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Messages - Aglet

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586
EOS Bodies - For Stills / Re: ISO 50
« on: January 21, 2013, 04:54:13 PM »
LOL. Earlier, it was suggested that it means 'Half The Photons' - that seems to be Mikael's definition, anyway.

 'Half The Photons' is correct IF you concede that enabling HTP raised the effective ISO amplification +1EV from whatever ISO you were at before activating HTP.
so the resultant metering of course causes a -1 EV exposure - and HALF THE PHOTONS! :)

Sorry, but you seem to be falling into the same trap and suffering from the same misconceptions as Mikael.

It's only half the photons if the aperture is set a stop narrower or the shutter speed is set a stop faster. Are you suggesting that enabling HTP directly affects aperture or shutter speed? 

In fact, enabling HTP does nothing to the resultant metering - the camera meters for the ISO you select, it doesn't indicate that it's actually exposing at a 1-stop lower ISO, but it is (and that's why ISO 100 is unavailable with HTP enabled).  Try it - set ISO 200 or higher (but not a H expansion, since those are unavailable with HTP), meter a scene, then toggle HTP and see if the metering changes - does it?  Even in P Mode with Auto ISO where the camera is selecting all the parameters, enabling HTP does not change the aperture, shutter speed, or ISO selected. 

HTP doesn't raise the ISO, unless you have it set lower than ISO 200 before enabling HTP (and if you're at an H expansion ISO, enabling HTP lowers it).  I concede that in the specific case of the camera being set to ISO 100 before enabling HTP, the metered exposure will change by one stop, and IF you are in an auto exposure mode or you manually adjust exposure to compensate by one stop, then the number of photons will be halved.  Also 'halved' applies only if ISO 100 was set - if it was set to 50, 125, or 160, the change will be more or less than one stop (but not 'halved').  But that's a byproduct of how HTP works, applicable in a limited range of circumstances.  To conclude that reducing the photons by half is the mechanism by which HTP works is like concluding that a stopped analog clock is keeping correct time because you just happened to look at it at whatever time at which it was stuck.

As for misunderstanding Mikael, as I indicated earlier and Meh just wrote, that's clearly not the case.  He specifically stated, at least five times in at least four different posts, that HTP halves the number of photons and/or the amount of light hitting the sensor, and used that phrasing in describing the mechanism of HTP.  That manifestly demonstrates that his understanding of how HTP really works is seriously flawed, and if you are supporting that explanation, you are also failing to understand how HTP works.

Actually, I think all we experienced types know how HTP works as many have amply explained it.
I think this very long argument is in the semantics of describing the comparison of HTP to non-HTP is where I see the confusion.

Now I'm trying to explain what I think Michael was trying to explain regarding HTP and losing half the photons and how this argument got started.
Like Suede, I read enough of this thread to see that all of you experienced tech guys DO understand HTP but I think your methods of explaining it are being misunderstood by some.  This is quite possibly a result of different linguistic syntax, typos, or lack of clear explanation by someone who should have been getting more sleep. ;D

Michael, correct me if I am wrong.
I think Michael WAS basing his explanation on the base of 100 ISO, and that enabling HTP now means you no longer have it available so your HTP base ISO is now 200 ISO and, therefore, you'll be using half the photons to create the same tone you would have if you were still using 100 ISO. 
I know you all understand this and you as well conceded this in this specific case in your 2nd last paragraph, above.
This is the foundation of how HTP works. Agreed, yes?
Because, regardless of this argument, we all know that one full step up in ISO means we'll now be using half the photons to create a given tone or shade.

I think this got out of context when thinking about the higher ISO settings, with and w-o HTP

E.G. If we take a normal 800 ISO setting and require 100 photons per pixel to generate some shade.
at 1600 ISO we should only require 50 photons to generate the same shade or 200 photons at 400 ISO.

we're still good to this point too, yes?

now we turn on HTP and set to ISO 800
The metering is the same as for the normal ISO 800, hence the exposure is the same and we still use 100 photons to create the same shade.

