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Messages - noisejammer

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31
Technical Support / Re: Color Management Woes
« on: August 15, 2013, 08:56:56 AM »
I use a U3011 - if you put the display into Adobe RGB or SRGB modes and then try to apply correction, it seems to go a little strange. I find leaving mine uncalibrated in Adobe RGB is more than accurate enough.

On the odd occasion where accurate colour is critical, I find that ColorChecker with a session specific camera calibration is the only way to make the output reflect the input.

You might also consider whether the environment you're working in is changing your perception of colour balance on the screen. I think[\i] this happens but it's very difficult to test on your own.

Based on your comment to xROELOFx ... try switching the screen to SRGB for viewing the web images.

32
Lenses / Re: Lens flare.... I want it! :)
« on: August 03, 2013, 10:23:48 AM »
Get yourself one of these...
http://www.etsy.com/shop/DogSchidtOptiks

Yes, the company's name really is Dog Schidt Optiks. At least you know what to expect...  :)

33
IIRC, the 5D II produces the same noise at 1200, 1600 and 2000. I believe this is an effect caused by their being two programmable amplifiers in the signal chain. Whether it's real or imagined, astrophotographers try to exploit the knowledge to optimise performance.

I'm scratching here but I think the source was Roger Clark's site - http://www.clarkvision.com/articles/index.html

Personally, I'd invest in first rate noise reduction software (I'm using Noiseware at the moment.) For imaging in extremely low light levels, it's common to try to profile the noise pattern that the camera produces. When done with care, this is at least half a stop more effective than the noise reduction Canon offers.

More than noise floors, I'd be somewhat concerned about the 5D II's ability to autofocus in low light - the 6D may be a better choice here. I'd also be cautious about focus shift when using fast glass... make sure the MFA is optimised at the aperture you plan to use.

34
Software & Accessories / Re: Who Adopted Adobe CC?
« on: July 22, 2013, 06:56:37 PM »
Nope, I didn't choose the CC route and having been encouraged to try alternatives, it's very unlikely that I'll give Adobe any more money.
I found that Capture One Express does at least as well as a raw pre-processor and can send the image straight into Photoshop.

C1 Express cost me $35 a couple of weeks back... what's not to love? It does need quite a serious machine - so try before you buy.

35
EOS Bodies - For Stills / Re: Fantasy Dayhiking Kit
« on: July 21, 2013, 01:45:20 AM »
I can't think of much that would persuade me to take a 200-400 with me on a hike around the block, let alone go for a day walk!

Having done a lot of mountain trips, I learned that cameras in my rucksack were pointless - stopping to get them out meant a loss of rhythm and added to already long days. This meant my camera had to be immediately available. My pre-digital mountain gear usually had an OM-2 a 24/2.8, a polariser and a GND. Occasionally, a 50/1.8 would make it into my bag but it was seldom used.

Enter the 21st century and a period of "progress." Until a few months ago, I'd pack a 5D2, maybe a 17 TSE, 21/2.8 or 25/2 and maybe a 50/2 MP. If I was brave, there would be a 100/2 MP or a 70-200 II or 400/4 or something else. Add a couple of filters and batteries and it's lots of kilograms to lug and the walk stops being fun. If a longer lens went along, it was with a monopod which needs a lens bracket and I may as well take an L-bracket for the camera. All this adds up.

Having used a lot of lenses over more than 35 years photography, I realised that fast lenses come at a premium - backache. A moment's thought should convince you that switching from f/4 to f/2.8 has around 4-6 times the weight. (The lenses must have twice the area and be twice as thick. Frequently, there are more elements, the mechanics are more complex and the lens is twice as long.) Anyway, it got to the point that I wasn't taking my camera with me because it was just too much hassle.

All this made me give a try at a mirrorless camera for my walkabout toy. I take a 12mm Touit and a 18-55 and that's it... It's the first time in years that my camera weight approaches what it used to be. Most of all, it's accessible.

36
I use my 5D2 for landscape work and have a good selection of Zeiss glass. Autofocus is thus totally irrelevant in my manually focused, live view, 0.1-shot-per-minute world. Since the 5D3 didn't offer much in the way of meaningful improvement - particularly resolution, dynamic range and low ISO noise, I decided to sit on my hands.

The cameras I have are still way better than I am and I don't want another camera that does the same job. If Canon releases something with a combination of enhancements that are significant to me, I'll take it. If not, my 5D2 / 1D4 / Fuji X-E1 combination is more than sufficient.

If - given the rapid development of the mirrorless segment this is a very big "IF" - there's a successor to the 5D4 (for lack of a better name), it will doubtless be quite a different animal from the 5D2. It might even be interesting.

37
EOS Bodies - For Stills / Re: 5D Mark II composition movement
« on: July 21, 2013, 12:37:23 AM »
I came across a 1D Mk IV which had a similar problem. I eventually tracked it down to damage in the dioptre compensation mechanism. I suspect the camera was dropped which broke the supports leaving a lens group free to wander around. As the camera was tilted, the optic would change its attitude wrt the prism and you'd be looking at a different part of the screen.

Anyway, the repair was quite easy - replacing the assembly took less than half an hour.

