November 01, 2014, 05:51:40 AM

Show Posts

This section allows you to view all posts made by this member. Note that you can only see posts made in areas you currently have access to.


Messages - Etienne

Pages: 1 ... 20 21 [22] 23 24 ... 45
316
Lenses / Re: What lens delivers the strongest background blur?
« on: August 11, 2013, 10:31:15 AM »
Note:  I signed up to this forum just so that I could reply to this thread, because I need to clarify the technical issues being discussed.

The formula referred to applies only when the background object is located at infinity, and shows that it is proportional to the entrance pupil diameter.  For a given fixed magnification, then, the compiled list is merely a list of lenses sorted by decreasing entrance pupil size.  Unfortunately, this information frequently fails to capture the most interesting behavior of the background blur of a lens, which is its diameter as a function of the distance away from the subject in focus.

For instance, it is possible to have two lenses, say Lens A and Lens B, such that for a given subject magnification the blur circle for objects "close behind" the subject is larger for Lens A than for Lens B, but the reverse is true for objects at infinity.  This occurs because (informally speaking) there are competing factors that contribute to the size of the blur disk.  To complicate matters further, the background distance at which this "switch" occurs is itself a function of the subject magnification.

One such example of this phenomenon is an 85/1.2 versus a 300/2.8 lens.  When both are shot around 1:10 magnification (which is near MFD for both real-world implementations), the former is predicted to have about 2x the blur circle diameter up to about 1 foot behind the subject, decreasing until the two have equal blur at about 11-12 feet behind the subject, after which the 300/2.8 will dominate.  What is happening is that a faster f-number will increase the blur at distances close to the subject, but a longer focal length will increase the blur of very distant objects because of perspective.

To further illustrate, suppose we compare a 50/1.0 against a 200/4 lens.  Both lenses have the same entrance pupil diameter at infinity focus (P = 50mm), so at the same subject magnification, a very distant background should have approximately the same amount of blur.  But which lens should blur objects closer to the subject more?  The answer to this question is one of the reasons why the (out of production) EF 50/1.0L is especially coveted for the way it images--it's not merely for the light-gathering ability of f/1.0.  The combination of a relatively short focal length and a very fast aperture can result in images with a distinctive look, because it simultaneously delivers background blur while showing more of the background scene (owing to perspective), compared to a telephoto lens.  By no means is this everyone's cup of tea, but there is a technical explanation for this behavior.

Of course, the entire complexity of the lens design itself must be taken into account for a more real-world understanding of its blur characteristics.  Aberrations such as Petzval curvature, astigmatism, and spherical aberration, can significantly affect the way the blur looks off-axis.  But for most well-corrected designs, the above holds true, especially for paraxial rays.

+1

This is a very clear and necessary addition to the conversation.

317
EOS Bodies / Re: Crop sensors need cropped lenes
« on: August 11, 2013, 09:35:39 AM »
I think dgatwood is referring to the internal elements.  While you might not be able to change the front element size, ultimately an EF-S lens only needs to cover an APS-C sized imaging circle with a sharp image.  What's that?  A quarter of a FF image circle?  Surely you wouldn't need the same sized internal elements for that?  Or, if you do go with similar sized elements, you might be able to introduce manufacturing efficiencies to keep costs down (as you only need the centre of the element to be of high quality).  Either way, I'm sure an APS-C lens could be made cheaper or lighter.  How much?  Maybe not much.  Maybe a lot.  Dgatwood guesses a 5% weight reduction.  That seems pretty conservative.

However, given that EF lenses exist in the most likely focal lengths and apertures, I think they would have to sell for a noticeable discount on the EF lens price to have any market success.  Maybe they could also be part of a new lens mount.  These will mount on FF cameras, but work in "crop mode" only.

