GH4 I purchased a GH4 after realizing that the FF advantage is a myth

J

jcs

Veteran
The Northrup video got me thinking about the following math to match a crop sensor to an FF sensor camera (this was also helpful: http://www.josephjamesphotography.com/equivalence/#introduction ):

• Multiply the focal length by the crop factor
• Multiply the f-stop by the crop factor
• Divide the ISO by the square of the crop factor
The first two equations deal with the difference in scale. The physical aperture (light opening, "entrance pupil") will be exactly the same:

Given:

f-stop = focal-length/aperture-diameter
aperture-diameter = focal-length/f-stop

GH4 Lens: 25mm f2.8
5D3 Lens: 50mm f5.6

GH4 aperture-diameter = 25mm/2.8 = 8.93mm
5D3 aperture-diameter = 50/5.6 = 8.93mm

Thus, the aperture diameter or entrance pupil will let in exactly the same amount of light. The 5D3 sensor has a focal length that is 2x farther from the entrance pupil, and since the sensor is 2x bigger, it captures the larger projection of exactly the same amount of photons. Since we've spread the projection of photons out with a 2x larger area, the sensels will get 2*2 (area) = 4 times less light than a 2x crop sensor. So, we have to boost sensor gain 4x to match the crop sensor. Now, if due to manufacturing or technology advantages the full frame sensor is more sensitive per sensel vs. the crop sensor, then a 4x gain boost to match cameras won't be accurate. FOV and DOF will be exactly the same regardless of sensor technologies. The only differences will be sensitivity, noise, and color characteristics.

After starting with a 5D Mark II, then going to a 5D Mark III, then adding a FS700+SpeedBooster, I began to suspect that there was nothing inherently special about FF. After reading about and understanding this math and physics, it's clear that there is no mathematical or physics-based advantage (in terms of light and photons) to FF over smaller sensors. Only when a larger sensor can be made more sensitive, less noisy, and/or provide improved color processing can a FF sensor perform better than a crop sensor.

The main reason the 5D2/5D3 became so popular was due to Canon's superior color processing. The 5D3's softness combined with low aliasing and excellent color processing for skin tones helped make it very popular as that is similar behavior to film. The ARRI Alexa has the best color processing and until the Dragon was released, the most dynamic range (not clear yet if the Dragon has matched or passed the Alexa, however it does an excellent job with skintones).

If we consider the SpeedBooster, using the same lens on both cameras, so the entrance pupil is the same size and the focal length is the same, then we'll have exactly the same FOV and DOF when the focal reducer shrinks the image circle down to the crop sensor. This means the f-stop is not changed, just the t-stop (the SpeedBooster for Canon EF to NEX is really a 1.1 crop, however the bokeh was nearly the same in testing between the 5D3 and FS700 with the 24-105mm F4L lens). This is one case where the smaller sensor has an advantage: since we're shrinking the photon projection area, we are increasing the amount of light to the sensor (thus gaining the ~1 stop of light increase in the EF to NEX case).

A current market advantage for FF over 2x crop is that there are more fast lenses for FF. We had to get a Voigtlander 25mm F.95 to come close to a 50mm F1.4 on FF. We'd need a 25mm F.7 to match the 50mm F1.4's entrance pupil size and thus bokeh. To match the 50mm 1.2, we'd need a 25mm F.6! Other than available/affordable lens choices, sensor technologies and color science, there's no mathematical or physical advantage to FF over crop sensor cameras. The noise characteristics of the GH4 are finer and nicer than the 5D3 and FS700 in low-light testing so far. The detail captured by the GH4 exceeds the FS700 (and slightly passes the C100/C300 (for 4K downsampled to 1080p)). 5D3 RAW still has the nicest skintones, however we're still learning to use the GH4. Understanding that there's nothing magical about FF got me more interested in giving a 2x crop sensor camera a try- so far the quality is impressive.
 
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The big advantage for FF to me is stills more than video, where super shallow DOF, superior IQ and DR make for better portraits and landscape shots, along with better print capabilities. The look of my Sigma 85 1.4 or Nikon 105 1.8 can't be matched in M43 land, same goes for something more exotic like a 200mm 1.8 - IMHO the most amazing portrait lens money can buy, I just wish my shooting could justify the investment.

When shooting FF video, I rarely shoot my 1.2's and 1.4's wide open because nailing focus is so tough, but there is a look that again can't be replicated in M43 land, even with a speedbooster. My GH4 arrives today, looking forward to comparing it to my A6000 and A7, and soon the A7s when it starts shipping. I'm going all fast Nikors, using dumb adapters and soon a speedbooster on the GH4. Rather than investing in large amounts glass for each system, I'm using a few different bodies with one set of lenses.

