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02-17-2016, 11:27 AM   #31
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QuoteOriginally posted by ohaya Quote
I guess the tubes I have now are what you would call "cheap eBay tubes", but as I said I don't think the SMC-A lenses will work, or, more clearly the SMC-A lenses will only work if I don't mount them completely (to the point they "click"), because as I said, if I do mount them to the "click", the lens aperture stays wide open all the time (cannot stop down). As i tried to explain, what I found was that if I connect the SMC-A lens to the tube, but don't turn it all the way until it locks, THEN the lens stops down. Otherwise it stays wide open.
I don't know what's going on with your lens but I mounted my FA50/1.4 to a cheap eBay tube with aperture ring off A setting, and I can see the diaphragm open and close as I turn the aperture ring back and forth.

02-17-2016, 11:32 AM   #32
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QuoteOriginally posted by excanonfd Quote
I don't know what's going on with your lens but I mounted my FA50/1.4 to a cheap eBay tube with aperture ring off A setting, and I can see the diaphragm open and close as I turn the aperture ring back and forth.
Hi,

Sorry if I wasn't clear, but the lens is an SMC Pentax-A, i.e., not an FA. Maybe the FA lenses function different from the older "-A" ones? I don't have any FA lenses yet (I think one is on its way today).

EDIT: Specifically, that lens I was using was this one: http://www.ebay.com/itm/231833744664
02-17-2016, 12:32 PM   #33
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QuoteOriginally posted by ohaya Quote
Hi,

Sorry if I wasn't clear, but the lens is an SMC Pentax-A, i.e., not an FA. Maybe the FA lenses function different from the older "-A" ones? I don't have any FA lenses yet (I think one is on its way today).

EDIT: Specifically, that lens I was using was this one: SMC Pentax A 28mm F2 8 Wide Angle K Mount Prime Lens Excellent Condition | eBay
FA series lenses are the second generation AF lens after A series lenses were discontinued. Basically, FA lens behave exactly the same as any A series lens with the addition of AF. If the aperture ring is taken off from the A position, then the A, F and FA series lenses behave like any M series lens. I have checked other AF and MF lenses (4 - all with A setting) within reach on my desk, and the diaphragm open and close as the aperture ring is turned back and forth.

Post a picture of your extension tube, it's possible the tube is the cause of your problem and not the lens.

Looks like you've been on a LBA binge.
02-17-2016, 12:49 PM   #34
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QuoteOriginally posted by excanonfd Quote
FA series lenses are the second generation AF lens after A series lenses were discontinued. Basically, FA lens behave exactly the same as any A series lens with the addition of AF. If the aperture ring is taken off from the A position, then the A, F and FA series lenses behave like any M series lens. I have checked other AF and MF lenses (4 - all with A setting) within reach on my desk, and the diaphragm open and close as the aperture ring is turned back and forth.

Post a picture of your extension tube, it's possible the tube is the cause of your problem and not the lens.

Looks like you've been on a LBA binge.

Hi,

These are the tubes I have now:

Vivitar Extension Tube at 22 12mm 20mm 36mm for Pentax with Case | eBay

And yes, although I didn't know what "LBA" meant, I guess I have been on one, and this forum hasn't helped any . I *have* been careful to avoid buying really "costly" stuff (this is, after all, a hobby), but the prices keep creeping up, so I have to be even more careful. Like in this case, there've been some tubes for > $200.... and I am not going to do that !

Thanks,
Jim

EDIT: In case it's not clear from the pics on the auction, these tubes are just metal tubes... nothing fancy... no diaphragm levers or anything - those levers are just to unlock the tubes.

02-17-2016, 03:17 PM   #35
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They are touted as "automatic" in the auction.

These have levers:
https://www.pentaxforums.com/forums/36-sold-items/167714-sale-sold-vivitar-22...es-pentax.html

The mount is not bare metal so you'll need to either removing some of the coat or use foil.
02-17-2016, 03:56 PM   #36
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QuoteOriginally posted by Not a Number Quote
They are touted as "automatic" in the auction.

These have levers:
https://www.pentaxforums.com/forums/36-sold-items/167714-sale-sold-vivitar-22...es-pentax.html

The mount is not bare metal so you'll need to either removing some of the coat or use foil.
Actually the ones I got look kind of exactly the same as the ones in that link?

Can you tell me what to look for on the ones I have? I can post some pics if I know what to look for.

Thanks,
Jim

EDIT: I'm starting to think that I'm somehow using the extension tubes incorrectly. Can you tell me how I *should* be using them (what mode the camera should be set to, what kind of lens, etc.) to make them work correctly?

EDIT 2: I don't know how I missed seeing this, but FYI, the set of tubes I have IS Vivitar AT-22:







So can anyone tell me how to use these with my K-r?

Thanks,
Jim

Last edited by ohaya; 02-17-2016 at 05:05 PM.
02-17-2016, 05:31 PM   #37
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Hi,

I've noticed a couple of things while the tube is installed:

- The lens is wide open, but then I confirmed visually that when I press the shutter button to take a pic, the shutter is closing down. But my images all seem to come out underexposed.

- I only can select M or Av mode, e.g., if I move the mode dial to say Tv, the screen still says "Aperture priority".