38
Lenses / Re: 50mm Primes that don't suck wide open?
« on: July 12, 2013, 07:43:44 PM »
Since the sensor doesn't actually detect light from a fast cone, it can't contribute to the bokeh

I'm not sure where you read this, but it's demonstrably false. I'm looking at two 7D + Sigma 50mm shots on my screen right now, f/1.4 and f/2, same subject/distance/etc., and the difference in bokeh is quite clear.
Apologies for trimming your post.

First, I'm well aware of the LL open letter and have referred people to it previously - here, on POTN and elsewhere.

I observed four effects -
1. Few people bothered to go to read the reference and digest its content.

2. It refers to a DXO study and there's a rabid hatred of DXO measurements, particularly since they tend to be quite scathing over Canon offerings.

3. Few people who read the letter did any testing  but this did not prevent them from commenting that it was a lie - perhaps a result of point 2.

4. There was a lot of nastiness - particularly from owners of 50L and 85L lenses - perhaps because they had a lot of dollars sunk in the lenses.

Because of this, I've changed my approach. I invite people to perform the experiments and simply judge for themselves. It cuts through the internet noise quite effectively.

Bokeh
Ok, so let's assume you've now performed the experiment using a 7D.

If you did it properly, you will have noted that the image is dimmer when the camera could not communicate with the lens. I venture that the same number of photons hit each pixel (within photon noise and your ability to align the tests) so presumably something else gets changed when the camera communicates with the sensor.

There is simply no way that a photon that is not detected can plausibly contribute to the bokeh. (If you doubt this, please suggest a mechanism.) Therefore, if there's a difference between in the image quality between (say f/1.4 and f/2), it can't be light that's doing it.

I strongly suspect that there is some image processing going on inside the camera to deliberately soften the image from lenses that have large apertures. It may be possible to demonstrate this idea by installing an aperture mask on a wide open lens and seeing whether the image quality changes (say between f/1.4 and f/1.8.)

Finally - another reference that may be of interest http://goo.gl/5We9r . Note how the 7D loses 0.65 EV when the sensor is illuminated by a f/1.4 lens. This strongly suggests that the pixels do not respond to light that's coming from a cone which is faster than f/2. Similarly, a 5D2 and 1D4 will lose 0.44 EV at f/1.4.

regards etc.

39
@Fleetie - thanks for doing the test.... I'll take a bow :)

@Drizzt321 - wide open an f/1.2 lens collects (1.4/1.2)^2 = 1.39 times as much light as a f/1.4 lens. This corresponds to 0.47 stops (not 1 stop.)

Of course, you would expect the f/1.2 lens to be brighter than a f/1.4 lens but this is NOT what Fleetie observed. When the camera communicates with the lens, it boosts its internal ISO (without telling you) so that the f/1.4 image becomes brighter than the f/1.2.

(IMO) This is a swindle that's perpetrated to persuade people to continue buying fast glass.

40
Lenses / Re: 50mm Primes that don't suck wide open?
« on: July 12, 2013, 08:16:58 AM »
I don't think so, that would make pictures taken with fast Canon EF lenses more noisy. It is a fact though that (depending on your camera model) the AF sensor knows it's a fast lens and this the f/2.8 cross points are activated giving you increased AF performance. This has nothing to do with the imaging sensor.
Um... AF performance has absolutely nothing to do with bokeh or detected light. Perhaps you should try to understand the post and then do the suggested experiment?

Remember, the boost is at most 1/2 to 1 stop. As it happens, the image noise does increase - albeit slightly. It takes considerable care to measure changes in the noise floor, particularly below 1600 - 3200 ISO.

41
Lenses / Re: 50mm Primes that don't suck wide open?
« on: July 12, 2013, 08:10:37 AM »
Uhmmm... I'm getting really confused about what you say.
There is something that I don't get at all.
If say a 5DmkIII can "see" only through a f/1.6 lens, so does this mean that everything faster is pretty much useless?
I do believe that the peripheral illumination could be as you say, so not sensitive from a certain relative aperture onward, but the central portion of the sensor should collect light coming from every angle from the lens aperture.
I am in office now, but I hope to be able to do some testing in this regard.
The test I would do is as follows:
- fix the ISO value
- fix the shutter value
- fix the ambient light level with controlled, artificial light
- take pictures at say f/1.4, f/1.6, f/1.8, f/2.0
- compare the brightness of the central pixel of each picture in the three channels (better to use a white paper i the center of the image so the channels would be roughly the same output)
- check if the RGB brightness will vary between the shots
I am pretty sure that it will.
I hope to be able to do so in the incoming week end.
BTW, I like so much you guys in this forum, you are always able to make me learn or at least think about new issues.
Best regards, have a nice day!
I think you missed the light from outside the f/1.6 cone arrives at the sensor from a steeper angle. Think of each pixel as a short straw with it's active part at the bottom of the straw and all should be clear - in effect the edge of the pixel vignettes each photodiode.  I'd expect the cut off to be gradual as the photodiode is shaded.

