Seems like everyone is doing reading on electronics now. So the question is what is the best reader. In looking at reviews, for general purpose tablets, it does look like the ipad mini is a great form factor.

The main issue is that the ipad mini 2 is coming out probably in September so it is a lot to lay down $329 only to see it obsolete at the end of the summer.

For budget folks, the kindle paperwhite at $119 is pretty hard to beat for a dedicated reader. The screen use e-ink so works super well in bright sunlight. And it is wifi only but that doesn’t seem to be much of a barrier as downloading a book is pretty easy at home or wherever.

And of course it’s battery will last for weeks. In terms of accessories, wirecutter points out that you don’t want to spend $25 on a $120 product, so the $10 Fintie is a good choice. It has the magnetic lock, so it turns off the kindle automatically when you close it.

On screen protectors, we haven’t found our Kindles to be really vulnerable to scratches, so there is a debate as to whether you need a screen protector. Particularly if you have a cover for it.

What a convergence we are seeing in the PC world. The world used to be filled with lots of different buses (serial, parallel cables, IDE, PCI) but as performance has increased the world has converged around serial buses (because it when things go really fast it is hard to make the signals across multiple lines work right, you’d rather have lots of separate serial lines than try to coordinate signals across 64 lines) and in massive integration so caches and things now are on chip.

The good news is that this makes connecting things easier than ever as the new Mac Pro and the MacBook Air announcements show. Specifically:

1. The move to PCIe SSD. The world has finally recognizes that the old hard drives don’t need a special connector (IDE, SATA, SAS), but instead you put all the flash into a PCIe card (typically 2 lanes or 2 links or 2 channels) and you get incredible performance. With SATA 6GB, you can get about 500MBps (we hooked up a pair with RAID-0 and got 1GBps) or just use PCIe and get 1GBps from the get go. The world now has native PCIe disk controllers which was the big step. It also means that for conventional PCs, we can get rid of all that cabling that goes to SATA devices (like in our aquarium PC and replace it with a single PCI SSD), that is great
2. Thunderbolt 2. Intel’s technology update which is essentially take a PCIe stream out of the box to other devices. The original Thunderbolt had four PCIe 2.0 lanes or four 10Gbps channels (two upstream and two downstream) so for any single device, the most performance you could get is 10Gbps which for storage is about 800-900MBps, but 4K resolution requires 15Gbps. Thunderbolt 2 allows channel bonding so you can get two bidirectional 20Gbps channels so it works with 4K displays using Displayport 1.2 and also should help on disk throughput to a theoretic 1.5GBps. This isn’t using PCIe 3.0, but that’s probably around the corner.

The net is the world is moving to PCIe as a wired standard and to Gigabit wifi 802.11ac for wireless. It is a wonderful world! Or course there will also be USB 3.0 for the random peripherals as well which using a similar technique as PCIe by the way providing 5Gbps raw in the new Superspeed mode which will give 400MBps in practice given transport overhead. So the world is indeed fast, fast, fast these days.

Scott and i have been getting super nerdy about reviews and image quality. It turns out that figuring out resolution of a camera is incredibly difficult and depends quite a bit on sharpening. If you use JPEG, then there are lots of settings and all cameras need some sort of sharpening. If you use RAW, then it depends on how much sharpening is used in post processing.

Finally, the resolution changes depending on whether you are looking at the center or the whereever on a lense, the aperture (the sweet spot is usually F/4-F/5.6) and the focal length on zooms (middle usually being the best). Net, net, most reviews are not comparable, so it is good to see folks using Imatest, but again there are zillion parameters. Here are some of the sites I use with caveats:

• Lensrentals.com. Their blog is good and they test since they have a large fleet of lenses. They use unsharpened RAW so most of the time, their resolutions will be low. All cameras can use some sharpening, so they are a lower bound.
• Photozone.de. Klaus is a one man shop and he also tests using Imatest. it isn’t clear what parameters he is using when he shows his figures
• PCMag.com. They use out of the camera JPEG which mostly is pretty useless. Sadly, no one seems to try to optimize the lens/camera/sharpening combination, so none of these tell you the best settings that work for a camera. 

Then we have DXOmark. They use their own proprietary test and it is pretty much impossible to tell what they are doing but at least they are trying. DPReview.com also uses their figures now, but it is too soon too tell.

And then there is imaging-resource.com and its sister slrgear.com that uses photos taken and some sort of blur guide that I’m not sure how to read.

