March 05, 2015, 11:06:29 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 - neuroanatomist

Pages: 1 ... 411 412 [413] 414 415 ... 1030
6181
Wrong: the dof calculator also calculates the circle of confusion. http://dofmaster.com/dofjs.html

The technical mumbo-jumbo can be ignored.

Sorry, but then I suggest that you just ignore it, instead of calling others' correct statements wrong based on your misunderstanding.

FYI, DoFMaster doesn't calculate CoC, it assigns a standard value based on sensor size. It uses that assigned value to calculate DoF.

6182
EOS-M / Re: How do you carry your EOS-M?
« on: July 15, 2013, 02:38:22 PM »
...at home, my current M kit fits nicely in a Pelican Storm im2050 with dividers. 

Canon (especially Canon USA take note  ;) ): there's room in the case for a couple more items, such as the recently-rumored new flash for the M line above the 90 EX and a new EF-M lens...

6183
EOS-M / Re: How do you carry your EOS-M?
« on: July 15, 2013, 02:33:44 PM »
Fits perfectly in my Lowepro Dashpoint 20, which is how I carry it when I'm on the go.

6184
Looking forward to them!

...if they could add master function in the 430ex II replacement, I am definitely in.

Unlikely.  There's no technical reason the 430EX II can't be a master, the control signals for Canon's optical triggering come from the main flash tube, and the 430EX II obviously has one of those.  So expect a replacement 4x0EX flash to be slave only, but able to be triggered by both RF (600EX-RT or ST-E3-RT) or optical masters.

6185
Lenses / Re: Dxo tests canon/nikon/sony 500mm's
« on: July 15, 2013, 11:55:45 AM »
If transmission really was the most important factor then the Sony should  be out scoring the Nikon.  The Sony equals or beats the Nikon in all the listed categories and has  the lowest transmission of the three lenses.

Transmission on macro scale, not micro. In fact, probably not even measured transmission, but rather the specified max aperture. That's why the 50/1.8 lenses outscore the 500/4 lenses.

If you look at the test results they are measuring the combination of lens and body.  Hard to do otherwise.  Makes comparison between manufactures difficult and less than meaningful.

Yes, and sorry, but I think you are missing the point.  For every measurement, all generated with a body attached, the Canon lens comes out on top, in some cases by a significant margin.  Yet, the Score is a tie.  So...the score is fabricated, pulled from their nether orifices, etc.

If you go over to photozone.de's page, they'll quite clearly state that the measurements (or scores) from one camera system (make + sensor size) cannot be compared with another. Given this I can't see why the same wouldn't be true for DxO. What does that mean? That you cannot compare a score of 25 for the Nikon lens with a score of 25 for the Canon or 22 for the Sony lens.

To be able to compare each lens properly would require each lens being mounted on the same camera.

How do they calculate their lens score? Would love to know but I'm pretty sure that it is corporate secret. For the Nikon one to be so high must mean that the readings are somehow weight on the sensor (e.g pixel size.)

The point is that they measure several parameters of optical image quality from the lens, such as sharpness, transmission, distortion, vignetting, and CA.  They could generate a Lens Score based on those parameters, but they don't. Had they done so, the Canon 500/4 II would have soundly trounced the Nikon 500/4. 

For those who argue that it's reasonable that DxO consider the camera in the 'Lens Score', note that the sensor is already factored into the measurements themselves.  P-Mpix measures sharpness of camera + lens, pixel size affects CA, etc.  Even their transmission measurement changes with different cameras.  So by factoring in the camera directly in the measurements (reasonable) then factoring it in again in the overall score where it's given an undisclosed (but evidently very significant) weighting, means their 'Lens Score' is as much if not more a camera score than a lens score.

One more point - considering just their P-Mpix measure of sharpness, by their definition the Nikon 500/4 results in a loss of more that 55% of the resolution of which the D800 sensor is capable, whereas the Canon 500/4 II only decreases the 5DIII's potential resolution by less than 14%.  Of course, the Canon lens also outresolves the Nikon by an absolute assessment, even taking the higher resolution D800 sensor into account.  But they get the same 'Lens Score'. Right.

They should rename their Overall Scores to a Camera Basic Score and a Lens Basic Score, so we could abbreviate them for what they really are: BS.  Actually, that's probably giving them too much credit, because real Bovine Scat makes good fertilizer, whereas DxOMark's BS has no real-world utility.

6186
Last not least, note that if people rave about thin dof they often mean "strong background blur" except if you like the "only the nose in focus" type shots, and same thing here: bokeh also strongly depends on focal length and object/background distance relationship.

Except that bokeh really refers to the quality of the OOF blur, independent of quantity.  But maybe that's a story for another day.  ;)

6187
There's no "story". DOF is a characteristic of a lens and has nothing to do with sensor size. End of story.

You couldn't be more wrong. Perhaps you're stuck in the circle of confusion...   ::)

If you take two pictures at the same position with the same lens on both a crop and a full frame, the distance between the nearest in focus object and the furthest away in focus object will be the same, so the depth of field does not change. Obviously the image captured will be different on each.