Real life example, and I have both of these sharp lenses:

Tokina 50-135 f/2.8 (FF equiv 80-212mm)   845g, 135mm long, uses 67mm filter
Canon 70-200 2.8 IS II     1490g, 199mm long, uses 77mm filter

I don't think the front element size is linearly connected to the aperture and focal length either. Look at the Canon 50 1.4 vs Sigma 50 1.4

318
Reviews / Re: Which camera should I buy for a first timer
« on: August 10, 2013, 10:04:17 PM »
I forgot to mention that my budget is in USD.

Sounds like am getting a T3i

Thank's everyone. I appreciate your replies. If I have any other questions I will ask here. I will let you guys know what my gear will be later.
I'd suggest you forgo a out of date T3i and consider a refurb t4i.  Its compatible with Canons new STM lenses which have smoother focusing for video.  The T3i is not optimized for a STM lens.  All future Canon DSLR's will likely be optimized for STM lenses.  The T4i and T5i are almost identical, so you don't need a T5i.  The T3i will not autofocus for video and does not have the touch screen.
When you do video with a STM lens, touching a point on the screen will cause the camera to smoothly change focus to the new point. 
You can trade in a worthless old Canon film slr or a broken power shot for a 15% percent discount off the refurb prices.  They are like new and have the same 1 year warranty as new.

Autofocus on T4i and T5i are worthless for filmmaking, They will hunt and are unreliable.
The T3i has handy 1080p digital zoom, and is cheaper at the same IQ
There are no good STM lenses yet, and who knows when they will be available.

319
Reviews / Re: Which camera should I buy for a first timer
« on: August 10, 2013, 12:54:23 PM »
Canon T3i (can be upgraded when you have more money). This camera also has useful digital zoom in movie mode.
Install Magic Lantern
Buy some good lenses: Tokina 11-16 f/2.8 and a Canon 50 1.4 may be all you need.
Tiffen 77mm variable ND filter Must! Get a 58mm-77mm reducer so you can use the Tiffen on the 50 1.4 as well -this will get you all the shallow DOF you will ever need,even in daylight.
You will need Audio gear: Rode videomic pro, get a Zoom H4 or H6(better)
Tripod
Slider, if you can afford it.

320
EOS Bodies / Re: Crop sensors need cropped lenes
« on: August 10, 2013, 12:33:01 PM »
I have a Tokina 50-135 f/2.8 equiv to 80-112 mm.
It's a great lens. Much smaller than my 70-200L 2.8 IS II. BONUS: It is par-focal and that makes a big difference in video.
Pair that with a Tokina 11-16 f/2.8 and it is a great light-weight package for crop.
You could also add Sigma 30 1.4 and/or Canon 50 1.4.

321
Technical Support / Re: Canon 70-200 and 5DII sloppy fit
« on: August 09, 2013, 09:18:11 PM »
BTW ...  if the lens is otherwise a winner, then I'd keep it. You might exchange it and get one with optical problems and have to exchange again.  A little wiggle is normal. If in doubt, take it to a local camera shop and ask the techie there if it appears normal.

PS... I have the 70-200L 2.8 IS II and it wiggles a little on my 5DIII as well. IQ and performance is stellar!

322
Technical Support / Re: Canon 70-200 and 5DII sloppy fit
« on: August 09, 2013, 09:15:43 PM »
Each of my lenses fit a little different. Some have play some are really tight. And they aren't the same fit on different cameras either. One lens can be tight on the 5DIII, moderate on the 60D, and a little loose on the 5DII.
There's tolerances on both camera body and lens. Most of my lenses have a little wiggle; it is normal and will not affect image quality.

Of course it depends on how much wiggle. I had a 40D and lenses seemed a little loose. I had Canon look at it, and it was a bad lens mount on the camera body.

323
Lenses / Re: canon 50mm 1.4 vs 1.2
« on: August 09, 2013, 03:02:07 PM »
I own the 1.4 and have been coveting the 1.2 for a while. I've just seen a mint condition 1.2 second hand for a decent price.


