Hi all. Those who've followed it, sorry to bang on again about my big lens purchasing options - I'm just trying to balance a budget, and I'd value an opinion on how much extra equipment I need in, er, support. This is about how much a cheap tripod and head compromises heavy glassware. I already have: Camaras: D700 and F5. Tripod: Manfrotto 055CXPro3. Stated weight limit 8kg. Lens options (beaten-up second-hand options in both cases): 1) 400 f/2.8 AI-S. Partly so I can combine it with a (modified) TC-16A and get some sort of autofocus - I'm not scared of manual focus, but it's nice to have an option, especially if (within its limited range) the TC-16A is reasonably fast on a D700. I don't mind a little post-processing to handle LaCA and vignetting; however, I'm concerned that I've often seen this lens used stopped-down, and I'm not so interested in using it as an overweight 400 f/4. This lens weighs roughly 5kg. 2) 500 f/4 P. Inability to combine with a TC-16A is annoying (although I'd be after a TC-14), but the reduced weight (3kg) is nice. It's also about half the price of the 400, given that I can get one in the UK whereas I'd have to pay import duty on the 400mm. Used bare, it's quite a big jump from my next-longest lens (200mm), though. I'd prefer not to have to shell out on a full Wimberley head - utterly smooth subject tracking is beyond my needs until I can afford an AF-S lens. My preferred option would be a Manfrotto 393 bracket, if it'll cope. My current ball head is hopelessly inadequate for anything of this weight, so a Sidekick or similar is out of the question; there doesn't seem much point getting an expensive ball head for a huge lens when a gimbal head is easier to use. Likely subjects, in decreasing order of priority: (mostly small) wildlife, photoastronomy (mostly deep-sky objects), possible portraits, a little (outdoor/daylit) sport without too much subject movement. I expect that means shutter speeds either faster than 1/100 or, for astronomy, in the several seconds range - I might be able to stay out of the "danger zone" for camera vibration. Don't worry, I'm not asking yet again for someone to help me decide between the lenses - at least, not directly. I would like to know: 1) If I go with the 400mm, will my tripod (which with the lens, camera and bracket is right up on its stated maximum load of the tripod, which I'd normally stay well below) hold up, if I treat it gently (pick fastish or - with mirror lock up - very slow shutter speeds, don't extend the column, block the wind)? Even with a TC-16A making things unstable? 2) If not, do I need to budget for a new tripod even for the 500mm? 3) Will the 393 bracket cope, or would I utterly regret it? It seemed okay at holding a current 400 f/2.8 and a 200 f/2 when I last saw one set up, but the new stuff is lighter than the manual focus lenses, and I didn't try shooting through it. 4) If I stay out of the vibration danger zone, is it possible to live with the existing lens feet? I've read Bjørn's rant, but I suspect he's more exacting than me. I know the perfect support would be something like a Gitzo systematic series 5 and a full Wimberley head, but I'm obliged to cheap out a bit. Yes, Thom's article on buying expensive stuff to start with is hanging over my head - I'd anticipated living with a Sigma 150-500 longer than I'm in fact prepared to, so the big glass shopping snuck up on me. If I really have to drop a thousand pounds on upgraded support, that pushes the 400 f/2.8 well out of my price bracket. If I have to do the same even for the 500 f/4, I need to spend some more time saving up. I'm not as critical as professional wildlife photographers, but if I'm going to get a cracking noise followed by a mangled pile of carbon fibre and glass the moment I try putting everything together I'd rather know in advance. Whether it's wasteful to buy a 500 f/4 if what I really want is a 400 f/2.8 depends rather on how much the 400mm really costs if I'm going to get decent images out of it. Any advice, including "you don't deserve decent glass if you can't treat it properly" appreciated.