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simon_crofts last won the day on October 9 2010

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  1. <p>Thanks for that link Igor D., that's a really useful site. </p> <p>p.s. if you don't read Polish flag, then click the English flag. The website is in English too.</p>
  2. <blockquote> <p>the D4 (and D4S) use a 16MP sensor mainly because it needs to do 10 fps.</p> </blockquote> <p>Not sure I agree with that at all (though quicker processing may have been a side benefit). The D4 (and therefore DF sensor) were issued simultaneously with the d800, so it's the same generation technology as the d800. The D4 and DF are of course optimised for low light and general performance, whereas the D800/D810 are rather aimed at studio use and similar usage where a high pixel count in good lighting conditions is the priority. I've heard from friends who own the D800/810 at least that performance in low light is relatively disappointing, which would figure.<br /> <br />For example at the moment, according to these very recent tests the DF is the best performing DSLR in low light available, with a slight edge even on the D4: <br /> http://www.adorama.com/alc/0012810/article/15-Low-Light-High-ISO-All-Stars<br /> So for professional use at least, there are good grounds for considering the DF ahead of the likes of the D810 on the grounds of sensor performance alone. It may not be what the DF is really about, but it's a bit misleading to dismiss the sensor as old technology. Not the very latest sensor perhaps (as the D810 is supposed to have been a slight upgrade on the D800), but still the arguably the best available for low light at least.</p> <p> </p>
  3. <p>That's pretty much how I work Michael. Another way of saying it is I create my own guide number (ie. aperture) for a given typical situation (preferred ISO). One doesn't always have to use 1 metre at 100 ISO as a guide number. In practise, once you've done it a few times, you just know that it's f11 at a typical working distance with a particular flash, and you don't even have to do any calculation - you already known your 'guide number' (= aperture) for a given situation - and tweak a stop or two either way as the subject gets closer or further.</p>
  4. <p>p.s. not dissing light meters especially in the studio, where different reflectors etc. make the guide number approach largely redundant, I am rather thinking of a small camera flash situation, especially outside.</p>
  5. <p>I use guide numbers all the time and find them vital. And I'm a pro. Shoot review and adjust only works if you have the chance to take the picture several times. Using a light meter only works if you have time, and (if it's an incident meter can get an assistant to where the subject is). And anyway, the meter will only tell you what you already know. For a given ISO and flash power (which outside, will typically always be full power), the meter will always tell you the same thing at a given distance. So why use it in typical predictable situations?</p> <p>I tend to use the guide number (actually my own one that I've come to through practise) so that I know in advance what aperture I need to set for a given distance. Typically for street phography, I might know for example that if the subject is going to be 3 metres away, and I'll be using ISO 400, I will need to use, say, f11, to get the right flash exposure. This will be absolutely consistent and bang on every time. Much more reliable than TTL etc. (and doesn't have the time delay associated with TTL). If I change to 800 ISO as it gets darker, I just have to open up the aperture one stop. Easy. If the subject is 4 or 5 metres away, I just open up an extra stop. If it's 2 metres away, close down a stop. It's all so fast and accurate and consistent.<br /> <br />Really recommend getting to grips with them.</p>
  6. <blockquote> <p>The information isn't hidden, it just takes a little effort to find</p> </blockquote> <p>I wasn't suggesting the information isn't available, just that you have to dig for it, and manufacturers like to give the impression that their latest flash is getting more and more powerful by quoting high sounding guide numbers. So for example, <a href="http://www.nikon.com/news/2008/0701_sb900_02.htm">if you look at Nikon's release about the SB900</a>, they claim: "The SB-900 offers a powerful guide number of 48/157.5 (ISO 200, meters/feet)". Which may well be correct, but they are quoting the guide number at ISO 200 rather than the more standard ISO 100, because that gives the impression of a higher number to a casual reader who is perhaps more used to hearing guide numbers in the 30's.</p> <p>Again, further down the same page, they tell you a bit more, that the guide number is: "34/111.5 (ISO 100, m/ft), 48/157.5 (ISO 200, m/ft)" - but they don't tell you what zoom settings that is at. If you dig around the internet, you'll find out that is at 35mm zoom. A non-zoom flash will usually have a wider spread, because it has to cover standard lenses to at least 24mm, so you may find a fixed head flash that has a smaller guide number but is actually more powerful than the SB900. All of which you can find out by digging - but you do have to dig.</p> <blockquote> <p>A small white room only affects the distribution of the flash reflected off the ceiling and walls. It can't increase the power of a flash aimed directly at the object/subject.</p> </blockquote> <p>Actually it can - and does. Though it depends on the test distance from flash to the subject. At one meter it may not make a noticeable difference, but if you are testing at 3 or 4 meters away the light reflected off walls can easily add a stop or so to the exposure falling on the subject - not just filling in shadow areas.</p>
