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View Full Version : Camera Test: 7D & GH1 skew comparison



Luis Caffesse
10-01-2009, 06:35 PM
Had a chance to play with a GH1 and 7D today - so figured I'd check to see how the skew compared. Figured you guys might be interested - so I put together a split screen in FCP to make it easy to see.

It's pretty self explanatory... I'll keep my opinion to myself for now.
Just check it out and see what you think.

6859995

I did this out of pure curiosity because I thought it would benefit me to know what I was dealing with on both cameras.
This isn't about arguing that one camera is 'better' than another.
(figured we could use a preemptive warning there)

Oh - and yeah, both cams shooting 1080/24
Both shots were transcoded to ProRes.


EDITED TO ADD:
PLEASE don't judge the image quality - crunching this video down for vimeo, followed by the vimeo compression, is killing the image completely.
But the angles of skew are the same... so just look at this for that one particular aspect.
Thanks.

Stephen Mick
10-01-2009, 06:39 PM
This footy doesn't look "filmic" at all.

And if you hadn't told me which was which, I'd have no idea. Skew between the two looks pretty similar to me. I forget, was that 1080/24p or 720p/60?

Luis Caffesse
10-01-2009, 06:39 PM
This footy doesn't look "filmic" at all.

You're lucky I know you... and therefore know that you're joking.
:)

NoahK
10-01-2009, 06:41 PM
Wow- GH1 skew is quite a bit more pronounced- though I would kind of expect that.

Noah

Mark Harris
10-01-2009, 06:44 PM
Am I insane, or do they look pretty comparable with the top one a hair more skew-y...chew-y...

Luis Caffesse
10-01-2009, 06:55 PM
Honestly, I expected the 7D to be much more pronounced in the skew department...given the bad rap the 5D has gotten on skew, and how much better the GH1 is with skew according to most reports....

Looking through it frame by frame, I really can't tell a difference between the two, which was interesting to me.

Oh, I should note that this was a 30mm prime on the 7D, the GH1 was shooting with the kit lens, zoomed in to 30mm as closely as I could to try to get the same FOV.

What I'm taking away from this is - if you're debating between buying a 7D or a GH1... skew shouldn't factor into your decision, other than to decide whether or not you can deal with it overall... but at 1080/24p one cam doesn't seem to be any better than the other in regards to skew. Not to my eyes anyhow.

EDITED TO ADD:
By the way, if the GH1 seems skewier (is that even a word) it's probably due to the OIS being left on the lens by mistake...if you notice, the frame floats a little at each extreme of the pans... i think that makes it seem like it has more skew... it was also sitting on top of the 7D on the hotshoe...so it was more prone to vibration.

When I get a moment I'll pull some stills from the raw comparisson and post them up so you can see.

Jason Ramsey
10-01-2009, 07:06 PM
looks pretty similar most of the time... couple of times the top image looked like it might have been worse off...

I wonder if the difference in focal length between the two cams makes a difference in "perceived" skew as well... Would bet it does.

EDIT: I guess the focal length is about the same on the two... just looks like one has a wider angle of view or something or something... distance to subjects looks the same,, but at the same time the edges aren't matching up... I don't know what I'm talking about :)

Later,
Jason

ydgmdlu
10-01-2009, 07:07 PM
See? It's just like I predicted (http://www.dvxuser.com/V6/showthread.php?t=184364)...

That brings us to the 7D. When the first sample videos were released, there were conflicting views on the jello; indeed, the jello seemed to vary from clip to clip. It was about as bad as the 5D on some clips, but in the fast motion clips in "Line of Sight," the jello was missing. Quite possibly, this is an indication that the 7D's rolling shutter (and clock) behaves a lot like the GH1's. In fact, I predict that that is exactly what we'll find once we get our hands on the camera.

BTW, thanks for doing this Luis. It saves me from doing the same test.

