[imtheguy]

I found a mint SP 500mm f/8 Tammy mirror for sale that i am lusting after but can't find any information on recent sales to make an offer. Anybody wish to toss me their recommended market value? Much appreciated.

OK, might as well ask the more important question...is the AD2 lens mount one that i can use for Pentax? Adaptor?

Thanks folks.

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Last edited by imtheguy; 04-09-2009 at 10:40 AM.

[Lowell Goudge]

I passed on one, including teleconverter for about $125 canadian at christmas.

although interesting, it does not in any way match the performance of my 300 mm F4 and 1.7x AF TC or my 1000mm F11 celestron C90.

I have managed to curbe my LBA by only getting things that outperform my existing 18 lenses.

Considering I have zooms covering 28mm to 200 mm at F2.8, and the above mentioned lenses, this really leaves me with very fast medium telephotos and wide angles to tempt me. These are somewhat scarce.

[imtheguy]

Thanks Lowell,
Would you expect my 55-300 f/4-5.8 with a 1.7 TC to perform well enough as compared to the SP500?

[snostorm]

Hi ITG,

I got what I consider an exceptional deal on mine -- $112 USD for the lens and a PK/A adapter. Considering the current craziness in pricing on the adapter, the lens was almost free. The SP 500/8 is one of the better ones out there IMO. I'd say that a good price for a nice example the lens alone would be $100-125.

You do need an adapter -- the PK/A adapter is relatively rare, originally selling for @ $30 USD, but the PK/A is now selling for @ $100 used. The SP500/8 Cat is a fixed aperture lens, so you can get by with a PK adapter (it doesn't have the electrical contacts that transmit aperture value). You should be able to pick one up for under $30 USD -- I have a couple of local dealers who still have old/new stock of these and would be glad to unload them.

It's a good lens, but there are some caveats -- the donut bokeh is usually the most objectionable to the most people. It's got a very thin DOF, so it's hard to focus with its relatively dark f8 aperture through an APS-C viewfinder. It's actually too light to stabilize effectively for handheld shots -- handholding a refractive 500mm has totally different shake characteristics, and the weight of one tends to slow down the hand shake significantly compared to the little Cat lens.

The SP500/8 Cat will, however, beat the pants off most of the 300/4 +1.7x AFA combos (especially the less expensive ones) for CA and PF control though since the design uses minimal refractive elements.

Would you expect my 55-300 f/4-5.8 with a 1.7 TC to perform well enough as compared to the SP500?

Unfortunately, your 55-300 would not AF at the longer focal lengths as the system requires a max aperture of wider than about f8 total to work, and you have to add a factor of x1.7 to the aperture of the lens because of the TC. The lens is probably sharp enough, but a bit too slow.

Bottom line about this lens -- easily the most cost effective quality 500mm you can buy, as well as about the smallest and lightest by quite a margin . . .but it needs light (f8), is most effective mounted on a tripod, and has very thin DOF and quirky bokeh. A very good 300/4 with an F 1.7x AFA is better handheld, but will cost a minimum of about $500 for both the lens and TC, and will be significantly larger and heavier, and the less expensive lenses in this class will show significantly more CA and PF -- To get very good control of these aberrations, you'd have to go to the F*/FA* 300/4.5s , the DA*300/4 or the Tokina or Sigma 300/4s if you can find one -- they are very rarely offered.

Scott