However, if you're talking about the depth of field for an equivalent picture, you'd have to move the full frame camera closer which would result in a reduced depth of field.

In the former case, my head shot just became an eyes-and-mouth shot that I had to delete because most people like to see their whole face in a portrait. The latter case is far more relevant to most types of photography. The exception might be macro photography, where at 1:1 magnification, you are at the MFD of the lens, regardless of sensor size.  But at macro distances, DoF is incredibly thin anyway (and the assumptions made by most DoF calculators don't hold).

As for DoF being solely a property of the lens, what, subject distance no longer matters??

The real story is that DoF is determined by subject magnification and lens aperture.

6188
There's no "story". DOF is a characteristic of a lens and has nothing to do with sensor size. End of story.

You couldn't be more wrong. Perhaps you're stuck in the circle of confusion...   ::)

6189
Lenses / Re: Dxo tests canon/nikon/sony 500mm's
« on: July 15, 2013, 05:11:22 AM »
DXO decided to dumb down their lens+body measurements and to report the results in some metric that they keep secret. From other discussions here, I can guess that it is heavily weighed towards higher MTF's, i.e., it measures mainly what we call "contrast". Then 36 or 22 mp does not matter much.

The most important factor in their BS Score is transmission, which is why the cheap 50/1.8 lenses from both Canon and Nikon score several points higher than any of these 500/4 lenses. It's only when you have lenses of identical max aperture that the other stuff has any influence.  BTW, while the 500/4s score 25, the Canon 50/1.8 on a 5DIII gets 28, and the Nikon 50/1.8 on a D800 gets a 31, and main measurement difference between the 50/1.8s is that the Nikon is 1 P-Mpix sharper (put it on the D3X, it's sharpness and Score tie the Canon). So, the Nikon 50/1.8 is 1 P-Mpix sharper and gets a Score 3 points higher, the Canon 500/4 is 3 P-Mpix sharper, but the Scores are equal.

BS.

I begin to wonder if the 'secret metric' you mention is sponsorship...   :o

6190
Lenses / Re: EF-M 11-22 f/4-5.6 IS STM Not Coming to the USA
« on: July 15, 2013, 04:38:11 AM »
I do not see the EOS-M system being abandoned by Canon in the near future.

By Canon, certainly not.  But what about by Canon USA?  The M has been out for about a year - if you're in the US and want the Canon wrist strap for it, can you order it from B&H?  No - because Canon USA decided not to sell that, nor the leather neck strap.

6191
EOS-M / Re: 43mm circ polarizer for the 22mm ES-M
« on: July 15, 2013, 04:31:10 AM »
There's also the B+W single coated CPL for $55 (at B&H).  I have the 43mm B+W K√§semann, it works very well (had it before getting the M + 22mm, since my Vixia HF M41 camcorder takes 43mm filters).

6192
Lenses / Re: Canon Sale?
« on: July 15, 2013, 04:24:36 AM »
Historically, another round of rebates happens in late summer or early fall.  Those two lenses are often (but not always) on the rebate list.

6193
I didn't look at RRS, but it sure looks slick.  Also, the RRS breaks down nicely and looks like it has some sort of protection for transit, which the Wimberly doesn't.  I tried to put a large ThinkTank lens pouch over it for protection, but no luck.  It cost $600.00 so I don't want it to get whacked for sure.

By 'protection for transit' I suspect you're referring to the pics of the neoprene pouch on their website. That's the LensCoat RRS PG Pouch. It sells separately (B&H) for $90 and while I bought one, I don't use it much. That pouch is big - with the gimbal parts inside, rolled up it's about the size of a 300/2.8 lens, not the most portable and not easily attached to a bag. Instead, I found that the gimbal parts (plus an MPR-CL II rail than makes the gimbal into a multirow pano rig) fits in a Lowepro Lens Exchange 200 AW (sized for a 70-200/2.8), which also attaches easily via Sliplock to my backpack.

FYI, LensCoat also make a neoprene gimbal pouch for the Wimberley II, in black and various camo prints - and much more reasonably priced at $20-25.

6194
Lenses / Re: 400mm f5.6 - Why ?
« on: July 14, 2013, 09:41:50 PM »
When you (and others) mention focus hunting and other autofocusing differences between lens, as a newbie i've wondered about that -- isn't it the camera that runs the autofocusing algorithm?  And the lens just responds to the commands the camera gives it?  So why should one 400mm lens autofocus better/worse than another 400mm lens here?  Or is it really more of a cooperative endeavor between camera and lens?

It's cooperative - there's an AF microprocessor in the lens that works in tandem with the canera's AF system.

6195
Software & Accessories / Re: UV filter advice
« on: July 14, 2013, 08:23:57 PM »
I'd get a B+W MRC, clear or UV, whichever is cheaper.

Pages: 1 ... 411 412 [413] 414 415 ... 1030