Thanks fWord.
Budget is always a problem. But with proper budgetting and planning, it can be affordable
Here's the link to the 280mm
http://us.leica-camera.com/photography/r_system/lenses/3807.html
Right, the 280/4...this is said to be one of Leica's best lenses, if not the very best in their stable. I haven't been able to afford it and have never used it, thus cannot comment. Having said that if you troll around Ebay you may be able to find the 280/2.8 instead which seems priced at the same level as the 280/4 at the times I've seen both available.
It's strange to see this however because the f/2.8 should actually be a heck of a lot more expensive than the f/4. Mamiya also has a white APO 300/2.8 that was made for their medium format systems. Said also to be one of the very best lenses out there and within your budget.
Do bear in mind however that a manual focus telephoto could be very difficult to use and if heavy like these lenses, may be confined to a tripod which could affect its application. For a handheld tele some people recommend the 400/6.8 with the shoulder stock. It's push-pull focusing mechanism and lightweight has allowed more skilled users to even do birds in flight shots. I've seen them go for as little as US$300 on Ebay. The only drawback of this lens is the simple design which results in field curvature (some say worsens as the lens ages), so you have excellent center performance and away from that performance rapidly drops. Upside is there is very good control of CA.
The 400mm lens I chose was the Telyt 400/5 for Visoflex (Type II from the 1960s) which is a massive lens at around 2.4kg and a long focus throw to allow for fine focusing. It is a lens that people recommend sticking to a tripod but I've managed to use it handheld mounted to a 1-Series camera. But it's taxing exercise akin to gym work. I haven't used the lens a whole lot although initial impressions are good with even center to edge performance but obvious CA under some conditions. As Thinkvision mentioned a while back this lens is compatible even with medium format so it's obvious as to how large its imaging circle really is and how good performance would be on a smaller format, even a 35mm sensor. Some samples were posted on the first page and when the lens had fungus. Pathetically, I've yet to get many shots with the lens after fungus was removed, but here is a sample:
Here is a 50% crop (from off-center, nearing the lower left of the image) to demonstrate sharpness and also bokeh, taken in shade, ISO 800, 1/250s, handheld. Under such conditions I interpret that image quality degradation will occur because of camera shake, subject movement and high ISO noise but the performance is indeed amazing still:
This would be of benefit for those looking for really affordable Leica tele lenses. With your budget I think you could pass on the Telyt 400/5. The weight and sometimes CA can be a put-off.