October 25, 2014, 12:01:10 AM

Show Posts

This section allows you to view all posts made by this member. Note that you can only see posts made in areas you currently have access to.


Messages - jrista

Pages: 1 ... 3 4 [5] 6 7 ... 299
61
EOS Bodies / Re: Multilayer Sensors are Coming From Canon [CR2]
« on: October 08, 2014, 10:48:11 PM »
Can someone explain to me why they're working on this rather than more megapixels?  Rather, why the focus is on more layers?  I understand it's to better represent colors.  But what is wrong with colors?  My cameras have always nice, realistic, vivid colors as long as I use a good lens.  I've never had a photograph where I even had the slightest hint of a thought that the color is not accurate.  When I look at my pictures, it looks like when I was there.  Granted, the dynamic range is not the same, but we're not taking pictures with our eyes, so that's expected.  What is it about color that they need to squeeze that last 0.01% of color accuracy out of the camera?

It's more than just better color fidelity. Bayer sensors have sparse data (sparse color data, you generally have more complete luminance data, but it's still not ideal), and need to be debayered. Assuming Canon is able to create a layered sensor with similar photosite counts as bayer sensors today, say 20mp, the image from a layered sensor should be much more complete, more detailed, sharper. The only real drawback to current Foveon sensors is they are really low resolution. For cameras of similar resolutions, Foveon is better because it's sharper out of camera for the given file size.

Sparse color information, and the act of debayering, is a primary source of color noise. Canon weakened the color filters in their more recent sensors (excluding the 7D II...not sure about that one yet), which results in more color bleed between pixels of differing colors, which just makes the color noise issue even worse. Luminance information is also biased...while it's higher resolution than the color information, different color channels have different sensitivities. When the color profile tone curves are applied to correct that discrepancy, it exacerbates noise (both luminance and color.)

When you gather a full constituent of color information at every photosite, if done right, you should have far lower color noise (doubtful it can be eliminated, but certainly lowered), and since every photosite gathers full luminance information, you won't get that increase in luminance noise due to different amplification of each color channel.

There are a lot of benefits for moving to a layered sensor design. The difficulties lie in getting good sensitivity at each layer, and in handling the photodiode count. A 20mp layered sensor with three colors is 60 million photodiodes that need to be read out. That's roughly triple Canon's current highest pixel count...I don't think even DIGIC 6 can handle that at even moderately reasonable frame rates...assuming 14-bit, a 20mp RGB layered sensor could do maybe 3.3fps with a pair of DIGIC 6 (based on the 10fps frame rate of the 7D II.) At best, that's a slow studio camera.

If Canon is intending to use this in the 1D X replacement, either they have something seriously powerful in DIGIC 7, or they are dramatically lowering the photosite count. If they released a 7mp RGB layered sensor with ~21 million photodiodes, they could get 12fps with dual DIGIC 5 or 6. They would need twice the throughput of DIGIC 5/6 to do 12fps at 14mp. They would need to process 2GB/s (which is basically the equivalent of eight DIGIC 5/6) to do 12fps at 28mp.

62
EOS Bodies / Re: Multilayer Sensors are Coming From Canon [CR2]
« on: October 08, 2014, 09:23:14 PM »
A problem with Foveon sensors is lousy color separation.  It's not a red, blue and green layer, it's three white layers with a little bit of bias on each one.  This is why they have lousy, inaccurate colors with lots of color artifacts like purple and green splotches all over the place.

I hope Canon has a way to dramatically improve on Foveon sensors before they'd release this into the wild.  Foveon's have lousy DR, lousy high ISO performance, lousy colors, and the lack of an AA filter means a ton of aliasing artifacts.

Hmm, that hasn't been my experience with Foveon images. They seem to have pretty good color fidelity at low ISO. They also seem to handle blues quite well, which isn't surprising given that blue is the top layer.

I was never impressed with the high ISO capabilities, and I think their higher ISO noise is pretty splotchy...but Canon noise is often just as bad (only Canon color splotches tend to be primarily reddish, with a bit of green.)

I'm talking about different splotches.  They aren't a few pixels like chroma noise, they're a few thousand pixels.

Yeah, Canon RAWs have the same problem. I am not sure it's thousands of pixels, but certainly several hundred.

