|
|
Post by CSLR on Dec 17, 2006 1:48:36 GMT
In another thread Jon askedAs this is a more appropriate place, I am opening this thread to discuss the details. The picture that we were looking at was this one of the former City Road SB station tunnel:-  Firstly I must clarify what we are looking at. The above picture is a low resolution copy made for posting and the impression of HDR is purely an illusion caused by the way the image was constructed. To give an example, this is a closeup taken from the image above.  This is the same section of the picture taken directly from the scan that was used to make the low resolution image.  Even this picture will not come through at its best as it is a jpeg compression. The original tiff file was created through a 48 bit fluid scan from a 35mm colour transparency. To view this in all its glory, you should really see it as a 19"x13" print - or larger. In response to the question of techniques used for multiple flash photography, there are several ways to do this. The most common is to illuminate a subject using a number of flashes that are out of shot and which are fired simultaneously. This is the method often employed in professional portrait photography. It can be used to illuminate railway subjects, but is not really suited to tunnels as there are very few places to hide the flashguns. The method that I have used here is to eliminate as much of the remaining lighting as I can to avoid it burning out sections of the photograph during a long exposure. This included the tunnel lights which were temporarily fitted with partial deflectors (these lights could not be turned off for safety reasons). The camera was mounted on a solid tripod to avoid any movement from wind or vibration. When lighting the subject, I moved down the tunnel firing off a flash at one wall at regular intervals. The camera could not 'see' me as I remained in the dark areas. I repeated this procedure another five times, illuminating different stretches of the tunnel on each occasion. With each pass, I filled in the areas of shadow that I had previously been working in. At the end of this I fired off flashes in the cross passages. At certain points in the tunnel, I varied the interval between flashes slightly to add extra light or to reduce it slightly in order to accentuate the shape of the tunnel and to avoid making everything look flat. Tips: 1. Wear non-reflective clothing. 2. Carry spare batteries in your pockets. 3. Tape over the red light on the back of the flash to avoid it appearing in the photograph. 4. Place a small light behind the camera so that you can locate where it is in the darkness. 5. You will not have to calculate the length of the exposure as this will be determined by the time taken to fire all of the flashes. 6. The aperture setting is generally the same as would be used for a flash photograph, but with the average distance of 'flash to wall' being substituted for the usual 'camera to subject' measurement. If the subject is dark, you may need to increase the aperture by 1-2 stops. All of these comments relate to photographs taken on film stock where exposures could be 40 minutes or more. If you are using light sources other than flash and/or if other light sources are present during the exposure, you are advised to learn about the effects of reciprocity failure - that is beyond the scope of what I am writing here. For digital photography different rules apply. Once you get past a few seconds exposure, digital pictures can be affected by noise. Following a discussion with Anne (V3.1), I am now experimenting with methods that will overcome this problem and initial results are promising. It is possible that you might find techniques out there that go some way to resolving this problem, but I prefer to develop specific solutions for my particular requirements. Note: The pictures on this page were taken during an official visit with a track possession order. For safety and security reasons, public visits are not granted to this site. In addition, the use of flashguns and/or tripods is generally prohibited on the London Underground system during traffic hours. These notes are therefore provided to satisfy the curiosity of the questioner, although they may well be adopted for use elsewhere. You should be advised that other techniques are available that will give similar results and which may be more practical for you. These pictures are copyright and are posted here with my permission for discussion purposes only. Please ask if you wish to use them elsewhere.
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Dec 17, 2006 11:46:14 GMT
Wow ... that was more than I was expecting - thank you for the information.
I'm mildly curious as to what you're experimenting with to reduce noise as well. Last time I did any serious nighttime photography (wandering along the Danube a few weeks ago), I shot most of the 'proper' shots at ISO200, with shutter speeds in the region of 3-6 seconds (and, of course, shot in RAW) ... didn't go too badly, but my nikon isn't the quietest of cameras.
