bobn2

bobn2

Lives in United Kingdom Worcestershire, United Kingdom
Joined on Aug 28, 2007

Comments

Total: 122, showing: 1 – 20
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On photo Leader of the pack in the My Best Photo of the Week challenge (3 comments in total)

Not enough depth of field.

Link | Posted on Apr 19, 2018 at 18:59 UTC as 2nd comment

'The good news is that most of that drop is due (once again) to the demise of the compact camera.' Not sure that quite came out the way you intended :-)

Link | Posted on Apr 3, 2018 at 07:27 UTC as 49th comment

Interesting that only one of those lenses is on Nikon's recommended list for the D850. They must thing they're OK after all!

Link | Posted on Mar 20, 2018 at 14:05 UTC as 42nd comment | 5 replies

'As with the rest of the range, the 50-200mm F2.8-4 is fully weather-resistant'. What does that mean?

Link | Posted on Mar 2, 2018 at 13:36 UTC as 26th comment | 6 replies
In reply to:

audiobomber: > "our shooting suggests that GH5S can outperform the a7S II whenever you require a depth-of-field that the Panasonic can offer."

Why not just stop the Sony down? Does equivalence not hold in video shooting? Not trying to be a smartass, I don't know much about video.

> "We're currently shooting the GH5S with a 0.71x SpeedBooster and a Sigma 18-35mm T2.0 CINE lens"

Wouldn't the GH5S with Sigma lens the same DOF as an f2.8 lens on an A7S II? With reduced IQ of course, due to the adapter.

What Richard's saying is precisely that equivalence holds. When they have the same depth of field, for the same subject and exposure time, they'll both receive equal light, and in that case has says that the GH5S does a bit better, because sensor size )or more accurately aperture size) is not an issue.
If they are at the same depth of field, as he says, they will have the same aperture (for the same AOV). Stop the A7SII down, and it will have a smaller aperture.

Link | Posted on Jan 26, 2018 at 15:08 UTC
On article Panasonic Lumix DC-GH5S Review (589 comments in total)

I'm thinking, when a camera is this video focussed, why not just make it a bone-fide video camera and leave out the still camera compromises?

Link | Posted on Jan 9, 2018 at 20:06 UTC as 94th comment | 1 reply
On article Panasonic Lumix DC-GH5S Review (589 comments in total)

Dual Base ISO: ' Such chips have two read-out circuits, one that maximises dynamic range at low sensitivity settings and a second designed to minimize noise but at the cost of dynamic range, at higher settings. It's something we first encountered in Nikon's 1 Series cameras but that's become increasingly common over the past few years, resulting in visible improvements at high ISO settings.'
Sorry, that is wrong. Such chips only have one read-out circuit like any other chip. They can change the internal capacitance of the pixel, which changes a parameter called 'conversion gain'.

Link | Posted on Jan 9, 2018 at 20:03 UTC as 95th comment | 2 replies
On article Take a look inside Leica's factory in Wetzlar, Germany (136 comments in total)

Thank you especially for photo 15, which should come in useful if a forum expert decides to tell me another time that Leica works in Imperial units.

Link | Posted on Nov 10, 2017 at 14:33 UTC as 2nd comment
In reply to:

bobn2: 'How did Sony do this given the already low levels of read noise its known for? Possibly by going to better or higher native bit-depth ADCs,', unlikely, if as you reported the sensor is the same. More likely they have cleaned up the power supplies a bit, which has lowered the reset noise. It's often been the case that Nikon gets a little more out of Sony sensors than Sony, and the speculation at the time has been that they used a different version. It's emerged since that they didn't (for instance, the D3X used the same sensor as the A900, not a Nikon special) - a lot of the difference was cleaner power supplies - they are quite critical in these sensor chips.

'Has it been confirmed that the D850 sensor is manufactured by Sony?'
Who's going to confirm it, until TechInsights does its teardown and finds 'Sony' on the silicon? All the evidence is that it is a Sony sensor. It has DRPix technology, that is only available to Sony and On Semiconductor. It is a FF BSI sensor, which so far is something only Sony has done technologically. The layout of the chip looks just like Sony's design team always does it, which is nothing like anyone else does it. It performs almost identically at the pixel electronic level as the D500 sensor, which is confirmed as Sony. Sony provides sensors for most of Nikon's cameras. It's a Sony.