63
EOS Bodies / Re: Multilayer Sensors are Coming From Canon [CR2]
« on: October 08, 2014, 09:18:15 PM »
A problem with Foveon sensors is lousy color separation.  It's not a red, blue and green layer, it's three white layers with a little bit of bias on each one.  This is why they have lousy, inaccurate colors with lots of color artifacts like purple and green splotches all over the place.

I hope Canon has a way to dramatically improve on Foveon sensors before they'd release this into the wild.  Foveon's have lousy DR, lousy high ISO performance, lousy colors, and the lack of an AA filter means a ton of aliasing artifacts.

Hmm, that hasn't been my experience with Foveon images. They seem to have pretty good color fidelity at low ISO. They also seem to handle blues quite well, which isn't surprising given that blue is the top layer.

I was never impressed with the high ISO capabilities, and I think their higher ISO noise is pretty splotchy...but Canon noise is often just as bad (only Canon color splotches tend to be primarily reddish, with a bit of green.)

64
EOS Bodies / Re: Multilayer Sensors are Coming From Canon [CR2]
« on: October 08, 2014, 05:07:26 PM »
I'm curious if this new layered sensor is the one that uses UV and IR layers to remove skin blemishes. If so, is this next Canon DSLR a replacement for the 1Ds, a studio and portrait camera?

65
Canon General / Re: seeimpossible.usa.canon.com?
« on: October 07, 2014, 08:06:46 PM »
F*cking Canon. Stupid enough to tease about their future advertising rather than working full tilt on their sub-par sensors.

Wow...civility just isn't a thing anymore around here... *sigh*

Later peeps. I came, I saw "impossible", I'm annoyed, goodbye.

66
Reviews / Re: Scott Kelby 7D Mark II Real World
« on: October 07, 2014, 08:04:09 PM »
Ok, another curious thing. Kelby said in the video that the 7D II was 24mp. Is that true? I thought the specs said it was 20.2mp. If it's 24mp, then I am now rather intrigued...that would mean Canon really did create a new sensor, instead of just revamping the 70D sensor with a minor DPAF improvement.

I am not entirely sure about noise...I'd prefer to see RAW to determine how much better than the 7D it is. One thing that I think is Canon seems to have improved is their color fidelity. None of my Canon cameras have ever produced color quality quite like the 7D II appears to. That was a very big complaint of mine about Canon...their lower Q.E. really hurts their color fidelity. I am not sure if this is a DIGIC 6 trick, or whether Canon actually updated their sensor technology...but if the RAW images have the same kind of color fidelity as Kelby's sports JPEGS, then they finally did something to improve their IQ. That's at least a step forward in the right direction (midtone color noise at ISO 100 aside...that's kind of an annoying problem, but it may just be jpeg compression artifacts.)

67
Reviews / Re: Scott Kelby 7D Mark II Real World
« on: October 07, 2014, 07:48:00 PM »
Looks like DIGIC 6 is doing a decent job. Not FF level quality, but definitely better than the 7D at high ISO.

The thing that was surprising to me was the amount of color noise in the boke background of the ISO 100 shot...seems like a lot of color noise for midtones....  ??? I'm hoping it's just a JPEG encoding thing, and that it wouldn't be there in the RAW.

Which begs the question...where are some 7D II RAW images? The OOC JPEGS look good for an APS-C, and that's probably primarily due to the DIGIC 6 processor...but how are the RAWs? Are the RAWs cooked by DIGIC 6 like the JPEGS? If not...is RAW IQ going to suffer?

68
You can always downsample the higher resolution macro to the same image dimensions as a lower resolution macro. The end result would be increased sharpness and finer resolved detail.

Even if your lens has an aperture setting that introduces visible diffraction? I imagine downsampling this would only result in digital "semi"-detail as a simply algorithm doesn't try to reconstruct data that isn't there.

When you reach hevily diffraction limited apertures, the detail is not there anyway. When your at levels of diffraction where the spot size is between the pitch of smaller vs. larger pixels, then smaller pixels CAN pick up more detail. It's actually possible for them to resolve more even when the diffraction spot is larger than the larger pixels. It's a progression of diminishing returns, eventually (say f/32) you get to the point where the differences are so small as to be meaningless. It's not that detail is there, then suddenly gone, the moment diffraction hits. This is a common misunderstanding (although I'm not sure your making it...just for the edification of everyone here).

