Maximum f stop usable in the Canon XH A1 - Page 2 at DVinfo.net

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Canon XH Series HDV Camcorders
Canon XH G1S / G1 (with SDI), Canon XH A1S / A1 (without SDI).


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Old September 9th, 2008, 03:14 PM   #16
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The fact that he shot at a much faster than normal shutter speed also probably affected the footage.
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Old September 9th, 2008, 04:02 PM   #17
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This may be a dumb question but isn't this the point of the ND warning ikon ie to prevent exposures that will be small enough to affect focus?
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Old September 9th, 2008, 04:14 PM   #18
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Well you have to use the ND when shooting outdoors under bright sun or you'll be way overexposed, so yeah, I guess you're right. Unless you use a really fast shutter speed, but that's going to mess with the image. It's also a good idea to have an ND .3 filter to stick on the lens if you want to open up wider under those conditions.
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Old September 10th, 2008, 02:10 AM   #19
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Originally Posted by Tom Hardwick View Post
Sorry Petri and with respect, but what you're saying just isn't true. Diffraction was certainly of GREAT concern in the good old days of film, as anyone shooting Standard-8 or Super-8 film (5.4 x 4.1 mm frame) found out to their cost.
Sorry, I forgot about really small format film. Never shot hardly any.

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Then you say that, 'diffraction starts to kick in the moment you touch that zoom rocker', and of course this is nonsense. The focal length of a lens doesn't cause diffraction on its own, it's small apertures that cause diffraction. The shorter the focal length the more diffraction affects the sharpness, but it's still aperture dependant.

It's the reason the Z1 allows you to limit how far the diaphragm blades stop down - Sony knows what shooting at small apertures will do to their reputation.

tom.
What I meant by"diffraction starts to kick in the moment you touch that zoom rocker" was that cheap long zoom lenses start to loose maximum aperture when you zoom in even a bit. That causes aperture to close and diffraction starts to affect the image. We all (?) know that diffraction is tied only to relative aperture (F-stop), focal length or film/sensor size plays no role in this. It is just that when sensors have too much resolution relative to their size we are faced with this phenomenon. And with super-8...
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Old September 10th, 2008, 02:55 AM   #20
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Originally Posted by Petri Kaipiainen View Post
What I meant by"diffraction starts to kick in the moment you touch that zoom rocker" was that cheap long zoom lenses start to loose maximum aperture when you zoom in even a bit. That causes aperture to close and diffraction starts to affect the image.
I can see how you think this but again it ain't so. Very nearly all zoom lenses lose speed as you zoom, but that's simply a design requirement to keep size and weight down. The 14x Fujinon supplied with Sony's EX1 isn't particularly cheap, yet loses speed like all the rest.

You're correct that they 'start to loose maximum aperture' but that's all they do - they have smaller maximum apertures than they do at wide-angle yet their diffraction losses are still in the small aperture range. Although max apertures are wider at wide-angle, it's these short focal lengths that are worst affected by diffraction.

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Old September 10th, 2008, 03:28 AM   #21
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Well you have to use the ND when shooting outdoors under bright sun or you'll be way overexposed, so yeah, I guess you're right. Unless you use a really fast shutter speed, but that's going to mess with the image. It's also a good idea to have an ND .3 filter to stick on the lens if you want to open up wider under those conditions.
Thanks Bill
What I meant specifically is that on page 37 of the XH A1 manual it says

'When recording in bright surroundings, the camcorder will set a small aperture and the picture may appear blurred. Turn the ND filter on/off according to the screen display'.

I suppose the question to everyone is therefore can you rely on using the ND filter when the warning icon appears ie is that sufficient to keep you within the exposure range needed to avoid blurring. To put it bluntly, does the ND filter warning icon do the job?
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Old September 10th, 2008, 03:50 AM   #22
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The ND filter v'finder warning is triggered (in all my Sony cams) by the diaphragm blades hitting their end stops - i.e. max or min aperture, so I'm guessing Canon use the same triggers.

So - flip those NDs into the light path way before the camera silently screams for them. Keep your apertures wide if you want the sharpest pictures.

