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Messages - Zv

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EOS Bodies - For Stills / Re: What a waste of 1-serie camera
« on: December 22, 2013, 07:57:51 PM »
I expected more resistance from the lens mount on a magnesium body which eventually supports lenses that weigh several pounds. :o In practical use, a 6D with Samyang 14mm would be more appropriate to stand behind the goal. 8)

Guess you never played football. The player in question gave it quite a whack.
Also, a 6D wouldn't make any sense ... you need the fps that the 1D bodies offer to shoot a fast game like football.
I'm from Brazil, so I played a lot of football in school. Actually I was goalie and has suffered a few strokes of the ball, but fortunately none in sensitive parts. ::) 6D is obviously not suitable for the hardness of sports photography, but can be a "disposable" body to stay in a place with high risk of total loss along with Samyang 14mm. I would not put 1DX + EF14mm L behind the goal, unless the equipment belonged to a newspaper and had insurance. In addition, WI-FI capability can serve for monitoring and remote release. After all, nobody wants to get in the way of the ball, is not it? :P

Interesting. You could potentially have two or three 6D cameras and be trigerring them remotely via wifi and smartphones to increase the chance of getting the shot.

Also in post you want to see and control the amount of color shift as the sun sinks. For example in shot no 1. lets say you correct WB to 5000k and then sync all. Great but now shot 100 is the wrong color because by that point the sun went down and things got cooler and you wanted to preserve that look. Auto is too inconsistent and you'd have to muck about fixing a lot more shots then resyncing. With a fixed value you know how much or how less you need to move it by.
Sorry for removing most of the comments to reply I just wanted to avoid another tunnel thread (there was one where we ended up making fun  :) ).
I do not disagree in concept too much I think. I just believe it is the same with ACR +1 step.
You just mention an example of a 5000K temperature applied to all via sync. Isn't the same if you have it all at 5000K at the time of shooting?
In both cases you would do either:
1. minor tweeks to some and/or
2. preserve the look of some.

Either starting from 5500K (or 5000) at the time of shooting or from a set temperature from ACR which by the way may also be the same (say 5500K or 5000)...

So I believe it is just a step difference either way  (always talking about raw files)

Now, I have observed that my 5D2 and 5D3 are way off (too warm) at tungsten lighting (as was my 40D). In that case a preset value in K would give better results from the start (which seems to be around 2700K at least for many of my latest interior shooting cases). Still it is not big deal to apply at post and I have the advantage of not forgetting the camera to that value.

It is just the freedom that raw files give us. I believe both ways are acceptable and it actually comes down to personal preference.

Ah yes I see what you're saying now. It's just an extra step to level all images in post to the same value. Hmmm yeah I guess that is essentially the same idea. Fair enough.

Btw what ever happened to that tunnel thread? Did it break the forum? CR was a bit wonky the last few days!

Shot to shot consistency! That's the words I was trying to say but totally spaced out on!

Third Party Manufacturers / Re: Sony A7R shutter vibration problem?
« on: December 22, 2013, 11:36:31 AM »
Just when many of us were celebrating the end of the mirror slap. :( Moving parts shutter weigh far less than the mirror, and shake is more noticeable?. :-\

No just as CR guy says - because the camera is much lighter than your typical FF DSLR and with a longer lens attached via lens collar and foot, the camera is just hanging in mid air. Normally thats cool on a rock solid 1DX or whatever but somehow on the A7R it's floppin about when the shutter moves. Even the tiniest vibration can muck up a shot with a tele lens.

Mirror slap is not an issue with DSLRs on a tripod due to mirror lock option.

My general approach is to set WB at a predetermined value, I use 5,500ºK, this takes one inconsistency out of the equation. If you use Auto WB you have to adjust for the cameras idea as well as the actual light, in post processing I find it easier to adjust everything by the same amount than try to even out the inconsistencies Auto WB introduces, then just tweak in groups as the light changed.

+1. For several years I used AWB but found I was spending a lot of time in LR micro adjusting the WB of each shot from a set to compensate for the white balance the camera selected for individual pictures.  Keeping the WB set for Daylight or 5500K alleviates those PP issues.
I can't see how that helps if the light for exterior shooting changes. 5500K will be wrong and you will still have to make changes. Unless you take a lot of pictures at the same external place at exactly the same conditions of course where the changes if any will be applied to more than one photos at the same time.

I think that's the point, you already know the exact k with out having to look it up, make the work flow slightly faster
Even with WB set to auto, you can always correct the WB in ACR for one picture, select it first, then select more in Adobe ACR and synchronize WB. It is simple and fast.

Yeah but if you use flash worst thing in the world is Auto WB. Knowing what temp you are shooting at has it's advantages in camera. I think it helps understand color temp better too.

Also in post you want to see and control the amount of color shift as the sun sinks. For example in shot no 1. lets say you correct WB to 5000k and then sync all. Great but now shot 100 is the wrong color because by that point the sun went down and things got cooler and you wanted to preserve that look. Auto is too inconsistent and you'd have to muck about fixing a lot more shots then resyncing. With a fixed value you know how much or how less you need to move it by.

It's hard to explain but it does help your workflow by shooting at a constant temp. Auto can be cool one shot and then warm the next. Then you gotta figure out "was it really cool or was it warm at that point?" With Daylight you know exactly how it was!

Reviews / Re: Rokinon 14mm f/2.8 Wide Angle Review
« on: December 21, 2013, 11:10:22 AM »

Brrrr that looks cold! Credit to you sir for dealing with the cold to get the shot!

EOS Bodies - For Stills / Re: Any reason to choose a 7D over a 70D?
« on: December 21, 2013, 11:04:21 AM »
Very interesting discussion. My wife has a  Rebel 4Ti and she is frustrated with it.   I was thinking of getting her a 70D, but may wait and see if the 7D M2 is a better choice.  She will need a new camera in Sept when we take our next photo trip.

What's the matter with your wife's T4i that it needs to be replaced? And with a 7D2? Did she suddenly become a sports and wildlife shooter? The 70D should be plenty of camera for most people. Get it. Use it. Be happy.

Wait for the mythical beast and you'll end up staying in wonderland forever!

Canon General / Re: Post Processing: A Guide for Nature Photographers
« on: December 21, 2013, 10:56:18 AM »
Lightroom does a pretty awesome job of sorting and cataloging images to help you find your best shots. However for the volume that nature photogs deal in I guess any help with reducing workload and post processing would be welcome. $20 seems reasonable I guess.

For me selection is the most unappealing part of photography. I wish there was a program that could read your mind and select the best shots for you! Even just 100 shots makes me procastinate a lot and avoid my computer like it's the plague!

Third Party Lenses (Sigma, Tamron, etc.) / Re: Samyang 14mm f/2.8 IF ED UMC
« on: December 20, 2013, 10:34:59 AM »

Software & Accessories / Re: My New and Improve GIOTTOS Blower-for safety.
« on: December 19, 2013, 08:44:48 PM »
Seriously how do the airports find these people? Do they put out an ad in the newspaper like this -

"Airport security staff required, must be insensitive, miserable and generally disliked by the public. Must have vendetta against rocket blowers and other photographic equipment. Minimal communication skills needed. Intelligence preferred but not necessary. Previous experience in customer aggravation welcome. Apply within."

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??

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.

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.

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.

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.

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