"It's changing all the time," says Mr Allen, who runs Fixation, a busy camera repair and sales business in south-west London. "I try to keep up to date with what people are expecting."
He and his team of 12 specialise in the professional sector of the market and do repairs for leading camera manufacturers such as Canon and Nikon.
"We take young people and train them because people like myself have been in the business for so long. Most cameras now are set up and checked on computers, so you need an agile mind."
But he says the camera technician's trade is suffering from a shortage of trainees as businesses like his struggle to find young apprentices. "People who have ambition wouldn't necessarily be driven towards doing a manual job these days - particularly in central London," he says.
"Their expectation, in my view, is greater than when I left school 38 years ago. They expect more remuneration.
"You can't pay them a huge amount because it's terribly labour intensive to teach them. It actually slows down the other people while you're teaching them.
"First we have to see whether they have any adaptability for tools and can use tweezers and small screwdrivers. And sometimes you can see they are finding it tough to concentrate."
The training can take years. Three of Mr Allen's technicians in their mid-20s are still training.
He complains that colleges in London no longer provide training courses for camera repair technicians. "They used to do a City and Guilds two-year course in the 1970s. But now there isn't anything relevant.
"We just put one of our lads on to a computer course. But from what he's learnt in 10 weeks, we could have taught him here."
His sentiments are echoed byLondon high street camera repairer Terry Boyle. "There's no new blood coming in," he says.
He recently took on two young apprentices at his workshop, The Camera Clinic in West Kensington, but says neither of them made the grade.
"We are screaming for another technician at the moment. But I know every technician within the M25. There's no one we can get.
"Why would a school-leaver want to come and work for someone like us for pound;100 a week? It's a very specialist skill and takes an extremely long time to learn.
"It's also a huge investment for someone like us. We have found it's very difficult to keep people motivated and interested.
"They see their friends earning lots more money. That's what we're up against."
Mr Boyle says his business also has had to move with the times, retraining staff to repair digital cameras and camcorders.
"Traditional camera repairs are a dying market, to be honest. We will probably see the demise of the 35mm camera and the film that goes in it. The writing is on the wall with digitalisation."
Much of the training in the industry is done by the leading camera manufacturers. Canon (UK), for example, runs courses for its technicians and authorised repairers throughout the country.
Roger Avis, managing director of Canon Business Service, the company's repair arm, says: "It is very specialised. I think it would be very difficult to put on a college course. Most of the training is around products. Although all cameras have the same sort of philosophy in terms of how they work, camera repairs are a lot more practical."
But he believes that technological changes in the market will bring a need for new skills, moving away from the traditional technician. "The market is moving into much more technology and digital. My guess is that will attract more people in because it is a different technology."
For more information contact Mike Allen at Fixation, telephone 0207 5823294