[ohaya]

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Hi,

I just got in a set of 3 extension tubes, and was messing around with them and my K-r with my DA 35mm lens. I originally thought, "Ok, this'll be easy.", but then I realized that the DA 35mm lens doesn't have an auto/manual switch and also doesn't have an aperture ring.

So then I figured that maybe if I put the K-r into M mode and used the green button, the K-r would automatically figure out the settings, but that didn't work. All the pics I took were seriously under-exposed.

So the first question I have is: Using a lens like the DA 35mm, which doesn't have an auto/manual switch for exposure, and also doesn't have an aperture ring, is it possible to use such a lens with an extension tube with the K-r? And, if so, how?

I guess that if the answer to that question is "no", then would using an SMC-M lens or an SMC-A lens that is not set to "A" work, and if so, how? Would I use that with the K-r in "M" mode then stop down the lens anduse the green button to get the K-r to figure out exposure?

Thanks,
Jim

[clackers]

then would using an SMC-M lens or an SMC-A lens that is not set to "A" work, and if so, how? Would I use that with the K-r in "M" mode then stop down the lens anduse the green button to get the K-r to figure out exposure?

It's how I did it when I had a play, Jim.

You lose autofocus but macro's where you benefit from really selecting the focal point because of the extremely small DoF. You may find it even easier to move the whole body back and forth rather than get it right with the focus ring. I even own a focussing rail for a tripod that does exactly that.

[ohaya]

It's how I did it when I had a play, Jim.

So is it a no-go (i.e., can't work with) the DA 35mm style lenses?

[dms]

I use k mount lenses with aperture ring on my K-x, K-20d, K-5, with standard Pentax auto tubes. Meter as normal (but not in A). You can get some with A contacts I believe--I do know a macro Teleconverter (Vivitar) w/ A contacts works. It does nicely for macro. But this is of no help for the 35mm macro you have.

I believe there are some inconvenient work arounds w/ lenses w/o aperture ring (maybe to turn lens so not fully mounted?)--others hopefully will comment--but I think if serious about using full range of macro options (bellows, extension tubes reversed lens, etc.)--an aperture ring is very important.

Ignore what I said about turning lens in mount--as there is no way to then set aperture.

Actually a modern teleconverter that works (passes the data) w/ your 35mm macro should be fine--in fact they are perhaps the most convenient way (gives larger working distance) and yield exceptionally high quality in the macro range if the lens is good. That will get you to M=2 w/ a 2x telconverter, and M=4 with two of them. I have not used two TC's at once--but respected authorities have shown excellent results doing this.
But it is a lot more money than purchasing an older used 50mm or 90mm Vivititar f/2.5, Pentax 50 mm f/4, or other macro lens (likely $75 to $200), which will get to m= 0.5 or 1.0, and will work w/ your extension tubes.

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Last edited by dms; 02-16-2016 at 10:38 PM.

[Digitalis]

you need a very short extension tube, of about 11~14mm for practical use on a 35mm lens. Since it is a DA lens without an aperture control ring your only option is to find an extension tube that has data contact pins like this:



These kind of extension tubes are rather expensive and difficult to find. Without the data transmission contacts you cannot control the aperture properly, you can still focus but that is pretty much it.

[Ole]

You can use the DA 35mm in Av exposure mode and it will expose correctly, but the aperture cannot be controlled and therefore it is of limited use.

The camera cannot stop the lens down with extension tubes, so the green button trick doesn't work.

Best is to go for a lens with an aperture ring and manually set the aperture on the lens (after you have manually focused with the lens fully open). There is no benefit to picking a lens with 'A' setting.

[Adam]

As others have said, the short answer is you can't use any DA lens with manual extension tubes or bellows. You need an aperture ring on the lens or on an adapter. The best solution would be to pick up something like the D FA 50mm macro for all of your extreme macro needs

Adam
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[ohaya]

As others have said, the short answer is you can't use any DA lens with manual extension tubes or bellows. You need an aperture ring on the lens or on an adapter. The best solution would be to pick up something like the D FA 50mm macro for all of your extreme macro needs

Egad! You mean I gotta buy ANOTHER lens !!!

