Resolution : Canon XL Lenses

[Aaron Scheiner]

Hi everyone

It's my first post and I'd just like to say that this site has been of tremendous help over the years, much appreciated.

I bought a Canon XL H1 about 4 months ago and I've recently acquired a couple of lens related accessories; namely a manual 16x lens, a 3x wide lens, a 1.6x adapter and an EF adapter.

I didn't get a manual with any of the accessories... and although they're all quite simple, I did have fun getting the back focus set on the 16x manual lens.

I used an externally-packaged 720p laptop monitor with composite in to calibrate back focus and other stuff and it all seems to be working quite well.

A few questions, though :

1) I've noticed the 16x lens zooms in and out during focusing (I believe this is referred to as breathing)... is it meant to be noticeable on the 16x lens ? or have I stuffed up somewhere ? I'd say the lens zooms in by about 0.3x during focusing. The front glass also rotates during focussing.

2) "HD Incompatible Lens" Is there some way of easily calculating the actual resolving ability of a lens in vertical pixels ? Has it been done already ? I'm really intrigued to find out if these lenses resolve HDV.

I've noticed on the wide lens that there is some colour fringing, primarily on the right side of the lens. It seems to be greatly reduced by zooming in by about 0.5x-1x.

That's about it... all in all a great camera.

[Robert Sanders]

All of these lenses are perfectly suitable to the XLH1 camera. However, the 3X lens is probably the lowest grade (optically) for HD work. I did use the 3X lens on a project (this was before Canon released the 6x) and, for the most part, it did the job. However, there was noticeable softening in the corners and some CA throughout.

The 16x lens is workhorse lens. Canon over built this sucker considering it's remarkable cost. It works very well the H1 and and I think the optics hold up for HD resolution. I'm not sure about the "breathing" issue. My 16x lens does not breathe at all.

[Marty Hudzik]

Originally Posted by Robert Sanders

I'm not sure about the "breathing" issue. My 16x lens does not breathe at all.

Are you kidding? So if you look at the front element of the lens and adjust the focus, you do not see that element move in and out slightly? The same goes for the image in the EVF, it should zoom ever so slightly forward or backward depending on the direction of focus.

I have used 3 different 16x manual lenses over the last 5 years and all of them exhibit this behavior. I don't mind much but I am puzzled to hear that yours does not do this....are you sure that you haven't just become "numb" to it or you don't notice anymore? I'm not trying to be smart but in the big picture it would seem more likely that you are overlooking it than there is a "rogue" model floating around out there without this issue.

Let us know if you are "sure". :)

[Robert Sanders]

Ok, Marty. Just for you. I'll pull the 16x out of storage and test it just to make sure. I haven't used the lens since early 2006. So it's possible I don't remember it.

[Marty Hudzik]

Robert,
If your lens is in storage don't pull it out just for this! I was simply asking because the breathing of the lens was a known issue back before I bought it in 2005. I don't mind it in the least.

If your 16x is in storage what have you been shooting with lately? Red?

Thanks.

[Robert Sanders]

No worries Marty. I'm now curious enough about the issue to pull it out.

I haven't shot anything since we wrapped up post-production on our feature. We've been in distribution mode and all the crap that goes with that end of the production cycle. And we're writing our next project.

So I haven't had an opportunity to shoot anything lately. But trust me. I'm itchy as all hell to get back behind the camera.

[Aaron Scheiner]

Well thanks for the info guys... really useful stuff.

I did some research, there's an interesting BBC whitepaper on the Canon XL H1.

They rate the camera's horizontal resolution with the 20x lens as 1600 pixels... which isn't bad. 1600x1080 = 1.72MP (compared to the Sony Z1/V1/FX1/Z5/Z7's 1.02MP).

Since my last post I've shot about 200 hours of footage on my XL H1 s and parts of that footage have been shot using the 16x manual lens. I had to oil the focus ring (this may have been a stupid move, but it works fine). I find this lens is amazing for low light shooting as it holds the f/1.6 aperture throughout it's zoom range. We shot using street light only, a few weeks back, coupled with the nanoflash the footage is amazing.