"If the Nikon ISO 64 is due to the ability of the 36MP and 46MP sensors to accept more total charge, why is it not possible for Sony to do the same with the 42MP sensor?"
Who says it isn't possible, looks like Sony just decided not to do it.

Link | Posted on Nov 3, 2017 at 20:41 UTC

At your next editorial meeting, perhaps you could discuss a small amendment to your house style to use a better notation for f-numbers. The 'F2.8' notation you use confuses a lot of people into thinking that aperture is measured in units of F. Hasselblad gets it right. In their release above the refer to 'The XCD 135mm f/2.8' and so on. This is easy for people to understand as a formula, where 'f' is the focal length. I discussed this once with one of your staff (as I remember, Richard) who agreed that the 'f/2.8' notation is clearer, but said he couldn't do much because it was your house style. Maybe you could change your house style?
A small point maybe, but anything that makes it easier for people to understand should be welcomed.
Sorry, a bit OT here, but just seeing the contrast between what you wrote and Hasselblad's release brought it to mind,

Link | Posted on Nov 3, 2017 at 16:24 UTC as 26th comment | 4 replies
In reply to:

bobn2: 'The a7R III, like many Sony predecessors, has a second gain step at the pixel level that amplifies signal, at the cost of higher tones, to preserve higher signal, and less noise, in dark tones." - that's not what it's doing. It's a change in capacitance of the pixel, which changes the relationship between the pixel charge and the downstream voltage, thus making the electronic noise look like fewer photoelectrons. It isn't a second gain step.

Hi Rishi, 'conversion gain' is a bit of a misleading term though a common one. The DR pix circuit is quite simple. The relationship of charge to voltage is simply related to the capacitance of the read transistor, by the well known equation V = Q/C, so the smaller is C, the more V you get for each Q (in this case, the Q of an electron). So the idea of 'gain' is quite misleading (it almost always is, with respect to sensors). What matters here is how much apparent electron noise each dollop of electronic noise is worth. If C is small, a volt of electronic noise looks like not much electron noise, if it's large, then it looks like more.
The reason you can't just make a sensor with low C is then it can't accept much charge, so its base ISO is high. The DRPix trick allows for the best of both by allowing an extra capacitor to be switched in, big C for low base ISO, low C for low apparent electron noise in low light.

Link | Posted on Oct 31, 2017 at 21:35 UTC

'The a7R III, like many Sony predecessors, has a second gain step at the pixel level that amplifies signal, at the cost of higher tones, to preserve higher signal, and less noise, in dark tones." - that's not what it's doing. It's a change in capacitance of the pixel, which changes the relationship between the pixel charge and the downstream voltage, thus making the electronic noise look like fewer photoelectrons. It isn't a second gain step.

Link | Posted on Oct 31, 2017 at 20:13 UTC as 59th comment | 2 replies

'How did Sony do this given the already low levels of read noise its known for? Possibly by going to better or higher native bit-depth ADCs,', unlikely, if as you reported the sensor is the same. More likely they have cleaned up the power supplies a bit, which has lowered the reset noise. It's often been the case that Nikon gets a little more out of Sony sensors than Sony, and the speculation at the time has been that they used a different version. It's emerged since that they didn't (for instance, the D3X used the same sensor as the A900, not a Nikon special) - a lot of the difference was cleaner power supplies - they are quite critical in these sensor chips.

Link | Posted on Oct 31, 2017 at 20:13 UTC as 60th comment | 2 replies
On article Here's why your beloved film SLR is never going digital (294 comments in total)

Nice article. Richard. Actually this is something I've looked at hard. In fact, it's not too hard to convert your old SLR to digital (the first DSLRs were just that), what would be more difficult would be to make a drop-in digital film which doesn't involve butchering the camera. What the 'I'm back' seems to do is place a translucent screen in the film gate and then have a digital camera take a photo of that, not an excellent solution. I wondered, though, whether there would be a market for converted DSLR. There's a fellow called Huw Finney that once went half way through a conversion of a Leica M2. The real problem with it all, though, is what you end up with would be less functional and more expensive than a modern DSLR.

