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07-04-2020, 12:10 AM   #1
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Extension tubes and aperture control.

How does one control the aperture on lenses that do not have an aperture ring when using an extension tube. Does it default to the widest aperture which kind of defeats the purpose of photography using extension tubes - close focus with a wide depth of field.Thanks in advance for your input.

07-04-2020, 01:37 AM   #2
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Tubes with aperture control are rare.
PENTAX Auto Extension Tube K 50mm reviews - Pentax Camera Accessory Review Database
You really need a lens with aperture control otherwise.
You can stick the aperture open if it has the aperture lever with something but then you need alot of light to see through the small aperture.
I have heard with canon electric aperture you can set the aperture on the camera and disconnect it to keep it closed.
07-04-2020, 02:58 AM - 2 Likes   #3
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QuoteOriginally posted by jim.haase Quote
How does one control the aperture on lenses that do not have an aperture ring when using an extension tube. Does it default to the widest aperture which kind of defeats the purpose of photography using extension tubes - close focus with a wide depth of field.Thanks in advance for your input.
The simplest way for using a lens without aperture ring with extension tubes (and as mentioned probably the most expensive, because they are rare) would be to use extension tubes (or de-glassed tele-converters) that allow aperture controll through the camera.
If you plan to use your extension tubes only with a single lens (the one without aperture ring) you can emulate the aperture controll with non-conductive tape or paint by applying this on your extension tube mount so the camera can read your maximun and minimum aperture of this lens (but except you remove and re-apply the tape everytime you use this lens, this will limit the usabillity of your extension tubes to 1 lens or at least to lenses with the same maximum and minimum apertures)


I think the most economic way will be to buy a old manual prime lens with aperture ring to use with your extension tubes (I sometimes use a Cosina MC Cosinon-T 135mm 1:3.5 with my extension tubes, the lens was even cheaper than the tubes, but it gives good results)

Cosina MC Cosinon-T 135mm 1:3.5 with extension tubes:
Dragonfly

Last edited by othar; 07-04-2020 at 03:04 AM.
07-04-2020, 03:01 AM   #4
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QuoteOriginally posted by jim.haase Quote
Does it default to the widest aperture
With Av or similar progam modes it defaults to wide open, with M mode the default should be fully closed -> but that is in my experience equally bad

07-04-2020, 06:00 AM   #5
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Depending on your planned use, a reversing ring plus an adapter for m43 or Sony NEX that gives continuous aperture control also works. The adapter is mounted on the rear of the lens and only used to adjust aperture.

Here's an example of the type of adapter:
Pixco Adjustable Aperture Pentax K PK Lens to Sony E Mount Adapter NEX NEX-7 | eBay
07-04-2020, 06:28 AM   #6
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QuoteOriginally posted by othar Quote
With Av or similar progam modes it defaults to wide open, with M mode the default should be fully closed -> but that is in my experience equally bad
I just tested this with my Pentax Auto Extension tubes and a DA lens. Works as you described.

KAF4 lenses (aperture motor) may work the same as Canon lenses - I don't know for sure, perhaps someone can confirm this. Set the aperture, stop down and remove the lens without turning off the camera.

Otherwise check the following threads for possible ideas:
using reversed lenses that lack aperture rings - PentaxForums.com
Auto aperture control for reversed lenses; any tinkerers out there doing this? - PentaxForums.com
07-04-2020, 08:43 AM   #7
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One of these is the way to go:

Jessops Auto Extension Tubes PK-A reviews - Pentax Camera Accessory Review Database

Also found labelled Aico, Vivitar and probably other marques.
07-04-2020, 09:10 AM   #8
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QuoteOriginally posted by marcusBMG Quote
One of these is the way to go:

Jessops Auto Extension Tubes PK-A reviews - Pentax Camera Accessory Review Database

Also found labelled Aico, Vivitar and probably other marques.


I've got a similar-looking set, labelled KENKO, with all seven electrical contacts, so full auto-aperture and EXIF data. Still got to use manual focus, however

07-04-2020, 11:34 AM   #9
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QuoteOriginally posted by UncleVanya Quote
Depending on your planned use, a reversing ring plus an adapter for m43 or Sony NEX that gives continuous aperture control also works. The adapter is mounted on the rear of the lens and only used to adjust aperture.

