[yusuf]

Anyone purchased cheap extension tubes from ebay which can do focus confirmation. I purchased one but it's iodized and does not work as expected, I tried to removed iodized part but still in no luck with focus confirmation, the whole base seems to be non-conductive.

Pls share the link if you purchased the one which works without any engineering.

Thanks

Update: What I really meant was an extension tube which allows me to use focus trap which requires contacts to be shorted

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Last edited by yusuf; 02-17-2012 at 06:17 AM.

[Philoslothical]

Shorting contacts isn't relevant to focus confirmation. If there is enough light, it'll work. The problem is that you lose a couple stops (at least) of light when using tubes, so there isn't always enough to trigger the beep/hexagon. I think you'll need to have the camera set to AF though (which won't impact anything else, since the tubes don't have linkage for the screw drive).

[yusuf]

Shorting contacts isn't relevant to focus confirmation.

Are you sure? I don't think so it works unless contacts are shorted.

[RioRico]

Yes, the contacts need to be shorted. I use a file or rough sandpaper to remove the non-conductive surface from cheap metal PK macro tubes. NOTICE: Do NOT apply metallic tape to the tube base to make it conductive. The thickness of the tape will make the tube jam on the camera mount. It can be removed but it's just an unnecessary pain. Such tape works fine with PK lenses -- at least, I've never had any jam on the camera, and I've put such tape onto dozens of lenses.

[yusuf]

Right, contacts need to be shorted. One I earlier had (purchased locally) was working perfect - it was cheap one too but then this ebay one didn't worked so wanted to know if anyone ordered from ebay and their worked off the shelf without any engineering.

[Stone G.]

Yes, the contacts need to be shorted. I use a file or rough sandpaper to remove the non-conductive surface from cheap metal PK macro tubes. NOTICE: Do NOT apply metallic tape to the tube base to make it conductive. The thickness of the tape will make the tube jam on the camera mount. It can be removed but it's just an unnecessary pain. Such tape works fine with PK lenses -- at least, I've never had any jam on the camera, and I've put such tape onto dozens of lenses.

I hate to disagree with you, because you are the expert. But I just tried with an M-lens on a pair of non-conductive tubes on my K-5 and it does give focus confirmation (beep and green hexagon lit). What it does not allow for is Catch-In-Focus. Same holds for my K200D. Double-check: A Takumar + K-adapter on my K-5 also responds nicely as far as focus confirmation is concerned (and of course, no CIF here either).

[Philoslothical]

I can only base my conclusions on the camera model I have, which is a K-r. I see from your signature you have a K-x, so I assumed they are similar enough in this regard. Older bodies might act differently, I guess. There are some differences in how different models behave regarding shorting contacts for other purposes.

That said, I just ran two tests with my K-r, just to confirm that I was remembering things correctly.

1. Black anodized extension tubes with a manual lens. No contacts shorted. I get the beep/hexagon easily, as long as the lens isn't stopped down too far.

2. An m42 lens which I made a paper insulator for (to prevent the mirror flop issue when using the green button with lenses that don't make proper contact). Absolutely no chance of conductivity with the paper in there, and I get the beep/hexagon easily.

It follows that shorting contacts is irrelevant to focus confirmation - at least as it pertains to the K-r. I'm very surprised the K-x would behave differently in this regard.

[RioRico]

I hate to disagree with you, because you are the expert. But I just tried with an M-lens on a pair of non-conductive tubes on my K-5 and it does give focus confirmation (beep and green hexagon lit). What it does not allow for is Catch-In-Focus. Same holds for my K200D. Double-check: A Takumar + K-adapter on my K-5 also responds nicely as far as focus confirmation is concerned (and of course, no CIF here either).

You are quite right. My one-tract-mind was fixated on CIF not FC. Using lenses with non-conductive bases, or bases that don't cover the contacts, just means working a little more slowly and carefully, and pressing the shutter at just the right time!

[Bob from Aus]

Is the point that when using the rings, you need to manually stop down (or have I missed that) and there is little light coming through.

Option2 if you are not using a tripod.

Most my macro work, I use manual focus and move backwards and forwards to get into focus. I also use a ring flash or some other flash arrangement to provide a small stop. So for me I ignore whatever the camera has stay and use manual everything. I have bellows, not rings and I only use my old pentax lenses with aperture rings. It gets very dark in the viewfinder, but is doable.

[Phil1]

For what it is worth and a bit off topic: I just received a used Kenko 25DG AF extension tube after futsing around with manual tubes and a converter with contacts and lens removed. It works great with catch in focus and all with my Pentax 85 FA F1:1.4. The focus range seems to work the full range but hunts a bit. It is best to pre focus the lens and move the body in and out a bit and bingo you catch it with or without flash. The body is a K20D. This should really be helpful to me with crappy eye sight and hand held close shots.

[yusuf]

ok, may be I should correct myself. what I meant was an extension tube which allows me to use focus trap.

[RioRico]

ok, may be I should correct myself. what I meant was an extension tube which allows me to use focus trap.

Aha! For focus-trap aka catch-in-focus you DO need to short the contacts. As I said, with extension tubes or wide-flange M42-PK adapters or other tightly-fitting mounts, use a file or sandpaper to scrape down to bare metal.