Fred Briggs

Fred Briggs

Lives in United Kingdom Nottingham, United Kingdom
Joined on Dec 23, 2002

Comments

Total: 55, showing: 1 – 20
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On a photo in the Sony a7C sample gallery sample gallery (4 comments in total)
In reply to:

Hugo808: At least we'll always know what year this was taken!

Or years!

Link | Posted on Oct 3, 2020 at 11:15 UTC
In reply to:

sgpscott: Thought provoking article, but when weighing up a scene, don't most 'knowlegable' photographers weigh up the priorities and set the parameters appropriately? The article mentions losing the lovely sunset, well if the sunset was my priority I would expose for the sunset and use graduated filters for a balanced image. What is true is that the effect of high 'iso' on in camera image manipulation is to reduce detail, but recovering a 4 stop underexposed file introduces exactly the same loss of detail as correctly exposing the same image with 4 extra stops of 'iso' so using iso as a metaphor for 'speed' in terms of image quality is still valid. I dont think we need to get too hung up on whether iso is sensitivity or not, it functions as a proxy for sensitivity as an exposure tool, in many ways as an underexposed recovery number.

I was referring to the original comment, not your reply - specifically where it says: "correctly exposing the same image with 4 extra stops of 'iso' "

I know the original comment does not necessarily mean to imply that the image is correctly exposed when 4 stops are ISO are used, but by using the words "correctly exposed" it could perpetuate this misconception.

Link | Posted on Aug 11, 2018 at 01:27 UTC
In reply to:

sgpscott: Thought provoking article, but when weighing up a scene, don't most 'knowlegable' photographers weigh up the priorities and set the parameters appropriately? The article mentions losing the lovely sunset, well if the sunset was my priority I would expose for the sunset and use graduated filters for a balanced image. What is true is that the effect of high 'iso' on in camera image manipulation is to reduce detail, but recovering a 4 stop underexposed file introduces exactly the same loss of detail as correctly exposing the same image with 4 extra stops of 'iso' so using iso as a metaphor for 'speed' in terms of image quality is still valid. I dont think we need to get too hung up on whether iso is sensitivity or not, it functions as a proxy for sensitivity as an exposure tool, in many ways as an underexposed recovery number.

You are not correctly exposing the image if you are using 4 stops of ISO adjustment. Given the same aperture and shutter settings both shots are equally underexposed with the sensor receiving exactly the same amount of light in both cases.

This sort of terminology is part of the problem - as a result people think ISO increases sensitivity and therefore increases exposure at the sensor - it doesn't. The only reason the exposure indication reads correctly in the second case is because the scale has been moved by four stops and is now effectively telling a a lie regarding the actual exposure.

This is done in recognition that the camera will add four stops of analogue and/or digital amplification post-capture when processing the image data in order to compensate for the under exposure. Using anything other than the base ISO setting is really just a way of giving the camera permission to take an underexposed shot.

Link | Posted on Aug 10, 2018 at 15:37 UTC

Further to my previous comment, I guess there can be a situation where you might regard an ISO setting as leading to lower exposure, but I think it is still an indirect relationship. If you need a specific aperture/shutter speed setting and this will result in under-exposure then you or the camera may increase the ISO setting to get an acceptable brightness in the final picture. However you have caused the under exposure by your choice of aperture/shutter speed, so it is not really correct to say that the ISO setting led to lower exposure.

Link | Posted on Aug 6, 2018 at 15:41 UTC as 233rd comment

It is hiss from an audio amp rather than hum which is more analogous to the noise found in digital photos. However, exposure v ISO setting is not a causal relationship, as you imply, when you say "the change in ISO setting almost certainly led to less exposure". There is a non-causal relationship, albeit the other way around where less exposure (due to low light) can lead to use of higher ISO settings.

In other words, cameras get set to higher ISO settings in circumstances where light is in short supply, so any noise, be it shot noise or electronic "hiss", is more significant with respect to the light signal captured, resulting in a degraded signal to noise ratio - perceived as a noisier picture.

Still - it is good to see DPR now saying that you cannot improve the sensitivity of a digital camera by increasing the ISO setting. I've been banging on about this for years and almost got excommunicated from here by your founder for heresy when I first started commenting on this subject!

Link | Posted on Aug 6, 2018 at 15:23 UTC as 237th comment

Not got a cooling fan then!

