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Messages - Zv

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271
Third Party Manufacturers / Re: Rumor: Sigma 16-20 f/2 DG Art [CR1]
« on: December 19, 2013, 09:46:50 AM »
4mm of zoom? Why bother? I guess there is quite a difference between 16mm and 20mm on FF but why not just pick one focal length and make it awesome. Like 16mm or 17mm f/2.8 would be perfect.

Would this lens be the worlds shortest zoom if it was made??

272
Lenses / Re: DXOMark: Sigma 24-105 f/4 DG OS Reviewed
« on: December 19, 2013, 09:36:04 AM »
Interesting discussion!

Now I think I understand practical purpose of this parameter in DxO stats.

Did anyone see lenses with calculated T-stop equal to F-number on them?

Many of the better primes (particularly the new ones) are much closer.  I've already mentioned the new EF 35mm f/2IS, which has both an f-number and t-stop of 2.  In the past, I would say that many primes are more likely to be close than zooms (where more compromises are made), and that does speak well of the light transmission of the new Sigma 24-105. because it manages to transmit just about (almost) the amount of light that the f-stop suggests.

How can the T value be the same as the f number if the lens clearly vignettes wide open? Is T value only measured in the center?

Just asking, I have no clue how the T value is actually determined.

273
Lenses / Re: DXOMark: Sigma 24-105 f/4 DG OS Reviewed
« on: December 19, 2013, 12:16:43 AM »
Okay, I think I understand how the whole lens, camera metering works. The lens tells the camera its max aperture, the camera takes a reading based on that and the light it's seeing, it's actually basing the calculation on the t stop it's seeing relative to the f stop it's given?

T stop is just a theoretical (measured in a lab??) value.

When you half press the shutter the meter is activated and the lens does nothing really, it's already wide open to allow as much light in as possible. The camera then does it's calculations based on the amount of light hitting the sensor.

When you fully press the shutter the aperture then adjusts to the required setting and the shutter moves to achieve a correct exposure.

The only time you might notice T stops is if you were using M mode and switching lenses for the same scene. For example lets say you set up a shot at f/2.8 1/60 ISO 100 and it looks perfect. You then switch lenses and set it to the exact same settings and notice the shot is under exposed slightly. No big deal you just crank up that ISO or adjust shutter speed and you're back on track!

An example where you might encounter this situation is say you're using the 24-105L and shooting at 24mm and say f/8. You decide you're not a fan of the 24-105L at the wide end so you switch to your 24L  or whatever and try again. Surprise surprise it looks better now!

That's basically what this is all about. The Sigma lens would be slightly brighter and of course better. But the amount is fairly small.

274
Lenses / Re: DXOMark: Sigma 24-105 f/4 DG OS Reviewed
« on: December 18, 2013, 10:46:09 PM »
So you attach an f/2.8 lens to the camera, the max aperture reading f2.8 you see is based on what the lens tells the camera, not what the actual light reading the camera see's based on the focal length?

Yes exactly. F stops only refer to the physical size of the aperture. It does not represent the actual amount of light the lens can transmit.

The maximum amount of light that gets through when the lens is at f/2.8 is what the T stop refers to. By the time that light has gone through the front element, all the elements in the middle (could be several) and out the back and onto the sensor it is no longer at 100% because some of it got reflected along the way. How much got reflected depends on the quality ofthe glass and the coatings.

Easy way to think of it. F stop is just how big the hole is. T stop is how much light is allowed to pass through the hole. If that hole is covered in spider webs not much light gonna get thru! Haha!

Also when you stick a filter in front of the lens it also affects the T stop since the filter is essentially adding another element in the light path.

It makes sense why prime lenses have better image quality than zooms. The zooms tend to have more glass elements thus blocking more light.

No lens is perfect, you'll always lose a bit of light.