Thanks again,
-Jon
|
|
|
|
Post by CSLR on Dec 17, 2006 13:33:22 GMT
I'm mildly curious as to what you're experimenting with to reduce noise as well. The application of some lateral thinking and the drawing on board of all available technology, sometimes using it in ways that it was not actually designed for. All will be revealed in due course  In the meantime, look at it like this. I previously mentioned reciprocity failure in film. The data that film manufacturers supplied was intended to warn users of the finite limitations of their products, but when you understood how it all worked, you could push way beyond that point and even use it to your advantage. Now apply that same theory to digital photography and see what happens. I know that the problem of noise in digital photography is a major one. I hope that other people are working to find other solutions to it independently of me. Although it is often useful to pool knowledge, I am not particularly interested in what they are doing at the moment. This is such a big problem that I think that more will be achieved if we do not all go in the same direction. The diversity that can be gained by some individuals following their own research routes, may ultimately give us all far greater flexibility; especially if a number of the eventual solutions can be combined. Do not worry, when I have worked it out in a way that everyone can use, I will be happy to share it. |
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Dec 17, 2006 20:27:18 GMT
I'm babmboozled by all this apeture setting malarky; I just have a 'point&shoot' camera!
|
|
|
|
Post by CSLR on Dec 18, 2006 1:43:00 GMT
I'm babmboozled by all this apeture setting malarky; I just have a 'point&shoot' camera! If it works, then go for it ATO. We are discussing the theory of taking a picture of a black cat in a coal mine at midnight. |
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Dec 18, 2006 20:40:07 GMT
We are discussing the theory of taking a picture of a black cat in a coal mine at midnight. With or without a flash? ;D |
|
|
|
Post by trc666 on Dec 18, 2006 22:59:49 GMT
The camera I have (Samsung S800) is pretty good for a compact, as I can manually adjust the shutter speed (ranging from 1500th/sec up to 8 seconds) and to a degree, the ISO setting as well. You could almost call it a professional compact. Digital zoom is horrible on it though, I never use it as it is extremely pixelated. Optical zoom goes up to 3x I think. Resolution is 8.1 megapixels.
That picture above is absolutely amazing by the way, probably one of the best I've ever seen! It almost looks as though the line has just entered the tunnel from an open section.
How long an exposure did you require for the photo, and did you use a zoom lens?
|
|
|
|
Post by CSLR on Feb 16, 2007 16:58:44 GMT
I am going to revive this thread because I note that I did not respond to the last question that was asked. No zoom lens was used for the photograph. I sometimes move the lens to a wide setting because of the limited amount of space in some locations, but I rarely use a true wide angle lens. Exposures are not made in the conventional way, therefore the length of exposure is almost irrelevant. For these types of pictures, the exposure lasts as long as is required to fill the area to be photographed with light, after that the exposure stops. What is important is the aperture. This has to be calculated by trial and error based on the light source. With flash, this will vary depending how close it is to the subject and how much overlap is allowed. As a ball-park figure, expect exposures in excess of 40 minutes. And remember, these techniques are for film. It is not easy to force a digital camera to give such long exposures and, if you do, you will encounter the problem of noise. Digital solutions are still at an experimental stage. Here is another multi-flash picture at a location with no installed lighting.  Old Swan Shaft in the southbound tunnel just outside King William Street station looking south. Taken using a tripod and multiple flashes; but as tickets are no longer issued on this stretch of line, I guess that I was not bound by the conditions of carriage  |
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Feb 17, 2007 1:33:23 GMT
Thanks CLSR for the amazing photo (even if the technical stuff is over my head!)
|
|
|
|
Post by connextrain on Feb 17, 2007 5:33:10 GMT
It certainly is a great picture! |
|
|
|
Post by ttran on Feb 24, 2007 0:27:24 GMT
Sweet picture CSLR. I hope you don't mind me adding a little something of my own to the thread, just to show ATO what fiddling with the appertures and all that confusing stuff can achieve!  I know it's not railway related but I was just experimenting with time exposures. Held the shutter open for about 5 seconds I think. |
|
Chris M
Global Moderator
Forum Quizmaster
Always happy to receive quiz ideas and pictures by email or PM
Posts: 19,758
|
Post by Chris M on Feb 26, 2007 10:47:44 GMT
The camera could not 'see' me as I remained in the dark areas. I've just been thinking about this, and wondered how you avoided being silhouetted as you would be between the camera and the illuminated section? |
|
|
|
Post by CSLR on Feb 26, 2007 12:33:20 GMT
The camera could not 'see' me as I remained in the dark areas. I 've just been thinking about this, and wondered how you avoided being silhouetted as you would be between the camera and the illuminated section?No, that is not the case. Note what I said, "I remained in the dark areas." This is how I do it. I am dressed from head to foot in dark, non-reflective material. In small tunnels, I often lie down at the point where the tunnel segments join the floor, parallel to where the track would be - eg. feet towards the camera (non-reflective shoes) head furthest from the camera.* At other times I will stand upright and push myself into the curve of the tunnel. I then fire the flash to the other side of the tunnel, I do not illuminate the area that the camera sees as being behind me. Because I always illuminate an area that is roughly at a right angle to me, I am never between the light and the camera and I therefore remain in the dark. When I cross to the other side of the tunnel, the area that I was previously hiding in will be completely burnt-out by the flash that I fire from that side. I have explained this in detail in another thread on this forum. * Please, please, please remember that most of these photographs are of disused tunnels. The one photograph that I have posted of an operational running tunnel was taken for official purposes during an out-of-hours possession order with the electrical current off, full safety back-up and operational support. These last points are vital. To avoid reflection, I could not wear a hi-vi and was actually trying to make myself invisible - the complete opposite of what would normally be done on a railway. This is why the area had to be secured and sealed. I cannot emphasise these points enough. Do not use these methods in operational running tunnels and always remember when and where the no flash no tripod rules apply. |
|
|
|
Post by connextrain on Mar 17, 2007 1:21:55 GMT
Thankyou for the infomation, it is very interesting!
