Comparison shots with and without 1.4X TC.

[glsammy]

I went to Bempton Cliffs today, and despite my previous experience I thought I just had to try out once more my 1.4X TC with the Sigma 50-500mm.
The conditions were ideal, good light and good subject.

Here's a typical shot with the 1.4xTC.
I used my monopod, plus had a shutter speed of 1/1600sec @ F10.0



And here's one without.

Shutter speed 1/1250sec @ F9.0.




Yet again proof that the 1.4X Tc doesn't go well with this lens. Now all I've got to do is make sure I don't try and use it again! That shot would have been excellent without the TC!

[Ollie]

Pleased you posted this Graham as I was thinking of giving my 1.4xTC a run on the Bigma next time out. After seeing this I won't bother. If you can't get a good one with that shutter speed and monopod I've no chance. I will stick to using it on the Canon 400mm.
The second shot is a great shot though.
Roger

[glsammy]

Yes Roger, don't bother. If you did, no doubt like me, you'd end up with the perfect pose, and a muddy messy image at best!
I was so careful with it, making sure the focus was spot on, perfectly still, no excuse except they don't like each other.
All the ones I took with the 1.4X were the same. I even shot in RAW mode, just so I could be certain the treatment for both was exactly the same.

[Fourwings]

Yep, I see what you mean about the 1.4x TC now, what a shame, thats a fantastic pose.
The bottom pose is great, sharp & detailed, a classic "Bigma" image.

I certainly will not bother trying my Bigma with a TC, I have big enough problems getting pin-sharp images at 500mm at the moment

[matt_xyz]

did you use autofocus Graham? i.e. is the TC preventing the AF from working properly? It's hard to see how the image would be so soft otherwise, since we know the TC is very clear and sharp when used on other lenses

Matt

[glsammy]

Originally Posted by matt_xyz

did you use autofocus Graham? i.e. is the TC preventing the AF from working properly? It's hard to see how the image would be so soft otherwise, since we know the TC is very clear and sharp when used on other lenses

Matt

No Matt. Manual Focus, auto focus with the Bigma doesn't work with any TC, it's at best an F8, far too slow. I tried initially the tape trick, but it was so unreliable I took it off. The focus I'm sure was spot on.

Every single shot of over a dozen I took all were like this, a muddy mess!

[matt_xyz]

Originally Posted by glsammy

No Matt. Manual Focus, auto focus with the Bigma doesn't work with any TC, it's at best an F8, far too slow. I tried initially the tape trick, but it was so unreliable I took it off. The focus I'm sure was spot on.

Every single shot of over a dozen I took all were like this, a muddy mess!

that's really strange isn't it? Oh well, at least you now know not to even bother trying it. You'll just have to make do with 500mm

Matt

[glsammy]

I'm going to withdraw my criticism for a while. I went out today with the 1.4TC on my 150mm, and I experienced exactly the same problem.
My camera was suggesting a shutter speed of 1/60 sec @ F8.0 for a shot of a darter in brilliant sunlight and an ISO of 400! Obviously that was hopelessly wrong and the resulting shot confirmed it.
I noticed them on my screen, so I took the TC off and tried without, all was well.
I put it back on and again everything was fine.
I'm beginning to suspect some bad contacts, perhaps the metering info wasn't getting through correctly?
I did notice on my camera display for a brief second an aperture setting of 00! At first I thought I must have misread it as when I looked again it was OK, but after seeing these shots I think that bad contacts is the probable reason for the shots being so bad.
I know the 1.4 isn't ideal with the Bigma, it definitely makes the shots soft, but not to the extent of those from Bempton and those I took today.
Further testing will follow!

[Tormentil]

Some residue 'sticky' from taping the contacts, perchance ??

[glsammy]

Originally Posted by Tormentil

Some residue 'sticky' from taping the contacts, perchance ??

Quite possible. I'll try again tomorrow, just to satisfy myself once and for all!