If you have 10µm and 5µm pixels, and your diffraction spot is 6µm in diameter. The 5µm pixels are going to "see" that diffraction spot...the sensor is diffraction limited, however your not losing resolution relative to a sensor with larger pixels because of it. However, as far as the 10µm pixels are concerned, it still just sees a spot of light smaller than it can resolve. The same would be true for a 7µm, 8µm, 9µm and 10µm diffraction spot. The 5µm sensor pixels can be rather thoroughly diffraction limited, and they will STILL be resolving more detail than the 10µm sensor pixels. That's because the 10µm pixels simply cannot see diffraction spots smaller than themselves.

The data IS there...it may be starting to get softened by diffraction on the smaller pixel sensor, but that doesn't change the fact that until your diffraction spot is larger than 11µm, your smaller pixels are still resolving more detail. Even at 11µm, the smaller pixels will still be resolving a rounder spot than the larger pixels (which will be resolving a rather blocky spot).

Diffraction doesn't reduce resolution. Diffraction LIMITS resolution. A higher resolution sensor is a higher resoluti on sensor. The resolution of an image created with a higher resolution sensor can be limited by diffraction...but it cannot be reduced by diffraction.

I don't know if that helps. This is one of those things that I have explained to people so many times over the years, and I guess it's just a difficult concept. :P

69
The difference is simply that the lower resolution sensor doesn't "see" diffraction that the higher resolution sensor can.

Sure, I guess we understand this (did we?). However, it is a valid consideration - not to dump high mp sensors and say "18mp is enough", but to watch out for. At least for macro, I have experienced myself that using small apertures has a very bad effect on the sharpness, and that's what you're after with macro. So high-mp macro will mean more focus stacking, and with smaller steps.

Not really. You can always downsample the higher resolution macro to the same image dimensions as a lower resolution macro. The end result would be increased sharpness and finer resolved detail. Think about it...there is no way that smaller pixels could ever be bad (all else being equal). At worst, they would only be as bad as larger pixels...but in no way can they ever really be worse (assuming proper use of an AA filter or equivalent functionality...it's possible to overdo anti-aliazing, such as with Fuji's X-Trans sensor...overdo AA, and you throw away useful information and diminish or eliminate the value of having more pixels.)

Remember that to have an effective comparison, you have to normalize. On a normalized basis, higher resolution sensors are still resolving more detail at native size, even if that does not seem to be the case when pixel peeping at 100% native size...once you do downsample, the difference in resolving power and sharpness should pop out at you like night and day (especially if were talking about something like the 5D III vs. D810/A7r, where the resolution difference is fairly significant.)

70
Using a f/11 on a sensor with an f/5.6 DLA is no different than using it on a sensor with an f/8 DLA. Diffraction cannot make a higher resolution sensor perform worse than a lower resolution sensor. At WORST, they perform the same, on average, a higher resolution sensor will still outperform a lower resolution sensor at smaller diffraction-limited apertures.

The difference is simply that the lower resolution sensor doesn't "see" diffraction that the higher resolution sensor can. Remember, diffraction is always present, a single point of light is always going to be an airy disk at the sensor plane...as the lens is stopped down, the size of that airy disk increases. It's the same size for both sensors at any given aperture....it's just that the sensor with f/5.6 DLA is "seeing" smaller airy disks than the sensor with f/8 DLA.

71
Most electronic shutters up until recently were progressive shutters...the sensor would be read top down or bottom up row by row. That's relatively fast, however not fast enough to prevent exposure gradients from occurring, where the rows read later are brighter than rows read earlier.

To guarantee that no light continues to expose the sensor during readout, a mechanical shutter is used to block light. That's the primary reason.

Today, more advanced electronic shutter technology called a "global shutter" is becoming more prevalent. A global shutter does a simultaneous dump of all pixels into a per-pixel backing buffer or "memory". This allows the exposure on the image signal to-be-read to stop. That buffered exposure is then read out, row by row. When the next frame of an exposure is ready (in either video or continuous stills), the sensor pixels and the backing buffer are reset to zero charge, and the new exposure starts.

Global electronic shutters are more expensive, as they require more logic per pixel. They need the necessary charge transfer logic and buffer memory, which requires more space. When you factor in shared pixel architecture, it gets more complicated. The transfer of pixel data into the buffer memory does take some time as well, and there is still a per-row activation required to initiate the transfer (although it can happen much faster than a full row readout), so use of a global shutter can still impose minor limits on frame rate when we get into the kinds of pixel counts we have for still photography (at least at price points that are acceptable to most photographers...when cost is no longer an object, you can achieve high quality IQ at exceptionally high frame rates...but it definitely increases the cost of the shutter.)