Here's an example of the type of adapter:
Pixco Adjustable Aperture Pentax K PK Lens to Sony E Mount Adapter NEX NEX-7 | eBay
I've used something like that to control the aperture of my 35mm f2.4 when reversed: Macro by any means necessary club - Page 36 - PentaxForums.com I used a deglassed Fotodiox PK lens to Nikon F body adapter.

If you were to combinethe adapter I used with a similarly deglassed Nikon F lens to PK body adapter, you could build yourself a K-mount extension tube with aperture control. This solution is not as good as a set of A-contact extension tubes or a deglassed A-contact teleconverter, though. Aperture control is manual only, and not through the camera body. Your aperture is only relative between "open" and "closed," you no longer able to set a particular f-stop, just a bigger or smaller opening. No PTTL flash, either. This cobbled together solution is probably going to be thicker than some of the tubes as well, limiting the focal lengths you can use. Too long a tube on too short a lens results in your point of focus being inside the lens. But A-contact extension tubes are not common, so this solution may be better than nothing.
07-04-2020, 05:46 PM   #10
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Kenko AF Extension Tube Set for Pentax K DSLR Camera ****
07-04-2020, 08:11 PM   #11
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QuoteOriginally posted by Thagomizer Quote
I've used something like that to control the aperture of my 35mm f2.4 when reversed: Macro by any means necessary club - Page 36 - PentaxForums.com I used a deglassed Fotodiox PK lens to Nikon F body adapter.

If you were to combinethe adapter I used with a similarly deglassed Nikon F lens to PK body adapter, you could build yourself a K-mount extension tube with aperture control. This solution is not as good as a set of A-contact extension tubes or a deglassed A-contact teleconverter, though. Aperture control is manual only, and not through the camera body. Your aperture is only relative between "open" and "closed," you no longer able to set a particular f-stop, just a bigger or smaller opening. No PTTL flash, either. This cobbled together solution is probably going to be thicker than some of the tubes as well, limiting the focal lengths you can use. Too long a tube on too short a lens results in your point of focus being inside the lens. But A-contact extension tubes are not common, so this solution may be better than nothing.
Reversing has benefits itself which is why I suggest something like this. I use a standard deglassed PKA teleconverter on some lenses and multiple element APO front filter macro lenses, or bellows, or whatever is handy including a DFA 100 WR... but the one thing I haven't tried yet is mounting one lens on another to get that multiplier effect.
07-21-2020, 02:03 AM   #12
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QuoteOriginally posted by othar Quote
If you plan to use your extension tubes only with a single lens (the one without aperture ring) you can emulate the aperture controll with non-conductive tape or paint by applying this on your extension tube mount so the camera can read your maximun and minimum aperture of this lens
I'd strongly advise against using any kind of paint on surfaces that experience friction while mounting or dismounting lenses or tubes. If you paint your tube where it mates with the camera, you risk getting sticky paint dust inside your camera.

A little electrical tape to insulate, and a little aluminum foil to short contacts is how I did it when I needed to. Also, if your extension tubes are black anodized metal you can carefully sand the anodizing away where it makes contact with the camera contacts with some very fine grit silica sandpaper if you need to short the contacts. I'd suggest doing this outdoors, and scrupulously cleaning the tubes afterward so as not to introduce dust into your camera.
07-21-2020, 07:17 AM   #13
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QuoteOriginally posted by Philoslothical Quote
I'd strongly advise against using any kind of paint on surfaces that experience friction while mounting or dismounting lenses or tubes. If you paint your tube where it mates with the camera, you risk getting sticky paint dust inside your camera.

A little electrical tape to insulate, and a little aluminum foil to short contacts is how I did it when I needed to. Also, if your extension tubes are black anodized metal you can carefully sand the anodizing away where it makes contact with the camera contacts with some very fine grit silica sandpaper if you need to short the contacts. I'd suggest doing this outdoors, and scrupulously cleaning the tubes afterward so as not to introduce dust into your camera.
While I understand your concern about using paint for creating the conductive and non-conductive pattern on the bajonett-mount my main point was that a missing aperture ring can be emulated that way
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