I am hoping to set up a Facebook group for birders and other wildlife enthusiasts to advertise items free of charge. At present I have many secondhand books for sale, plus the Canon camera, 400mm lens and 1.4X extender. Whilst pagers often carry adverts for telescopes etc. selling on eBay doesn't attract the buyers for more specialist items. I intend to direct people here from the Facebook group, hopefully others will direct people to their own sites in a similar manner but Facebook will make interested people aware of what's for sale. I know Facebook already has a marketplace, but I looked for a specific camera much loved by birders and didn't find one despite sifting through several hundred adverts.
If you don't have a website you can post details directly with an e-mail address.

CANON 400mm F4 DOI IS Lightweight lens £1300

Perfect for travelling, easily used handheld. This is the lens I've used for years when going abroad, as it causes no hassle with hand-luggage weight limits etc. and is easy to carry in the field. As a MK 1 it does have its faults, but I have found it perfectly acceptable. The MK 2 has better sharpness and contrast, but unless you're an out and out photographer seeking absolute perfection this is perfectly fine for bird photography the large aperture and image stabilisation allow use in low-light conditions. Many of the shots on the website were taken with this lens. It was serviced by Colchester cameras before my trip to Australia in 2019 (receipt available). The big advantage of it-PRICE, a new MK 2 is £6500, a secondhand one £4200, but I am selling this for under £1300. Checking eBay yesterday prices for a Mk1 were from £1600 upwards. How much under is subject to negotiation, postage and packing about £20.

Condition is good, optically perfect, but the underside is heavily "scratched" due to handholding. (Canon paint isn't very durable). The hood is wrapped in black tape but it is non-adhesive and easily removed, the hood is unmarked. I have never used the travelling case or the tripod mount (easily refitted) and I used an OP/TECH strap fitted to the lens rather than the camera body to carry it. Most of the time I used a 1.4X Canon extender with it, I tried a 2X but found a better result using a 1.4X and "blowing up" the image if necessary. My last extender is for sale below, as will be the camera body soon, (I am not giving up but have switched to a mirrorless system with a 100-500 Canon zoom, which is even easier to handle and gives good results in more adverse conditions).

CANON Extender 1.4X Mark III £325

Excellent condition, the latest model which is apparently almost a necessity if using a modern telephoto lens. Canon say the MK I and II are not compatible, this is probably b******s but there is a definite improvement when using a MK III. For this reason I don't want to haggle much on this, cheapest I have seen on eBay was £319 but that had far more signs of wear. Postage free.

Condition is excellent, optically perfect, and as it was mounted on a lens more or less permanently there is little wear from taking it on and off repeatedly. The vast majority of my photos have been taken with this or a similar extender, using both the 400mm and a 500mm which I used to own when I did a lot of twitching. Complete with soft pouch and box, you won't find a better one.

CCS Heritage LARGE LENS RUCKSACK £50

A fairly old item but rarely used. Excellent quality, canvas, well padded with two side pockets, waist & chest straps as well as shoulders, plus two straps to hold a tripod. The side pockets have fully waterproof flaps but I have never had a problem with water, the canvas keeps rain out perfectly well. I used it to carry a 500mm lens with converter attached, and a EOS 7 fits easily in to one of the pockets. It will take the a 400mm lens with body attached but if using a converter the waterproof lid doesn't come down fully and could let water in if wind and rain are about. Personally, not being a photographer as such, I rarely used it as a rucksack unless the weather was inclement, preferring to carry the lens/camera on a tripod for instant action.

Condition is Very Good, Clean. Dimensions are 45cm X 31 cm X 28cm approx (HxWxD) Internal 19.5cm at widest point. Side pockets are 28cm x 15cm x 9cm. Very approx. because no rigidity, but will take a large camera body. Price subject to negotiations, P&P about £10.