Finally resolution is just one of the many parameters, there are others that are measurable like distortion, chromatic aberration and vignetting, but sadly none of these tests measure the effect of tweaking the parameters of the camera *and* the post processing software. What we need is a test that is truly end to end, that tells you how to set the camera, what to set the lense and how to set the ACR parameters to get the most from a camera.

I haven’t seen many tests of this lense and lensrentals.com and photozone.de are one of the few shops that shows the results. Here they are shot at a standard Imatest distance of 18 feet.

As an aside, the big question is what he is really measuring. Not too many entries on this, but here’s a quick summary:

What is weighted mean for Lensrentals: I’m using the 1.0/0.75/0/25 weighted mean on the maximum number of calculations of 80:20 boxes. I thought 0.25 more appropriate since there are so many edge and corner numbers compared to central 1/3.

How much sharpening is he applying?  I measure off unsharpened raws converted by dcraw in Imatest. (So these are worse case numbers since we know sharpening helps alot and they talk about standardized sharpening, so it isn’t clear what he is measuring .

For your XXXX/YYYY format is this the Center/Lens Average? In the Imatest SFR test would the following be the magic decoder ring from the SFRPlus module

• Center = Imatest MTF 50 LP/PH
• Center Mean Lens Average = Imatest MTF 50 LP/PH
• Weighted Mean Corner Average = Imatest MTF 50 LP/PH Corner Mean

On a Canon 5D2, here is what you get:

100-400mm at F/5.6 at 400mm. Center is 740, 655 average and 540 corner. These are in line pair per height, so to convert to equivalent megapixels (740*2)^2* (36/24 = 3/2 aspect ratio) = 1480**2 * 1.5 = 3.2MP. These ar emuch lower because of the sharpening difference i think.

400mm F/2.8 at F/4 which is a $12K lense so about the most possible at the center is 935, 865, 740, so taking the average, we get (865*2)^2 * 1.5 = 4.4MP

70-200 F/2.8 IS II is another spectacular lense with center MTF-50 of 875LP/Ih and 755 average.

Sigma has been really doing a great job lately and the coolest thing now is that you can download firmware into their lenses at home rather than needing a factory adjustmnet

LensRentals.com – Photo/video thoughts from the largest rental house

I am certain, though, that Sigma Photo, Inc. has changed a lot in that time. Truth is, they’re making serious waves in the photo industry these last few years. They’ve improved their repair service and quality assurance. They’ve released some world-class lenses at way less than world-class prices lately.

LensRentals.com – Photo/video thoughts from the largest rental house

And now they’ve released their USB dock and Optimization Pro software. I’ve spent the weekend playing with it. Partly because I really think this is a revolutionary product, partly because if I didn’t have an “I’ve really got to do this for work, honey” excuse I’d have been restaining the deck.

My conclusion, as usual, first: if anything is going to get the attention of those who like to disable features in firmware, overprice lenses, and limit our ability to customize, this might be it. I did some adjustments this weekend, in about 10 minutes, which would have required a trip to factory service on a Canon or Nikon lens. An let me stop the Fanboy stuff before it starts: you may never have needed to make this adjustment on your 10 or 20 Canon or Nikon lenses, but I’ve sent dozens of them in for factory service adjustments for exactly the issue I’m going to demonstrate today.

Sigma has been really doing a great job lately

LensRentals.com – Photo/video thoughts from the largest rental house

I am certain, though, that Sigma Photo, Inc. has changed a lot in that time. Truth is, they’re making serious waves in the photo industry these last few years. They’ve improved their repair service and quality assurance. They’ve released some world-class lenses at way less than world-class prices lately.

LensRentals.com – Photo/video thoughts from the largest rental house

And now they’ve released their USB dock and Optimization Pro software. I’ve spent the weekend playing with it. Partly because I really think this is a revolutionary product, partly because if I didn’t have an “I’ve really got to do this for work, honey” excuse I’d have been restaining the deck.

My conclusion, as usual, first: if anything is going to get the attention of those who like to disable features in firmware, overprice lenses, and limit our ability to customize, this might be it. I did some adjustments this weekend, in about 10 minutes, which would have required a trip to factory service on a Canon or Nikon lens. An let me stop the Fanboy stuff before it starts: you may never have needed to make this adjustment on your 10 or 20 Canon or Nikon lenses, but I’ve sent dozens of them in for factory service adjustments for exactly the issue I’m going to demonstrate today.