But behind the scenes, inside the camera, the ISO (sensor gain) is actually ISO 400, and the subsequent processing of this raw file is tweaked so that those 100 photons create the same shade as they did with non-HTP 800 ISO.
The HTP advantage is that since the shot was really done, internal to the camera, at a 400 ISO sensitivity there's 1EV more headroom in the highlights available and the processing allows for a more gradual transfer curve near the top EV levels to prevent or reduce the likelihood of clipping bright shades of gray-white.
The HTP disadvantage is that this comes at the expense of signal to noise ratio which is most evident in shadow areas where fixed read noise becomes a considerable amount relative to the small signal of darker tones/shades.

we're still good ?..  I know what I'm talking about?.. :)

I think Michael merely views an HTP ISO 800 as ISO 400, 1600HTP as 800, etc.
I think his viewpoint is from INSIDE the sensor, and this does not surprise me considering how attentive he is to sensor metrics.
If you view things in this way then you ARE using half the photons compared to using the normal ISO and exposing appropriately.
If you view things in this way then you ARE changing the metering and therefore the exposure and the number of photons/electrons by -1 stop.
When using HTP you ARE getting more shadow noise for a given shade because it's only using half the photons to create compared to using the one step lower non-HTP ISO.

I think perhaps Michael did not succeed in making his point of view clearly to those of us who look at this from a different viewpoint is all.
If I had to explain this in another language i don't think i'd do a very good job of it myself.

I hope I presented a clear explanation of what I think is Michael's viewpoint.

Did I help clear anything up for anybody?

587
EOS Bodies - For Stills / Re: ISO 50
« on: January 21, 2013, 01:22:10 PM »
LOL. Earlier, it was suggested that it means 'Half The Photons' - that seems to be Mikael's definition, anyway.

 'Half The Photons' is correct IF you concede that enabling HTP raised the effective ISO amplification +1EV from whatever ISO you were at before activating HTP.
so the resultant metering of course causes a -1 EV exposure - and HALF THE PHOTONS! :)

Did you not understand what Michael meant vs what he may have typed or did you just feel the urge to have a battle from the same side of the argument?

Honestly, Neuro, we appreciate your extensive technical knowledge but some of us old guys are occasionally reminded of a a couple brothers scrapping over a toy by such an extensive display of (where do I get that cool little animation for) beating your head on a brick wall.

I hope you keep up your high rate of helpful and clear advice but temper it with a bit more restraint and human understanding in such cases.  I think you might have driven Michael to drinking after this thread. ;)

588
Third Party Manufacturers / Re: D5200 review
« on: January 21, 2013, 01:18:07 AM »
Why someone would talk about Nikon products on a Canon forum?
I think you got the wrong forum.
Cuz, that's what THIS forum section is for, seriously! :)
see below when you click on Forum Home

Third Party Manufacturers
Nikon, Leica, Sigma, Tamron, Tokina and the rest go here.

Anyone else looking fwd to CP+ in less than 2 weeks to see what kind of new goodies get announced?
I'm thinking the gang over at Nikon might just drop a new semi-pro body with this new sensor that will be even more impressive as an overall package.

OTOH, I'd like a 7D Mark II that doesn't give me picket fence vertical stripes in base ISO shadows cuz my 100-400 L is lonely since i sold the original 7D that wasn't good enough for what I wanted to use it for.

589
EOS Bodies - For Stills / Re: ISO 50
« on: January 21, 2013, 01:08:58 AM »
clip..
1... I have done tests with my D600 and there is less noise at ISO 50,..

Whoa, stop the presses.
your D600 has noise?!?...
That's a distinctly Canon issue. ;)

BTW, sounds like most of the ISO-arguing around 50-100-HTP and D-L know enough about how to USE it.

@neuro, @trumpet, @ etc...
don't forget @michael seems to speak english as a 2nd language so I often find his sentence syntax confusing but after wasting time reading nearly 3 pages of arguments from you all it seems to me you're perfectly aware how this technology works but can't seem to see that for the scrap that's broken out over semantics and typos.

I initially thot I'd make more use of iso 50 on my 5D2 at some point for making cleaner low key shots.  Turns out I rarely shoot anything like that to advantage.

I DID get out for an hour of photo-therapy around sunset on Saturday, a nice way to deal with too much stress from work and family.
Shot with 5d2, d800, d5100s and a Q.  The first 2 were equipped with 70-200mm zooms and I was shooting the same high key scene in dim overcast skies and snow everywhere, including inside my car cuz it was too cold to step outside of it.
I liked shooting the 5d2 w 70-200/2.8L is2
I loved shooting the d800w 70-200/4 vr3, crisp handling, spot-on WB, better AF in blowing snow; a condition that often had my Canon cameras failing to AF properly all too often.
D5100s AF'd well but gave me some odd WB, often a bit green but easy to fix in post.