275
Lenses / Re: DXOMark: Sigma 24-105 f/4 DG OS Reviewed
« on: December 18, 2013, 10:13:54 PM »
I have always been a bit confused about the whole f stop vs. t stop comparison. If I understand it right then a 100 mm f/2 lens has a 50mm max aperture, 100/2 = 50. The lens may pass less light, that is the t stop, an actual transmission or equivelant rating. Does the camera recognize this and make exposure calculations on a lenses light transmission capabilities or does it default to the embedded code of the lens? Is slight underexposure only an issue at max aperture?

If you have two lenses of similar design - one T 2.8 and other T 3 and put them both on the same camera at the same settings you would notice one is slightly brighter. With the camera in Av mode the metering system would compensate via shutter speed so they look similar. The downside being you lost speed. How important that is depends on what you're shooting - action vs landscape for example.

Since the 24-105L isn't really known for it's action freezing abilities it's not even an issue. For low level light situations it could make a slight difference though. But then again for low light you'd use a faster lens.

However, more light is always welcome so in the grand scheme of things better T stop values are desirable.

276
Slight off topic thinking out loud.

Names we'll prob never see from Canon -

2D - can you imagine a 2D2? Sounds too much like a star wars character.
3D - do we need special glasses or what? Also too close to nintendo 3DS.
4D - four also reads as death in Japanese.
8D - 2 x 4 = 8 still a multiple of four. Superstition may keep this name at bay! Also sounds like you're saying 80.
10D - we already had it. Could make a comeback though.

You can see why they chose 1, 5, 6 and 7 now. Maybe they're runnin out of numbers?

I really hope they don't use random made up words instead!


277
Could we see the 7D line become 8D or 9D instead? Maybe Canon want to push the APS-C models further down the chain?

Maybe if they made a 7D2 it might confuse some people as to which is "better" the 6D or 7D2. The numbers are a bit close and some already have the notion that the 7D is full frame.

But none of that makes sense because the 7D would still exist. They can't erase it completely!

We should start a petition to keep the 7D name alive!

278
Lenses / Re: Two Lenses Coming for CP+? [CR2]
« on: December 18, 2013, 12:41:03 PM »
I don't get how the 135L can be so cheap and the 35L so expensive?

It is the difference in designs. A 35mm lens on a 44mm flange distance is a retrofocus design, that is it has to bend the light multiple times to get it to focus on the sensor, telephoto lenses, in contrast, are very simple lenses to design and build, it is a straight shot through to the sensor and additional elements are just for correcting aberrations.

The TS-E 17mm was the lens that made me realise all Canon lenses are exactly as designed, and the compromises in them are there for specific reasons, cost, quality tradeoffs, etc. Look at the 70-200 f2.8 IS MkII compared to the MkI, sports shooters love it because it is sharper and focuses faster, meanwhile portrait shooters are not so keen because of the slightly harsher bokeh, all trade offs, but all built in at the design stage. Anybody that can make a 17 mm lens with zero distortion is very clever, anybody that can make a 17mm lens to work on a 44mm registry distance is comfortably smarter than that, but to then drive home the total dominance of lens design and build capability by making it a tilt shift lens is, quite simple, showing off.

Canon make the lenses they do for marketing reasons, they come with the limitations and characteristics they do to meet the brief for that lens. It seems the brief can be top quality at any cost and we will sell them for what we can get, the prestige thing, like the 17TS-E and the 200 f1.8, it was said that Canon made a loss on every 200 f1.8 they sold; or the brief can be how cheap can we make it to get people into a system, the 50 f1.8 and many kit zooms spring to mind.

Another consideration is that the needs of film and digital sensors is quite different, most of these lenses core layouts were designed long before digital and the need for perpendicular, or as close as possible, light rays, another major consideration for wide angle and retrofcus designs. Certainly any new wide angle designs will take that into consideration.

Ah I didn't realize the 35 was a retrofocus design. I guess that makes sense now. Thanks!

279
Lenses / Re: Two Lenses Coming for CP+? [CR2]
« on: December 18, 2013, 12:38:09 PM »
These days it may seem anathema, but I have been so unimpressed with the Sigma's bokeh (a pretty huge deal in a wide aperture prime) that I went with the Canon 35mm f/2 IS instead, despite a slight sharpness downgrade from the Sigma.  I certainly think that Canon can improve on the Sigma design by offering a properly weather sealed prime that has both great sharpness, much more accurate AF, and smoother bokeh transition.

