How do I get permission for photography? Is permission really needed?
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As discussed above, often it is best to avoid problems by getting a permit ahead of time (apply 2 months or so in advance) if you plan on doing any significant amount of photography or videotaping. A permit may be obtained by writing to the Joint Director of Public Relations, at the Rail Bhavan in New Delhi, or to the Senior PRO (Public Relations Officer) of any regional division, or the Chief Public Relations Officer (CPRO) of a zonal railway. List...
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the stations where you intend to take photographs, and the dates for which the permit is desired.
You must also state that the photographs are for personal use and not for commercial gain, and that you will not "tarnish the image of the railways" or otherwise defame IR with your photographs(!). You will receive a sheaf of permission letters -- multiple copies of the permit, which you hand out on demand to various officials later. Normally permits are issued only for still photography. Video photography permits involve more red tape.
Although a station master may not always ask to see the permit, it's a good idea to drop by the station master's (or assistant station master's) office and let him know before engaging in extensive photography. A station master at some of the bigger stations (e.g., New Delhi) might also dispatch an orderly to accompany you while you are photographing, which prevents further hassles with security personnel. Similarly, before photographing at a shed you should talk to the shed foreman. A permit from the CPRO of the zonal railway is almost a necessity at some loco sheds (e.g., Bandra Marshalling Yard) and even that may not work; a letter from Rail Bhavan is often not sufficient. Even railfans with multiple permit letters have sometimes been turned down by shed foremen and others.
[2001] It has recently been reported that in some cases the CPRO's office now charges a fee for the photography permit, about Rs 2000, although it is not clear if the fee is for a permit for a specific location or one valid across many areas. Many offices do not yet charge this fee.
A photography permit may also be obtained from an Indian embassy or consulate, especially one of the larger ones. This can take a long time, however.
Note that videotaping or using movie cameras is not permitted, technically, under the terms of the standard photography permit issued to railfans; however, possession of an official piece of paper on Railway Ministry letterhead may be better than nothing in some sticky situations, and may smooth over the concerns of security personnel or other railway staff.
Sheds and Workshops, Production Facilities: Permits are needed to enter and visit carsheds, loco sheds, workshops, and production facilities. You may be able to get an invitation from an official at such a facility; otherwise, you need to get a permit from the concerned PRO's office. Loco sheds, workshops, etc., are under the relevant zonal railways' PRO; manufacturing facilities like CLW, DLW, etc., have their own PRO offices. Even with the permit, you need to arrange for the visit at a specific time -- you will be escorted around the facilities and cannot roam around on your own (this is mostly for your own safety since there are hazardous locations and equipment in these facilities). The permits for visiting these facilities may or may not allow photography, and you are advised to double-check with your appointed guide when you do visit the facility.
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Source: IRFCA

How should I proceed with photographing or videotaping trains, locos, etc.?
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For a comprehensive account of all that is involved in photographing IR, and suggestions on equipment, etc., please see A railfan's guide to photography on the Indian Railways by S Shankar.
IR is skittish about anybody photographing or videotaping anything at supposedly strategic locations such as railway stations, bridges, workshops, etc. Technically,...
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a permit is required for almost all photography or videotaping done on or near railway premises.
However, in practice, this rule is often used by the railway security persons (RPF, GRP, etc.) just as an opportunity to extract bribes. More often, a security person might just be operating under an antediluvian notion of "security" and harass photographers with or without permits. Other railway staff (drivers, station masters) are sometimes quite sympathetic to railfans while others (shed foremen, particularly) might insist on following the rules and seeing a permit.
Lineside photography in general does not require a permit (unless near a bridge, tunnel, etc.), but security personnel may sometimes be ignorant of this. One will often find security personnel and railway staff both more friendly and accommodating at the smaller stations.
Many railfans have had good results without an official permit by being discreet and using small cameras (compact point-and-shoot cameras) which can be concealed easily. Bulkier and complex equipment (such as sophisticated SLRs, long zoom lenses, tripods, or video recorders) is more likely to be noticed and may result in questioning or trouble, especially if the photographer does not have a permit. Similarly, flashes may draw more attention, so unless it is essential, it is probably better to avoid them. The best advice is to avoid overdoing it and not to draw too much attention to oneself.
Some hints
Avoid the platforms or areas near the RPF or GRP post where the security personnel tend to be. Overbridges often provide good vantage points of tracks and shunting yards. An empty train stabled on one track can sometimes provide the best views of action on adjacent tracks, provided one can get into it (and remember to get out of it before it is shunted away...).
The end of a platform is a good place to get shots of a train pulling in or out of a station, without the crowds that are present near the middle of the platform. If you have a good SLR with a fast lens, ISO 100 film is the best as you can make good enlargements of the interesting portions of prints. With a compact point-and-shoot camera, or for candid pictures and action shots, it may be better to use ISO 200 or 400 film, which is also more versatile in different light conditions.
Although Station Masters and other officials at railway stations are not technically empowered to give you permission to take photographs, if you do not have a permit, it is sometimes a good idea to talk to the Station Master or other official and make sure that they understand you only intend to take a few hobby photographs. This will help avoid awkward confrontations with police or other security officials.
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Source: IRFCA