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02-16-2016, 11:38 PM   #16
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QuoteOriginally posted by ohaya Quote
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?
The lens focuses wide open and the camera stops the lens down when you press the shutter button. I get the impression you are more used to M42 lenses than k-mount? They are very different in many ways.

And, yes that TC you link to does have the contacts you need.

02-17-2016, 12:07 AM   #17
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QuoteOriginally posted by jatrax Quote
The lens focuses wide open and the camera stops the lens down when you press the shutter button. I get the impression you are more used to M42 lenses than k-mount? They are very different in many ways.

And, yes that TC you link to does have the contacts you need.
Ok, thanks, and yes, definitely, more familiar with M42 (from the old days). I found that I have some K-mount lens, but just a couple.

EDIT: Oh, and also thanks for confirmation re. the aperture behavior. I guess even an SMC-A lens is not good for use with these "dumb" extension tubes...
02-17-2016, 12:58 AM   #18
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QuoteOriginally posted by ohaya Quote
Ok, thanks, and yes, definitely, more familiar with M42 (from the old days). I found that I have some K-mount lens, but just a couple.

EDIT: Oh, and also thanks for confirmation re. the aperture behavior. I guess even an SMC-A lens is not good for use with these "dumb" extension tubes...
Why not, as long as you have aperture control on the lens, depending on the type of extension tubes (cheap eBay tubes - Av mode, stop down metering), (Pentax K mount tubes - M mode, set aperture on the lens and Green button to meter), (Tubes with contacts - Lens in A mode, use camera's wheels to control aperture and shutter speed).
02-17-2016, 01:28 AM   #19
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QuoteOriginally posted by excanonfd Quote
Why not, as long as you have aperture control on the lens, depending on the type of extension tubes (cheap eBay tubes - Av mode, stop down metering), (Pentax K mount tubes - M mode, set aperture on the lens and Green button to meter), (Tubes with contacts - Lens in A mode, use camera's wheels to control aperture and shutter speed).
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.

02-17-2016, 02:53 AM   #20
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There are 5 kinds of extension tubes for Pentax K:
1. cheap €bay tubes (tube with a thread at each end, two "tread to PK" rings)
2. simple extension tubes (tube with basic PK mount at each end)
3. aperture control tubes (same as previous but has diaphragme release lever)
4. automatic control tubes (same as previous but has electrical contacts to enable modes (Av e.g.))
5. AF control tubes (same as previous but has drive shaft allowing the body to adjust the focus of the lens and/or two extra contacts to the inside of the mounting ring for powering SDM lenses)

Types 1 & 2 are to avoid, i recommend you to use type 3 or up.
I began macro using a type 3 set but subsequently bought a used type 4 set on €bay.
Type 5 is, from my point of view, expensive and useless because most people who are used to shot macros don't use AF.

Last edited by tryphon4; 02-17-2016 at 05:17 AM.
02-17-2016, 05:33 AM   #21
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QuoteOriginally posted by tryphon4 Quote
There are 5 kinds of extension tubes for Pentax K:
1. cheap €bay tubes (tube with a thread at each end, two "tread to PK" rings)
2. simple extension tubes (tube with basic PK mount at each end)
3. aperture control tubes (same as previous but has diaphragme release lever)
4. automatic control tubes (same as previous but has electrical contacts to enable modes (Av e.g.))
5. AF control tubes (same as previous but has drive shaft allowing the body to adjust the focus of the lens and/or two extra contacts to the inside of the mounting ring for powering SDM lenses)

Types 1 & 2 are to avoid, i recommend you to use type 3 or up.
I began macro using a type 3 set but subsequently bought a used type 4 set on €bay.
Type 5 is, from my point of view, expensive and useless because most people who are used to shot macros don't use AF.
Hi,

Do you have any links to type 3 and type 4?
02-17-2016, 05:52 AM   #22
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QuoteOriginally posted by tryphon4 Quote
Type 5 is, from my point of view, expensive and useless because most people who are used to shot macros don't use AF.
Correct, you would have to be pretty daft to use AF with extension tubes.

