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

[Bieomax]

Just thinking you may have to be careful with some lenses as if they already have a close focus distance, so using to much extension on tubes or bellows you can move the entire focus range so close that it's actually inside the lens and thus not able to actually focus on anything

So to give an example the Sony 30mm 2.8 macro lens has a 13cm focus distance, so that's 13cm from the sensor position, this means if you've set the lens for its 1:1 macro you have about 3cm from the front glass of the lens where the lens is focused on. So since tubes/bellows shorten focus distance it's very easy with this lens to quickly move your focus range so it's inside the lens body and thus unusable.

The 16-50 lens you got with the a77 should have a minimum focus distance of about 30cm from the sensor.

[DistantMelody]

Hello Mark

That may be what happens with the lens that came with the camera. I have made another video.

The tubes turn the zoom ring into the focus ring. This limits the AF very much. It said in the item description for the tubes that they work with any lens but this is not the case. I am only able to focus with the small and medium tube when using the standard lens sold with the camera. It is lucky that I have this borrowed Sigma which works with all of the tubes and even with all three together. Do you have any tips for getting around this obstacle? Have I done something wrong?

[Bieomax]

nothing much you can really do, just when doing macro with tubes be aware of the lenses minium focus distance. and tailor the amount of extension tubes you use with that lens.

the main thing with its all is to remember that when a lens is on the camera normally its focus ranges is from infinity to its close focus range (minium focus is measured from the sensor not the end of the lens ) so when adding space (tubes/bellows) between the camera and lens means that you shift the focus range from infinity closer to the lens, so when you have tubes on dont expect to be able to landscapes with large depths of field in focus.

each lens also will have its own level of magification so you may find that a 50mm lens will let you see more detail close up but as the down side is that the distance between you and the subject will be really close, were as a zoom lens with a 300mm top end may not get you as much detail/magnification but will give you a much better distance between you and the subject.

its all horses for courses really, you tailor what lens you want to what subject types your working with.

i've just ordered a set of them af tubes but it'll be a week or so before they get here so i'll have a play with the 16-50mm 2.8 ssm lens that you got with the A77 too and see what they can do. i normally use a bellows but its a diy/home made rig and i wouldn't trust it with the wieght of the 16-50 since its got a good heft of wieght behind it compared to the sony 50mm 1.8 or some of my older m42 prime lenses

[DistantMelody]

Hello Mark

It is cool that we will have the same tubes. I am experimenting using flash at f22 with the tubes to combat the longer shutter speeds. It gives more detail without the blur. Just one problem, that the lens blocks part of the camera flash creating a dark area. And some black spots on the image too. 😕 Are those from pieces inside the lens/camera? Does it mean I need to take it somewhere for cleaning?

[Bieomax]

Depends on how how bad/big it is, if you end up getting lightroom they've a handy spot remover tool you can set the circle size and just click on them, 9/10 times that's good enough.

Are you using the flash on the camera? Or an additional flash? As you can get an extension cable for flashes so you can hold them else where. And if you get a sony flash most have the wireless function.

If not get a bit of white card and use it to bounce some extra light onto the subject

[DistantMelody]

Hello Mark

It was a big spot and a little spot. I used a camera cleaning brush to dust the pieces off the mirror and the photos look ok now. In PSE there is a plaster tool that sounds similar. It is also a circle and has adjustable sizes but it doesn't work well. If there is a spot on a textured area it removes the texture. If the spot is near the edge of the frame it becomes a black circle.

These tubes are very interesting. I can make a setup in a small room but on the photos everything is big and detailed. For landscapes a person needs a great view but for this we can take any object and try to make it look cool.

I used the camera flash yesterday. I also have a ring flash but it is bad quality. It only fits one of my lenses and it fires so weakly that the image is dark. I don't know how to set the apeture and the shutter speed, only one or the other. So I had to charge the ring flash from the camera battery, take it off, quickly start the shutter (for 30 seconds) and keep firing it by hand (about 5 or 6 times) and the image was still dark. I couldn't leave the flash on because then the camera decides on a short shutter speed.

I would like to get a better flash soon. Something that is easier to work with. It would be great to have a wireless one as you say. Is the Sony flash the best? Indoors I have white light lamps in addition to the flash (also bad quality, they seem to be a head from one light and stand from another combined because they can fall off). They were new, I didn't buy used. Do you have white light lamps?