After reading a recent Panasonic release (http://goo.gl/279uS) I learned that it is typical for current sensors to accept light that impinges between 15 and 20 degrees from the vertical. This corresponds to a light cone of f/1.86 and f/1.37, in general agreement with my measurements.

When you do your test, remember to half-release the lens from the camera so that the camera doesn't know there's an attached lens. Shoot a manual series (raw, full aperture, trade exposure against ISO.) You can then repeat the set with the lens fully mounted and compare images.

The result will then be fairly obvious. If you have software that allows you to compare pixel levels, so much the better.

42
Lenses / Re: 50mm Primes that don't suck wide open?
« on: July 12, 2013, 05:46:56 AM »
I did a comparison of those 2 lenses with the Canon 50/1.4. I found that the Canon is faster (i.e. brighter in terms of T-stop or light transmittance) than the Zuiko f/1.2 lenses. But there wasn't a lot in it.
So there are people with taste for older glass on this forum too. :) I'd turf out your fungus lens before it infects others and recommend you try the Rokkor 58/1.2.... you will like it.

To business - I'm deeply skeptical that the T-stop of the OM 50/1.2 is slower than the EF 50/1.4. Although there should only be 1/3 stop in it, none of your cameras are capable of detecting light that comes from faster than f/1.6. The 7D (iirc used for your test) is not capable of detecting light from a cone faster than f/2.

Nevertheless, Canon cameras appear to register better sensitivity when coupled to EF lenses. This is because the camera knows that it's connected to a fast lens and silently boosts its ISO. Of course, it has no idea about the OM 50/1.2, so it does nothing and gives you a faithful measure of the detected light.

I tested this quite carefully - the trick is to partially rotate the lens so that the electrical connection is severed - it's real. Curiously, my ZE 35/1.4 and Sigma 50/1.4 lenses also appear to be faster than they really are...

Others tested the 50L and found it behaves like a 50/1.6 on a 1D4 / 5D2 and a 50/2 on a 7D. I can't speak to a 5D3 - I decided that I'd be upgrading when I got to be better than my camera.

Canon is not the only culprit caught up in this game. Nikon, Sony and Pentax were also caught cheating customers out of large aperture. Per my comments, my Fuji X-E1 doesn't cheat with SLR lenses (but I've no idea whether it does with fast Fuji lenses.)

Now all this returns to the question of which lens is sharpest wide open. Well, the short answer is they're all pretty good at f/1.6 and excellent at f/2.   Since the sensor doesn't actually detect light from a fast cone, it can't contribute to the bokeh - but since it's inside the mirror box, it could bounce around and degrade the contrast. Bear in mind that there's more than half a stop between f/1.6 and f/1.2 so 30% of the light intercepted by the lens is bouncing around...

43
Lenses / Re: 50mm Primes that don't suck wide open?
« on: July 11, 2013, 02:08:46 PM »
I've own the Canon 50/1.4, Sigma 50/1.4, OM 55/1.2, Rokkor PG 58/1.2, Zeiss ZE 50/2 MP, OM 50/1.8 and probably a few others that I can't remember.

First, most full frame digital sensors cannot accept light that impinges from a cone outside the f/1.6 region, so it's moot whether a fast lens is of any particular benefit. Still, I expect this will change over the next year or three as new sensor technologies are adopted. As an aside, some CSC sensors accept light from far wider angles and CAN exploit f/1.2 optics. I have tested this on my Fuji X-E1.

So based on this, the lens with the best sharpness / bokeh trade-off is a converted Rokkor 58/1.2. It can have difficulty reaching infinity focus but this can be dealt with using live view. I've not observed spherochromatism either. Typically $600+ for one in good condition - quite amazing for a 40 year old lens....

The Zeiss ZE 50/2 MP is superb at all apertures, exhibits negligible focus shift on stopping down and is about as sharp as can be had. It can also do 1:2 macro which is sometimes helpful.

The Sigma 50/1.4 has excellent bokeh but suffers from spherochromatism and considerable focus shift. This is fine provided you don't stop it down - but then it becomes a one-trick-pony.

The Canon 50/1.4 is very good. It does have vignetting when wide open (typical of fast lenses) but its biggest drawback was slow autofocus and fragility. It is a very good lens and excellent value for money.

The OM 55/1.2 is soft when wide open and sharp at f/2. I'm not finished with it yet. typically $550+

The OM 50/1.8 is sharp at all apertures but has weird bokeh - probably a result of its rudimentary aperture control. That said, they can be had for about $30 and are compact, well made and robust.

44
Canon General / Re: CPS Canada Shipping
« on: July 09, 2013, 03:56:43 PM »
Is your gear not covered already?
Seriously, in Canada it costs about $1.30 per thousand dollars per month to insure your gear against replacement and all risks. If it's insured, why give Purolator more money... and if it's not can you really afford to cover the loss of your gear?

45
Canon General / Re: Debranding a 5DIII
« on: July 09, 2013, 03:52:44 PM »
It kind of seems crazy to remove the Canon and 5D Mark III and then leave it with a big red ring...

On the white lenses - sure there may be some thermal benefit but the real reason is that they are easy to spot in TV images.... Canon gets free advertising every time a 'tog appears in the background.

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