That is horrible . why wouldn ' t you just run brewmaster ? <| sep |> I researched this pretty hard and discovered how undervalued the 55250 mm IS STM lens is . The copy I have is very sharp , much sharper than dxomark claims . I ' ve compared it to a 70200 mm 2 . 8 II , and a Tamron 70300 mm VC and the 55250 was the winner . The $ 2000 70200 was sharper , but the $ 500 70300 mm VC was not . Bottom line putting a full frame lens on a crop body doesn ' t work so well . So , your options areCanon 70300 mm . expensive , less sharp , clanky focus motor . Canon 70200 mm f 4 IS . $ 1 k , sharper and faster , but with less reach and heavier . I imagine a cropped image to match the FOV of 250 mm would about match the 55250 mm STM . Tamron 70300 mm VC . Full frame lens on a crop body . Slower focus , not as sharp . I owned one for a while and sold it . Canon 70300 mm IS L . Very good . Also full frame . 10 x the price of a 55250 . $ 1300 So , where does that leave us . Oh , the 100400 mm . The only FF lens really worth putting on a crop body . The first version is coming down to about $ 700 now . The mark II is still expensive . The mark I is reasonably sharp . This is probably the best option . digitalpicture . comReviewsISO 12233 SampleCrops . aspx ? Lens 113 Camera 736 Sample 0 FLI 4 API 2 LensComp 856 CameraComp 736 SampleComp 0 FLIComp 5 APIComp 1 So what about the 150500 or 150600 mm zooms . The older versions can be quite bad on a crop body , but are under 1 k . The new tamron and sigma lenses are just over 1 k . I ' ve used one in a camera store so I can only say they are heavy , but that reach would be amazing . The inexpensive 75300 mm lenses are terrible . Your 55250 mm is better . That would leave us with a 400 mm prime maybe . Well , they ' re also in the $ 1 k range . So , that $ 150 refurbished 55250 mm STM lens is seriously undervalued . I ' d love to see Canon put out some APSC long zooms . Edit I reread your post and I didn ' t really answer your question . If you want something for portraits that ' s faster and in the 100200 mm range , then these are goodCanon 85 mm f 1 . 8 and 100 mm f 2 primes . They are reasonably priced used and are quite good . Better gets more expensive quickly . The 100 mm f 2 . 8 macro can also be used for portraits and macroThe 135 mm f 2 . 0 makes amazing portraits , but it ' s $ 800 . If you want to trade off a little reach for speed and sharpness , the 70200 mm f 4 IS is a good choice , and around 1 k .