I'm forced to get Canon L lenses

[blondandfun]

How does the XH-A1 image get so sharp? Is it the glass? I cannot get even close to same sharpness with my t3i and Sigma 28mm F1.8 lens at a long distance. It's a great macro and near-distance lens, but after 30-50 feet it's impossible to get perfect focus like the A1. I have tried a canon L lens and it's noticably better sharpness, but it's still not as sharp as the xh-a1 at infinity focus.

So the xh-a1 lens does not lose focus even when the F stop is all the way up to F1.4, whereas the prime lenses do? How does that make sense? It seems the only way to get focus on the prime lenses is to make the F stop F4, but that makes it useless indoors...

[Janke]

It's hardly the lens. It suffices for 18 megapixel stills, so the sharpness of a 2-megapixel HD video should not depend much on the lens.

If the problem is only at long distance, and only with the Sigma, you probably have a mis-aligned lens that doesn't focus to infinity.

So the xh-a1 lens does not lose focus

Smaller sensor, deeper DOF.

whereas the prime lenses do?

Different camera technology. Larger sensor (less DOF), less digital sharpening, anti-aliasing filtering, line skipping etc. all make the T3i video less sharp than it might be. I see no need for L-lenses just for video...

[kaydawgy]

Yeah I have that same Sigma 28mm 1.8 lens. Awesome lens, however it goes just a hair past infinity.

[Bif]

Is it the glass? I cannot get even close to same sharpness with my t3i and Sigma 28mm F1.8 lens at a long distance. It's a great macro and near-distance lens, but after 30-50 feet it's impossible to get perfect focus like the A1. I have tried a canon L lens and it's noticably better sharpness, but it's still not as sharp as the xh-a1 at infinity focus.

You've got a few "factors" at work here, the ones already mentioned above, and one few people take into consideration.

Sigma, Tokina, Tamron and the other "3rd party" lens makers DO NOT have near as good QC over their products as Canon, Nikon, Zeiss, and the others known for quality products. Individual samples vary and you don't really know how good a sample you have.

I have a Canon EF 28mm f1.8 (Canon's counterpart to your Sigma) and am very happy with it's performance both in still work and for video. Of course without "line skipping" still performance does result in crisper images, but this is my main lens for video due to it's "normal" perspective.

In one assignment while on active duty I spent most of my tour of duty working in the base photolab. I printed a bunch B&W shot by others using an assortment of lenses including many "3rd party" optics. I saw more variation in basic sharpness than you would believe (I even went so far as to go out with some owners and help them shoot test film to diagnose sharpness problems).

I've not had nor seen a "bad" Canon lens. I have seen some variation in Nikkor wides (I went through 3 28mm samples before I got a sharp one in 1975) and one Nikkor zoom formula was notorious for not being sharp but photojournalists loved it anyway, the 43-86mm - I forget the aperture on it.

Bruce Foreman

[Janke]

Awesome lens, however it goes just a hair past infinity.

If it goes past infinity, there's no problem. You can still focus to infinity. (In fact, most autofocus lenses do go past infinity, in order for the electronics to be able to find the correct focus by "see-sawing" over it...)

Sigma, Tokina, Tamron and the other "3rd party" lens makers DO NOT have near as good QC

Agreed, but they are designed for up to 18 Mpix stills, so their optical quality is definitely enough for video, as I said above.

My Tamron 17-50mm non-IS lens is exquisitely sharp, shoots great 18 Mpix stills, but the video from the T2i/550D is definitely softer, and that is not due to the lens.

Example (be sure to watch in full size, so click image):

test.jpg

Top image: 18 Mpix still shrunk to 1920 wide, 100% extract. This shows how good a HD video might be, if the camera was perfect.

Bottom image: HD video, 100% extract. Softness is due to the way the camera processes the sensor's info into video, not because of a soft lens.

Both examples shot with Neutral style, lens at 50mm, f:2.8, 1600 ISO due to low light. No sharpening of either image.

This proves that lens quality is of secondary importance for DSLR HD video.


Edit: To see how sharp large stills can be converted to HD video, check this (be sure to watch in full HD ! ) : http://vimeo.com/32485966

No ordinary HD video camera (camcorder or DSLR) can match that. Maybe Red, or similar cameras can, I dunno...

[AJUK]

That's a great example Janke. I never thought to try shooting an HD resolution still to compare. I've definitely noticed the softness (especially on wide angle shots) and I had assumed it was down to the choice of lens.

[Janke]

I've definitely noticed the softness (especially on wide angle shots) and I had assumed it was down to the choice of lens.

You usually don't notice softness in close-ups, because the details are large on screen.

In wide shots, details are small and they look smudged even though the resolution is exactly the same.

If, in a few years, VDSLRs will have processors capable of realtime-downscaling the full sensor data with the same quality as photoshop can dowscale single stills, the image quality will take a quantum leap...

