Problem with Kenko extension tubes auto focus

[DistantMelody]

Hello everyone

I have a Sony SLT-A77V and finally have Kenko extension tubes with autofocus The autofocus doesn't work. Please see my video:

I tried it with manual focus too but it is still just a blur. What could be the reason?

Thank you,

DistantMelody

[DistantMelody]

I have tried them with a Sigma lens and was only able to focus manually. AF doesn't work for me yet. Please see my the sample shots I took (photo 1 is a 2cm wide doll's hand with powder from being sanded, photo 2 is a cushion cover).

[Bieomax]

Hi Dm, I wouldnt worry too much about af when your doing that much magnification, as manual focus is better for controlling where your focus is and should be, since you have a narrower depth of field.

The main thing with the tubes would be being able to control your aperture so you can maximise your depth of field and sharpness of image.

[DistantMelody]

Hello Mark

Thank you.

But why doesn't the AF work? Is it a fault with the tubes or camera?

My own judgement doesn't seem to be good enough because the images are mostly blurry. When I have the apeture at f4.0 only a small area is in focus but the shutter speed is fast, which is good because any tiny movement shows up at this magnification. When the apeture is at f22 - f29 the area of focus is larger but the shutter speed is extremely slow, so the photos are blurry.

I found that the wheel normally used for zooming, with these tubes is for focus. And the focus wheel does very little.

I have a problem with this lens. Most of the close-ups I did were aimed at the ground. I had the camera on a tripod as usual. The lens wheel moves by itself, simply because of the weight of it. I set the focus, take a picture, and see that the lens has moved and gone out of focus. This may also be causing the images to be blurry. I tried holding the lens wheel to keep the focus as I set it but that creates trembling of its own. Have you had this problem? Is there an addition that can be joined to the lens to stop the wheel from changing?

Would it be helpful if I put some examples of the shots I took and 100% close-ups?

[Bieomax]

Af could be a couple of things, if the extension tubes have the eight pins all the way through the that will be fine(ish) with newer lenses which also have eight pins and a focus motor inside the lens, the issue then could be that there isn't enough light being reflected up to the focus module, this is the same as if you use a teleconverter which takes you lowest f stop to above either f5.6 or f6.5 ( can't recall which off the top of my head) but again not enough light and af stops.

If your lens has 8 pins or 5 pins but has a screw drive for Autofocus then I don't thing the tubes will allow for auto focus.

Since most tube/bellows macro is a tripod affair the af isn't much of an issue

Now your zoom creeping can be solved probably with essentially a large elastic band which half sits on the lens body and half on the focus ring. Maybe look on a well known auction site for the word band with lens at the front (trying to avoid my post been disallowed) maybe look at 2 if your focus and zoom rings move easy

Are you using a remote release or the timer function for the shutter? Also switch off steadyshot then tripoded as some think it's counter productive when the camera is secure.

I've been off of this forum for sometime due to our firstborn coming a few weeks early and all that it entails, but what software are you using now?

And I'd really recommend signing up to the dyxum.com forums you'd likely get responses a lot faster then here.

[Bieomax]

Sorry a little more on the af (hard to review my posts when typing on a phone)

Most manufacturers as far as I know do all focusing with the lens wide open and then when just before it does its shutter to capture your image it moves the aperture/iris/diaphragm to the requested size.

From what I remember there is only 1 lens that will Autofocus above the f5.6 ceiling ( camera will focus as this but anything higher it won't) and that is the reflex 500mm f8 lens ( which is also the only mirror lens which has Autofocus)

[Bieomax]

Difference between inlens af motor and the screw drive from in camera body af motor


http://i379.photobucket.com/albums/oo239/mhr1001/Mobile%20Uploads/DSC_0009_zps6dgfiyk4.jpg

Left is a sony 16-50mm ssm lens with eight contact pins and internal focus motor, right is the minolta 100mm which the older 5 pin with the af screw drive at the rough 7 o'clock position

[DistantMelody]

Hello Mark

Congratulations on the birth of your child!

I have registered on Dyxum. I have the same name there. You were right. The lens and the tubes have different joints.

Does it mean that with this lens there won't be autofocus? The tubes and camera have the same joints. I don't know if I can film macro videos without auto focus.

I have a sony remote control. I use it. I will try without the steadyshot next time.

I haven't bought any new software yet. I have also been away for some time and didn't have any camera equipment with me. But now that I am back I have been experimenting with this new toy. It gives vast capabilities for filming/photographing in a small area.

The rubber band idea is a good idea. I will look. They need to be quite wide and strong?

[Bieomax]

Thank you she's keeping us very busy

Ok looking at the video and the tubes you have, I would potentially say they have a fault as they look to be able to cater for both old and newer lenses since you have the full pin set and the screw drive,

when you attach the lens you have there and or your 16-50 does your camera see the lens ( does the aperture f number show?) if yes then some of the connections are working. I guess this set has a number of tubes? I would test each of them with all your lenses to see if any work as you should get some hunting from the lens even if it can't lock on a focus.

[DistantMelody]

Hello Mark

I was able to change the apeture when taking photos. I am using all 3 tubes for maximum magnification and coolness. In the video I had the original camera lens. Now I am using the Sigma because it seems to have a wider range of focusing distances (manual). I will test each tube as you say and see what happens. In the photo on the left is the camera with tubes attached and on the right is the Sigma lens.