http://www.pentax.jp/japan/news/2011/201101.html
Main Specifications
| マウント Mount | ペンタックス645A F2マウント 645A F2 Pentax Mount |
|---|---|
| レンズ構成 Lens | 8群12枚 8 groups, 12 |
| 画角 Angle of view | 95°（645D装着時。中判フィルム一眼レフ装着時は109°） 95 ° (645D when seated. When installing medium-format SLR film is 109 °) |
| 絞り羽根枚数 Number of diaphragm blades | 9枚（開放～F8：円形絞り） 9 (Open ~ F8: circular aperture) |
| 最小絞り Minimum aperture | F32 F32 |
| 最短撮影距離 Minimum focusing distance | 0.4m 0.4m |
| フィルター径 Filter size | 40.5mm（レンズ前面には装着不可、同梱の専用フィルターのみ本体内蔵のフィルター取り付け枠に装着して使用可能） 40.5mm (in front of the lens is not attached, and available built-in filter attachment frame attached to the body only in special filter included) |
| フード Hood | 組み込み Embedded |
| 最大撮影倍率 Maximum magnification | 0.11倍 0.11 times |
| 大きさ、重さ The size, weight | 90.0mm（最大径）×140.0mm（長さ）、約1070g（レンズ本体） 90.0mm (diameter) × 140.0mm (length) of about 1070g (lens) |
Whilst it is stated in the above Japanese page that the price for this lens would be "opened", the AP(UK) has reported that it will be sold at £3799.99 and the on sales date will be April 21:-
http://www.amateurphotographer.co.uk/news/Pentax_25mm_f4_645D_lens_targets_outdoor_photographers_news_305510.html
What an expensive lens it really is! :-o