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Author Topic: Canon EF 12-24 f/2.8L [CR1]  (Read 14326 times)

Dick

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Re: Canon EF 12-24 f/2.8L [CR1]
« Reply #30 on: February 27, 2013, 04:11:35 PM »
Sounds like a lens I'd want to have. Then again... shooting wide shots only here and there, I just couldn't justify the ridiculous price tag they'd put on it.
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Re: Canon EF 12-24 f/2.8L [CR1]
« Reply #30 on: February 27, 2013, 04:11:35 PM »

jrista

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Re: Canon EF 12-24 f/2.8L [CR1]
« Reply #31 on: February 27, 2013, 04:18:20 PM »
I would absolutely LOVE a 12-24 f/2.8 L for wide-field astrophotography! Imagine the length of exposures you could get, or at lower ISOs, with a 12mm f/2.8 lens! Ooooh, the bliss! I'd spend the money for it, too...12mm f/2.8 astrophotography...man I'm DROOLIN!!  ;D
If you're using a 7D, why not get the cheap Tamron 11-16/2.8 for astrophotography? Wider, fraction of the cost, and it exists now  ;)

Do you mean Tokina 11-16? I don't think Tamron makes such a lens.

I stick with Canon lenses. I've used third-party lenses and teleconverters before, and had problems. Currently, the only third-party thing I use is a Kenko 1.4x GDX Pro 300 teleconverter...it works well most of the time, but with the new Mark II lenses, the camera doesn't get the right information and over-exposes by a stop. I don't like those kinds of issues, and I've had other problems using a Sigma lens in the past, etc. At least when you stay within the brand, those kinds of things never occur.

Besides, I would expect an EF 12-24 f/2.8 L to offer the best resolution possible in such a lens design. I can't imagine Tamron or Tokina, or Sigma or anyone else, to produce lenses that rival the newest lenses from Canon. I've never seen such resolution before, even in Canon's past lenses (with the exception of maybe the 300 f/2.8 L). The Tokina 11-16 seems to do well against past-generation Canon lenses, but even Canon's own older designs, such as the 16-35, often don't compare to the newer L-series lenses released in the last couple of years. I would also use the 12-24 for landscapes, and the 24mm focal length (on FF, ~16mm on APS-C, although I intend to either get a 5D III or the Canon megapixel monster for my landscapes in the future) is one that I like for landscapes, and it would be nice to have a single lens that covers the wide to ultra wide focal lengths for both landscapes and astrophotography, so I don't have to swap out lenses when I head out to do that kind of photography.

pwp

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Re: Canon EF 12-24 f/2.8L [CR1]
« Reply #32 on: February 27, 2013, 04:18:49 PM »
I have the Sigma 12-24 and in reality probably pull it out a couple of times a year. I've got a good copy. It's a limited use lens that has greater relevance for crop shooters. Still, it's about time Canon got a high IQ UWA into the market. Whether it's f/2.8 or f/4 probably doesn't matter too much. I'd be more likely to buy a stellar 14-24 f/2.8 than a merely good, higher priced 12-24.

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Re: Canon EF 12-24 f/2.8L [CR1]
« Reply #33 on: February 27, 2013, 04:22:29 PM »
If its wider and shaper than the nikon, expect these two things.

1. A ridiculous price tag.

2. A stupendous waiting list.

cliffwang

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Re: Canon EF 12-24 f/2.8L [CR1]
« Reply #34 on: February 27, 2013, 04:32:12 PM »
It does sound a bit far fetched to create this with the recent optical quality of their L glass. Personally I'm not interested in something to merely equal the Sigma 12-24 optically.

If the IQ of Canon 12-24 L is only slightly better than the IQ of Sigma one, Canon has better not put this lens on the market.  I had Sigma 12-24 years ago.  The IQ is too soft, so I decided to sell it.  Now I am very satisfied  my Samyang 14mm which has much better IQ than Sigma 12-24.
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rs

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Re: Canon EF 12-24 f/2.8L [CR1]
« Reply #35 on: February 27, 2013, 04:47:49 PM »
Do you mean Tokina 11-16? I don't think Tamron makes such a lens.
Yeah, I meant the Tokina. You make a great point there about compatibility, and if you plan to go FF, the extra cost of the large UWA imaging circle and inconvenience of the front element shape won't be wasted on you.