Rakesh Jacob
10-01-2009, 07:13 PM
thnx for the test Luis, one less thing to think about :)

EDIT: NOW could you put both of those cams on top of an EX1 that happens to be on top of a shoulder mounted RED1 and go running down 6th street at midnight, that would pretty much take care of the rest of my ponderings that keep me up at night. Oh and try and keep the ISO, aperture and effective FoV the same, thnx you're a doll :)

ChipG
10-01-2009, 07:26 PM
Good news is it looks like a little cc in post and you'll be able to match these cams up pretty nice. No need to part with either.

ydgmdlu
10-01-2009, 07:27 PM
Good news is it looks like a little cc in post and you'll be able to match these cams up pretty nice. No need to part with either.
That's what I've been saying. :)

Jim Klatt
10-01-2009, 07:29 PM
now could you put both of those cams on top of an ex1 that happens to be on top of a shoulder mounted red1 and go running down 6th street at midnight, that would pretty much take care of the rest of my ponderings that keep me up at night. Oh and try and keep the iso, aperture and effective fov the same, thnx you're a doll :)

lol

Luis Caffesse
10-01-2009, 09:10 PM
Good news is it looks like a little cc in post and you'll be able to match these cams up pretty nice. No need to part with either.

I would guess you should be able to get them to match up pretty well in camera if you wanted to - I didn't even try to get them to match up contrast/color wise.

Barry_Green
10-01-2009, 09:12 PM
When doing a skew test, it helps to set the shutter as short as possible so that the lines that we do see are crisper and not hidden under motion blur.

That said, from this test it does look like they're pretty much comparable, and that's a big relief. I was expecting the 7D to be a lot more rubbery, but it doesn't look like it is!

Luis Caffesse
10-01-2009, 09:33 PM
Good point, Barry - the shutters were set the same, but i can try to do this again tomorrow with a higher shutter speed.
Might be interesting.

Coco Bermudez
10-01-2009, 09:40 PM
Hey Luis...great test.

I also have the GH-1 and I am waiting for the 7d to arrive tomorrow. Have to ben able to color correct the footage and see which image holds better?

As first impression, which cam do you like to shoot with most? I love the GH-1 but I wonder what your first impression is?

USLatin
10-01-2009, 09:59 PM
Nice test Luis. Thanks.

Luis Caffesse
10-01-2009, 10:02 PM
Hey Luis...great test.

I also have the GH-1 and I am waiting for the 7d to arrive tomorrow. Have to ben able to color correct the footage and see which image holds better?

As first impression, which cam do you like to shoot with most? I love the GH-1 but I wonder what your first impression is?

Well, I'd like to keep this thread specifically about skew...otherwise every thread in here is going to become a general GH1 vs 7D thread. :)

That said - it is by no means a slam dunk in either direction as far as I'm concerned.
I am 100% on the fence right now to be honest... but it all depends on what kind of shooting you do and what your needs are.
I'm not trying to be diplomatic here... honestly I really wish one were obviously 'better' for my needs...

Thing is - one may be obviously better for YOU depending on what you're looking for and what you need -
What is important to some people may not be important to others -

But at least from what I saw today I feel like skew is one of the things we can take out of the equation between the two cams.

(you like the way I worked it back around to skew?)


As far as color correction - I haven't played around with it enough to really draw any hard conclusions. That's on the list of things to do...

ydgmdlu
10-01-2009, 10:20 PM
I wonder how anyone ever got the impression that the GH1, in 24p mode, was that much better than the 5D in terms of jello. Was it because everyone was concerned about the mud issue instead? I guess that if there's one good thing to come from the mud, it's that people were scared of doing quick camera moves, which also happened to minimize the jello. :grin:

Jeez... Assumptions, assumptions. Let's try to be careful about them now.

Jean Dantes
10-01-2009, 10:45 PM
Thanks for this test Luis!

If possible, can you please test the 7D skew @ 50P/60P vs the GH1 skew @ 50P/60P (since you're in NTSC land, I guess it'd have to be 60P for GH1 anyways).