At some point, I figure electronic first curtain shutter will become the norm for DSLRs. Eventually, the shutter should eventually be dropped entirely for a full global electronic shutter, even if the mirror remains. I don't foresee Canon doing anything with global shutter until they reduce their transistor size. At 500nm, adding a global shutter would decimate their IQ. At 180nm, they would definitely be more capable of adding global shutter technology, but it still takes up die space and reduces fill factor a bit.

72
Software & Accessories / Re: Need help putting together a ND Filter Kit
« on: October 04, 2014, 03:06:04 AM »
I personally highly recommend the Lee filter system. I spent a lot of time years ago looking into filter systems. It ultimately came down to Cookin Z-Pro and Lee. In the end, I chose Lee, as at the time they seemed to have the most flexible system (tandem adapters, hoods, configurable stacking options for each holder, a flexible CPL option, etc.) They still have most of the same advantages today.

The really nice thing about the Lee system is it is adaptable to lenses with up to 100mm filter thread diameters with a special adapter, and up to 82mm with a standard adapter ring (such some of Canon's newer L-series ultra-wides). It can also be adapted to lenses with very small filter thread diameters. The one single system can be used with pretty much every lens except those that use a rear filter slot, like Canon's supertele L-series lenses.

I've used the Lee holder, in different configurations, to hold anywhere from one to seven filters. One to four with a single holder, and up to three in one and four in the second for two holders in tandem. You can change out how many filters are stackable by guying different slide guide filter screws, and changing out how many slide guides are on the holder. For really ultra-wide lenses like 16mm (or 10mm on APS-C), this flexibility is useful, as dropping to two slide guides helps reduce the vignetting that occurs, while at the same time offering more stackability with longer lenses, the tandem option (which can be useful when you have a non-even horizon, allowing for different GND angles), and the ability to use Lee's very nice (but also very expensive) CPL filter in tandem with a 4x6" holder.

One of the things that I've found useful with Lee's system is the ability to add hoods. Sometimes this is very necessary, as when you start stacking filters, especially non-coated resins, the chances for flare greatly increase. The hoods allow for a lot of flexibility as they are bellows-like, and can be adjusted for different lenses. They don't generally work with really ultra wide lenses, but they work with most.

The Lee system is compatible with any 4x6" filters as well as 4x4" square filters. The former are used for GNDs, reverse GNDs, and a couple other unique options, where as the latter are used for solid ND filters, polarizers, gel holders, etc. You can use Lee, Singh Ray, Hitech, and a number of other brand filters in the Lee system. For DSLR-size lenses, this filter size is pretty ideal. They are a bit large for 67mm filter thread lenses, but are just about perfect for 77mm filter thread lenses.

You can get a starter kit for Lee Filters:

http://www.bhphotovideo.com/c/product/491474-REG/LEE_Filters_SET_RESIN_DIGI_Digital_SLR_Starter_Kit.html

When I purchased this, it was on sale, and a LOT cheaper. I don't even think I spent $200 on it. So, a price of $320 is well up there, seems a bit too much to me, but, it's the same kit I started with. I've added quite a number of filters over the years, namely the four primary GNDs in both soft and hard grad: .3, .6, .9, 1.2. I recently broke my 2-stop Pro-Glass ND, and I have a couple of other Hitech ND filters (including a 10-stop, which turned out to be an IR 10-stop that doesn't work with a standard color bayer sensor), none of which I really like...Hitech filters just aren't the same quality as Lee or Singh Ray.)

You want GND filters for landscapes that have a good horizon with a strong contrast differential (high dynamic range scenes), so you can bring the dynamic range within the range of the sensor. This works great when you have an even horizon. When you have an uneven horizon, soft grads are more useful than hard grads, especially the ability to blend a couple of them together. A reverse grad is useful for coastlines. Solid ND filters are very useful for allowing greatly reduced shutter speeds for longer water exposures. A 10-stop filter is useful for coastlines where you want to fog out the motion of the waves super-blur clouds, and create other effects with the in-motion parts of your scene. (Just, beware of Hitech 10-stop filters, it can be difficult to figure out which one is which, if you get the IR (infrared) one, it just doesn't work with normal cameras.)