If this lens will ever become a reality, I expect Canons high MP FF body to be out by then. It's been rumoured for long enough...

I just hope this lens (if it ever becomes a reality) is less Sigma 12-24 and more Nikon 14-24 when it comes to image quality.
« Last Edit: February 27, 2013, 04:49:56 PM by rs »
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Canon 14-24

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Re: Canon EF 12-24 f/2.8L [CR1]
« Reply #36 on: February 27, 2013, 08:03:44 PM »
Aw man, now I need to change my user name to Canon 12-24!

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Re: Canon EF 12-24 f/2.8L [CR1]
« Reply #36 on: February 27, 2013, 08:03:44 PM »

jrista

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Re: Canon EF 12-24 f/2.8L [CR1]
« Reply #37 on: February 27, 2013, 08:50:20 PM »
Aw man, now I need to change my user name to Canon 12-24!

LOL  ;D

drjlo

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Re: Canon EF 12-24 f/2.8L [CR1]
« Reply #38 on: February 28, 2013, 02:15:36 AM »
Personally, it would be much more useful for me if Canon came up with 16-35 f/2.8 MkIII with sharpness in line with 24-70 II and 70-200 f2.8 II, as well as a real good 35 mm end..

pedro

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Re: Canon EF 12-24 f/2.8L [CR1]
« Reply #39 on: February 28, 2013, 02:18:56 AM »
I would absolutely LOVE a 12-24 f/2.8 L for wide-field astrophotography! Imagine the length of exposures you could get, or at lower ISOs, with a 12mm f/2.8 lens! Ooooh, the bliss! I'd spend the money for it, too...12mm f/2.8 astrophotography...man I'm DROOLIN!!  ;D

In terms of exposure time, here is what I figure. Currently, with my 16-35 f/2.8 L, I usually get about 30 seconds  at 16mm out of it, at ISO 800 - 1600, for a decent "printable" shot (i.e. a shot that could be printed at native size...13x19 for the 7D...without particularly noticeable startrailing. Rule of 600 would indicate 38 seconds, so I shorten that a bit for printability). For a web-sized shot, I can usually expose for about 40-45 seconds, and often use a higher ISO. With the 12-24 f/2.8 L, I figure I could get 45-50 seconds out of it for printables, and maybe as much as 65-75 seconds for web-sized shots! And that is nothing to say of the wider field of view, which would be nice at times...

@jrista: Did I get that wrong with rule of 600? I thought the calculation 600:lens length refers to its LONG end? So the 16-35 won't give you more than about 16 sec of exposure. Therefore I like the 5D3 which allows me to crank up the ISOs significantly compared to my trust rusty 30D. Cheers, Pedro
« Last Edit: February 28, 2013, 02:21:41 AM by pedro »
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jrista

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Re: Canon EF 12-24 f/2.8L [CR1]
« Reply #40 on: February 28, 2013, 02:32:10 AM »
I would absolutely LOVE a 12-24 f/2.8 L for wide-field astrophotography! Imagine the length of exposures you could get, or at lower ISOs, with a 12mm f/2.8 lens! Ooooh, the bliss! I'd spend the money for it, too...12mm f/2.8 astrophotography...man I'm DROOLIN!!  ;D

In terms of exposure time, here is what I figure. Currently, with my 16-35 f/2.8 L, I usually get about 30 seconds  at 16mm out of it, at ISO 800 - 1600, for a decent "printable" shot (i.e. a shot that could be printed at native size...13x19 for the 7D...without particularly noticeable startrailing. Rule of 600 would indicate 38 seconds, so I shorten that a bit for printability). For a web-sized shot, I can usually expose for about 40-45 seconds, and often use a higher ISO. With the 12-24 f/2.8 L, I figure I could get 45-50 seconds out of it for printables, and maybe as much as 65-75 seconds for web-sized shots! And that is nothing to say of the wider field of view, which would be nice at times...