I mainly shoot street and family photos. pretty much exclusively @ widest aperture so I would be buying the 1.2 to shoot @ 1.2


does anyone have an opinion on whether the 1.2 is worth it if I already have the 1.4?

Is there much real world difference between the two? (ignoring the obvious like build quality, size, weight and weather sealing)

I like my 50 1.4. It's light, unobtrusive, and versatile. It does a good enough job in the dark. pretty good at f/2, and biting sharp by 5.6

Your money is better spent on a different focal length for variety. Maybe 35 f/2 or 1.4, or my next lens: 24L f/1.4  :)

324
EOS Bodies - For Stills / Re: My Canon 5D III went down today :((
« on: August 09, 2013, 10:52:34 AM »
Try a different card

I'm shooting with 32GB Lexar Pro 1000x CF. I do have another card at home, I can give it a try at lunch today.

Do you think I have a bad Lexar CF???

It's not the camera.
I had a similar thing happen with that Lexar card and a bad CF card reader on my PC.
Use Sandisc recovery tool to get the images back, and then reformat the card in the camera.

325
EOS Bodies - For Stills / Re: My dead 5D Mark III Story
« on: August 09, 2013, 09:35:40 AM »
This is an odd story.
I've used my 5DIII in light rain, no problems so far.
In the past I've also used my 40D, 60D, 5DII and other cameras in enough drizzle that they are slightly wet when I came in, not to mention cold to warm transitions. I've just patted the water off and let them sit without  removing lenses or batteries until fully dry.
Haven't had a problem with any of these cameras.
I suspect that something was wrong with this camera since it was built.

326
EOS Bodies / Re: EOS 7D Mark II Information [CR2]
« on: August 07, 2013, 05:23:11 PM »
.
Nothing ignites passionate argument like Religion, Politics, and ... DOF on APS-C

Yep.  It's the inevitable death-spiral of a 7D rumor thread.

- A

+1

327
Lenses / Re: Canon EF 100-400 f/4-5.6L IS Update [CR2]
« on: August 07, 2013, 01:38:28 PM »
The photographer in me is hoping for a home run on this lens,
and the banker in me is already crying.

328
EOS Bodies / Re: EOS 7D Mark II Information [CR2]
« on: August 07, 2013, 01:33:21 PM »
.
Nothing ignites passionate argument like Religion, Politics, and ... DOF on APS-C

329
EOS Bodies / Re: EOS 7D Mark II Information [CR2]
« on: August 07, 2013, 01:24:39 PM »
To summarize:

Full-Frame is better at everything, Crop is cheaper.

While that is a fact, it does not summarize the original thread. In fact, it does not even relate to the original thread!
People (including some of CR's more illustrious contributors) keep posting in this thread how FF is better than Crop. We get it! Why whip this dead horse? If someone disagrees, be magnanimous and quietly laugh at their ignorance or denial.
This thread is about the "hopes and dreams" of people who cannot upgrade to FF or choose not to. Let's discuss this particular thread within that purview, yeah?

This thread was all over the map long before my comment, which was to poke fun at all of that stuff.
I am not anti-crop. Although I the 5DIII is my favorite, I have and use a 60D, and an EOS-M, and I am keenly interested in the upcoming 70D and possible EOS-M successor.

330
Not only is it arbitrary, but it also changes over time.  For example, when I was growing up, 28mm lenses were far more common than 24mm lenses.  But these days, I doubt many people are buying 28mm lenses - all the interest is in 24mm lenses or wider. 

The same could be said for 85mm.  While appreciating that many people buy 85mm lenses, I suspect that the "standard" longer prime would be in the 90-135mm range (especially when you consider all of the macro lenses in that range that are sold).

I agree with the 24mm vs 28
But 85mm is still by far the most popular short telephoto.
B&H has almost 1400 reviews of the 85 1.8, and only 90 reviews of the 100 f/2, even though these two lenses are about the same price, same size, and deliver the same IQ

Pages: 1 ... 20 21 [22] 23 24 ... 45