Lensjoy

Lensjoy

Has a website at www.lensjoy.com
Joined on Aug 24, 2011

Comments

Total: 19, showing: 1 – 19
In reply to:

Lensjoy: The human eye is most sensitive to green. When calculating luminance (Y) from the respective RGB values for gamma 2.2, the formula is:
Y = 0.2126*R^2.2 + 0.7152*G^2.2 + 0.0724*B^2.2
Blue is only 7 percent of perceived luminance! So if I were to design a sensor doing what Sigma is purporting to do, I would put the high resolution four pixels in the center green layer, not the top blue layer.

Perhaps Sigma is doing something more complex than the schematic in the article above implies, but from the above description I expect this sensor design to have faults that we'll see remedied in a future version. I wouldn't buy the camera yet.

Thanks, this explanation really helps. My next question would be, what is the exposure latitude like for that top layer since it receives all wavelengths together rather than just red, green, or blue? It will be interesting to see how the sensor stacks up in that department. Since there's no blue color filter, I also wonder how it deals with yellow since a bright yellow will register high intensity on the top layer as well as the red and green layers, making it difficult to distinguish from white light. I've seen some Foveon tests on color separation, but never seen a white/yellow pattern. Maybe there's a reason for that, because it shows the problem. Admittedly, white/yellow distinction is a fairly rare situation photographically.

Direct link | Posted on Feb 17, 2014 at 22:03 UTC

The human eye is most sensitive to green. When calculating luminance (Y) from the respective RGB values for gamma 2.2, the formula is:
Y = 0.2126*R^2.2 + 0.7152*G^2.2 + 0.0724*B^2.2
Blue is only 7 percent of perceived luminance! So if I were to design a sensor doing what Sigma is purporting to do, I would put the high resolution four pixels in the center green layer, not the top blue layer.

Perhaps Sigma is doing something more complex than the schematic in the article above implies, but from the above description I expect this sensor design to have faults that we'll see remedied in a future version. I wouldn't buy the camera yet.

Direct link | Posted on Feb 16, 2014 at 21:00 UTC as 7th comment | 5 replies

The schematic of the sensor layout looks wrong to me. The eye is most sensitive to green, and least sensitive to blue. If wanting to capture maximum luminance resolution, the green layer in the middle of the stack should have the highest resolution, not the blue layer.

Direct link | Posted on Feb 10, 2014 at 21:53 UTC as 84th comment | 3 replies
On Can computer corrections make simple lenses look good? article (162 comments in total)

The idea is interesting, but the execution needs more thought. Without knowing anything about the lens' optical characteristics, I can go into Photoshop and apply these two operations to the original version above:
1. Filter/Sharpen/Smart Sharpen Lens Blur 79%, 5.7 pixels (more accurate checked)

2. Filter/Sharpen/Unsharp Mask 47%, 5.7 pixels

I haven't corrected it for chromatic aberration, but examining the green channel alone it's clear that the corrections above produce a better result with much better separation of tonality in the details, and more fine detail. If I had a chromatic aberration tool I am confident I could outdo their effort. Perhaps someone here can apply that with these steps and post the final result.

Direct link | Posted on Oct 2, 2013 at 00:43 UTC as 12th comment
On Photoshop CC: Adobe responds to reaction article (1853 comments in total)

What steams me the most about Adobe's plan is that if I have existing files and don't keep my subscription current, I can't edit those files as I could with a perpetual license. Also, if I don't use Photoshop for a month, I'm still paying for it. If Adobe were to go to metered access where I paid by the hour for the product I might be happier than with a subscription. At least I would be paying for what I use. Subscriptions are just a way to get money from people even if they are not doing anything with the product or don't need the new features.

Direct link | Posted on May 12, 2013 at 05:57 UTC as 98th comment | 4 replies
On Hands-on with the Samsung Galaxy S4 post (135 comments in total)

You've probably heard this before, but please focus on photography! The time spent reviewing phone features could be better spent on lens reviews, editing software, camera tips, and other things we care about that are lacking both at dpreview and other places online. I wish dpreview were the go-to place for photographers rather than a me-too place where I can find just another tired cell phone review.

Direct link | Posted on Mar 17, 2013 at 02:01 UTC as 31st comment | 5 replies

My ideal camera is something like the D800/EOS 5D with a sensor that tilts inside the camera body in both the vertical and horizontal axes. This would offer view-camera adjustments to focus that essentially make any lens into a tilt lens. Since these cameras have large numbers of AF sensors, it should even be possible for the camera to adjust the tilt itself for optimum depth of field in the scene. Build it and every landscape photographer will buy one.