Thanks again for this test! Much appreciated!

Luis Caffesse
10-01-2009, 10:46 PM
Thanks for this test Luis!

If possible, can you please test the 7D skew @ 50P/60P vs the GH1 skew @ 50P/60P (since you're in NTSC land, I guess it'd have to be 60P for GH1 anyways).

Thanks again for this test! Much appreciated!

No problem - I'll see if I can do that tomorrow as well if time allows.
Shouldn't be a big deal if I'm doing another one at 1080/24 already.

Barry_Green
10-02-2009, 09:45 AM
And... while you're skewing around... how about on each cam, 24 vs. 60? I.E., does the skew performance stay the same on them, or is either of these cams noticeably more skewy in 24 than they are in 60?

Rakesh Jacob
10-02-2009, 09:50 AM
And... while you're skewing around... how about on each cam, 24 vs. 60? I.E., does the skew performance stay the same on them, or is either of these cams noticeably more skewy in 24 than they are in 60?

He'd need 2 7Ds and 2 GH1s. But I'm sure there's DVX family out there in Austin with cams willing to help out!

Stephen Mick
10-02-2009, 09:53 AM
I'm ready with my 7D to help out. Just waiting for the wookie to call.

Barry_Green
10-02-2009, 10:03 AM
He'd need 2 7Ds and 2 GH1s. But I'm sure there's DVX family out there in Austin with cams willing to help out!
Nah, you just gotta be a little more clever about it. If we've already established that the GH1 and 7D are basically identical in skew in 24p, then use one in 24P and the other in 60p, and compare. If there's a difference, presumably it would show up in the 60p version having less skew. Then, swap modes and try again.

:D

Rakesh Jacob
10-02-2009, 12:00 PM
Good point Barry, but still if some one's willing to help out that would rock!

Also Luis have you compared noise in low light/high ISO between the 7D and GH1? And what are your impressions?
Thnx in adavnce, you sir are a credit to the Wookie race! :)

Luis Caffesse
10-02-2009, 01:10 PM
Just FYI - not sure I'm going to have time to get to that skew test today... just got back from a meeting that ran way too long, need to get some actual work done (so I can pay for this 7D)

Might get a chance later this afternoon - if not, I'll definitely do some more in depth stuff tomorrow.

-Luis

stephenvv
10-02-2009, 01:32 PM
Thanks for doing this but actually to me, the real useful rolling shutter test is handheld and steadicam/car mount stuff. I will never do a pan like this in real shooting - this test only has bearing on shooting poles out of moving windows (also not a common shot).

I would want to see a OIS-off test handheld and steadicam to decide how the cameras compare in real world shooting.

USLatin
10-02-2009, 03:24 PM
Thanks for doing this but actually to me, the real useful rolling shutter test is handheld and steadicam/car mount stuff. I will never do a pan like this in real shooting - this test only has bearing on shooting poles out of moving windows (also not a common shot).

I would want to see a OIS-off test handheld and steadicam to decide how the cameras compare in real world shooting.

While I think that this test is perfect to help us quantify the skew difference, I have to agree. It would be just as interesting if not a little bit better to see real world applications. The whip pans are real world though.

It would be interesting to see some hand held whip pans, and most of all the dreadful no-IS shake that brings about that nasty jello. But watch out for splinters. ;) If you are still "skewing around" of course. Lol at that one Barry.

PaPa
10-02-2009, 03:38 PM
great test. No doubt they are very similar in skew.

One thing i noticed, is the difference between holding the camera handheld, versus on a shoulder rig, is night and day. Handheld, its very dangerous to hold it with any lens over 50mm. But on a shoulder rig, no problemo. It's only the panning where you need to be careful, but even then its not that big an issue.

stephenvv
10-02-2009, 03:51 PM
I just DP'd a zero budget feature shot with HV20/30's and panning was never a problem. Car mount was a nightmare however and handheld/shoulder rig occasionally problematic.