Everybody, get out and shoot more! :)

590
Reviews / Re: Review - Canon EF 70-200 f/2.8L IS II
« on: January 18, 2013, 09:07:18 PM »

It has slightly less vignette @ 2.8 but that's about it. Neither are terrible lenses but to claim either is vastly superior in IQ is nonsense.

The prime certainly wins on speed, weight, bulk, price, and stealth. If only it was a bit faster and had IS.  ;)

I suspect this prime is likely to have more consistently smoother bokeh and less CA than the battleship zoom.  For that alone it's worth at least half the cost of the zoom.

591
Third Party Manufacturers / Re: D5200 review
« on: January 18, 2013, 08:59:59 PM »
It's out, DxOmark has published their tests on the D5200 and it's bloody impressive in the basic metrics!

D5200 dethrones the Pentax K5 series as the top-scoring crop-sensor camera.


www.dxomark.com/index.php/Publications/DxOMark-Reviews/Nikon-D5200-New-sensor-and-new-leader/Measurement

I don't care for their overall scoring, but looking at the individual test results, this thing is performing very well for such small pixels.  This would make it it entirely possible to produce a 54MP D4x body or a lower MP FF with even better performance.

Pixel-level signal to noise is going to suffer because of the smaller pixels, but when you put them together in a print, even a very large print, it is going to deliver some significant improvements.  It's high ISO performance isn't bad either.

Still looking forward to finding out how well it's new metering and AF system perform.

For now Im still quite happy with the image quality I can pull from it's predecessor, the D5100.

592
Reviews / Re: Review - Canon EF 70-200 f/2.8L IS II
« on: January 17, 2013, 01:36:02 AM »
I have the first version of this lens and am very happy with it. One knock I've seen commented on about the mkII is the bokeh is a bit more 'nervous' as compared to the first version. Not to say it's bad, but just not as 'creamy' as the original version. Aside from the cost to upgrade, this one quality is of concern to me in contemplating an upgrade. Can anyone comment on this comparison, is it fair to say the mkII isn't quite as nice in this one respect as compared to the original 70-200/2.8 IS?
I've shot all 3 of Canon's EF 70-200 2.8 L's
You can not beat this latest v2 for sharpness, it's fantastic!  So is the IS, very capable.
A bit of CA in FF corners but that's minor.

But yes, it's bokeh, at least in some situations, can be hideous and distracting, especially, in my findings, at wider apertures if there were fine structures just out of the focus plane (tree branches for example).  Unfortunately I ran into too many other compositions where the background blur quality was really poor, even when separated from the in-focus subject by a large distance.

I think this is one of those unfortunate compromises when an incredibly sharp zoom is built that has a lot of corrections to fix everything that's IN focus, the stuff that's OUT of focus can sometimes suffer.
I can also create an attractive bokeh, but I've preferred the look of the original non-IS lens for that at times.  The v1 IS was so not-sharp at the long end I got rid of it quickly.

Go play with one in the store.  You can see some of this effect even in a viewfinder as you adjust focus and zoom.  Can be really apparent if you can point out a window at some trees or shrubs where there's some fine structural elements and you'll see the kind of distortion caused as you the controls or even pan the scene.  I posted a sample in the lens gallery here.

My new Nikon 70-200/4 VR also does the same thing to a slightly lesser extent which some have referred to as "radial bokeh."  I need to do more testing before I determine which lems is more agreeable to me now that the 6D is a camera I also find capable of agreeable image quality to match.

If bokeh quality is as important to you as extreme sharpness then you have a tough decision to make.
I'm also waiting to see how the new stabilized Tamron 70-200/2.8 performs.  I've had good results from the earlier version.
I haven't played with any of Canon's f/4 Ls in this range.

593
Canon General / Re: DxOMark vs. Reality
« on: January 15, 2013, 04:20:13 PM »
I've requested permission of a family whose casual photos I shot last summer where FPN is noticeable on dark clothing.
I expect they'll approve my request.
It's about the last time I used the camera.  Customer was totally pleased with the results, I was not.

I've basically sidelined the 5d2 as an inadequate FF Rebel with serious FPN problems, not worthy of MY use so it's seen very little action with me.
I got the thing to do landscape and other outdoor and high DR work.  It's not been able to adequately fulfill that role, the way I want to use it, so to me it was an expensive PoS with limited ability.  It DID deliver some really great images in many situations where lighting was not challenging, but was not able to do so when and where I needed it to. At the time I was also using a 40D which showed less FPN when using similar PP.  I still like and use the 40D.
So a new 5D2 having worse raw file IQ than my older, cheaper camera was a big disappointment, to put it mildly.

