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Tuesday, 09 September 2014

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I own an A6000 and love it.The image quality is second to none. I upgrade from the NEX-C3. Besides the Sigma's and Sony's 50mm I shoot it with old Minolta MD lenses. In the 24mm focal I have a Sigma Ultra Wide II f2.8 which rocks. Particular for the 18 euros it cost me. My only regret is that there are no button profiles. I'd have one for manual focus lenses and one for AF lenses.

One of your other favorite cameras (as I recall) is on sale, too. The GX7 is $300 off ($699 body only).

Racquetball?! Genius. Seriously. I have a retrieve-obsessed lab, and always hate using tennis balls since the fuzz is abrasive to her teeth. This is such a great idea! Thanks!

Butters pictures! ;-)

It's always good when camera gear is on sale. Fuji also has a series of X-lenses presently on sale.

Speaking of mirrorless cameras, and now that TOP is up to flank speed again, how's life with the Fuji X-T1 and Olympus E-M1?

Haven't heard much from you about those recently....

Amazon has a couple left with zoom lens for only $100 more. I ordered one for my domestic partner. But if she doesn't like it, it's not going back!

The blue ball looks egg shaped on my monitor, and I assume that is it is spherical.

Distortion when mapping pixels to widescreen monitor?

Pincushion distortion in lens (probably not for the Zeiss lens and probably yes for Sony zoom),

Or, trick of the eye?

Caution when using racquetballs with large dogs -- they can aspirate (inhale) the ball and choke. I know this from experience with a retriever.

(Mike -- I'll understand if you don't post this. At least take it under advisement with Butters.)

I bought the NEX-6 about 18 months ago, strictly to get a decent camera system that was much more conveniently sized for air travel on business trips than my DSLR cameras. I attempt to carry everything of importance with me in my carry-on luggage, and the need to include a CPAP machine in that luggage had created a logistics challenge for my existing camera equipment.

At the time, I wondered seriously if I would regret the photographic sacrifice I was about to make, but THAT assumption was a BIG error in judgement!

I now use the NEX-6 for over 95 percent of all the pictures I take - which shows you my opinion of it. I have added some E-mount prime lenses, including the Zeiss 24mm that Mike loves - although that was purchased from a store in immaculate used condition for $450, rather than at its $1000 list price.

Mike remarked that there are probably good quality E-mount lenses available that are significantly less expensive than the Zeiss, and I can attest that this is the case. I have a Sigma 30mm f:2.8 that I use regularly, and it currently sells for $199.

It's not quite as good as the Zeiss 24mm, but in *my eyes* it is much, much more than acceptable, and 30mm on an APS-C sensor is closer to my personal preference for focal length than 24mm, so it gets used more than the Zeiss 24mm. (I was very disappointed by Sigma quality some years ago, and almost did not buy this lens even though a number of people were raving about it on-line. I'm very happy that I did make the purchase.)

At the current price for the NEX-6, I am having to struggle to avoid buying another one just for redundancy. Perhaps I have spent too many years in aerospace? :-)

- Tom -

In terms of your favored camera, I expected the recently announced Zeiss Loxia 2/35 with the Sony A7R would be tugging at your heart-strings (just as much as the new model Miata).

Okay, Mike, if you have no immediate replacement for the NEX-6 lined up, why are you getting rid of a camera that you like so mich?

[Who said I'm getting rid of it? I have no plans to get rid of it.... --Mike]

There are some very good and very cheap lenses for E-mount. Here's my "holy trinity" for my NEX-7:-

Sigma 30mm f/2.8
Sigma 19mm f/2.8
Sony 50mm f/1.8 OSS (now comes in black too!)

My Sigmas are the old, "pre-ART", versions. The Sigma 60mm f/1.8 is also reputed to be great.