I don't quite understand... I think I'm doing things correctly and as I said, I can see the shutter close down, but why are my pics all coming up dark?
02-17-2016, 05:44 PM   #38
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QuoteOriginally posted by ohaya Quote
I don't quite understand... I think I'm doing things correctly and as I said, I can see the shutter close down, but why are my pics all coming up dark?
When using a manual lens, (anything without being in the 'A' mode or not having the 'A' mode) then only M or Av will work. You can select the other modes but they just go to Av.

Let's try something simple. You are using an 'A' lens right? Put the lens on, no tubes. Point it at something and adjust the exposure so you get a good exposure, test your settings and write them down. Now put the tubes on and the lens. Put the camera in M mode and enter the settings you wrote down before. Add a little exposure to compensate for the loss in the tubes by reducing the shutter speed one full stop.

Now point the camera at exactly the same thing and take a picture. Is the exposure roughly the same as before or not?

02-17-2016, 05:50 PM   #39
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You can clearly see the levers in the last photo in the post I linked above"



In your second photo above you can see the linkage on the top tube at the 12 o'clock position.

The green button will not likely work without the "data" pin being shorted.
02-17-2016, 07:51 PM   #40
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QuoteOriginally posted by jatrax Quote
When using a manual lens, (anything without being in the 'A' mode or not having the 'A' mode) then only M or Av will work. You can select the other modes but they just go to Av.

Let's try something simple. You are using an 'A' lens right? Put the lens on, no tubes. Point it at something and adjust the exposure so you get a good exposure, test your settings and write them down. Now put the tubes on and the lens. Put the camera in M mode and enter the settings you wrote down before. Add a little exposure to compensate for the loss in the tubes by reducing the shutter speed one full stop.

Now point the camera at exactly the same thing and take a picture. Is the exposure roughly the same as before or not?
Hi,

With a 100mm lens at f/13, shutter 1/25 (selected automatically). Lens was in "A" setting:



Then I added the shortest tube, and camera in 'M' mode. I took the lens off of the "A" setting and set it manually to ~f/11. The shutter on the camera set to 1/25:



The latter is a little underexposed compared to the former, but close, I think, so I tried the lens between f/8 and f/11:



Ok, so that kind of worked?

But that was setting the exposure for the pics with the tube completely manually. I guess the question is how can I do this with the extension tube and have the camera assist me in setting the exposure?
02-17-2016, 07:54 PM   #41
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QuoteOriginally posted by ohaya Quote
I guess the question is how can I do this with the extension tube and have the camera assist me in setting the exposure?
From those test pics you did fine without AE.
02-17-2016, 08:14 PM   #42
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QuoteOriginally posted by Digitalis Quote
From those test pics you did fine without AE.
Yes, but I only knew approx. what the exposure should be (1/25 @ ~f/13) from the first test which was without the tube and did use AE.

---------- Post added 02-17-16 at 08:28 PM ----------

QuoteOriginally posted by Not a Number Quote
You can clearly see the levers in the last photo in the post I linked above"



In your second photo above you can see the linkage on the top tube at the 12 o'clock position.

The green button will not likely work without the "data" pin being shorted.
Hi Not a Number,

AHHH! Ok, so this is similar to another situation I had a couple of days ago, trying to get catch-in-focus working with a M42 lens, and I had to short the data pin on the mount to the ring area? I just tried that, and it does seem to work:



By "work", I mean that, with that shorted, I can put the K-r into "Av" mode and then I set the aperture in the lens aperture ring and the camera then sets the shutter for me automatically, when using the extension tube.
02-17-2016, 10:48 PM   #43
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QuoteOriginally posted by ohaya Quote


So can anyone tell me how to use these with my K-r?

Thanks,
Jim
1. Set your mode dial on the camera to M.
2. Move the lens off of A setting.
3. Set the desired aperture value on the lens.
4. Focus and Compose image.
5. Press the Green Button to meter.
6. Release shutter.

AT-22 is a good set of extension tubes, you can compose and focus with the lens wide open which is very helpful as adding extensions darkens the viewfinder significantly. The generic eBay tubes are like the old M42 tubes, where you would compose and focus with the lens wide open, stop down the lens to the desired aperture to shoot.
02-17-2016, 11:33 PM   #44
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QuoteOriginally posted by excanonfd Quote
1. Set your mode dial on the camera to M.
2. Move the lens off of A setting.
3. Set the desired aperture value on the lens.
4. Focus and Compose image.
5. Press the Green Button to meter.
6. Release shutter.

AT-22 is a good set of extension tubes, you can compose and focus with the lens wide open which is very helpful as adding extensions darkens the viewfinder significantly. The generic eBay tubes are like the old M42 tubes, where you would compose and focus with the lens wide open, stop down the lens to the desired aperture to shoot.

For the above to work, I need to short that data pin on the body, as in the pic in the post before your post, correct?
02-17-2016, 11:58 PM   #45
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QuoteOriginally posted by ohaya Quote
For the above to work, I need to short that data pin on the body, as in the pic in the post before your post, correct?
That's right, I forgot about the need to ground the data pin by scratching off the anodizing on the black lens mount, sorry about that. I haven't used the AT-22 after I acquired the AT-23.
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