@jrista: Did I get that wrong with rule of 600? I thought the calculation 600:lens length refers to its LONG end? So the 16-35 won't give you more than about 16 sec of exposure. Therefore I like the 5D3 which allows me to crank up the ISOs significantly compared to my trust rusty 30D. Cheers, Pedro

It simply referrs to the focal length you are using. Doesn't matter if the lens is prime or zoom...a zoom is nothing more than a lens that lets you change the selected focal length without swapping lenses. If I use the 16-35 @ 16mm, then the rule of 600 would logically apply to 16mm, not 35mm.

pedro

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Re: Canon EF 12-24 f/2.8L [CR1]
« Reply #41 on: February 28, 2013, 03:15:59 AM »
I would absolutely LOVE a 12-24 f/2.8 L for wide-field astrophotography! Imagine the length of exposures you could get, or at lower ISOs, with a 12mm f/2.8 lens! Ooooh, the bliss! I'd spend the money for it, too...12mm f/2.8 astrophotography...man I'm DROOLIN!!  ;D

In terms of exposure time, here is what I figure. Currently, with my 16-35 f/2.8 L, I usually get about 30 seconds  at 16mm out of it, at ISO 800 - 1600, for a decent "printable" shot (i.e. a shot that could be printed at native size...13x19 for the 7D...without particularly noticeable startrailing. Rule of 600 would indicate 38 seconds, so I shorten that a bit for printability). For a web-sized shot, I can usually expose for about 40-45 seconds, and often use a higher ISO. With the 12-24 f/2.8 L, I figure I could get 45-50 seconds out of it for printables, and maybe as much as 65-75 seconds for web-sized shots! And that is nothing to say of the wider field of view, which would be nice at times...

@jrista: Did I get that wrong with rule of 600? I thought the calculation 600:lens length refers to its LONG end? So the 16-35 won't give you more than about 16 sec of exposure. Therefore I like the 5D3 which allows me to crank up the ISOs significantly compared to my trust rusty 30D. Cheers, Pedro

It simply referrs to the focal length you are using. Doesn't matter if the lens is prime or zoom...a zoom is nothing more than a lens that lets you change the selected focal length without swapping lenses. If I use the 16-35 @ 16mm, then the rule of 600 would logically apply to 16mm, not 35mm.

@jrista: oh, didn't know that then. great! thanks for the explanation. then I already have my (at least) 16-24 once I purchase the lens. and that's plenty compared to a phantom lens that might surely be sold at twice the price of the 16-35 should it ever reach the shelves...glad to learn this...that gives me at least 35 sec at the wide end then...wow. 8) So taking a picture at let's say ISO 3200 or even 6400 means capturing way more light than at ISO 800 on a 30D...!!!
« Last Edit: February 28, 2013, 03:21:42 AM by pedro »
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jrista

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Re: Canon EF 12-24 f/2.8L [CR1]
« Reply #42 on: February 28, 2013, 03:51:35 AM »
@jrista: Did I get that wrong with rule of 600? I thought the calculation 600:lens length refers to its LONG end? So the 16-35 won't give you more than about 16 sec of exposure. Therefore I like the 5D3 which allows me to crank up the ISOs significantly compared to my trust rusty 30D. Cheers, Pedro

It simply referrs to the focal length you are using. Doesn't matter if the lens is prime or zoom...a zoom is nothing more than a lens that lets you change the selected focal length without swapping lenses. If I use the 16-35 @ 16mm, then the rule of 600 would logically apply to 16mm, not 35mm.

@jrista: oh, didn't know that then. great! thanks for the explanation. then I already have my (at least) 16-24 once I purchase the lens. and that's plenty compared to a phantom lens that might surely be sold at twice the price of the 16-35 should it ever reach the shelves...glad to learn this...that gives me at least 35 sec at the wide end then...wow. 8) So taking a picture at let's say ISO 3200 or even 6400 means capturing way more light than at ISO 800 on a 30D...!!!

Actually, to get really technical, the rule of 600 really is kind of a bad way to figure out how long you can expose a night sky with digital sensors. You'll find a lot of anecdotes, such as use the "FF effective focal length on APS-C" and whatnot. None of it really applies, since what actually matters is pixel density, which is independent of form factor.