Direct link | Posted on Oct 27, 2012 at 02:28 UTC as 26th comment

I like the new design overall, especially the preview of replies feature. One thing I still want is an "expand all replies" feature to allow quick reading of all replies rather than having to click and wait for each one to display individually. It's always been a bother to wait for the server to respond and for that reason I seldom read all the responses to topics where I've wanted to do that.

Direct link | Posted on Sep 28, 2012 at 19:42 UTC as 129th comment
On Photokina 2012: Interview - Stephan Schulz of Leica article (221 comments in total)
In reply to:

Rachotilko: I would like to ask the informed ones here (people with actual experience with different sensor formats):

Herr Schulz talks about different image characteristics of the bigger formats compared to the 35mm FF. I take his claim seriously - at least because there are some supporting comments in this discussion.

My question is: what is the primary cause of the difference in image characteristics ? Herr Schulz used an analogy: S is better than FF the same way as FF is better than small sensor compact. Which I think is completelly wrong: excessive noise of compacts is sufficiently demonstrable in common print sizes. But D800E is capable of taking high ISO shots without noticeable drop in IQ.

The only part that can bring about advantage in terms of IQ to "above FF" (such as S or MF) systems is *optics*. There simply are limits on what FF lens can do (in terms sharpness, distortions, CA, diffraction), that can be overcome only by means of the format enlargement.

Is this assertion right ?

(continued) If one must stop a medium-format lens down more, doesn't that mean sharpness is reduced? Not for two reasons. First, the pixels are larger at the same resolution on larger formats. Second is that tilt lenses can provide an improvement in DOF so one doesn't need to stop down as much when the scene allows it. That's a reason Leica offers a tilt lens. Of course, so do Nikon and Canon. With the right optics on a D800, medium and large format can still produce a better image. But the differences are small, and what Schulz doesn't say is that the market for that difference is also small. I can produce a better image than Leica at less cost from my 4x5 camera, but at greater overall difficulty. The difference is that Leica produces a better image than the D800 at much greater cost and greater difficulty.

Direct link | Posted on Sep 24, 2012 at 22:28 UTC
On Photokina 2012: Interview - Stephan Schulz of Leica article (221 comments in total)
In reply to:

Rachotilko: I would like to ask the informed ones here (people with actual experience with different sensor formats):

Herr Schulz talks about different image characteristics of the bigger formats compared to the 35mm FF. I take his claim seriously - at least because there are some supporting comments in this discussion.

My question is: what is the primary cause of the difference in image characteristics ? Herr Schulz used an analogy: S is better than FF the same way as FF is better than small sensor compact. Which I think is completelly wrong: excessive noise of compacts is sufficiently demonstrable in common print sizes. But D800E is capable of taking high ISO shots without noticeable drop in IQ.

The only part that can bring about advantage in terms of IQ to "above FF" (such as S or MF) systems is *optics*. There simply are limits on what FF lens can do (in terms sharpness, distortions, CA, diffraction), that can be overcome only by means of the format enlargement.

Is this assertion right ?

I shoot with everything from a 1/1.7" P/S compact through 35mm FF, 645, 6x7, and 4x5. To some extent there is truth in Schulz' opinion that medium format is different from 35mm at the same resolution. Two major factors come into play. First is that with a larger sensor there is shallower depth of field at equivalent focal length. Portrait photographers like medium format (and large format too) for that reason. The backgrounds and bokeh effects produce better portrait images.

The second factor is that diffraction effects are reduced per pixel on larger formats. This gives a photographer the ability to stop a lens down more using a larger sensor without compromising the image quality. That means that on a D800 one sees loss of sharpness around f/11-16 on most lenses but on medium format it doesn't happen until f/22-32, and large format more around f/32-45. This effect gives the photographer more range of sharpness with depth of field to work with on larger formats.

Direct link | Posted on Sep 24, 2012 at 22:06 UTC
In reply to:

shifttilt: The Nikon 24mm PC lens is really awful (blurry in the corners and difficult to get full depth of field) not to mention overpriced compared to the Canon 24mm Tilt/Shift II, let's hope this lens functions better and works easily on a D800.

Corner blur can be a consequence of lens design constraints. Good tilt/shift lenses are not flat field, unlike fixed ones. See http://www.luminous-landscape.com/tutorials/focusing-ts.shtml. If the center is sharp, the corners will be blurry. This goes away when stopping down. The best focus is obtained by finding the near and far points in relation to the plane (actually, sphere) of focus and focusing halfway in between, then stopping down. It's not easy to do right, as any view camera user knows.

Direct link | Posted on Sep 7, 2012 at 20:26 UTC

Government, get out of my camera bag!

Direct link | Posted on May 21, 2012 at 20:11 UTC as 8th comment

I don't see anyone complaining about their cell phone or computer here, but modern digital cameras are really a computer and a lot of software with a big sensor chip wrapped around old-fashioned shutters, mirrors, and optics. Really, it's time to acknowledge that software errors like this are part of technology and stop bashing the manufacturer. We all want perfection, but sometimes problems don't appear until they are out "in the wild" where massive numbers of people exercise every feature of the product more than testers can. Please get out and shoot some photos instead of wasting time on a fact of life.

