Five years ago or more, owning a full-frame DSLR was a privilege only for the very wealthy, with prices being in the region of £2500 plus, just for the camera body. Most of us, myself included, started with a crop-sensor DSLR, but possibly had a secret desire to use full-frame but knew it was out of reach financially,

Older full-frame DSLRs have now trickled down into the second-hand market, and it is possible to buy a used full-frame camera such as the Canon 5D (Mark I) in good condition for under £400. Admittedly the older models of the 5D do not have Live View or Movie capability, but the ability to get truly wide-angle shots, the luxury of a huge bright viewfinder, and the low-noise qualities of the big sensor make these cameras very attractive.

The downside is that the lenses designed specifically for crop sensor cameras are not suitable for full-frame use. However, in the case of Canon, the older EF lenses from the film era will work fine on full-frame digital. The secondhand  prices of these old lenses are often quite low, in part because the range of focal lengths for full-frame is not very useful for a crop-sensor. For example, a 28 to 135 mm zoom is ideal for full-frame but is of limited use on a crop sensor camera.

I am now a full-trame convert, and hope at some stage in the future to be able to buy a more modern full-frame camera (the Boss says only when she has had that new Kitchen). But for people such as myself on a limited budget, the second-hand route to full-frame is now a realistic option. 

Gotta agree with you Edward. After a long time planning I have now treated myself to a 5D MKII with battery pack and 3 Sigma lenses, 12-24, 24-70, 70-200, all used but bought from reputable dealers. The result of a financial settlement, although not a new kitchen!!! Decided long ago that full frame was the way to go after the batteries died on my 500D and I borrowed one of my mates 5D's to finish off the day.

A lot of the new APC-s crop sensors now have MP counts into the high 20's and 30's. But MP count is not everything!! After all the 2 top PRO cameras, Nikon D4 and Canon 1D MK IV both utilise sensors of under 20mp. The difference being that the 20 mb pixels on a full frame sensor retain more detail than the 36mb pixels on an APC-s crop sensor because the actual 'photosites' within the pixels are larger and therefore able to retain more light and thus produce better detail. The other winner for me is the additional weight of the body, being of 'non plastic' construction. Lenses as you say for crop sensors will not work on full frame cameras but full frame lenses will work on crop sensor. If you have any old FD lenses they can still be used, but you need an adaptor and go back to manual focus and exposure .... so again you can win with older lenses that are probably better quality than a lot of those on the market today.

But, yes, I would agree, if you have the resources the upgrade to full frame, used or new, will never be regretted. 

Interesting you have gone full-frame too, Dave. I will look out for your submissions with your newly-acquired 5D MkII, although at the resolution on PoE, the differences may not be dramatic. It is when you look at the RAW files on your own PC, you really see the difference with the big sensor.

A downside of looking closely at the RAW files is that it is easy to see lens deficiencies which might not have been so obvious when the lens was on a crop-sensor camera, particularly in respect of vignetting and peripheral sharpness. But being obsessive about such things can be depressing, unless of course you can afford a full set of Canon 'L' series lenses. I would say, though, that once you have decided to go full-frame, it is prudent to get as good quality glass as you can afford. Your Sigma lenses are excellent and cover a wide range of focal length (12 mm is amazingly wide on full-frame) so you seem to have got that aspect covered.

I can tell there's no stopping you now, Dave, once you get the bigger bag.

The 12 - 24 is also a very useful focal length range on a crop sensor camera, and is still quite wide, so you get the best of both worlds!  The widest I can go on full-frame is 19 mm.

The choice is simple. If you can afford to upgrade to a full frame sensor, then go for it. It's a bit like comparing the quality of medium format film to 35mm. The negative, being bigger in the medium format gives more quality. A 10x8 negative even more. With full frame sensors becoming more aimed at the non pro market, the prices will almost certainly come down as production increases.

My first digital SLR was a Nikon D70 with half the megapixels of my second camera, the D300. Both can give me good print quality up to A3. No doubt if I attempted to greatly crop my images there would be inevitable fall off in quality. We should also be mindful of the lenses we stick on our camera bodies. The key to quality revolves around decent glass, a good photographic eye, every bit as much as the name stamped on the camera, or dare I say it the specification.     

Next year may well see me crossing the portals of a camera emporium, and it will be a full frame sensor which next graces my ever older set of shoulders. It will be the “bees knees” of course. I'll be like a kid with a new toy. I'll even keep the box!  

As soon as a purchase is made, the camera very soon will be declared obsolete. If we chop and change with the wind, we are either very wealthy, naïve, or being employed professionally when the costs are soon recovered.