Maybe 5d2 was one of the better tools available at the time, doesn't mean it was good enough.  A better tool was announced less than 3 weeks prior to the 5d2, the d90.  However I was an ignorant Canon fanboy at that time and paid little attention to the competition with all the full-frame excitement and high expectations.
Now a cheap consumer camera from a competitor nearly 2 years ago, at 1/5th the cost, grossly outperforms 5d2 in this part of the operating regime it only reinforces my opinion that the 5d2 was, and still is, a grossly overhyped bit of gear.  Despite that, the vast majority of users are happy to continue using it.  That's fine for them.
Those who are content with the shortcomings of a tool they're using are not going to convince those of us who need a better tool that it's OK!  Thanks for trying.  People on here are truly helpful and a great resource to plenty of newbies. :)

Hopefully I'll get permission to post a few samples where maybe you'll actually SEE the problem.  Possibly helping spare some avid users some unpleasant surprises that they haven't yet discovered.

You guys may need to be reminded. I'm not a Canon hater, just a disappointed long time Canon user who opened his eyes and found better tools for certain shots from the competition.
I still like using my bucket of Rebel bodies, 40D, and 60D and am looking fwd to an improved 7D Mk 2 or 70D.

@privatebydesign - i often print big too. expose for the highlights, bring up the rest with various curve tools until the image DR is compressed to a useful range for printing.  This is where the 5d2 (&7D) can fail if there was a lot of DR in the original scene.  The sensor may be similar or even the same between this and your 1 series body but there's a lot more to the rest of the electronic guts that can make the difference in FPN.  Quality is rarely skimped on the 1 series.

I got better results with my 40D, 60D, and various Rebels than what the 5d2 delivered.  And now my modern Nikon gear blows them all away whenever I need to do this this kind of processing.  Right tool for the job, but not necessarily the same tool for all jobs.

@Mikael Risedal - Thanks for knowing and understanding. :) I don't know if I've seen your real world comparison shots other than the one of a shed with interior shadows.  Apparently that does not qualify as a real world image for some people.  What if you want to spy on the contents of your neighbor's shed?  ;)

I suspect Neuro will tell me that I wasted 1 or 2 possible stops worth of DR on some of the shots by some of the method I used.  I.E.  I could have ETTR more if I were using Neutral or Faithful instead of Standard settings so my RGB playback histogram would more closely reflect raw headroom.  Yup... Might have.  I don't have to worry about this on my other bodies tho.

594
Canon General / Re: DxOMark vs. Reality
« on: January 15, 2013, 11:58:08 AM »
How come the 5D2 IQ was impeccable before the D800? I find it still impeccable today. :|
it was not when it was released
it is not much better after all the firmware updates
it made a big splash being the first CHEAP full-frame and those who wanted or needed that were so enthused with this new toy they paid little regard to its IQ shortcomings because it offered IQ benefits and features previously unavailable.

Endlessly trumpeting on that basis suckered me in to buying one; my most regrettable Canon purchase.
not for lack of due diligence, but for lack of honest and clear information about the 5D2's weaknesses, which became clear enough after I used it for a while. .. and after others began posted about its less than ideal low ISO FPN issues.

If you still find it meets your needs you either lucked out with a good one or you don't mind crushing your blacks a few more levels than some of us.

edit adding DxOmark comment below:

and THIS is what annoys me about DxOmarks results. not just that they assign a vague overall score to a camera, based solely on measured sensor merits, but that they do not adequately disclose the testing criteria and data in a way that would allow the technically astute reader the opportunity to evaluate the data on their own.  And, for the most part that I've found, neither do other sensor tech sites.

When FPN affects a sensor to the degree some of the Canon's (and some other mfr's products) were affected, it would have been very valuable to have a good idea whether the noise was random and acceptable or whether it was patterned and possibly objectionable to prospective purchasers.

DxOmark's data is useful but incomplete and that makes it much less useful than it would have been in my particular instance.

595
Lenses / Re: Reasons why 14-24L zoom will not be coming soon
« on: January 14, 2013, 11:46:55 PM »
FWIW, I've recently tried (by way of purchase) a new Tokina 17-35mm f/4, hoping to find a lens that performed better at the wide end than the 17-40 f/4 L. (to use on my FF F-mount system)
I've only done some flat-field, close-in test photos and a few other landscape types.

For the price, I'd not take the Tokina over the Canon 17-40mm f/4 L.
On F-mount it's a cheap enough option to consider.
 