All the arguments over sensor size are really played, as mentioned pick the right tool for the job. It's nice to have so many options.
 
Technically correct - it is a myth.

In reality - consider a full-frame 20/2.8 available for $250, match that DOF and FOV on a smaller chip?.. The lens is gonna cost and worse it is gonna be a plastic fantastic lens..

S
 
My experience with Full Frame:

Back when 5D Mark II was all the rage I had been using the GH2 but decided to get a 5D Mark II to see for myself how much better it was. For photos it was awesome. For video I was greatly disappointed. I was used to the sharpness of the GH2 and the 5D Mark II seemed ULTRA soft - almost to the point of looking out of focus when it was supposed to be in focus. I went right back to the GH2. (by the way I was using high end L glass with the camera so it wasn't the glass)

When I look at things with my own eyes - whatever I am looking at is sharp and in crisp focus - like the GH2 was and my current GH4 is. You wouldn't walk around with "blur" glasses on all the time to intentionally make things look blurry or soft and that's how I thought about the 5D Mark II after using it (by the way its the same with the 5D Mark III as well). You can always soften an image (if for whatever reason you wanted to do that) without degrading the image but when you sharpen an image in post, you are always adding sort of a fine grain to the entire image and there is no way around that. The only thing I want to have to grade in post is color if anything, not sharpness or softness.

Low light shooting is way down on the list if even when filming in proper light the image is too soft.

I guess it all boils down to a person's preference of how they like their images to look. I personally like my subject to be sharp and crisp - even in shallow DoF shots. Some I guess like the more dreamy, soft look of FF.
 
vorrik said:
I guess it all boils down to a person's preference of how they like their images to look. I personally like my subject to be sharp and crisp - even in shallow DoF shots. Some I guess like the more dreamy, soft look of FF.
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That dreamy, soft look of FF can be replicated with M4/3 using skillful lighting and skillful diffusion. When I saw the movie "Somewhere In Time" in a theatre when it first came out, I couldn't fully enjoy it the first time for trying to make notes on the back of business cards in the dark. The lighting and diffusion they used on Jane Seymour affected the way I photographed women in my studio for years after.

I did something I called the "Somewhere In Time Portrait" and had women coming in wearing dresses their mothers and grandmothers made and wore. I had an awful lot of fun with that. And I still have some of the diffusion filters I used at the time but I no longer have a studio facility where I can apply the soft, dreamy lighting under proper and full control.

My GH4 arrives end of next week!!!!!!
 
Hmm. FF doesnt have to be soft - just the 5dmk2 was, and most other options, that doesnt make it a theoretically soft format..
 
I was really disturbed by that Northrup video when I watched it. He clearly is a big fan of fullframe cameras. If you watch any of his other videos he always has the same level of disgust for m43 when it comes to shooting stills. With that said he does like m43 for shooting video so you have to take what he says from the correct perspective. Most of his logic in the video is being applied to shooting stills which typically do not benefit from the binning or line skipping that we enjoy with our video.

So for shooting stills, fullframe may have a noise advantage but for video a lot of the playing field is leveled. The video also doesn't account for sensor sensitivity and technology. I used to have 1/3" video cameras that were equal in sensitivity to an older 1/2" video camera. If we were strictly going off of Northrup's math then there is no way that could be the case. The reality is that sometimes sensor technology gets better and the signal to noise ratio gets better. Comparing two different sensors is like comparing apples to oranges because you have to factor in a lot more then just the size of the sensor.

The part of that video that really had my blood boiling was how he was saying companies like Panasonic are duping all of us by saying a lens is at a certain F stop. Having used adapted lenses I know if a Panasonic lens says it is F2.8 it really is F2.8 because an old Nikon or Canon lens at F2.8 will be as bright. No tricks or deceiving at all there. Sure you may get a different noise level and depth of field amount but a F2.8 is still a F2.8 lens. If it wasn't then a Nikon F2.8 lens adapted to a GH4 would be considerably brighter then a Panasonic F2.8 lens. It is not and both lenses are virtually equal in terms of brightness so yes If Panasonic says it is a F2.8 lens then it is in fact a F2.8 lens.