  7. <p>There's a very interesting article been posted trying to adopt a reasonably scientific approach to testing the differences between digital and film. This includes specifically a Nikon D800 compared to a Mamiya 7. As expected, the Mamiya 7 blows the D800 right out of the water. There are lots of other interesting comparisons and thoughts in the article too though, well worth reading:</p> <p>http://petapixel.com/2014/12/18/comparing-image-quality-film-digital/</p>
  8. <p>It seems to me folk are over-complicating it. Guide numbers are inherently simple things. Assuming you're using the guide number in metres (ie. not a guide number measured in feet), the guide number is simply the aperture that you would use to get correct exposure <strong>firing the flash at full power</strong>, at 100 ISO, at an object located 1 metre away from the flash.<br /> <br />So the easiest and quickest way to measure it is to do just that. You can get at least to get within half or perhaps quarter of a stop or so accuracy very quickly indeed (it should only take a few seconds to do this) just place an object, preferably something with mid-tones, one metre away from your flash. Set the flash to full power, and your camera to 100 ISO and to the highest recommended sync shutter speed available to cut out ambient light (better that the room doesn't have bright daylight). Start by setting an aperture where you expect your guide number to be (typically somewhere between f11 and f36). Take a picture with the aperture set to somewhere around where you expect the guide number to be, if it's correctly exposed then that's your guide number. If it isn't, make an adjustment and try again (and make sure you allow plenty of time for the flash to fully recharge).</p> <p>If your lens doesn't stop down to f32 or thereabouts, modify the above by placing the object at 2 metres, and multiply the aperture you end up with by two to get your guide number. Eg. if the flash gives the correct exposure at full power using f16 at 2 metres, then the guide number for that flash is 32 (or at least very close to that).<br /> <br />One wrinkle to watch out for, is that many manufacturers (Nikon, Canon) exaggerate their flash number by giving the power at the centre of the frame when the flash is zoomed (if your flash has a zoom head). To find the 'real' guide number with the flash zoomed out to a more standard setting, make sure you've set it to somewhere around, say, 24mm.</p> <p>Another trick is that guide number is often exaggerated by measuring it in a small white walled room which reflects light back into the subject. Do you tests in a larger room, preferably without white walls, but be aware that in a small white room your flash will gain a lot of power.</p>
  9. <p>The internet has been full of these declarations for years that X latest small format digital camera is finally at the same quality as medium format 6x7. It's all nonsense - it just isn't. At least, it's always possible to find conditions under which the small format digital can compete - if you don't focus the medium format camera properly, or if you you use a bad quality scanner (this is probably the commonest one - using a flatbed or low end scanner), or don't flatten the film in the scanner, and so on, it's possible to reduce the medium format quality enough to prove anything.<br> And of course there are circs in which the small format digital wins - if you need to shoot a lot of frames without expense, taking pictures with fast lens in low light, you need to get the picture out quickly, and so on. That's why we use them, and they're great for that.<br> I've just been preparing a series of big enlargements (around a metre) from a mix of 6x7 film (Mamiya 7 and Mamiya 645) and digital (mix of Nikon and Fuji cameras). The film enlargements are glorious, even when looked up very close. The digital ones - well let's say they are best viewed at the 'correct' viewing distance. They're pretty good - but not as good.<br> And yes, a colour negative film like Portra also still has (a bit) more greater dynamic range than the digital RAW files.<br> Don't get me wrong, the digital cameras are wonderful, I love them to bits, they're amazing at what they do, but the kind of conclusions in the article linked to are just the latest internet fluff which has been bandied around for ages.</p>
