format being the norm, when it is nothing like the norm for video or motion picture formats.

We have to start thinking in terms of FOV ( field of view ) where it doesn't matter what lens or format you shoot with, it's the FOV and DOF ( depth of field ) that create much of the "look" that we are after.


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Erik Naso
Re: Focal length doubling
on Oct 11, 2011 at 6:31:26 pm

Large sensor video cameras are still relatively new in the market place. 35mm SLR has been around for a long time and we have lots of great glass to use. Who knows what the next sensor will be. S35 seems to be the big deal now. In time I hope lens manufactures will make more specialized zooms for large sensor video cameras. That is what is missing in a big way. If I could turn my AF-100 into a ENG camera look out! Wouldn't that be great!. I have seen the 2/3rd B4 lens mod and it looks interesting but you have to have a doubler to not vignette and the lenses are designed for 3 Chips not a single sensor. It will happen but who nows when............

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