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Mar 17, 2007 16:57:00 GMT
I have only just come across this thread, CSLR's photos are fanbloodytastic, I only wish I had the talent to do similar, well done mate.
|
|
|
|
Post by rob66 on Apr 2, 2007 8:27:42 GMT
I took about 100 photos a few weeks ago on the Central Line: Used my 35mm and digital as a back up. The digital camera was hit and miss - the shots underground were terrible with streaks of light and reflections spoiling the photo. Only a few turned out ok but the photos from my 35mm were better with just a few that came out bad. I didn't use flash (no need to) Would like to buy a better digital camera but would the results still be the same?
|
|
Oracle
In memoriam
RIP 2012
Writing is such sweet sorrow: like heck it is!
Posts: 3,234
|
Post by Oracle on Apr 2, 2007 9:01:41 GMT
I used to use my 35 mm camera for colour slides. Of course today slides can be scanned, turned into positives, etc. I thought that film had died but I was looking around the local College with my son who was interested in doing Photography GCSE. They have a lovely darkroom, and teach students developing and printing. The tutor said that they do now do digital photography but there was a need to use film especially for artisitic and freestyle use.
That said some of the new digitals that I have been looking at are incredible. I have to take shots for my magazine and they have to be hi-res...going straight to disc. On talking to the sales people it seems that in the end it's down to the lens quality as regards quality.
Would be interested to hear what others think.
|
|
|
|
Post by CSLR on Apr 2, 2007 9:05:57 GMT
The digital camera was hit and miss - the shots underground were terrible with streaks of light and reflections spoiling the photo...Would like to buy a better digital camera but would the results still be the same? There are differences in the lenses which may have caused the reflection problems. Also, you may have suffered from noise on the digital pictures if you used anything more than a very short exposure. If you could post all or part of a picture that has some of these problems, we might be able to work out what the problem is and give some idea on how to overcome it. |
|
|
|
Post by compsci on Apr 2, 2007 13:54:51 GMT
What types are the cameras? Compacts, SLRs or something in between? Certainly in terms of reflections and other issues not directly related to overall image quality a 35mm and digital SLR with comparable lenses should produce comparable results.
|
|
|
|
Post by CSLR on Apr 2, 2007 16:17:18 GMT
There will always be slight differences between lenses and you will also note small differences in focal length when using the same lens on a digital or an SLR camera. Overall though, I agree with compsci that these differences are minimal.
The odd problem that you occasionally come across with underground photography - and the one to which I was referring - is internal reflection within the lens. Even this is relatively rare and is seen less in cheaper cameras where a 'lens' contains fewer optical elements.
Rob66 mentioned that he was considering buying 'a better digital camera', which suggests that he might be using a compact at the moment. Like compsci, I would like to know what camera was used and at least see an example of an affected image so that we can try to work out what has happened.
|
|
|
|
Post by tubeprune on Apr 2, 2007 17:30:33 GMT
I am about to buy a new camera. I'm only an amateur but I want something compact, good lens, optical zoom, high ASA capability for poor light conditions. Somthing I can carry around in my pocket unobtrusively so I don't get mugged for it. Money not particularly a problem - within limits. Current camera Canon S60 but recently broken by teenage relative not taking care of it. It was OK but a bit heavy and older technology. Any members suggestions welcomed.
|
|
Oracle
In memoriam
RIP 2012
Writing is such sweet sorrow: like heck it is!