Link | Posted on Jul 3, 2017 at 16:28 UTC as 20th comment

"We are so small between the stars, so large against the sky." c1967 - Leonard Cohen

Link | Posted on Apr 23, 2017 at 08:07 UTC as 13th comment | 2 replies
On article Sources of camera noise part two: Electronic Noise (242 comments in total)

Nice to see DPReview finally coming out of the Dark Ages on this topic! However I have a quibble:

"Where your camera is contributing noise is in the darkest captured tones."

I would say that the camera is contributing noise equally in all parts of the image, not just the darkest parts. However, it is more visible in the darker areas because in terms of signal to noise ratio this is worse in the darker areas, or indeed in any part of a picture with low overall exposure compared to one with greater exposure.

The signal to noise ratio is what matters, and while more noise will make this worse, so will less signal, and less signal is what you have in dark parts of pictures, or in pictures with low exposures which require either high ISO settings (in-camera brightening) or more post capture brightening.

Fred

Link | Posted on May 13, 2015 at 23:41 UTC as 53rd comment
On article What is equivalence and why should I care? (2501 comments in total)

Excellent article - obviously a lot of thought has gone into this. Hopefully it will reduce the amount of misinformed and often over-emotional debate on format differences.

Now you just need to do a similar job on the multiple myths of ISO setting changes being responsible for "increasing sensor sensitivity", "changing exposure" and "creating additional noise" !

Fred

Link | Posted on Jul 7, 2014 at 10:43 UTC as 526th comment
In reply to:

OfcrMike: Wow, some of my fellow commenters have some pretty high standards. Blown highlights, blocked shadows, soft edges... indeed. You're probably all amazingly talented photographers whose every exposure is Perfection itself. Like you, it baffles me that your websites are not as successful as DPR. It is a wonder that Sony didn't invite all of you to the hands-on event in Tennessee. Perhaps Nikon will invite you to experiment with the new Df? We can only hope. If not, we mortal photographers will have to make do with DPR & Steve Huff and their realistic, real-world approach to showing us how new cameras might perform in the hands of photographers who are merely well-above-average.

It is not a question of how skilled a photographer the reviewer is compared with the rest of us. If the DPR samples were taken in Auto mode then the photography skills (or lack thereof) of the reviewer are immaterial because they were just not used.

The settings which could have made all the difference to the quality of the samples were not controlled by the photographer, but were a best guess (in most cases pretty poor) by the camera. The operator was apparently simply engaged in pointing and shooting.

Other reviewers on the same Sony event have managed to apply some basic photography skills to this exercise and have produced more useful samples as a result. I'm sorry to harp on about this DPR, but it is just not good enough, and has been an embarrassing weakness in an otherwise professional site for a long time.

Link | Posted on Nov 2, 2013 at 02:05 UTC
In reply to:

Wenetu: Just look at the original jpgs with Exiftool, settings reveals that they used the camera as a point and shot: program auto, AF area and point auto, metering auto,... it's normal you got just point and shot results.

I suspected that was how the cameras had been used, but didn't really want to believe it. I am sure that the reviewers in in a high pressure situation, but would it be so difficult to select Aperture Priority mode and take a little control over the process!

I would go so far as to say that pictures taken in Auto mode should not be put forward as legitimate samples, except possibly to assess the effectiveness of Auto mode, and even then should always be labelled as such.

Link | Posted on Nov 1, 2013 at 15:52 UTC

Unfortunately these seem no better than the A7R samples in terms of applying appropriate settings to different scenes, and I have downloaded them all and looked at them carefully.

As mentioned already, in many cases way too slow shutter speeds have been used, resulting in blur, especially with moving subjects. Also poor choice of aperture for landscape and other scenes where significant depth of field is required, meaning large parts of the images are recorded as a blurry mess.

Someone else said that snapshots and simple everyday shots are the best way to get an idea of what a camera can do. I certainly agree that most of these shots are no better than snapshots, but disagree that they are in any way useful for assessing the camera - at least not if you want to differentiate between what a camera phone and a state of the art FF camera can do.

I am sure the A7 and A7R are very capable when used thoughtfully, but I think DPR are doing Sony no favours with these samples!

