October 21, 2014, 02:35:26 AM

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Messages - jrista

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46
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.)

47
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.

48
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.

49
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.)

50
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.

51
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.

52
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.

53
I can see this being a good product for Canon. I don't think its crass, certainly not like a Hello Kitty item would have been. It's white. Well, white with a little offwhite. I can see a lot of women being interested in this, and even beyond that, I can see it being "stylish" (there are a couple places in Colorado packed with high-end restaurants and clubs, and it;s pretty common to see guys in all-white suits and things like that). In particular, though, women are becoming the dominant buyers of a lot of items like this, and it'll probably end up being a lucrative thing for Canon.

(Although, I think it could become even more lucrative if hey would offer more variety...a black case, maybe a couple other colors. I could easily see people matching their Rebels to their phones and tablets.)

54
Third Party Manufacturers / Re: Nikon's 2.300$ D750 said to best 5DIII
« on: October 01, 2014, 01:26:35 AM »
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.

55
Third Party Manufacturers / Re: Nikon's 2.300$ D750 said to best 5DIII
« on: October 01, 2014, 01:15:43 AM »
The reviewer made note of how the high DR at High ISO is so huge. So did the D750 get a high ISO DR boost over the D3S?

From what has been tossed around over the past month High DR is a low ISO thing, I have seen many test examples that show DR dropping hard at higher ISO. D3S & D800 included...

Check out the A7s...it has good low ISO DR (over twelve stops), but it also has excellent high ISO DR (it tops the 1D X, meets or beats it at every ISO, with as much as a 2-stop lead at ISO 51200). The D810 also does extremely well at high ISO, getting very close to 5D III performance with smaller pixels.

I don't know how well the D750 does, but I suspect it will perform similarly.

56
Third Party Manufacturers / Re: Nikon's 2.300$ D750 said to best 5DIII
« on: October 01, 2014, 01:10:21 AM »
Until I can look through a Nikon viewfinder and change ISO settings with my right index while also adjusting any other setting I need, I'm sticking with Canon.

Haven't you heard?  With a Nikon camera, you don't need to change ISO – just set ISO 100 and you're done.  In post you can push it to ISO 3200, with a SoNikon sensor that's easy-peasy and the IQ is still better than Canon.  Or so I've read somewhere or other...   ::)

You make fun of it...but it's possible. Because there is practically no read noise, digitally lifting ISO 100 to ISO 1600 or 3200 is effectively the same thing as actually using those ISOs (with the added benefit of having massively more dynamic range).

When you lift ISO in post, doesn't it chop down the DR?

Dynamic range is the space within which you perform the lift. It changes the contrast, but the dynamic range is your working space within which you change the contrast of your images. You pretty much have what you have when it comes to DR as far as editing latitude of any given file goes. If you are working with an OOC RAW, then your limited by what the RAW started with. If your working with an HDR, your limited by the results of your HDR blend.

57
The A7r files were exposed at a cooler temperature...4100 something. In my comparisons, I always normalized the white balance to 5200. When you do that, the A7r gets a lot warmer, and the color channels align more like the 5D III.

58
Interestingly, I don't really see any significant difference between them, even in the +5 ones (calling the 5D3 one "falling apart" is totally ridiculous, it's a perfectly usable picture). Admittedly my eyes are old and I'm looking at the pictures with a relatively lowly monitor, but that's what I'd mostly do anyway. I guess it means the DR difference isn't a good reason to go for Sony, *for me* - your mileage may vary.
Well, you must be blind, then. :P Sorry, but the difference is night and day obvious with the +5 stop pushes.
I'm not quite blind, yet. :-) I didn't say I can't see any difference, just not a significant one. Not when viewed on screen without magnifying or deliberately pixel-peeping. And I'm pretty sure most non-photographers would agree.
Quote
The 5D III is completely and utterly unusable, period.
That would depend on the intended use, I should think. Even and indeed especially professionals should be able to adjust their standards depending on client's needs.

If you haven't downloaded the RAWs and taken a look at them, then I encourage you to. Lifting the shadows a couple stops doesn't render the 5D III image unuable, however it does exhibit banding before you even lift three stops. The "utterly unusable" image is the +5 stop 5D III image. Maybe it's not as obvious in the small JPEGs I shared in the first post...but when you see the RAW, I think you will understand.

The difference between the A7r and 5D III is night and day. Whether that matters to you or not is something I won't judge, but just from a simple empirical standpoint, the +5 stop 5D III image is....really poor.

Calling the 5Diii unusable is a joke.

That is not what I said. I said the +5 stop pushed 5D III image of my living room was entirely unusable. Again, I encourage you to download the RAWs and compare them. I'm not calling the 5D III an "unusable camera"...I never have, I never will. I am simply calling the result of a +5 stop push with a 5D III RAW image "utterly unusable." I would honestly be surprised if anyone disagreed with that assessment after playing with the RAWs themselves...however if you insist the image could be usable after seeing the RAWs for yourself....well, to each his own, I guess.

59
Sorry guys, looks like my OneDrive upload stalled yesterday. I am reuploading now, same place as the original two. In the mean time, here are the histograms:



Here is a magnification of the highlight end:



As much as the A7r image may LOOK as though it is more exposed than the 5D III, it is not (especially when the white balance is corrected, the A7r WB was much cooler, I set it to the same 5200 as the 5D III image). The histogram is pushed farther to the right in the 5D III image. The 5D III image looks darker because...it has less dynamic range. More of the signal was exposed in tones that, on a relative scale, are deeper for the 5D III compared to the A7r. The exposure advantage, as far as ETTR goes, leans towards the 5D III here.

60
Third Party Manufacturers / Re: iPhone 6 gets an Exmor
« on: September 29, 2014, 05:31:07 PM »
Apple consider themselves to be a premium brand so it makes sense that they would use the best sensor tech available.

Yeah, indeed.

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