The other issue I have is how the world seems to be obsessed with never using lights in a production. I feel the pain for wedding videographers who really don't have a choice in a church but there is no reason at all why an low budget film or corporate production should not be using lights. With the use of proper lighting the necessity to push cameras to higher ISO levels is mostly negated resulting in little to no advantage for fullframe. Remember we can always add light to compensate for lower sensitivity. It is really an easy and cheap thing to add. fullframe users cannot add detail.

Not saying fullframe isn't nice. Just saying its advantages are based on obsessions. An obsession of insane thin depth of field and an obsession of shooting with no lights at all. In a real world production where those are not important m43 can be immensely beautiful and fun to work with.
 
Thomas Smet said:
The other issue I have is how the world seems to be obsessed with never using lights in a production. I feel the pain for wedding videographers who really don't have a choice in a church but there is no reason at all why an low budget film or corporate production should not be using lights. With the use of proper lighting the necessity to push cameras to higher ISO levels is mostly negated resulting in little to no advantage for fullframe. Remember we can always add light to compensate for lower sensitivity. It is really an easy and cheap thing to add. fullframe users cannot add detail.
Click to expand...

For nolo budget films lights may be more 'expensive' than what funds are available, along with any light over 1500W requires 'specialty power' relative to standard house wiring (220/240 V house power not withstanding...). So, I do look at examples of 'no lights', (note that does not mean 'no lighting' to be clear given a recent thread on 'no lights' and "Dallas Buyer's Club"(2013)...).

I'm not a fan of 'full frame' 35mm stills used in 'video' productions. For most of the over 100 years of movie making the 35mm academy frame is about the size of the APS-C sensor size. The M4/3's is somewhere between 16mm and 35mm in that regard...

To be sure in the era Vistavision, Todd-AO, et al. there were larger negative sizes, and even today with IMAX... but for the most part the standard 35mm movie film size is Academy and various 'croppings' of that size.

I think 'shallow DOF' basically crap, and will go the way of 'pan+zoom' of the late 60/70's and Hongkongkungfu movie style. There may be a few applications of shallow DOF... but they are relatively few...
 
Trad S35 'cinema' has usually been shot with fast glass, say an S35 lens set involves a 18/2, well pretty much the only affordable way to get that look is with a FF camera. (28 2.8 ish)

The recent Voigt and SLRmagic fast lenses have helped in that regard for mft - at no minimal cost.

Nothing about FF means you need to shoot at 1.2 - most sensibles use it at 4/5.6 which gives an exact match to S35 at 2/4

Just the FF version has bigger pixels and dust on the sensor is a smaller % of the image.

Conversly FF35 and even S35 zooms are huge which may push one towards MFT - well it would if all the zoom lenses were not made of playdough

Each format has its pros and cons - which generally revolve around lens cost/mass etc.

A decent shooter with the right lenses will get a decent look from almost any format..

S
 
Like j1clark said, FF is an oddity in terms of filmmaking.

Also wanted to add another thought. I haven't watched this Northrup video (any links?), but whenever people pipe up with all the supposed advantages of full frame (shallower depth of field, low light ability, low noise), few people seem to point out the advantages of M43 and specific M43 cameras:

Significantly smaller and lighter cameras and lenses (makes everything more portable, and more likely for you to carry with you, as well as more discreet, and less intimidating)
Electronic viewfinder (full-time live view and display of information, preview, focus peaking, zebras, etc)
No mirror (contributes to smaller cameras, and no mirror slap)
Awesome hybrid abilities (Panasonic's cameras - ability to take video and stills at the same time or very easily switch between them)
Awesome IBIS (Olympus' cameras - ability to use way lower shutter speeds, up to 5 stops I've heard so great for low light, and have stabilization on every lens, regardless of type or vintage)
Ultra fast auto-focus for both video and stills
Outstanding lenses for less money than the FF equivalents
Automatic electronic correction of lens aberrations
An unmatched mix and range of form factors for bodies (ex: anything from a GM1 to a GH4, or even an AF100, Blackmagic, etc)
Multiple manufacturers producing bodies and lenses (lots of choices and competition, without having to completely change systems in order to take advantage)
Broader depth of field (easier to control what you want to have in focus)
Probably other advantages that I can't think of right now

In other words, M43, and specific M43 models are very, very competitive with any other photographic systems and cameras, and absolutely useable, useful, and in some cases advantageous for professionals and amateurs alike. In fact, mirrorless is the future and the way forward, although that is beginning to have little to do with full frame vs. cropped frames, with Sony's latest cameras.
 
Sorry for asking, but where is the "Northrup" video? I'd like to see what this is all about.

Thanks.
 
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