Link | Posted on Oct 31, 2013 at 19:24 UTC as 21st comment | 7 replies

As the A7R is being touted as a landscape camera, I'm disappointed in the landscape pictures. Being taken at f/3.5 and f/4, these give no indication of what is achievable with the camera - most of the scene is just mush.

This seems to be a general theme with DPR - inappropriate aperture settings making it impossible to judge camera and lens quality in different photographic situations. As well as landscapes at large apertures we also often get wide open apertures in scenes with lots of depth, meaning that only a small part of the image, generally the centre, is in focus.

This makes it impossible to judge camera/lens resolution, especially at the edge of the frame, due to content at the edges often being at much different distances to the centre and hence way out of the focal plane.

Yes it is nice to see lenses wide open to judge sharpness and bokeh when trying to isolate a subject from background/foreground, but please don't use these settings on every type of scene!

Link | Posted on Oct 30, 2013 at 00:38 UTC as 61st comment | 2 replies

It occurs to me that this filter array would lend itself to a system which did two samples per exposure, with the colour filter displaced by one pixel for the second sample.

This would give you 100% luminance resolution, equivalent to a monochrome sensor, and twice as good colour resolution as currently available for a given array. I suspect the better SNR would more than compensate for the reduced exposure time for each sample.

Just need to find a way to implement the filter switch - either mechanically or electronically!

Link | Posted on Jul 16, 2013 at 20:33 UTC as 28th comment | 1 reply

TV /video systems from way back gave greater signal bandwidth for luminance v chrominance, on the basis that this provided the best match to the human visual system.

Until now Bayer type sensors have been throwing away two thirds of the critical luminance signal. I think this is a very clever system and shows great promise for the future.

I just hope they license this widely to other companies and don't just use it with their own sensors.

Link | Posted on Jul 16, 2013 at 20:20 UTC as 29th comment
On article Just posted: Our Canon EOS 70D hands-on preview (355 comments in total)
In reply to:

Roland Karlsson: Oops - commenting her goes fast. And your question is fast far away from the top. So - I reiterate my question.

Can you get all 40 MP as an output?

That would be fun, both for 3D images and depth detection.

Not sure about Andy's statement regarding it turning into a perfectly normal 20MP Bayer sensor. I think we need to know more about the sensor architecture to judge that. For example are the two charges read separately and then averaged for the readout, with some implications for well size and SNR, or does an electronic switch connect the two wells such that the charge is combined and can be read off as a single reading. it would be good if DPR could find out more on this.

Link | Posted on Jul 4, 2013 at 19:11 UTC

The Cloud aspect of this is just a smokescreen to make it seem like a different product. In reality this is just a move from selling perpetual licenses to paying monthly to use the software. It still gets installed locally on the PC, and you do not need to use the cloud facilities - the software just calls home periodically to check that it is still being paid for.

With the old model you decide when to pay for a new version. If you decide you won't or can't pay for the latest version your software keeps working indefinitely, and you can still edit your files at any time.

In the new Adobe Creative Cloud world you have to commit in advance to paying indefinitely, with no assurance of what the future price will be. Stop paying and the software stops working next time it calls home.

No doubt any file you create with the CC version will not be usable with earlier versions of the software, so you can forget working on any CC created files unless you keep your subscription going.

Link | Posted on May 9, 2013 at 16:31 UTC as 421st comment | 1 reply
In reply to:

erikandmarcie: Summary of this article states:

"should give similar noise at ISO 3200 as a conventional Bayer sensor does at ISO 1600"

But actually, that's not true. ISO performance will be the same, all else equal. It's just higher ISO's won't be needed since more light reaches the photo site.

I would interpret this as a camera of this type, if set to the same shutter and aperture as a conventional camera, assuming equal sensor sizes, would have a stop greater exposure at the sensor. In conditions where there is not enough light this will mean less ISO amplification needed to create the correct image brightness. Accordingly a one stop lower ISO setting may be used, and less ISO amplification means a better signal to noise ratio.

In conditions where there is enough light to fully expose the sensor at the minimum acceptable shutter and aperture settings, then this would translate into the ability to use one stop faster shutter speed or one stop smaller aperture for the same exposure (at the sensor).

A sensor with this technology could be smaller than a conventional sensor but still give equal performance, and this may be the primary way the technology is exploited - i.e. current full frame performance at less than full frame size, and so on down the range of sensor sizes.

Link | Posted on Feb 10, 2013 at 20:03 UTC
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