Here is a better way to figure out what you can really handle (for "native resolution" presentation, anyway...you could transform for web sized with a scale factor): Determine the arc degrees per pixel for a given focal length and pixel size.

If we assume a 12mm lens on a FF sensor, that gives us a horizontal FoV of approximately 111°. If we assume we are shooting with a 5D III, that means we have a pixel row of 5760 pixels, or ~52 pixels per degree. The reciprocal of that gives us the number of degrees per pixel, which in this case is 0.0192°/px. To calculate how many seconds it will take a star to traverse one pixel, divide that number by the arc degrees per second a star moves across the sky thanks to the rotation of the earth (360° / (24h * 60m/h * 60s/m) = 360° / 86400s = 0.0042°/s). At 12mm, a 5D III will experience a time on pixels period of 0.0192°/px / 0.0042°/s, or ~4.6s/px.

So, assuming a time on pixels period of 4.6s/px on the 5D III at 12mm, we can figure out how long, in total, we might be able to expose for by determining the number of pixels we are willing to let a star traverse before we assume trailing will be visible. For maximum quality, or the ability to see absolutely zero startrailing at "native resolution", and even offer enough sharpness to enlarge a night sky photo, you wouldn't want a star to affect much more than 4 pixels in a 2x2 block...a 2 pixel pitch. That would mean at 12mm, you could only expose for 9.2 seconds. Thanks to atmospheric effects which causes stars to affect more than the mere 2x2 pixel grid their point light source might affect directly anyway, we can generally assume a larger star trailing pitch. In my experience, 6-9 pixels is easily good enough for native resolution output (and much more than that for web size). Assuming the factor of 9 pixels is valid, that gives us an exposure time of about 42 seconds for a 12mm lens on the 5D III. On the 7D, the same 12mm lens is the FoV equivalent to a 20mm lens on FF, which ultimately gets us to ~3.8s/px, or an exposure time of about 34 seconds for a 12mm lens on the 7D.

If we want to figure out how long to expose for web-sized images, you could make the assumption that the scale factor between native size and the final web size, times the base 9 pixel pitch, divided by two is sufficient to minimize trailing at any size:

Code: [Select]
scaledPitch = (dimNative/dimWeb * 9) / 2
I generally like to scale my images to around 900 pixels long size for the web. The ratio between native size and web size is 5760/900, or 6.5x, which when halved leads to a pixel pitch of ~29 pixels. At 12mm on the 5D III, that gives us a maximum possible exposure time of ~ 2min22sec, which still seems too long. To compensate, I assume the scaled pitch is diagonal, so computing for the horizontal or vertical pitch I get (sqrt(diagPitch^2 / 2) = horizPitch; sqrt(29^2/2) = ~20 pixels. That leaves us with a maximum exposure time of ~90 seconds for a 900 pixel web sized image (~5x7" size on the average screen).

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Re: Canon EF 12-24 f/2.8L [CR1]
« Reply #42 on: February 28, 2013, 03:51:35 AM »

pedro

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Re: Canon EF 12-24 f/2.8L [CR1]
« Reply #43 on: February 28, 2013, 05:47:00 AM »
booah. quite some math...thanks a lot for your highly engaged post. not that I would "get" it, but I will try to figure that out. must be great to know all that about photography, so 600 rule naked and uncensored seems quite a bit "stoneagish"...hence I am not great in math, it must do  8) but I keep on reflecting your formula. saved it to my notebook to have it with me. Best regards.
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pwp

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Re: Canon EF 12-24 f/2.8L [CR1]
« Reply #44 on: February 28, 2013, 07:41:15 AM »
Personally, it would be much more useful for me if Canon came up with 16-35 f/2.8 MkIII with sharpness in line with 24-70 II and 70-200 f2.8 II, as well as a real good 35 mm end..

+1....now you're talking!

-PW

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Re: Canon EF 12-24 f/2.8L [CR1]
« Reply #44 on: February 28, 2013, 07:41:15 AM »