Scott has really figure this out, the important figure of merit for a lens+body combo are the number of lines it can resolved for every physical millimeter of the sensor at an MTF-50 (where you have 50% contrast). The Sony RX100 actualy does the best at 270 li/mm mainly because it is easier to design a smaller lense against a smaller sensor.

So John has an NX300, I wonder what the best lense is for him. Photozone.de seems to have the best measurements. Assuming the NX210 is about the same as the NX300, here are the figures all on the NX200:

Samsung NX 20mm F2.8. This lense does somewhat better but it is 2628 wide open at F/2.8 and best if F/5.6 of 2063 at the center. The extremes are 1995 and 2542 respectively.

Samsung NX 16mm F/2.4. This thing suffers from something called field curvature. It means that at a given focus distance, only the center is sharp. The focal plane isn’t very flat for this lense, so the edges suffer from this problem making the edges even lower resolution. But basically at F/2.4 wide open, it is 2843 lw/ph (line width vs picture heigh for the Samsung NX200. But the best at the center is 3189 at F/4, but at the edge this falls to 1789 and then 1415 at the extremes. This is a really soft lense at the edges.

Samsung NX 30mm F/2. This is a 46mm equivalent prime lens. It is 3189 lw/ph at F/4 and peaks in the extremes at F/5.6 where it is 3033 center, 2770 border and 2652 extreme.  So it is about as sharp as the 20mm and 16mm in the center, but it really excels in the cornets.

Well, if you are off on a long trip, how do you make sure your clubs make it in one piece. Here are some tips:

Golflink. First is that you pay a premium if the bag is big and heavy. They cost about $100 and you want to find one with a pull handle and wheels and up to 15 clubs (48 inches tall). Club Glove is a PGA favorite. You shouldn’t pack every club as excess weight increases fees. Take a photo for insurance purposes. Pack each club head by wrapping it individually. If you are hard core, use a Club Glove Stiff Arm to protect the bags in the case.

Golfsmith. Hard case is really the best, but an integrated bag is the best of both worlds as it is nearly as sturdy as a hard case, but you can use on the course. Pack towels around the clubs before you put your bag in the case. Some people put their clubs in upside down so the heads are protected.

Amazon folks definitely love the Club Glove  Burst Proof with Wheels 2 and the Stiff Arm for $219 and $26 respectively.

The various specs are so confusing. Imatest which pcmag.com and imaging-resources.com uses and dxomark which dxo and dpreview now uses are different metrics for the same thing. How good is a particular body and lense combination. Truth is that a great body (NEX-7) can turn in a low resolution camera with a mediocre lenses (it’s kit lense) produces an effective 9-10 megapixels whereas a very good lense (Olympus prime) and body (MD5) can produce a 12 megapixel image.

What is more complicated is that resolution changes dramatically from the center (where it it shapest) to the edges (worse) and the corners (even worse). And the focal length on a zoom and the aperture have a dramatic effect (on a Sony RX-100, F/4 is 30% sharper than wide open at F/1.8).

The most confusing part is that the measures are different so Imatest likes to talk about lp/ih that is line pairs per image height and DXOmark likes to talk about effective pixels (without defining what that means), although the idea of having a single figure of merit is sure useful when you realize that resolution varies substantially across lenses, apertures and focal lengths!

And the other problem is whether you are using JPG or RAW and what image sharpening you are adding. As my buddy Scott points out, you can increase resolution from 2400 to 3500 just by sharpening! Also, the new DxO tests are confusing as well it seems that this is mainly because sharpening is such a big factor. Specifically it looks like the d800 dxomark MP ratings are low (they are undersharpening), the 5d3 are oversharpened. Looks like photozone.de has the best measurement. Maybe the large lesson is that sharpening is a huge factor in effective resolution. You need sharpening by the way because the anti alias filter intentionally blurs things. Nowadays the more modern cameras are getting rid fo the antialiasing and instead removing moire in software in those cases where it exists. Way smarter as antialias really reduces resolution.

So how is anyone supposed to think about this? Well, perhaps the first thing is to get some sort of simplification across Imatest and DXOMark particularly in those cases where the Imatest thing has me starting at acutance charts looking at resolution maps across an image. Ugh.

First question is how to think about Imatest in terms of effective resolution. So what is the actual line height for a given sensor. You can look at this as a pretty easy rough math problem (because hunting for the exact resolution vs image height spec is actually pretty hard, but here are the rough numbers)

image height = sqrt( megapixels / (aspect ratio))

megapixels = height^2 * aspect ratio

In most modern cameras, they still use the 35mm film aspect ration (24x36mm or 4:3 aspect)

What does this all mean, well if you look at Imatest results from PC Magazine, the resolutions from their various reviews and using the formulas above makes it pretty clear that the sensor size is really not super relavent for these ILCs and point and shoots. What matters is the glass, although these tests are really had to interpret as the writing is vague and they are using JPG, so it is not clear what sharpening they are using. Scott reports that for instance before sharpening (which really corrects what an anti-aliasing filter removes) that you can double resolution!