596
Lenses / Re: Your favorite lens is?
« on: January 14, 2013, 11:25:19 PM »
Isn't someone going to say EF-S 18-55? It's supposed to be the number one Canon lens for numbers produced.... someone has to like it.... anybody?????

its not a very good lens, if they upgrade the optics to be the same as the 18-55 EF-M it will be a big improvement for this kit lens

For all its issues, I still love the EF-S 18-55mm IS for its flexibility, price and weight.  You just have to understand its weaknesses to be able to enjoy this lens at least for casual photography.  I for one can't complain on some of these pics:

http://www.flickr.com/groups/canon18-55is/
definitely great performance per price and good for close up work if you don't need or have a nice macro.
or when you need a lens for hazardous work that's likely to result in, uhm, damage.  Combine with a 2nd-hand Rebel.

597
Lenses / Re: 17-40 vs 16-35, which one got the mojo ?
« on: January 14, 2013, 03:56:45 PM »
I've found the 17-40 comparable with the 16-35 between apertures of f/8 - f/11. f/4 is a bit tricky though and best avoided unless left without an option.

I've would recommend that the OP should go through the image threads for both the lenses and (i) try to see the difference in IQ; and (ii) decide which lens has "mojo" that you are looking for.

I think that sums it up - if you are shooting primarily landscapes with a tripod or are doing studio work between f/8 and f/11 it probably doesn't matter which lens you buy - you may as well choose the cheaper option which is the 17-40.  If you need to shoot at f/4, the 16-35mm is probably better.  And of course if you want the subject isolation you get with f/2.8 or you want to shoot action, the 16-35 is probably your choice.

+1
I haven't bothered with the 16-35 v1 cuz it's not sharper than the 17-40, v2 looks significantly improved.
I found the 17-40 has really poor corner performance at the wide end, mushy even when stopped down a lot.  Performance varies with subject/focal distance. Seems worse at long landscape distances. But it does have a little more "something" when used on FF compared to the 10-22mm on crop, which I still do use occasionally.
FWIW, you can buy and try a used 17-40L and resell it if you don't like it and probably lose less than the rental cost.

FWIW, I've recently tried (by way of purchase) a new Tokina 17-35mm f/4, hoping to find a lens that performed better at the wide end than the 17-40 f/4 L. (to use on my FF F-mount system)
I've only done some flat-field, close-in test photos and a few other landscape types.

It's the only lens whose FF corner performance, at least on the near flat-field tests, was absolutely abysmal. Pure mush at any f stop.  Real-world images at normal distances were better but still poor corner performance until about 24mm.
Accutance was otherwise quite good in center and border areas and geometric performance was very good, holding straight lines very well with minimal distortion.
However, for the price, I'd not take the Tokina over the Canon 17-40mm f/4 L.
On F-mount it's a cheap enough option to consider.

598
Lenses / Re: Reasons why 14-24L zoom will not be coming soon
« on: January 14, 2013, 03:09:19 PM »

A zoom will almost certainly have more distortion than the prime at 14mm.  Correctable, yes...but only by adding softness to corners already unlikely to be exceptionally sharp.

Again the Nikon example is being ignored, the 14-24 outperforms the 14 prime in almost every metric

Not ignored, but I'm not sure it's a relevant comparison. The 14-24mm is much newer than the Nikkor 14/2.8.   

Compare the 70-200/2.8 IS vs. the MkII to see how far Canon went in a similar period of time. 

The Samyang 14mm prime is even sharper than the vaunted Nikon 14-24 and much better in the corners too...  At the expense of a lot of bulbous barrel distortion in the middle.  Not much of a problem for nature but nasty for anything with straight lines not running right down the center of your composition.
So Nik's 14-24mm is a compromised but very nicely behaving UWA lens for a variety of uses and you get to pay many x the price for that.  Canonites can expect Canon to produce a similarly well behaved and likely even better optic but you'll be paying for that.

599
Lenses / Re: Your favorite lens is?
« on: January 14, 2013, 02:34:12 PM »
Hands Up!, the 100-400mm L
not the best lens by a long shot, hideous transition zone bokeh but when this thing delivers, it REALLY delivers.  Not my most used lens but has provided some of my most outstanding, mostly nature, images.

600
EOS Bodies / Re: EOS not good for NASA?
« on: January 14, 2013, 02:25:52 AM »
Space is mostly dark, eh..
Don't want to be using Canons that fill all that dark up with faint reddish stripes and such, gets confusing.  :P

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