JorgeLima

JorgeLima

Joined on May 4, 2012

Comments

Total: 6, showing: 1 – 6
In reply to:

munro harrap: In practice it is very limited because there is no VR. A long lens for wide-angle use is always bad. You forget that length too easily. The 24-70 Canon and Nikon lenses for full-frame rack out to their longest length at their widest setting- as do the 28-85 Nikkor and other older designs, and this means you are HERE using in effect a non-stabilized 70-200 SIZE glass to achieve 27-55mm effect-your in-stability is increased .Regardless of its speed that you cannot use most of the time, that is an extraordinarily long barrel for a 27-55mm lens- a zoom length of precious little use anyway!!

Wait till they IS it!!

And I think you're right! Narrow field means more sensitivity to camera shake. There is even a rule used in that one should use at least 1/X shutter speed with a X mm focal distance lens (with 35mm film) when shooting hand held. Meaning that with 27mm one could easily shoot hand held at 1/30s. However, there is a point in the comment of munro harrap. The longer and heavier the lens is, the higher the chances and amplitude of the instability. Also in the digital era people are less forgiving to blurs caused by shake or defocus, even when we don't make big prints we can always zoom in and find tiniest of the flaws.

Direct link | Posted on Apr 29, 2013 at 22:26 UTC
In reply to:

Francis Carver: A lens is a lens.... now, the manufacturer like Canon may affix to the model name something fancy and smart-sounding, like "Cinema," but still... a lens is a lens. These would be interesting; although certainly not unusual single focal lenses if sold for around $1,000, well $1,500 maximum, but at the crazy prices alluded to in the press release, i.e. OVER FIVE THOUSAND DOLLARS (!!!), you won't see many camera stores stocking up on them, will you now? Well, maybe in Riyadh and Zurich.

I disagree, lenses for cinema have different requirements. Just to name one which is completely irrelevant for photography, the angular magnification must be constant across the focusing range. Then, being aimed at a niche market, even if, technically speaking, there was no reason to make them more expensive, the market rules dictates their price.

Direct link | Posted on Jan 11, 2013 at 14:17 UTC
In reply to:

benmlee: The fact is he was a Kodak scientist. Kodak had the technology, resource, and people, and totally blew it.

As far as I know Kodak was an important player in the digital sensor business, was not just a film company. They were even supplying CCDs for scientific applications, not to mention the sensors found in Leica cameras. Maybe they made some wrong moves in the business.

Direct link | Posted on Dec 3, 2012 at 23:40 UTC
In reply to:

KoKo the Talking Ape: I notice that the image captures quite a wide angle. I imagine that is because that spherical lens is designed that way. Is that required, or could you get that high resolution in a narrower field of view? Getting a very high pixel image is not all that groundbreaking if you get those pixels by taking a bigger (wider angle) image.

And is there a theoretical limit to pixels per solid angle in an image, aside from lens limitations? How many pixels are actually in the light within a given field of view?

The number of pixels per solid angle can be any. The question is are they resolving more detail than fewer? Maybe you what to know if there is a theoretical limit for the resolving power of an optical system. The only theoretical limit I can remember is the diffraction. The diffraction limits the angular resolution in a way which depends on the light wavelength and diameter of the aperture. Nevertheless we should not see it as a limitation of the lens, because even a perfect lens (i.e aberration free) with an infinitely large aperture has an angular resolution which is just 3 times better than a diffraction limited F/1.4 lens. However, in practice the angular resolution is limited by aberrations, not by diffraction. The aberrations may come from the lens itself, but also be introduced by atmospheric turbulence. The later is almost always visible when using long telephoto lenses, specially when looking close to horizon.

Direct link | Posted on Jun 22, 2012 at 22:52 UTC
In reply to:

micksh6: Front element seems to be rather large. 75mm F1.8 lens requires only 42mm front element diameter. This looks close to 50mm probably?

For comparison, Pentax 77mm F1.8 limited lens has 49mm filter thread and its front element is smaller, probably around 43mm.

I wonder why is that. Maybe this lens is a bit faster than F1.8?

Your calculation is right for the pupil size. The front element isn't necessarily coincident with the pupil. Of course, the optical designer may try to place the pupil close to the front element to reduce the amount of glass used and thus the cost. To be exact things a far more complicated, but take as an example a 28mm F2.8 lens, your calculation would give 10mm front element, which is actually close to the apparent size of the aperture, not the front element.

Direct link | Posted on May 25, 2012 at 09:16 UTC
In reply to:

Guidenet: There are huge computers in modern cameras. These computers have operating systems and applications just like your home computer. When a new operating system for Apple, Windows or Linux is released, we can expect a few crashes here and there until it gets ironed out. It's fairly normal. Even with huge beta periods and a lot of testing, computer bugs crop up after release. Nobody likes it, especially the releasing company. No matter how un-rushed you are to market, it happens.

There are two types of errors; syntactical and logical. Syntax errors are usually all caught in beta and other testing. This is where you made a grammatical error in your coding. A logical error is much harder to find. It will only crop up when that logic is tested. It might mean a series of events simultaneously triggering another series of events where something in the middle tried to divide by zero.

Finding these bugs is not that hard and pretty trivial to repair. I'd buy one today without issue.

Just a small correction: Syntax errors do not require testing and they don't reach beta releases. They are simply caught by compilers. Logical errors do require extensive testing in every possible combination of conditions. Sometimes it is impossible for the development team to cover all possible conditions on their tests, that's why they make beta releases.

Direct link | Posted on May 4, 2012 at 22:21 UTC
Total: 6, showing: 1 – 6