I'm use either a pentax k1000, or OM-1.
Originally Posted by Mick Fagan
May other concern was weight, as I've have a 2x tele, and a zoom for the om1. its alot of length and weight to hand hold.
The image becames quite a bit darker with the tele on; Prob has to do with the F-stop increase right???
Also i'm just shooting birds right now, and my 70-210 zoom works alright, there are times i just can't get close enough. Hence, my interests in a 500 Cat lens, compactness, and more magnification ( :) i learned some new terminology)
Thanks for all the advice.
I think the problem that some people experience with this type lens is caused by the fact that they are easy to hand hold. There is a specific technique involved to assure sharpness when handholding any long lens.
I have thought about getting one, but after looking all the possibles I didn't want one.
IMHO all of the above is true to some degree. I have a 500mm Porter's cat. As said, it may not be the sharpest, but it does a good job. Using it on a tripod, it compares favorably with my 450mm Soligor Petzval design. Mainly, it's easy to carry and use. I'm not unhappy with it.
I' too have a Sigma 600mm F8 mirror lens to suit Canon FD mount which I fit to my Canon EF body using an optical adapter. As Mick says, it's not brilliant but no slouch.
I've owned a Canon FD 500mm mirror, plus a couple of different Russian 500mm lenses (and a 1000mm), and for sharpness the Russian lenses win hands down. How sharp? Not as sharp as a 500/4.5L Canon, but much sharper than any manual focus zoom lens I've used with any teleconvertor (and I've owned all the Canon teleconvertors).
If you can find one the old Vivitar solid cat lenses were also very good.
Personally I would look out for a fixed 400mm lens - I've used a Sigma f5.6 400mm with good results - much sharper than azoon with a TCV..
Another alternative would be an old Pentax 500/4.5 screw mount lens with an K mount adaptor. I've seen them priced pretty reasonably..
I just had a quick look at KEH - they list a few 500mm mirro lenses with T Mounts for under $70.....
for an example- here's a shot with a Tamron/T mount.
As I recall, this was with the lens supported on a post. View is a bit soft, but it does the job. My experience with store-brand mirror lenses was very bad though I still have a 300mm something-a-tar I got cheap at a swap meet
I owned a 500mm Nikkor Cat a number of years back and found the lens far too soft for my liking (I ended up giving the lens away); my other telephoto Nikkors (300, 400 and 600mm) are IF-ED glass so maybe my basis of comparison is unfair. That said, I did find the "donut effect" interesting, but not something I would use on a regular basis. From time to time, however, I have been tempted to give a try out to the 500mm Nikkor Cat ("New") to see if any improvement is evident in the last release of the design...
I suspect that alignment is an issue with inexpensive cats. The Vivitar solid cats were reliable, although the t-stops(equiv. f/stop corrected for transmission) were in the zoom range. I have an old Russian MTO which is quite contrasty and sharp, but it is only light compared to a refractor of the same spec.
I have nothing to add to this thread, other than to note the irony of a thread started by "Labrat87" about lenses referred to colloquially as "cat" lenses, posted in the "Wildlife" sub-forum :p