Posts: 3,234
|
Post by Oracle on Apr 2, 2007 17:56:35 GMT
I swear by my Olympus compact which I have had for nearly two years now. I upgraded it with a 500 MB card then a 1 GB card. I only now bother with the highest-resolution shots and with the large card (same as a Fuji it seems) I can take a huge number. A photo of mine of an ice cream van is going in VINTAGE ROADSCENE issue 95 out shortly. A shot of mine of Marchwood Level Crossing appeared in RAIL a few issues back.
Of course about two minutes after I paid somethng like £260 for my Olympus they brought out a new model that was cheaper and with even more megapixels! That said my camera has withstood attempts by young relatives to drop it, prise open the shutter door, leave it in their coat pocket and generally blow it up.
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Jul 18, 2008 22:12:00 GMT
 Here's a shot I took before the ELL closed (taken from the station platform with no flash I might add). Just thought it was an example of digital photography in low light, hand held. |
|
|
|
Post by Chris W on Jul 19, 2008 9:05:32 GMT
I've been testing a Nikon D60 for work. Its become apparent that the Nikon range of DSLR's are NOT suitable for LU photography.
The camera emits a bright light when focusing, from a lamp adjacent to the lens. IMO even though the flash is switched off (doesn't pop up when the photograph is taken) this focusing light would constitute flash photography, which genuine enthusiasts will know, isn't permitted on LU.
|
|
|
|
Post by pakenhamtrain on Jul 19, 2008 9:14:51 GMT
Chris have you tried to use manual focous? Looking at the D60 there is a switch on the lens(Although that depends on if the lens you have has one)
|
|
|
|
Post by Chris W on Jul 19, 2008 10:34:04 GMT
Chris have you tried to use manual focous? Looking at the D60 there is a switch on the lens(Although that depends on if the lens you have has one) Manual focus would be the obvious way around it, but IMO that would be a PITA, when other cameras don't have this annoying "feature" when using auto-focus. To me it increases the risk of accidentally shining, what is an extremely bright light, at a driver/in service train, as some might innocently forget to switch to manual-focus. Its difficult enough to take photos for private/personal use (without being harassed by SA's who don't know the rules) at the best of times so I'd rather reduce the risk of mistakes being made - this why IMO its not suitable (its just my personal opinion)  |
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Jul 19, 2008 11:53:21 GMT
I've been testing a Nikon D60 for work. Its become apparent that the Nikon range of DSLR's are NOT suitable for LU photography. I think you can turn off the auto focus assist light. It is only required in very low light. I have a Nikon D60 (and taken quite a few shots on the tube and MTR), so I'll check the manual and get back to you. Edit: It can be turned off by many methods - page 57 of manual. |
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Jul 19, 2008 15:41:42 GMT
My Canon EOS350D has that light, but there is sufficient light on even the darkest of stations for it not to be needed, so it doesn't come on.
|
|
|
|
Post by Chris W on Jul 19, 2008 16:30:04 GMT
My Canon EOS350D has that light, but there is sufficient light on even the darkest of stations for it not to be needed, so it doesn't come on. Same with my 400D - in fact its NEVER come on since I bought it in April last year... As for the Nikon D60, I must admit that it is a better lower light/indoor camera than the Canon when on standard/auto settings and put it down to the focus lamp - I hadn't investigated whether the lamp could be switched off (mistakingly thought besides manual focus, that this was the design of the camera). Would be useful to compare images in lower light/indoor settings when the lamp is turned off Thank you stephenk: I'm happy to be corrected |
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Jul 20, 2008 2:09:31 GMT
Chris W - another tip for using the Nikon D60 in low light is to use VR and auto ISO in PSAM modes. If you have a VR lens, make sure it is turned on - it is invaluable at lower shutter speeds. The D60's auto ISO is adjustable. You can select the shutter speed at which it bumps up the ISO, and also select max ISO. It only works in PSAM modes. I usually select 1/15sec as the minimum shutter speed as I get an almost 100% rate of sharp photos with VR turned on at that shutter speed. If you want blurred motion shots, then you can probably get away with 1/4sec if you have a steady hand. I select IS800 as max ISO as I find images too noisy at higher ISOs.
|
|