I've been using an elderly 24mm f2.8 Nikkor on my NEX-6. It's amazing that I don't miss the autofocus. Here's the latest...
https://www.flickr.com/photos/11302402@N00/15193545485/in/photostream/player/

Mike,

Glad the dogs like their new toys. My experience with our dogs has been almost universally the same. -- they really do like these balls a lot and are obsessive about them. Just like butters. Seems to me like Penn has a real business opportunity with these balls, other than as something to pound on a racquetball court? Oh well --just so they keep making them!

Still on the road -- drinking some really good wines and Ports in Porto, Portugal. Making some good pics along the way too. More When I get back in another week.

Best

Oldbro

Robert Hudyma wrote:
> The blue ball looks egg shaped on my monitor, and I assume that it
> is spherical.
>
> Distortion when mapping pixels to widescreen monitor?
>
> Pincushion distortion in lens (probably not for the Zeiss lens and
> probably yes for Sony zoom)


Mapping a flat, 2D digital pixel file to a flat, 2D computer display is a simple, linear scaling operation that can't cause any distortion.

The blue ball looks egg-shaped because, from a projective geometry point of view, you're not sitting at the proper distance from your monitor :-)

To eliminate the anamorphosis created by this incorrect observation distance, you should place your eyeballs at the same relative distance of the display as the lens' optical center was from the film or sensor.

What is the "proper", non-anamorphic observation distance of a picture ?

Assume, for example, that a 35mm wide-angle lens is used with a 24x36mm film or sensor format.

The ratio between the lens' focal length and the picture height would then be 35mm/24mm ~= 1.4583

Assume that you're visualizing a picture taken with a 35mm lens on a wide-screen display with a 16:9 aspect ratio and a 23-inch diagonal. The height of said display would then be 23" * 9 / √(16²+9²) ~= 11.276".

The correct observation distance would then be 1.4583 * 11.276" ~= 16.44", or about 418 millimeters; any other observation distance (assuming a picture taken with a 35mm lens, visualized on a 23" display) would introduce anamorphic effects, like egg-shaped blue balls.

The ray projection behavior of a conventional, rectilinear — i.e. non-fisheye — glass lens is identical to that of a pinhole camera whose pinhole to imaging plane distance is identical to the glass lens' focal length — e.g. 35mm.

Visualizing the light path through a pinhole camera should make it obvious that pinhole cameras — as well as rectilinear photographic lenses — essentially accomplish a gnomonic projection of the subject lying in front of the lens on the flat film or sensor surface lying behind the lens.

In this picture, the pinhole camera can be imagined as having its pinhole at the location of the orange-colored globe's center, and the pinhole camera's film plane would be the gray plane tangent to the south pole of the globe, with which the projected rays are intersecting.

Imagine an arbitrarily wide brick wall, photographed with a camera with an arbitrarily wide film.
With a rectilinear lens, a brick at any distance from the image center would have the exact same size on the film plane as the brick at the image center.
If the bricks were imaged larger and larger as their distance from the image center increased, the lens would indeed be exhibiting pincushion distorsion.

People can misinterpret the geometrical effects of a perfectly well-behaved rectilinear wide-angle lens, including the anamorphic effects caused by a geometrically improper observation distance, and often cast aspersions like "this lens exhibits distorsion" ;-)

@Robert Hudyma - It's distortion, but not something that the lens is doing wrong. It comes from mapping a wide slice of 3-dimensional space onto a 2-dimensional (flat) plane in a way that makes lines look straight. All rectilinear wide-angle lenses will do it. (That is also why the people closest to the edges of the frame in team photos tend to look weird.) Lenses with a lot of "barrel distortion" (which isn't so much "distortion" as it is "telling the unvarnished truth, painful though it may be") will keep the ball round, but at thee expense of making any straight lines look properly curved (something your visual system corrects for in everyday life, but won't do when looking at a small flat picture that it knows is a small, flat picture).

Here's a little experiment to try: put your eye very close to the image, about where the camera would have been in relation to the full-sized real-world scene. (If you're anything like my age, that's going to involve reading glasses.) You should notice that the ball appears spherical from that position.

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