Messages

136

EOS Bodies - For Stills / Re: Does Canon really have a Flagship Stills Camera?

« on: April 22, 2013, 12:59:08 PM »

... I never quite understood why people say that FF and APS-C have different DoF (provided the same optics, aperture, and distance to the object are used).

Marketing through misinformation, obfuscation, leading and derogation.

DoF is related to angle of view and aperture. To get the same angle of view at the same distance from the subject, on FF you need a longer focal length (1.6x if we consider a Canon APSC) than on crop.

Then, because f/stops are related to focal length, if you keep the same aperture on both systems you'll see that on crop you end up with a narrower iris. This is why you have more DoF

No it isn't, and this common misunderstanding is why people keep failing to get their heads around this.

Depth of field is a function of two metrics alone, reproduction ratio (how big the subject is projected onto the capturing device)  and aperture. Now if you want to make comparisons across sensor sizes you have to make a standard for reproduction size, it doesn't matter what the standard is, but if you don't you can't make relevant comparisons.

"DOF is determined by subject magnification at the film / sensor plane and the selected lens aperture or f-number." http://en.wikipedia.org/wiki/Depth_of_field

I would strongly suggest people stop talking crap and start reading and learning something authoritative about the subjects they seem so intent on teaching other people about.

137

EOS Bodies - For Stills / Re: Does Canon really have a Flagship Stills Camera?

« on: April 22, 2013, 09:32:00 AM »

To come out with a meaningful figure across sensor sizes you have to standardise output. The "standard" DOF calculator assumes an 8"x10" print viewed at 12" and average eyesight. If you magnify a sensors output more to get to that 8x10 then you have to use a smaller CoC value, because you are enlarging it more.

Crop cameras, as always, can cause confusion. As Nero says, for the same lens from the same place a crop sensor image will return less dof than a FF camera if both images are uncropped (this would have the drawback of completely different framing though, so isn't an accurate comparison). If you crop both images to the same framing the dof is the same (this would emulate focal length limited situations, birding etc). If you use two different lenses (or a zoom) from the same spot to get the same framing (this would be the more normal scenariofor most people) the crop camera image has less dof. You see, depending on how you work the figures a crop camera can be said to have more dof, less dof, or the same dof as a FF sensor.

By the most pragmatic view, two people standing in the same place and taking the same framed image with different sensor sizes (which necessitates different focal lengths), a smaller sensor output has more dof because it uses a shorter focal length to achieve the same framing. Ever wonder why f8 on a P&S renders everything in focus? It is because you are using a 6mm lens.

One of the great mysteries to me is why people debate aperture (particularly very fast lenses) and use cropped images to do it; if you crop an image you decrease it's dof. Want an f1.2 image but only have an f1.8 lens? Stand back and crop.

138

Software & Accessories / Re: Ballhead, clamp and release plate for panos/portrait

« on: April 20, 2013, 11:41:05 PM »

Yes it is an Acratech GP. Far and away the best general purpose photo head I have ever used. I use it inverted most of the time and it makes tripod and head leveling a complete non issue. I can't believe other manufacturers have not copied the design concept yet, it is not evolutionary, it is revolutionary.

139

Software & Accessories / Re: Ballhead, clamp and release plate for panos/portrait

« on: April 20, 2013, 10:54:07 PM »

I dislike the center column they have in Manfrotto 055XPROB for which I really cannot lower pod than the column permits (unless I shoot upside down).

That isn't true, the Manfrotto 190/055 legsets are very adaptable, they allow for both ground level, and cantilevered over table type setups very quickly, easily and securely.

Here is a shot with the 055CXPRO3 set at ground level, just slide the column to the horizontal position.

140

PowerShot / Re: SX50 outperforming 5DIII +100-400mm

« on: April 18, 2013, 07:31:54 PM »

Funnily enough I was in Best Buy yesterday and saw the SX50, it is tiny!

When compared to which point & Shoot??

Compared to a 5D MkIII and a 1200mm lens! 

141

PowerShot / Re: SX50 outperforming 5DIII +100-400mm

« on: April 18, 2013, 01:28:33 PM »

I just applied a little sharpening to the head and a little Gaussian blur to lose the noise in the background. Thought the forum sizing has lessened the effect a bit on your larger version it looks much better.