  10. <blockquote> <p>my film is still too cold to load and wasted if not used</p> </blockquote> <p>For using in cold, digital may be unreliable, and batteries may not be usable. Film may be more reliable. What kind of temperatures are you talking about? If you're having difficulty loading film because it's too stiff in the cold, have you considered simply getting a few extra film holders which you can preload? For my smaller Mamiya 645, I often carry four or so preloaded just to make it quick switching films.</p> <p>Full frame digital really won't compete with 6x7 for quality so it's no replacement, and anyway it has quite different characteristics. But I doubt that the batteries and specification in an expensive digital back are going to cut the mustard if you're going to be taking pictures in real cold. Below about -20 or -30 Celcius you'll have to adopt a specialist strategy no matter what you use, and above about -30 you shouldn't really be having problems with film.</p>
  11. <p>I sometimes do the cull in Lightroom - and with an SSD Macbook images loading from one image to the next is more or less instant - less than half a second at least. It may depend on what your preview settings are.<br> <br />But my favourite way is to synchronise a Lighroom collection to an iPad using Photosmith, and head off to a cafe and do the initial cull or two over a coffee. with 2048 pixel previews, and using the auto-advance setting in Photosmith I can hit a rating on an image an the preview instantly moves to the next image so that I can get through them with a single gesture, not having to press anything to advance to the next image. This afternoon for example I got through an initial cull on 2000 images in around an hour over a longish coffee.</p> <p>There is also Lightroom mobile, but I tried it once and it doesn't have auto-advance, or at least I didn't find it, so I rejected it as too fiddly for the moment.</p> <p>You do have to synchronise your collection back and forth between Lightroom and iPad when doing this, but you can do other things while this happening. You can synchronise two or three (or more) weddings ahead, so that if you get the urge you can do the ratings on a quiet moment on a train if you suddenly have the urge.</p>
  12. <p>Michael, I believe that in the US the three year limitation period also begins to run from the date that the copyright holder ought reasonably to have found out about the infringement. The principle is called 'discovery accrual'. you can read about a recent US case about it here for example:<br> http://www.whitecase.com/articles/052014/second-circuit-adopts-plaintiff-friendly-discovery-rule-for-copyright-infringement-claims/#.VHHrP9a5BlU<br> Also, in any case if the plaintiff tries to conceal the infringement fraudulently, then I think I'm right in saying that the 3 year limitation doesn't apply in any case.<br> So in practise, the 3 year limitation often isn't as limiting as it sounds.<br> Tim, you may also be entitled to additional sums in addition to the amount you would have charged as a fee. It's possible that these amounts can be much more substantial than the fee itself. You can't charge a fee for the time taken to track down infringers, but there are other damages that you can add on. You'd have to ask a US lawyer about what they are in the US, but you can read about the kinds of things you can claim for in UK law here:<br> http://www.epuk.org/Opinion/994/stolen-photographs-what-to-do</p>
  13. <blockquote> <p>Content creators who have benefited from this type of "theft" tend to think of infringement as free marketing and advertising thereby becoming the benefactor through its capitalization.</p> </blockquote> <p>I disagree - mostly. There is a place for allowing images to be spread for example where you are trying to promote a particular project and have an identified business plan/income stream that will benefit from the images getting attention - such as an artistic project where you hope to sell prints into the art market. But mostly you do better to enforce rigorously - where practicable (and it's not always practicable, there is a time/benefit/practicality calculation to be done) - rights to your IP, and remove the perception that your images are there for the taking for free. Also, when you enforce the rights to your pictures, you are doing not only yourself a favour but the entire photographic community, there are too many people who have got hold of the crazy notion that it is OK to help themselves to whatever images they want.</p>
  14. <p>BTW, I'd describe my use of the cameras as fairly heavy - and they're not being treated with kid gloves. Typically they may make 2000 - 2500 exposures in a heavy days shoot, get covered in sweat, and I've had them on assignment on eg. sailing ships and small boats, quite a bit of foreign travel etc. At some point I expect one or the other to give up from the abuse (my previous D700's and D2x's needed several repairs), but so far so good.(touches wood).</p>
  15. <p>I've got two DF's, between them over 100,000 shutter actuations. I use the exposure compensation dial all the time changing it pretty much on every exposure - not had any problems at all.<br /> At first the exposure compensations dial was the aspect of the camera that I was least sure about - specifically the fact that it had a lock on it and how easy it would be to operate. In practise, I've grown to really like it. Generally, I've found it to be just a brilliant camera. There are a few little niggles that annoy me (it's too easy to knock the diopter adjustment and also the the exposure mode switch), but I'm still in love with this camera.</p>
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