Lens experiment, 500mm x 2

[DrEntropy]

Steve's mention of that comet got me thinking. Put an old manual focus 2x extender on the 500mm mirror (also MF). Set it on a tripod and aimed it down the block.

First shot is with a zoom set at 35mm to approximate a 50mm "normal" lens. Second with the combo tele. Not the sharpest shot, used my digit to fire the shutter. Both full frame, just reduced to post.

 

[Basil]

Not bad for such a long focal length hand held. From the phone number, is that the Anti-Christ Cab Company?

 

[DrEntropy]

Not bad for such a long focal length hand held. From the phone number, is that the Anti-Christ Cab Company?

If only I could be THAT steady! The long lens was stick mounted but the shutter was triggered with a finger. May go to the park where those osprey are nesting in the cell tower across the canal, with the same rig. But use a cable release and mirror up. Just an experiment, a cheap way to get extreme magnification. It works out to be about equivalent to a 1,500mm on the APS-C sensor.

Yellow Cab Co. has used that number here for a long time, first saw it in Miami in the late '70's. Hard to forget if you really need a cab!

 

[DrEntropy]

Trip to the water yesterday was a bust for the mirror lens attempt to get the osprey, but gave me some info: the nest is on the opposite side of the tower. Gonna recon a spot across the water, closer to the tower later. All I got with any bird parts was this shot, the extender is sub-par.




The only fair shot for the effort was with the D7200 and the 18~140mm, hand-held:



And a Loch Ness substitute.

 

[GregW]

So the mirror with extender is an f16 wide open?

 

[DrEntropy]

So the mirror with extender is an f16 wide open?

Probably. Maybe somewhere between that and ∱22, methinks.

 

[Basil]

Probably. Maybe somewhere between that and ∱22, methinks.

A 2x extender should (theoretically) add 2 stops. My 1.4x adds 1 stop

 

[DrEntropy]

Went to an area to the south side of that tower this AM, opposite of the prior location and much closer. Absolutely no osprey activity, the young ones have fledged and I missed it. Now only an occasional bird. Waited around for about an hour, got a crow leaving the top array. Basically got squat.

The 500mm full-frame (without the extender).


Cropped and run thru Darktable.