Where Canon has a problem is the price department.  If they aren't a bit more competitive with the pricing it will be very hard to market an only marginally better lens at a price point that could easily be more than double that of the Sigma.  I saw a sale on the Siggy yesterday for $699, so the price is certainly already dropping.  That's a tough sell for Canon.

The 24-70II is optically fantastic, but its very steep MSRP has meant that a LOT of people have opted for the almost as good but much cheaper + VC Tamron.  This a trend that Canon can't afford to keep repeating.

It would be nice if the 35L was dropped in price too! It's one that I want but damn that thing is still going for $1500 or more these days. Seems to have gone up in price! I don't get how the 135L can be so cheap and the 35L so expensive? If the drop the price to $1000 even I'd buy it over the Sigma. And then Canon could release the 35LII at the same price as the 35L is now?

Same with the 50L. I'd value that at $900. At that price I'd buy it. You can't seriously charge people $1500 for that when the 24-70L II is $1699 with rebate! I mean I'd rather fork out the extra and say screw the 24L, 35L and 50L!

But even then I still want a prime. I feel like I'm done with zooms.

Check this one then:

https://foto.no/cgi-bin/bruktmarked/visAnnonse.cgi?id=210639

6000,- nok is 984 usd. It's a 2007 model..

Does it include shipping to Japan?? Why is it more expensive in the country it's made in??

280
Article on stolen camera gear.....

http://petapixel.com/2013/12/17/lenstag-infographic-breaks-gear-stolen-gear-gets-stolen/

And by the way, Christmas is the peak for stealing things from vehicles....


I didnt know about lenstag. Need to check that out. Thanks for sharing this!

281
Lenses / Re: DXOMark: Sigma 24-105 f/4 DG OS Reviewed
« on: December 18, 2013, 12:20:02 PM »
The t-stop of 5.1 for the Canon 24-105 is a bit of a shocker to me.  tsk tsk Canon!

So basically the Sigma is about the same price and about the same sharpness, but half a stop brighter.

Not surprising since it has a bigger front end! Why is that a shocker?

An f/4 zoom lens is not one you'd expect to have optimal light transmission anyway. It has IS that easily makes up for it. Good for Sigma though for improving on the design. However that seems to have come at a price - added bulk.

Separate note. Even though I buy in yen I always write prices in USD here on this forum because that's what most people understand. It doesn't bother me. Keeps things standardized. But the point is when we convert we all get funky numbers. I think when quoting a street price we should just use amazon.com or something.

282
Lenses / Re: Two Lenses Coming for CP+? [CR2]
« on: December 18, 2013, 09:57:11 AM »
These days it may seem anathema, but I have been so unimpressed with the Sigma's bokeh (a pretty huge deal in a wide aperture prime) that I went with the Canon 35mm f/2 IS instead, despite a slight sharpness downgrade from the Sigma.  I certainly think that Canon can improve on the Sigma design by offering a properly weather sealed prime that has both great sharpness, much more accurate AF, and smoother bokeh transition.

Where Canon has a problem is the price department.  If they aren't a bit more competitive with the pricing it will be very hard to market an only marginally better lens at a price point that could easily be more than double that of the Sigma.  I saw a sale on the Siggy yesterday for $699, so the price is certainly already dropping.  That's a tough sell for Canon.

The 24-70II is optically fantastic, but its very steep MSRP has meant that a LOT of people have opted for the almost as good but much cheaper + VC Tamron.  This a trend that Canon can't afford to keep repeating.

It would be nice if the 35L was dropped in price too! It's one that I want but damn that thing is still going for $1500 or more these days. Seems to have gone up in price! I don't get how the 135L can be so cheap and the 35L so expensive? If the drop the price to $1000 even I'd buy it over the Sigma. And then Canon could release the 35LII at the same price as the 35L is now?

Same with the 50L. I'd value that at $900. At that price I'd buy it. You can't seriously charge people $1500 for that when the 24-70L II is $1699 with rebate! I mean I'd rather fork out the extra and say screw the 24L, 35L and 50L!