Direct link | Posted on May 5, 2012 at 20:33 UTC as 15th comment | 1 reply
In reply to:

Marty4650: It's pretty obvious what is happening here.

Compact cameras are a dying breed. They are getting killed by camera phones below them, and small MILC cameras above them. Aside from the highest end models (like the S100, LX5 and XZ-1) they will cease to exist in a few more years.

So the marketing departments take over and start stuffing more megapixels, more zoom range, more scene modes, more gimmick features, and more of everything else except image quality.

Because it is physically impossible to provide better image quality when building a 30X zoom based on a tiny sensor.

All of these cameras are a total waste of money for most people.

Get a good camera phone... or just buy another lens for for your MILC camera. You will be better off.

Consumer-grade cameras will be killed by camera phones, but enthusiasts will still find a niche for a camera that's focused on photography. Camera phones still suffer from horrible shutter lag, lack of manual controls, and many other technical faults photographers care about but consumers don't have a clue about. Phones don't shoot in RAW, have nasty compression artifacts, poor shadow detail, the list goes on and on. When you look at the engineering needed to create a camera such as the Canon S95, I don't see phone manufacturers stepping up to the bar to do it. They want to provide data access to download games, video, music, and anything else they can charge for to make a profit. Photos are user-created content, and don't fit the business model of phone manufacturers. Real cameras let The People create content. In the hands of a competent person, the content quality is far better with a device designed specifically for that task. That's why I hope they survive.

Direct link | Posted on Feb 28, 2012 at 22:29 UTC
On Nikon D800 preview (1110 comments in total)

D800E candidates, remember these caveats:
- If you plan to sell your D800E someday, there will be a much smaller market for it.
- Very likely, the sharpness difference can be mitigated on a D800 with judicious use of a Lens Blur filter. If you're not planning on enlarging past 24x36 inches, you'll never notice any difference.
- There are very few simple and fast solutions to remove moire once it's in an image. It can turn up in the strangest places.

If you need a D800E, you are probably experienced enough to KNOW that you need it for your work. Everyone else is likely better off with the D800.

Direct link | Posted on Feb 21, 2012 at 00:48 UTC as 143rd comment | 2 replies
On Adobe faces criticism for change of upgrade policy article (398 comments in total)

I've always upgraded on every other Photoshop release, all the way back to Photoshop 3.0. Adobe never seemed to offer enough improvements to make it worthwhile on their release schedule, but I've found value by waiting an extra release cycle. I suspect many others will agree. I don't think I'm cheating Adobe for paying for six releases of their software over that time.

Hey Adobe, how about this: Deliver a new version of Photoshop half as frequently with twice the improvements and maybe everyone will decide the upgrade is worth it. Today's product planning simply extracts money from customers without delivering real benefit for what we pay. Adobe also needs to do a better job communicating with their customers so we get the features we need rather than what the developers think is cool.

Direct link | Posted on Dec 1, 2011 at 22:56 UTC as 12th comment
In reply to:

tomboyter: I believe that the S100 image is out of focus. Other early adopters have noticed that the camera has trouble with focus on close subjects, and looking at the text lying on the table it appears to me that the problem is one of critical focus rather than resolution. If cannot believe that Canon would release an inferior product and call it progress.

I'm happy I bought the S90. I was thinking of upgrading to the S100, but these images clearly show that's a mistake. Let's hope Canon fixes the problem; I'm shocked they would release something that makes a two-generation-old camera look better.

Direct link | Posted on Nov 29, 2011 at 02:42 UTC
On Why make a small-sensor mirrorless camera? article (279 comments in total)

Seems like a bit of a yawn to me. The 1" sensor is bigger than what's in enthusiast P/S cameras such as the Canon S90, but the interchangeable lens design screams for a better sensor than 1".

What I want is the 1" sensor in a nice, small P/S body for better low light performance and better image quality. That would make more sense, and represent a breakthrough in the enthusiast P/S market. Instead, we get this.

Direct link | Posted on Sep 22, 2011 at 20:59 UTC as 42nd comment | 1 reply

Seems like a bit of a yawn to me. The 1" sensor is bigger than what's in enthusiast P/S cameras such as the Canon S90, but the interchangeable lens design screams for a better sensor than 1".

What I want is the 1" sensor in a nice, small P/S body for better low light performance and better image quality. That would make more sense, and represent a breakthrough in the enthusiast P/S market. Instead, we get this.

Direct link | Posted on Sep 22, 2011 at 20:37 UTC as 137th comment
Total: 19, showing: 1 – 19