Link | Posted on Oct 11, 2017 at 13:31 UTC as 103rd comment
On article Yashica is teasing a comeback to the camera market (299 comments in total)

Look over here:
https://www.yashica.com/ourglory
It seems there is a Yashica product, a wide angle adapter with claimed 4k capability for smart phones.
It gives some specs
High Resolution
Upto 20M pixels meets all shooting requirements
Unique Aspheric Lens Design
Eliminate dark corners & blurry edges
Crisp & Colourful Image
HD optical glass with extra high transmission rate
Universal Clip
For any smartphone
Multi-functional Clip Bag
Suede-made clip bag can be used for both storage & lens-cleaning

Link | Posted on Sep 15, 2017 at 17:57 UTC as 89th comment | 1 reply
On article Nikon D850 Review (2094 comments in total)
In reply to:

calson: Not a proper test. If there is noise at ISO 64 when the EV is adjusted in processing then the image was underexposed. Nikon DSLRs since the D3 (2007) have produced better image files from overexposure than underexposure. Recognition of this is why the advice has been to expose to the right on the histogram.

Take any camera and underexpose by 1EV and then overexpose by 1EV and the overexposures will nearly always produce the better image after converting the RAW file. With an underexposure there is less real data in the file and so adjusting the EV after the exposure will of course increase the visible noise in the file.

The D850 is evidently more forgiving of a bad exposure made by its user. Nikon with the D3 and subsequent cameras designed them to be more forgiving of overexposed elements in a scene (less data lost) as when photographing a bride in her white dress in full sunlight and not blowing out her dress.

@calson - 'If there is noise at ISO 64 when the EV is adjusted in processing then the image was underexposed.'
However the image is exposed, there will be a low end of the exposure range. The test just shows how much noise there is in that low end.
'Nikon with the D3 and subsequent cameras designed them to be more forgiving of overexposed elements in a scene (less data lost) as when photographing a bride in her white dress in full sunlight and not blowing out her dress.' I think you're just referring to the raw headroom available. Nikon's is pretty much average for the class.

Link | Posted on Sep 11, 2017 at 19:34 UTC
On article Nikon D850 Review (2094 comments in total)
In reply to:

HenryDJP: The DR on my D810 is amazing! I love it, but if I was considering the D850 I would be even more excited with this camera had Nikon gave it a hybrid viewfinder. The best of both worlds of EVF and OVF. Truth be told, even with mirrorless advances I would go for an OVF any day of the week first. I never understand why Canon users continue to buy Canon's DSLR's when the DR sucks so badly?

I think that a hybrid finder would have made the VF quite a bit larger and resulted in a loss of light from the DSLR VF. Essentially it would need a beam splitter before the eyepiece (thus the light loss) and a display squeezed in there somewhere.

Link | Posted on Sep 11, 2017 at 16:08 UTC
On article Nikon D850 Review (2094 comments in total)

"Theoretically we might also see some benefit in performances in the corners with wide-angle lenses, but that doesn't come into play with the 85mm lens we use for these tests."
It's not so much to do with the angle of view as the position of the exit pupil, and pretty much every wide angle for digital has its exit pupil a long way from the sensor (that's why they are so big). Flip the mirror up and put on a Hologon, you might see a difference.
The advantage of the BSI sensor might be less low-f-number shading, due to faster microlenses. It would be interesting if you could find a way to test for this. It's known that manufacturers correct for this in the signal processing, so what you'd want to look for is the noise - is it producing less noise than a D810 at f/1.4 and the same shutter speed?

Link | Posted on Sep 11, 2017 at 16:05 UTC as 307th comment

I notice also, if you go to the Impossible Project website it says 'The Impossible online store will be closed from September 10th – September 13th. Watch this space.' Interesting coincidence of dates. Looks like it will be rebranded.

Link | Posted on Sep 9, 2017 at 21:00 UTC as 10th comment

Those don't look like a FF 52 and 36mm looking at the diagrams, the angle of view looks quite small, more as though they a re telephotos for the 1 system, especially given that they are both telephoto designs with negative power at the back. Mind you, they have negative power (huge) at the front, too. But the patent does give a image height of 21.6mm, which would be FF. Odd.

Link | Posted on Sep 7, 2017 at 19:33 UTC as 36th comment | 3 replies
Total: 122, showing: 1 – 20
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