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Old September 10th, 2008, 04:17 AM   #23
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Hi Richard..................

The answer is, of course, yes, it does the job.

Do I consider the entire mindset of this thread to be a bit OTT, is also a yes.

Of course, everybody is, strictly, correct.

Now, I might notice it, you may notice it, and I have no doubt whatsoever that the distinguished posters to this thread would notice it.

BUT!

Yer average Joe Blogs in the street who might, just, be on the receiving end of a particularly bad example of lens diffraction (courtesy of the good 'ol Beeb) wouldn't know squat diddly from a bit of bad focus (of which there is a great deal).

Personaly, hey, I've shut my A1 down to near blackout with the ND's maxed and it's still been too bright, but, hey, the footage passed with flying colours and not a murmur of "diffraction" to be heard from the assembled herds of "experts".

Once your head gets so far up your rear end this sort of discussion can get as carried away as it has, it's time to take a step back and ask yourself - what am I trying to achieve here?

Who's gonna watch this?

What's important - the medium or the message?

Yer average Joe is more than happy if it's relatively in focus and has slightly better colour than the 'LSD freak show" phase of CSI Miami (you'd be suprised at how many didn't even notice the latter!).

Absolutely no disrespect to any of the other posters here, I've read their post carefully and there's been some pretty comprehensively good stuff here, no question.

At the end of the day, the guidlines are just that, shoot what you can with what you have and leave it at that.

Concentrate on the message and not the medium (all other things considered, of course).

My 2 cents.


CS


PS. Nice to be back.
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Old September 10th, 2008, 08:24 AM   #24
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"Concentrate on the message, not the medium." Very nice, sir. Very nice.

I actually have some first-hand experience in using the A1 with a very closed iris. I was shooting an outdoors auto show and I was experimenting with "Deep focus," the idea being that closing down your aperture widens your depth of field.

I wanted muscle cars close to me, and ones far from me, to all be in perfect focus. Plus it was super bright, so I closed the iris way down, to like 9.5 (if memory serves) for most of the day.

The A1 takes stunning images and most of the footage was just great. But some footage was very dissapointing - looking washed out and slightly blurry. I've got another custom truck show this weekend and I will certainly be using ND filters to cut the sunlight instead of using the aperture.

If you want more info, and a longer-winded explaination, check out my blog posts about the subject (and how I fixed some of my footage) at XR.

Will Mahoney's Blogs - Color Correcting, Deep Focus, Bright Sunlight and Classic Cruisers!
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Old September 10th, 2008, 08:58 AM   #25
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Chris

I agree this kind of thing can get totally out of hand (I've witnessed it) but as long as it doesn't take over your thoughts as you shoot, the info is a good tool to have in your box for the overall product.

Besides, the way things are going, who knows what will or won't be acceptable in the future? If I happen to get some really compelling footage, I'd sure like to have shot it in a way that might hold up down the road. That's why I got this A1. It's not the best but its the best I can get for now. And I want to use it at its best. That's all.

But your point is well taken.

JMHO.
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Old September 10th, 2008, 11:03 AM   #26
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Originally Posted by Will Mahoney View Post

I wanted muscle cars close to me, and ones far from me, to all be in perfect focus. Plus it was super bright, so I closed the iris way down, to like 9.5 (if memory serves) for most of the day.

The A1 takes stunning images and most of the footage was just great. But some footage was very dissapointing - looking washed out and slightly blurry. I've got another custom truck show this weekend and I will certainly be using ND filters to cut the sunlight instead of using the aperture.
Will:

If your "very dissapointing" footage was so bad it was unusable, I think I know what you mean. Did the white balance look off too (brownish)?

One of my A1s used to do that every once in a while in bright light when capturing a clip. Usually the next clip was fine even though I didn't change anything. It was something you couldn't see on/in the viewfinder, but on a monitor it was awful.

I sent that A1 back.

Jeff
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Old September 10th, 2008, 03:13 PM   #27
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May I guess the Canon XH A1 is a changeable mood camcorder?
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