topic Re: Problem with Kenko extension tubes auto focus in Alpha & NEX interchangeable lens cameras

Problem with Kenko extension tubes auto focus

DistantMelody — Mon, 21 Jul 2014 11:30:16 GMT

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

Re: Problem with Kenko extension tubes auto focus

DistantMelody — Mon, 21 Jul 2014 14:37:46 GMT

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).

Re: Problem with Kenko extension tubes auto focus

Bieomax — Mon, 28 Jul 2014 09:32:46 GMT

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.

Re: Problem with Kenko extension tubes auto focus

DistantMelody — Mon, 28 Jul 2014 14:31:58 GMT

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?

Re: Problem with Kenko extension tubes auto focus

Bieomax — Mon, 28 Jul 2014 19:28:16 GMT

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.

Re: Problem with Kenko extension tubes auto focus

Bieomax — Mon, 28 Jul 2014 20:59:10 GMT

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)

Re: Problem with Kenko extension tubes auto focus

Bieomax — Mon, 28 Jul 2014 20:57:31 GMT

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

Re: Problem with Kenko extension tubes auto focus

DistantMelody — Tue, 29 Jul 2014 13:23:37 GMT

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?

Re: Problem with Kenko extension tubes auto focus

Bieomax — Tue, 29 Jul 2014 21:04:01 GMT

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.

Re: Problem with Kenko extension tubes auto focus

DistantMelody — Wed, 30 Jul 2014 17:58:41 GMT

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.

Re: Problem with Kenko extension tubes auto focus

Bieomax — Wed, 30 Jul 2014 22:23:55 GMT

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.

Re: Problem with Kenko extension tubes auto focus

DistantMelody — Sat, 02 Aug 2014 15:48:51 GMT

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?

Re: Problem with Kenko extension tubes auto focus

Bieomax — Mon, 04 Aug 2014 14:50:17 GMT

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

Re: Problem with Kenko extension tubes auto focus

DistantMelody — Tue, 05 Aug 2014 10:52:22 GMT

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?

Re: Problem with Kenko extension tubes auto focus

Bieomax — Tue, 05 Aug 2014 16:46:05 GMT

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

Re: Problem with Kenko extension tubes auto focus

DistantMelody — Tue, 05 Aug 2014 18:21:25 GMT

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?