Nonetheless, assuming these are out of the box JPG settings:

Sony RX100. 28mm. F/1.8, 2126li/ph center that is the worse case of wide open but at center (you can invert the formula above to get an effective point megapixel resolution. (2126^2 * 4/3 = 6MP equivalent) against a 20MP lense. That is pretty incredible for a wide open lenses. The sweet spot for this lense is around f/2.8 which is at 2,300 lines = 7MP). It is nice to do this as a ratio of the potential resolution possible which is 3800 lines in the RX-100 case. Now that’s a best case since it is in the center obviously.

Ricoh GR. Interesting to see that at wide open the 28mm fixed lense at f/2.8 resolves about teh same at 2105 li/ph (about 6MP) so not much different than the RX100. It doesn’t have an anti-aliasing filter like the Coolpix A (the modern trend as it improves resolution). The edge score stays at 1,927 li/ph (5MP equivalent). They have a wide-angle adapter to get to 21mm lens, without significant light loss which is 2,016 li/ph at 21mm lense effectively.

Samsung NX300 with 45mm f/1.8 2D/3D. Interesting to see how on Imatest, there is sort of limit of 2000 to 2400 lines (5-8MP) for this class of camera. AT f/1.8 in the center it is 2,205 with a maximum resolution of 2,720 lines at f/5.6 (10MP) for a 20MP sensor. These are optimistic as these are center only measurements of course.

Samsung NX300 with 18-55mm f/3.5-5.6. He says he is using a center weighted test so maybe this means not center only. In any case, wide open at 18mm f/3.5 of 2095 li/ih (5.8MP vs 20MP sensor) with the edges at 1,536. The best wide is at f/8 giving a 2360 lph average (6.8MP) with 1900 lph at the edges. The lense gets worse as you zoom in (which I haven’t seen before and then gets better all the way racked out). So at 35mm f/4.5 wide open, it is 1857 lph (4.6MP) center averaged and 1,658 lph at edge improving to 55mm with 2,241 at f/8 (6.7MP) with 2,000 at the edges. Noise is also probably a stop worse than an NEX-6 although, he doesn’t give specific analytic metrics.

Samsung NX210 with 12-24mm f/4-5.6. This is a wide angle but slower lenses. It was tested on an older Samsung which also had a 20MP sensor. At 12mm f/4 wide open, it got (not clear but these look like center only measurements) of 2,385 li/lh

Photozone.de seems to have at least a more uniform test:

The various specs are so confusing. Imatest which pcmag.com and imaging-resources.com uses and dxomark which dxo and dpreview now uses are different metrics for the same thing. How good is a particular body and lense combination. Truth is that a great body (NEX-7) can turn in a low resolution camera with a mediocre lenses (it’s kit lense) produces an effective 9-10 megapixels whereas a very good lense (Olympus prime) and body (MD5) can produce a 12 megapixel image.

What is more complicated is that resolution changes dramatically from the center (where it it shapest) to the edges (worse) and the corners (even worse). And the focal length on a zoom and the aperture have a dramatic effect (on a Sony RX-100, F/5.6 is 30% sharper than wide open at F/1.8).

The most confusing part is that the measures are different so Imatest likes to talk about lp/ih that is line pairs per image height and DXOmark likes to talk about effective pixels (without defining what that means), although the idea of having a single figure of merit is sure useful when you realize that resolution varies substantially across lenses, apertures and focal lengths!

So how is anyone supposed to think about this? Well, perhaps the first thing is to get some sort of simplification across Imatest and DXOMark particularly in those cases where the Imatest thing has me starting at acutance charts looking at resolution maps across an image. Ugh.

First question is how to think about Imatest in terms of effective resolution. So what is the actual line height for a given sensor. You can look at this as a pretty easy rough math problem (because hunting for the exact resolution vs image height spec is actually pretty hard, but here are the rough numbers)

image height = sqrt( megapixels / (aspect ratio))

In most modern cameras, they still use the 35mm film aspect ration (24x36mm or 4:3 aspect)

What does this all mean, well if you look at Imatest results from PC Magazine, the resolutions