But even then I still want a prime. I feel like I'm done with zooms.

283
Lenses / Re: DXOMark: Sigma 24-105 f/4 DG OS Reviewed
« on: December 18, 2013, 09:43:51 AM »
I wonder if this lens is really aimed at Nikon users.

As others have said, for Canon users this may be a nice lens, but it's not an "must have." The street price of the 24-105 "L" is less. Just about every full frame Canon user who would want this lens already has the Canon version. There are currently more than 500 in stock on the Canon refurbished store (selling for more than the street price of a new "white box" version).

Basically, the market is flooded already, so I wonder if Sigma may have made a mistake with this lens unless they are just targeting Nikon users.

I admire what Sigma has been doing lately and I appreciate the competition from third party manufacturers, but I'm scratching my head over this one. It runs contrary to most other recent releases from Sigma, Tamron and Tokina – where they have either been focusing on giving consumers choices that Canon and Nikon don't offer or they've been undercutting Canon and Nikon on price with staples like the 70-200 f2.8.

Big +1.  As soon as this lens was announced, I felt that the only way that it would be a success is if it destroyed the 24-105L optically.  It didn't seem to offer any other compelling reason to purchase:  focal length the same.  IS/OS.  Same maximum aperture. 

Downsides included:  Heavier and larger front element.  Not weather sealed.  Sigma's reputation for sometimes inconsistent AF accuracy.  Third party lens with potential downsides that come with that.

I think the consensus out there is that in SOME ways the Sigma is better optically, but it certainly doesn't blow the 24-105L out of the water.  That is going to make it a hard sell.  Just out of curiosity:  a lot of you own the 24-105L - are you planning on selling it to get the Sigma? 

I don't own the 24-105L right now.  I've owned two copies in the past and liked them considerably.  I own let my last copy go when I got the Tamron 24-70 VC and found that I wasn't using the Canon anymore.  But if I owned the 24-105L right I certainly wouldn't be selling it to get this lens.

I bought my EF 24-105L second hand. Got it fairly cheap too. I knew fine well going in that it was not going to a lens that had amazing IQ and that was fine because I just needed something to work with in the general focal range. For that it performs well, especially from 35mm onwards I'm seeing really quite sharp images. 24mm performance could be better but I can live without since I have the 17-40L and now the Samyang 14mm (on my 7D it gives an almost 24mm look). The weather sealing has came in handy when on vacation / at te beach etc. the lens isn't light by any means but a decent amount that I can handle.

Will I change for the Sigma? Nope. The Sigma's bigger and heavier and not sealed. Don't give a damn about a tiny bit extra sharpness at the wide end.

I think for those who don't need the extra range the 24-70 f/4 IS beats both the Sigma and 24-105L and provides a nice third option. If I was to change I'd prob go for that one, just wish it was a little cheaper though.

284
Lenses / Re: Two Lenses Coming for CP+? [CR2]
« on: December 16, 2013, 08:03:29 AM »
Oh PLEASE dear Canon, give me something wide. Like 15mm f2.8 fisheye / 17-40L IS  :-\

BTW hello to all you wonderful camera friends. I've been here and sneak peeked in many months and now my first post  8) Have a awesome day


Roham From Oslo/Norway

Welcome to CR RohamR! There are a lot of people here wanting some wide angle action next year! Me included! I really hope we see that rumored 16-50 f/4 IS. That would be perfect!

285
EOS Bodies - For Stills / Re: What happened to A-DEP?
« on: December 16, 2013, 07:37:56 AM »
Unless I'm mistaken, it has disappeared off of Canon bodies...?

I don't think I ever used it when I had my T2i. Seemed to be very much like P mode. And on a crop camera that most people will be using with slow aperture kit lenses there isn't much shallow dof to control. Everything looks the same unless you are really close to your subject. Plus creative auto lets you control the background blur and is easier to use.

I'm glad they got rid of it. It doesn't really help newbies understand the relationship between aperture and dof IMO. 

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