Camping?

[cdifoto]

This is with the 10D + Meyer 135mm + Soligor 3x. Works out to being 648mm equivalent. And I think f/11. Handheld at 1/640th. Not sure if that's shake, misfocus, or Tcon IQ drop. Probably misfocus.

20920

[Sungrazer]

Do you notice much of an IQ drop with the Soligor on your other lenses? Are any fast enough that you can still autofocus?

[cdifoto]

Do you notice much of an IQ drop with the Soligor on your other lenses? Are any fast enough that you can still autofocus?

I haven't pixel peeped it to know for sure, but it's a Pentax Screw Mount (M42) converter so AF doesn't apply.

[coldrain]

Well, a crop can say more about what is the main culprit in the sharpness.
But the drop in brightness by a 3x TC be quite severe for manual fucussing, doesn't it? That would be more than 3 f-stops loss of light I think.

*quick calculation*

Suppose the photo would be 20 high and 30 wide (just for calculation sake). The surface would be 20 x 30 = 600.

With a 3x TC the TC would actually crop the center part of the lens, and you only get the light of that center part spread over the sensor/viewfinder.

30 / 3 = 10.
20 / 3 = 6 2/3.

6 2/3 x 10 = 66 2/3

600 / 2 = 300 (1 f-stop loss of light)
300 / 2 = 150 (2 f-stops loss of light)
150 / 2 = 75 (3 f-stops loss of light)
75 / 2 = 37.5 (4 f-stops loss of light)

So 66.667 would be quite in the middle of 3 and 4 f-stops, so a whopping 3.5 f-stops less light in the viewfinder.
Making it an 2.8 -> f4 -> f5.6 -> f8 -> f10 lens. That indeed will be quite hard to judge focus! Do you have a split focus screen in your 10D?
Also, the sharpness of the lens will lose 66% because you spread the resolution of the center part over the entire image.

648mm from that tiny lens, that just is amazing!

[cdifoto]

Well, a crop can say more about what is the main culprit in the sharpness.
But the drop in brightness by a 3x TC be quite severe for manual fucussing, doesn't it? That would be more than 3 f-stops loss of light I think.

*quick calculation*

Suppose the photo would be 20 high and 30 wide (just for calculation sake). The surface would be 20 x 30 = 600.

With a 3x TC the TC would actually crop the center part of the lens, and you only get the light of that center part spread over the sensor/viewfinder.

30 / 3 = 10.
20 / 3 = 6 2/3.

6 2/3 x 10 = 66 2/3

600 / 2 = 300 (1 f-stop loss of light)
300 / 2 = 150 (2 f-stops loss of light)
150 / 2 = 75 (3 f-stops loss of light)
75 / 2 = 37.5 (4 f-stops loss of light)

So 66.667 would be quite in the middle of 3 and 4 f-stops, so a whopping 3.5 f-stops less light in the viewfinder.
Making it an 2.8 -> f4 -> f5.6 -> f8 -> f10 lens. That indeed will be quite hard to judge focus! Do you have a split focus screen in your 10D?
Also, the sharpness of the lens will lose 66% because you spread the resolution of the center part over the entire image.

648mm from that tiny lens, that just is amazing!

I'm glad I'm not as geeky as you Coldy. :eek: :p

I'm also glad there's a scale on the Tcon:

21273

:D

PS: I'm about 99% certain I had it stopped down to f/4, hence showing it at this setting. But no I don't have a split image, and yes it was dark as snot.