Just kidding !

[Digitalis]

There is no benefit to picking a lens with 'A' setting.

If you are working with a extension tube with the proper contact pins: a macro lens with an A setting will record the aperture you used to EXIF: which i'm sure you'll agree, is rather useful.

[ohaya]

You can use the DA 35mm in Av exposure mode and it will expose correctly, but the aperture cannot be controlled and therefore it is of limited use.

The camera cannot stop the lens down with extension tubes, so the green button trick doesn't work.

Best is to go for a lens with an aperture ring and manually set the aperture on the lens (after you have manually focused with the lens fully open). There is no benefit to picking a lens with 'A' setting.

I think I tried it (the DA 35mm) with Av mode, but it still was underexposed. If I use Av mode, and if I can't use the green button, how do I get the K-r to set the shutter speed? Or is it supposed to do that automatically when it's in Av mode?

---------- Post added 02-16-16 at 10:41 PM ----------

If you are working with a extension tube with the proper contact pins: a macro lens with an A setting will record the aperture you used to EXIF: which i'm sure you'll agree, is rather useful.

That (an extension tube with the proper contact pins) would be ideal? Do those still exist?

[Zephos]

I have been wanting these for a long time, but seeing how I am no closer to getting them than I am to getting that 100mm Macro, here's a link to a rare listing:

Kenko Uniplus AF Tube 25 and 1 5X Teleplus SHQ Teleconverter Pentax PK AF Pz SDM | eBay

[dms]

lfgray1949 reviewed the 1.4 TC as follows w/ your 35mm lens.

HD Pentax-DA 1.4x AW AF Rear Converter
... But there is at least one situation that works very well for me, and that is the source of my "9" rating. This thing seems to work very well with my DA 35mm f2.8 Macro. Even for non-macro usage, the teleconverter gives me an excellent 49mm lens, although at the wider apertures, there is naturally less sharpness at the edges than I get from the unconverted 35mm. But for macro work, this has become my favorite choice, compared to the 35mm without the teleconverter and also compared to my DFA 100mm f2.8 Macro. I love the pictures I get, and for most purposes, the 49mm focal length i...

Read more at: Member Profile - Pentax Lens Reviews & Lens Database

[jatrax]

That (an extension tube with the proper contact pins) would be ideal? Do those still exist?

Please read post #5. Yes, they exist but are rare and usually expensive. Many people, myself included have resorted to buying old teleconverters with contacts and removing the glass. Some models make that quite easy as the glass assembly just screws out.

[ohaya]

Hi,

A couple of things.

- I just found one of these:

Takumar-A 2x Tele-Converter Reviews - Pentax K-mount Teleconverters and Adapters - Pentax Lens Reviews & Lens Database

I've read that the glass can be removed from these easily, so would one of those work (even with the DA 35mm)?


- I tried using an SMC-A 28mm with the extension tubes I got, and I found something strange (to me at least): If I take the lens aperture ring off of the "A" setting (e.g., select an aperture), it looks like if I mount the lens all the way until it clicks, the lens still stays wide open all the top, i.e., it doesn't stop down.

On the other hand, I noticed that if I turn the lens almost until just before it "clicks", the lens does stop down when I change the aperture ring.

Is this normal behavior for an SMC-A lens? I always thought that if I took the lens off of "A" that the lens aperture would follow the aperture ring setting?

I guess that the SMC-A lenses are designed such that when you set the aperture in the aperture ring, then the camera is supposed to signal to the lens when it's about to take a pic and then the lens closes down? But if that's the case, how does the camera determine what the shutter speed should be? Does it do that calculation in realtime, i.e., exactly at the moment that the shot is being taken?

Thanks,
Jim

[excanonfd]

If you could find it, Vivitar AT-23 extension tube set is the one with contacts, AT-22 without. I'll never part with mine, to be able to go beyond 1:1 magnification (AT-23 + 1:1 macro lens) and still have automation is a huge bonus. Here is a CPC-2x Tele-converter with the glass removed, which luckily screwed out - this is the much more affordable alternative to the AT-23.