My 16x lens does breathe, the front element does rotate during focussing and I've noticed that the image is softer between about 25% and 0% from the top of the frame.

The 3x lens is horrible... but not that bad compared to my Sony Z1 with a wide adapter on it. Hopefully I'll be able to compare against the EX3 with it's wide adaptor soon.

Anyway, thanks for all the info.

[Chris Hurd]

Why would you compare the 3x lens to anything other than another standard definition lens?

[Aaron Scheiner]

Because it's interesting to see how far those SD lenses can be pushed... their actual resolving power.

Lenses don't change much... good quality lenses can't be mass manufactured in the same way sensors can, so as sensors increase in resolution and quality so the gap between those sensors and lenses widens (and people have to pay more for a lens that will match the resolving power of their sensors).

It's just interesting :) .

[Steve Phillipps]

I agree Aaron, it's good to know what's acceptable. There's been a lot of talk about SD lenses on HD cameras over the last few years, especially with the advent of "cheap" HD lenses for broadcast cameras. You can now get an HD lens for say £3000 while an equivalent range SD lens might be £13,000, and we're supposed to believe the HD one will perform better?
And I think the key here also is "acceptable", which depends what you're doing with the footage. You might measure an HD lens and find it is better than a decent SD one, but in general viewing rather than testing there might be very little in it, and certainly not enough that anyone watching the programme would think "ooh, that looks really soft and yucky". And if you can pick up an SD lens for £500 that looks to a viewer virtually identical to a £12,000 HD one then you'd be crazy not to.
Steve

[Aaron Scheiner]

£3000 while an equivalent range SD lens might be £13,000

Absolutely! I recently read a couple of posts by someone who had bought a Fujinon wide lens for the EX3... it's not a cheap lens but the frame grabs he posted from it showed a number of issues. He figured it was probably a defective lens, so he sent it back and they said it was within the acceptable parameters for that lens. The lens in question is the Fujinon XS8x4AS-XB8, which seems to go for about $4000.

There's also the threshold at which the viewer won't notice the difference in your footage and therefore going for something fancier doesn't make much sense (as you said). It's like putting in 50% to get the extra 10% that 90% of your audience won't notice. You can see this with the Canon 7D/5D MKII and with CMOS cameras in general. The 7D is a great camera, I own one and I love it, but I realise it has limitations. People often don't understand some of those limitations and the public often don't care when those issues become noticeable.

I recently shot some aerial footage using my Canon XL H1... Using a combination of high shutter speeds, deinterlacing and stabilisation in post, it's possible to get incredibly good aerial footage out of that camera especially when coupled with a NanoFlash. The XL H1, like many CCD cameras allows for innovation. You can't do that same stabilisation technique on an EX3 or a 7D or a 5D MKII or a V1... because of the lack of a global shutter on CMOS cameras. It's all cost cutting.

Compromises... the problem is that when a compromise becomes available and gets marketed it kills some of the alternatives.

On a lighter note I see someone had developed a global shutter for CMOS cameras :

rolling shutter - LCD shutter experiment on Vimeo

.

:)

[Chris Hurd]

Originally Posted by Aaron Scheiner

Because it's interesting to see how far those SD lenses can be pushed... their actual resolving power.

If you're not already aware, you'll find out quickly that the 3x lens cannot be pushed very far at all.

It's the softest of all Canon XL lenses.

[Wolfgang Neun]

Originally Posted by Aaron Scheiner

I did some research, there's an interesting BBC whitepaper on the Canon XL H1.

Aaron,
Will you please be so very kind as to give us a link to this white paper. I can't find it nowhere on the BBC site.
Thanks! Wolfgang.

[Steve Phillipps]

I haven't seen the XL-H1 either, but the XH-A1 is here http://thebrownings.name/WHP034/pdf/...Canon-XHG1.pdf
Steve