Quandry

[Pops]

I have the Sigma 105mm DG Macro lens which I use on a Canon 400D.
This morning I took delivery of a Canon 25mm Ext Tube. Fitted it straightaway and went out to test it. When I switched on I was a bit put out to note that while the shutter speed showed in the display the Aperture reading was 00.
I carried on and took a few shots of a very obliging spider varying the shutter speed, altering the EV and using different distances from lens end to subject. Must say that I was rather disappointed with the results. One shot in particular that looked perfect through the lens was of the spider pushing a small fly into his mouth. I was focusing with the centre point of the AF point selection directly over his mouth and with metering set to evaluative because he was hanging down in front of the window. The resulting shot was a mess and not at all what I saw through the viewfinder.

Can anyone explain please.....
Why would I lose visual Aperture reading.
Have I made an error in purchasing the ext tube.


.

[Ian]

Re: Quandry

I have the Sigma 105mm DG Macro lens which I use on a Canon 400D.
This morning I took delivery of a Canon 25mm Ext Tube. Fitted it straightaway and went out to test it. When I switched on I was a bit put out to note that while the shutter speed showed in the display the Aperture reading was 00.
I carried on and took a few shots of a very obliging spider varying the shutter speed, altering the EV and using different distances from lens end to subject. Must say that I was rather disappointed with the results. One shot in particular that looked perfect through the lens was of the spider pushing a small fly into his mouth. I was focusing with the centre point of the AF point selection directly over his mouth and with metering set to evaluative because he was hanging down in front of the window. The resulting shot was a mess and not at all what I saw through the viewfinder.

Can anyone explain please.....
Why would I lose visual Aperture reading.
Have I made an error in purchasing the ext tube.


.

Actually, nothing looks particularly sharp, to me honest - though the magnification you've got here has got great potential!

I do wonder if the aperture was stuck at f/2.8. Have you tried setting the camera to full manual? Does the exif data reveal anything?

I will try to get an answer from Sigma for you.

Ian

[Pops]

Re: Quandry

Actually, nothing looks particularly sharp, to me honest - though the magnification you've got here has got great potential!

I do wonder if the aperture was stuck at f/2.8. Have you tried setting the camera to full manual? Does the exif data reveal anything?

I will try to get an answer from Sigma for you.

Ian

I tried manual mode Ian and still got 00 for the aperture reading. I was of course using manual focus.
Your certainly right in saying no part of the shot looks sharp.
If he is in the same place tomorrow I intend to take a few shots without the tube attached for comparison. I really should have gone and done that straightaway but I didn't think at the time.
Exif data reads shutter 1/80 .. ap f0

[Stephen]

Re: Quandry

Is it possible that the Canon ext tube is not compatable with the Sigma lens and the aperture data is not being transmitted to the camera........... hey well it makes sense to me

[Pops]

Re: Quandry

Is it possible that the Canon ext tube is not compatable with the Sigma lens and the aperture data is not being transmitted to the camera........... hey well it makes sense to me

It could well be Stephen. maybe Ian will be able to confirm that later from Sigma.

[Ian]

Re: Quandry

I tried manual mode Ian and still got 00 for the aperture reading. I was of course using manual focus.
Your certainly right in saying no part of the shot looks sharp.
If he is in the same place tomorrow I intend to take a few shots without the tube attached for comparison. I really should have gone and done that straightaway but I didn't think at the time.
Exif data reads shutter 1/80 .. ap f0

Does the extension tube have any electrical contacts that match up to the pins inside the camera's side of the lens mount?

Have you tried using the tubes with another lens - like the kit lens?

Sigma will probably need to know what the part number is for the extension tube.

Ian

[Pops]

Re: Quandry

Does the extension tube have any electrical contacts that match up to the pins inside the camera's side of the lens mount?

Have you tried using the tubes with another lens - like the kit lens?

Sigma will probably need to know what the part number is for the extension tube.

Ian

Sorry for the delay in replying, just come back on.
Just tried the tube with the kit lens and the Aperture reading shows OK.
This prob could well be a lens compatability thing because the kit lens will not focus at all with the tube attached. (tried with manual and af)

On the box it reads ... Canon Extension Tube EF25 11.
Apart from the bar code the only other number is 9199A001(AA)

[Ian]

Re: Quandry

Sorry for the delay in replying, just come back on.
Just tried the tube with the kit lens and the Aperture reading shows OK.
This prob could well be a lens compatability thing because the kit lens will not focus at all with the tube attached. (tried with manual and af)

On the box it reads ... Canon Extension Tube EF25 11.
Apart from the bar code the only other number is 9199A001(AA)

Sigma lenses occasionally need firmware of chip upgrades to maintain compatibility with later cameras. This could be an example.

I'll send the details off and let you know once I get a response.

Ian

[Ian]

Re: Quandry

Initial response from contact at Sigma is that he thinks it should work. The first line of investigation is to check contacts for dirt.

But I have asked him to dig a bit deeper - I'll let you know if he finds anything.

Ian

[Pops]

Re: Quandry

Initial response from contact at Sigma is that he thinks it should work. The first line of investigation is to check contacts for dirt.

But I have asked him to dig a bit deeper - I'll let you know if he finds anything.

Ian

Thanks Ian.
Been a bit tied up today with hospital visit but intend to spend some time with it in the morning. Will check the contacts before doing anything.

[Ian]

Re: Quandry

Thanks Ian.
Been a bit tied up today with hospital visit but intend to spend some time with it in the morning. Will check the contacts before doing anything.

The official line is that there are no known incompatibilities with your combination of kit, so it kind of points to a faulty lens, unless you manage to fix it in the mean time - good luck and keep us updated

Ian

[Pops]

Re: Quandry

Gave all contacts a going over with a lens brush and a soft cloth this morning.
Fitted everything back together and .....................
it worked just fine. The aperture reading was showing up nice and clear. Because the first fitting was straight out of it's storage bag I gave that a good clean as well.

Thanks for all your time spent on this.

[Ian]

Re: Quandry

Gave all contacts a going over with a lens brush and a soft cloth this morning.
Fitted everything back together and .....................
it worked just fine. The aperture reading was showing up nice and clear. Because the first fitting was straight out of it's storage bag I gave that a good clean as well.

Thanks for all your time spent on this.

Result!

Ian