73
Photography Technique / Re: Photographs in the "Blue Hour"
« on: October 03, 2014, 11:03:25 PM »
Here are a couple from Provo, UT. The first is of the LDS temple, and the second is a panorama from a 24mm lens, taken when I climbed up the large 'Y' on the mountain.  Both are just before sunrise:

Temple and Timp by yorgasor, on Flickr

Provo Blue Sky Panorama by yorgasor, on Flickr

This last one is of Utah Valley, taken just after sunset:

Utah Valley Car Lights by yorgasor, on Flickr

Wow. These are fantastic.

74
Third Party Manufacturers / Re: Nikon's 2.300$ D750 said to best 5DIII
« on: October 01, 2014, 12:04:29 PM »
Anyhow, good news is the competition is good for all of us and hopefully these companies wil continue building tools that we can enjoy. Here is a good article about the D750 written by Thom Hogan:

http://www.dslrbodies.com/newsviews/d750-too-little-too-late.html

I though Hogan's article was good, and pointed out some of the flaws I see in Nikon's product naming and marketing strategy. It's schizophrenic, haphazard...sometimes just weird. But, I think Tom missed one thing: Many D750 buyers will simply be D700 owners looking for an upgrade. He couldn't seem to find a position for the D750...I think a key part of it's position is the logical upgrade for D700 owners.

As far as I know, many Nikonians don't consider the D750 the real successor of their beloved D700: it's more a kind of "D620".
Which is not necessarily a bad thing, IMO.

Possibly jrista was taken in by the name of the D750 as a successor to the D700 (I was, at first).  Hogan's view that the D750 isn't a D700 successor is echoed by the Nikon shooters I've spoken with – including several pros using D700 bodies. 

Their complaints included things like the D750's lack of a PC sync port (means needing to buy hotshoe RF flash triggers, bummer Nikon lacks Canon's -RT flash system), the lesser build quality, the 'consumer' remote port (not sure if there's a functional difference, or it's like Canon's -E3 vs -N1 plugs and means currently owned remotes aren't compatible).  They weren't really bothered by the drop from 8 to 6.5 fps.  The general feel was that the D750 was a consumer camera, not a pro camera.  One commented (a little bitterly) that maybe Nikon thought including a Full Auto (green-square) mode made up for dropping the pro features...

I've read similar things on DPR forums, however it does not seem clearly cut and dry that D700 owners think it's not a viable upgrade. It seems more split than that...with many people saying that some tradeoffs were made, but that they still think it's a good upgrade for their D700.

75
I do believe better gear could have made my earlier shots better. I started with a 450D and kit lens, then got the 100mm macro, then the 16-35 and 100-400. The 16-35 enabled better landscapes. The 100-400 enabled bird photography. I spent a lot of time trying, learning, and experiencing the limitations of my gear (like 3.2fps and basic AF.)

I always feel as though I'm experiencing one limitation of my gear or another. When I got the 7D, it was the most liberating camera purchase I'd ever made at the time. It made the 100-400 lens work. :P If I'd started with the 7D, I do believe I'd be farther along in my photography than I am today, as I'd have been able to spend more time learning about the nuances of bird photography, rather than the nuances about how to get around the limitations of my 450D.

You probably always learn, and can probably always progress, regardless of the equipment in hand. However, I strongly believe that when your not learning how to get around hardware limitations, your learning how to actually do the kinds of photography your interested in. Moving from the 100-400mm lens to the 600mm f/4 lens was another liberating experience. I haven't felt the limitations of my gear nearly as much since the 7D and 600mm. Even adding the 5D III to my kit has not nearly had as much of an impact on my work as those other two additions. It's opened options for astrophotography, and allowed me to use already-existing skills to get close to birds and get better IQ in the process, and allowed me to fully utilize the capabilities of the 600mm lens. But it just hasn't had as much of an impact overall...as it really didn't eliminate any key limitations that I have.

Most of my limitations now, are just myself and my skill level (with the exception of astrophotography...still have LOOOTS of hardware limitations there.) Every time I go out to photograph birds and wildlife now, it's me learning how to photograph birds and wildlife...and much less about learning how to use my camera, or work around my camera.

Pages: 1 ... 3 4 [5] 6 7 ... 299