Liquidstone wrote:
Five of my well-loved TCs mounted - (L - R) Canon 2x + Sigma 2x + Sigma 1.4x + Tamron 2x + Tamron 1.4x, total of 16x TC.
Would you like to share any images taken with it?
If I calculated it correctly, it would be f90 wide open but you might still want to stop it down a bit for improved sharpness. Unfortunately the diffraction will kick in quite heavily still, with the minimum spot size at f90 (with theoretically perfect optics) being 60 um, which is about 10x10 pixels with the current cameras!
The hyperfocal distance at f90 is 128 kms, so you might still want to focus the lens very carefully before judging the sharpness of the combination. At 50 meters, you will have a luxurious 3 cms of DoF. Better be careful with those portraits.
astrolucida wrote:
Would you like to share any images taken with it?
If I calculated it correctly, it would be f90 wide open but you might still want to stop it down a bit for improved sharpness. Unfortunately the diffraction will kick in quite heavily still, with the minimum spot size at f90 (with theoretically perfect optics) being 60 um, which is about 10x10 pixels with the current cameras!
The hyperfocal distance at f90 is 128 kms, so you might still want to focus the lens very carefully before judging the sharpness of the combination. At 50 meters, you will have a luxurious 3 cms of DoF. Better be careful with those portraits. ...Show more →
Hehehe.... the combo actually functioned and took a photo.
Have you tried imaging any objects that are much further, e.g. the Moon?
In my case, all the tests show that my 400f2.8L II + Canon 2x TC produces actually less detail than upscaling 400+1.4x. However, when I point it to the Moon, I always use two 2x converters stacked, getting 1600mm, f11 wide open. And I get more detail than I get with 2x + 1.4x converters.
So, in my experience, for very long focal length combinations with TCs, subjects at infinity produce much better results than those even at 100 meters away.
Liquidstone wrote:
Five of my well-loved TCs mounted - (L - R) Canon 2x + Sigma 2x + Sigma 1.4x + Tamron 2x + Tamron 1.4x, total of 16x TC. Not having some ETs on hand, I can't seem to fit in the 6th one, a Canon 1.4x.
I wonder what the universe is like without teleconverters?
Have you tried imaging any objects that are much further, e.g. the Moon?
In my case, all the tests show that my 400f2.8L II + Canon 2x TC produces actually less detail than upscaling 400+1.4x. However, when I point it to the Moon, I always use two 2x converters stacked, getting 1600mm, f11 wide open. And I get more detail than I get with 2x + 1.4x converters.
So, in my experience, for very long focal length combinations with TCs, subjects at infinity produce much better results than those even at 100 meters away.
The most TCs I use on the Sigmonster in serious moonshots is 2.8x (2x + 1.4x), and 2x at subjects with fine detail (birds). I sometimes play around with 4x TC (2x + 2x) at astros, and perhaps I get a tiny incremental increase in detail captured on a per frame basis, but I've to use very high ISOs and noise starts to be an issue.
Liquidstone wrote:
The most TCs I use on the Sigmonster in serious moonshots is 2.8x (2x + 1.4x), and 2x at subjects with fine detail (birds). I sometimes play around with 4x TC (2x + 2x) at astros, and perhaps I get a tiny incremental increase in detail captured on a per frame basis, but I've to use very high ISOs and noise starts to be an issue.
Great image!
As for high ISOs, you can actually get away with rather long exposure times without getting any blur due to the movement of the Moon.
My rule of thumb (calculated for 10D) says:
1/4s at 400mm
1/10s at 1000mm
so your 800x2x2=3200mm would require 1/30s. If you are using a 50D/500D you might need 1/50s.
In my experience I can easily get 1/100s or shorter at ISO 100 (at f10) when the Moon is larger than just a crescent. Your combination is f22 wide open and if you stop a bit, you'll end up at f32. That would mean that at ISO 400 you would get 1/40s or shorter, which should be just enough. Naturally you need a very solid mount, mirror lock and remote shutter. Even then you should take many images and pick the sharpest one, due to atmospheric turbulences.
As for high ISOs, you can actually get away with rather long exposure times without getting any blur due to the movement of the Moon.
My rule of thumb (calculated for 10D) says:
1/4s at 400mm
1/10s at 1000mm
so your 800x2x2=3200mm would require 1/30s. If you are using a 50D/500D you might need 1/50s.
In my experience I can easily get 1/100s or shorter at ISO 100 (at f10) when the Moon is larger than just a crescent. Your combination is f22 wide open and if you stop a bit, you'll end up at f32. That would mean that at ISO 400 you would get 1/40s or shorter, which should be just enough. Naturally you need a very solid mount, mirror lock and remote shutter. Even then you should take many images and pick the sharpest one, due to atmospheric turbulences. ...Show more →
The posted crop already used 1/30 sec, ISO 320. With another 1.4x TC, I'd need 1/30 sec, ISO 640, which is beyond my ideal ISO for lunar pics (ISO 200-400).