[blondandfun]

Does the C300 have the digital sharpening that the XH-A1 or is it also poor for that? If you were shooting a concert, for example, from a far distance, you want everything in focus as crisp as possible.

DSLRs don't do that.

Fictional filmmakers can get away with soft images and just say "it's artistic", but commercial work it all has to be perfectly sharp as client's expectations are higher now.

[Dr. Benway]

Sigma 28mm F1.8 lens

I learnt a long time ago to only use Canon L lenses with my Canon cameras to save doubt, and ultimate disappointment.

It's a personal choice but one with which I have always been happy. Sigma, Tamron and Tokina, I'll never buy again.

[vince]

Any idea how much improvement can be obtained in actual resolution by capturing directly from HDMI? I remember from tests with the HV20 that there was an improvement from 600 lines to 750 lines on still pictures but on moving pictures this difference became less. I know with Canon DSLR's the picture is cropped but what about HDMI capture from the 1/3 CMOS sensor now widely used in most Canon camcorders. I could do some testing but not sure how to set up a comparison test. I have the ability to capture uncompressed from HDMI.

[cgbier]

I learnt a long time ago to only use Canon L lenses with my Canon cameras to save doubt,

...and then there's always Zeiss

[Janke]

there's always Zeiss

Even that won't make the video from a T2i/550D (or similar) any sharper. (Maybe very slightly contrastier, but that would be all...)

Stills would indubitably be better than with a Tamron, Sigma or other low-cost third-party lens.

[cgbier]

WEll, I just meant it as an alternative to Sigma & Co. Doesn't always have to be L-glass

[blondandfun]

In the context of what I shoot which is events on a merlin steadicam, I also chose Sigma because of its high weight and smooth focusing ring. That's why I take precedence of the just 5 or so people in this forum that do that and what they have to say. 98% of this forum is for fiction which has different demands and requirements than documentary shooting.

The steadicam merlin is actually useless for many lightweight DSLR rigs, I don't own one but the Sigma 11-17mm is the go-to lens used by the top event producers in the world for the merlin steadicam.

I shot a event last night where 2 dancers were dancing indoors and they were different distances from the camera. It was hard to have both dancers in focus without having to take the F stop "lower" to F3-4. The XH-A1, on the other hand, can have the F1.4 and everyone is in focus.

[Janke]

an alternative to Sigma & Co

Yes, Zeiss is great - if you have the money (but I think that goes for L-glass, too?) ....

It was hard to have both dancers in focus without having to take the F stop "lower" to F3-4. The XH-A1, on the other hand, can have the F1.4 and everyone is in focus.

That is because of the wider DOF due to a smaller sensor in the XH-A1 - it has nothing to do with the actual sharpness of the lens. The smaller the sensor, the wider the DOF - really small sensors can give you focus from just a few ft to infinity, wide open...

[Janke]

I did a quick test with both the T2i and the HV30:

videotest.jpg

All are 100% extracts from screen grabs, no sharpening.

The light was low, so the footage was pretty noisy. The still is taken with the same exposure, at 800 ISO. Noise is more visible in the HV image, due to the smaller sensor. Neither video reaches the quality of a still shrunk to 1920 size.

[Dr. Benway]

...and then there's always Zeiss

Aye. I'd need a huge lottery win though.

[Flozem]

Aye. I'd need a huge lottery win though.

Hah - you can say that.... I could prolly buy three to four L lenses for one Carl Zeiss

[deckmaster]

to take the F stop "lower" to F3-4.

do you get everything focus on f/3.4? just for the clarification

[blondandfun]

do you get everything focus on f/3.4? just for the clarification

I hope you included the smiley to indicate you know it was a stupid question. For indoor use, F3.4 is worthless on a DSLR (well canon consumer DSLR)... I'm honestly thinking of ditching the technology and going with micro 2/3's technology, which is 5x sharper. Canon is such a big consumer oriented company it's always putting out the absolute WORST technology.

[deckmaster]

I hope you included the smiley to indicate you know it was a stupid question

No, I put smiley to make my question positive.I am still learning DSLR,what I learned that if you need to be everything in focus it should be minimum f/5.6 or more.

[Janke]

I learned that if you need to be everything in focus it should be minimum f/5.6 or more.

It is all relative, depends on distances and focal length of lens.

See http://en.wikipedia.org/wiki/Depth_of_field

and http://www.dofmaster.com/dofjs.html

- the latter will help you calculate the DOF.

[deckmaster]

depends on distances and focal length of lens.

Normally its applicable on photos, my question was, is it applicable on video too?

[Janke]

Exactly the same. Video is just 24, 25, 30, 50 or 60 photos every second...

[deckmaster]

Exactly the same

I have got Tamron 17-50 mm f/2.8 lens, so what will be the f stop to get everything focus without much compromising to the quality in indoor parties (about 3 to 6 meters range),I am going to use led video light.