Type III Extension tubes come in sets like this:


Last edited by Digitalis; 02-17-2016 at 06:22 AM.
02-17-2016, 08:04 AM   #24
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QuoteOriginally posted by Digitalis Quote
Correct, you would have to be pretty daft to use AF with extension tubes.

Type III Extension tubes come in sets like this:
In the image you posted, where is the "diaphragm release"? Is that button you can barely see it? Or is the button to unlock the tube so that you can unmount it?
02-17-2016, 08:31 AM   #25
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I think they are talking about the auto-aperture lever. This lever actuates by the camera to allow the lens to stop down
02-17-2016, 08:40 AM   #26
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QuoteOriginally posted by ohaya Quote
In the image you posted, where is the "diaphragm release"?
On the interior of the lens mount, it is used to open or close the aperture down on manual aperture lenses.


QuoteOriginally posted by ohaya Quote
is the button to unlock the tube so that you can unmount it?
correct.
02-17-2016, 08:42 AM   #27
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QuoteOriginally posted by Not a Number Quote
I think they are talking about the auto-aperture lever. This lever actuates by the camera to allow the lens to stop down

Does the K-r have an "auto-aperture lever", or can the K-r (== does the K-r have the ability to) actuate that lever in the extension tube?


A slightly tangential question: If I was using an M42 lens with the dumb extension tubes that I have now, and if I put the M42 lens into manual (using the lever on the M42 lens), I think the M42 lens will stop down whenever I change the aperture using the aperture ring on the M42 lens, right? And, if that is correct, then shouldn't I be able to use "M" mode on the camera and the green button to set the exposure.

In other words:

- Set aperture on the M42 lens aperture ring (==> lens stops down), then
- Put camera in "M" mode, then
- Press green button, then
- Take picture

Would that work correctly, i.e., I'd get proper exposure?
02-17-2016, 08:47 AM   #28
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QuoteOriginally posted by ohaya Quote
Does the K-r have an "auto-aperture lever", or can the K-r (== does the K-r have the ability to) actuate that lever in the extension tube?
ALL pentax DSLRs have an aperture lever.

QuoteOriginally posted by ohaya Quote
If I was using an M42 lens with the dumb extension tubes that I have now, and if I put the M42 lens into manual (using the lever on the M42 lens), I think the M42 lens will stop down whenever I change the aperture using the aperture ring on the M42 lens, right? And, if that is correct, then shouldn't I be able to use "M" mode on the camera and the green button to set the exposure.
Fundamentally yes, that would work. The problem with that is your viewfinder will be dark as hell with the lens stopped down like that. Though keep your camera in M mode, AE isn't infallible.
02-17-2016, 09:06 AM   #29
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QuoteOriginally posted by Digitalis Quote
ALL pentax DSLRs have an aperture lever.

Do you know where that would be on a K-r?



Fundamentally yes, that would work. The problem with that is your viewfinder will be dark as hell with the lens stopped down like that. Though keep your camera in M mode, AE isn't infallible.
Yes, understood about going dark. Actually I have a Soligor that has a second ring/lever where you can preset an opening. So you set that to, say, f/8, then you use the aperture ring to full open and focus, then you move the aperture ring to stop the aperture down and the aperture ring will stop at the preset opening.

I think that should work? It does work Ok with just the plain lens on an M42-to-K mount adapter.

Jim

EDIT: I wanted to clarify those last two sentences (mainly the last sentence). What I was trying to say with that last sentence was that those steps worked ok when I used just a M42 lens set to Manual, with an M42-to-K mount adapter, so I think that putting the lens in a dumb extension tube is kind of equivalent to a M42 lens set to "Manual" and in an M42-to-K mount adapter.

Last edited by ohaya; 02-17-2016 at 10:46 AM. Reason: Clarifying
02-17-2016, 10:18 AM   #30
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QuoteOriginally posted by Digitalis Quote
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.
Good luck finding one!
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