One area where PS is much better than Lightroom, is problem sharpening.

EDIT: I just downloaded the new full sized copy and it looks very crunchy, something strange has happened to the file. But you get the point, real world comparisons demand optimal exposure and processing to be an accurate guide to what we can get out of them.

Funnily enough I was in Best Buy yesterday and saw the SX50, it is tiny!

142

Lenses / Re: 300 f/2.8L and 400 f/2.8 at f/2.8

« on: April 18, 2013, 12:46:53 PM »

An important thing to remember about dof, if your subject is the same size in the frame the dof is the same regardless of lens focal length. The perspective is different, but the dof is constant. http://luminous-landscape.com/tutorials/dof2.shtml

Now if you are shooting at the same distance the 400 dof at any given aperture is less, of course, but in your original post you said this "I did realize of course that with the 300 the runners are closer to me when I fire the shutter, vs. the 400, which could matter.  "

Also, it is probably the CR forum re-size algorithm but neither of your shots look sharp, however, if on the "missed" shots an adjacent runner etc does have critical sharpness then you are almost certainly looking at a non optimal AF setting for the situation or a technique issue.

This isn't a personal attack, I have been using the 300 for years for surfing and yacht racing, my critically sharp keeper rate for those is 90-95%, even working from a moving boat. I have recently started doing dog herding trials and my critically sharp keeper rate is way down and I am not even moving! Changing lens can be just as dramatic a difference.

Keep improving your technique, I still am after 30 years, and play with the myriad of AF settings the 1DX has, Sportsshooter.com sometimes have people post their complete AF settings for a sport, I know the Sports Illustrated standard 1D MkIII/IV settings were published to give people starting points for different events. If you are not a member join, and ask some questions there, some of those guys really know their AF settings.

143

PowerShot / Re: SX50 outperforming 5DIII +100-400mm

« on: April 18, 2013, 11:51:58 AM »

A bit of optimal processing brings them even closer. For years the best sensors for noise per area were Canon P&S sensors, hard to believe I know, but if they had made a FF sensor using the P&S technology we'd have been using 200MP+ sensors with backlight performance for a while.

144

Software & Accessories / Re: Help me finalize my tripod & ballhead choice

« on: April 18, 2013, 11:02:46 AM »

You are most welcome, funnily enough I was looking at the Promediagear YouTube video for their flash brackets recently. They seem to make a very high quality product and the 5D MkIII L-plate looks to be one of their best fitting designs.

145

Software & Accessories / Re: Help me finalize my tripod & ballhead choice

« on: April 18, 2013, 10:41:03 AM »

And this.

http://www.promediagear.eu/promediagear-l-bracket-for-canon-eos-5d-mkiii-grip.html

146

Software & Accessories / Re: Help me finalize my tripod & ballhead choice

« on: April 18, 2013, 10:39:55 AM »

Quick Google images search threw this up.

http://www.ebay.com/itm/L-shaped-Vertical-Quick-Release-Plate-Camera-Bracket-for-Canon-EOS-5D-Mark-III-/281081812071

147

1D X Sample Images / Re: Any Thing shot with a 1Dx

« on: April 14, 2013, 11:08:10 PM »

Welcome back Garry :-)

I had a similar reaction to yours over some posters here, but like you (I think) realise that there are lots of cool people here too.

148

Speedlites, Printers, Accessories / iDC Triplethreat

« on: February 09, 2013, 04:16:56 PM »

Just a heads up, I really like the iDC Triplethreat flash bracket. I wanted to get another couple (I keep losing them!) and emailed iDC, I pointed out that at $59 they were well above the price of the Bruce Dorn version available for pre-order from B&H, I made them an offer of $100 for three.

They just emailed me back saying they are selling their last remaining stock for $33.99 each, then they are done. I ordered three, I just need to stop losing them now!

http://www.idcphotovideo.com/store/triple-threat-traditional

EDIT: I forgot to add why I prefer them to other designs, I love that they are evenly spaced around the modifier shaft, I can use two on one shaft for six lights (I have five 550EX's and three 600EX-RT's) but best of all, they don't have clamp coldshoes, the slots work much better for the lever style Canon strobes. Great $35 worth.