[old4570]

Ok , it must be overdue by several decades ..
Im going to try and make this as simple as possible ( Because it is simple )

By adding tubes , you move the lens out from the camera :
And as we all know , the further out you screw ( focus ) your lens , the closer to the camera you focus ..
So by moving the entire lens out , we bring the focus closer to the camera ( simple right ) or lens if you wish .

So the question begs , exactly what happens right ....



Pictured is my K10D with the 36mm tube installed :



And here are the two remaining tubes from the set ( 12mm and 20mm )

Lens is a Pentax A 50mm F1.7
First picture will be less tubes to get some scale of things ..



Aaaah that is a nice little lens , if you dont have a A 50 F1.7 ( oh dear )




And here is the result with the 12mm tube





20mm Tube ( notice the image is getting darker the closer we get to the lens )





36mm Tube ... ( Now we are getting into Macro territory )
Also note the image is getting much darker , so at this point we need to really consider lighting solutions ..





Pictured is a more powerful Metz Flash that directs light at the subject ( Cheap nasty solution )





And the metz is a little overkill ...


So there you go , that's how easy tubes are ...

You can double up on your tubes swap them around and try for as much macro as you wish ..

Just remember , the more tube you use , you may need to supply more light ....
Keep your ISO as low as possible , keep your shutter speed up , and aperture (?) I like to keep mine higher than most ..

[pathdoc]

A tripod is also a wonderful thing for this sort of work, as are a cable release or IR remote release and (if your camera supports it) live-view for focusing. The tripod gives you the luxury of allowing VERY long exposures under ambient light with highly stopped-down lenses, while keeping the ISO down as low as possible.

[tryphon4]

Well you can shoot handheld but it is the school of patience.
In such a setup like this one you can replace the cobra flash by a macro ring flash, I own the Metz one and find it very useful to obtain a correct light on the subject.

Here is one of my first macro setups, a bit more than 5:1 using 6 extension rings, a 1.4x TC and a 1:1 macro lens:


By now i prefer this kind of stuff, more flexible:

[pathdoc]

Impressive results can be had by ganging two lenses together, e.g. a 135 on the camera (wide open) and a 50 or 28 reversed with a male-male filter thread adapter ring (and stepdown rings as required). Magnification equals the focal length of the lens mounted on the camera divided by the FL of the reversed lens. Needless to say, if one could find (as a theoretical example) an old K 18 and K 135, so the filter threads are roughly the same size and you don't risk lost light or vignetting effects and have an aperture ring on both lenses, the results might be truly impressive.

[sjovolde]

Does anyone make a set of extension tubes for Pentax that have the contacts to transmit lens data. I don't care about focusing, just running the fstop and using the pttl metering for my flash. If not what makem of extension tubes do you recommend?
Thank you.
Evan

[WPRESTO]

I think you will have to look on EBAY for used tubes, but be sure to look at an end view so you can see the contacts for transferring aperture data.

BTW: A caveat v-a-v tubes: for zoom lenses, close-up filters, preferably 2-element achromatics, are commonly better. The problem with tubes on a zoom: the focusing distance changes when you change the FL, much closer at a wide setting than a tele setting. So if you use a tube + zoom and get your subject in focus, then zoom the lens, the subject will go wildly out of focus. You might be able to re-achieve focus using the focus ring on the lens, but more likely you'll have to move the lens + camera forward (if zooming wider) or back (if zooming longer), sometimes by a substantial distance.

[tryphon4]

BTW: A caveat v-a-v tubes: for zoom lenses, close-up filters, preferably 2-element achromatics, are commonly better. The problem with tubes on a zoom: the focusing distance changes when you change the FL, much closer at a wide setting than a tele setting. So if you use a tube + zoom and get your subject in focus, then zoom the lens, the subject will go wildly out of focus. You might be able to re-achieve focus using the focus ring on the lens, but more likely you'll have to move the lens + camera forward (if zooming wider) or back (if zooming longer), sometimes by a substantial distance.

It is the same with a close-up lens (achromat): the goal is to improve the mechanical register. When you add a close-up lens you decrease the focal length and it has for consequence an increase of the mechanical register regarding the focal length.

This set looks good, you should ask about the electrical contacts before ordering:
Firstcall Extension Tube Set DG Pentax Set of 3 - Camera Lens Accessories - Firstcall Photographic Ltd

I own a Jessops set, some are sometimes available on €bay:

Camera
PENTAX K100D

Focal Length
100mm

Exposure
1/15s

ISO
400

Camera
PENT100D

l L
1

Depending on the lens focal length, i use either extension rings or a close-up lens (sometimes i use both).
Extension rings are useful with short focal lenses, close-up lenses are useful with long focal lenses.

My newest setup is this one (Laowa 60mm F/2.8):

It needs no extension ring to get 2:1 magnification but if you add 65mm extension rings to it you almost get 4:1 magnification!!!

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Last edited by tryphon4; 07-22-2016 at 11:51 PM.

[WPRESTO]

It is the same with a close-up lens (achromat): the goal is to improve the mechanical register. When you add a close-up lens you decrease the focal length and it has for consequence an increase of the mechanical register regarding the focal length.

The point is, it is not the same with extension tubes versus a close-up filter. If you put a 20mm tube behind a 20mm lens (focus set at infinity) the focus point will be 80mm. If you put the same 20mm tube behind a 200mm lens (focus again set at infinity) the focus point will 2420mm. On the other hand, if you attach a Canon 250 achromatic close up filter on the 20mm lens, the focal point will be 250mm from the front of the lens. If mounted on the 200mm lens, the focal point will still be 250mm in front of the lens. If the 250 close-up filter is mounted on a zoom, with the lens set at infinity, the focus point will be 250mm from the front of the lens regardless of the FL set on the zoom.

[tryphon4]

It is another way to tell the same thing, i agree with you.

[Sage97]

Definitely want to try that 36mm tube but what kind/brand is it? Also, I don't have the 50mm lens. Will it work with the 43mm?

[WPRESTO]

Definitely want to try that 36mm tube but what kind/brand is it? Also, I don't have the 50mm lens. Will it work with the 43mm?

The tubes will work with any FL lens, but in general, the longer the FL the less magnification. A 43mm lens + 36mm tube will provide greater magnification, and a shorter lens-to-subject distance than the same tube mounted on a 50mm lens.

[Sage97]

The tubes will work with any FL lens, but in general, the longer the FL the less magnification. A 43mm lens + 36mm tube will provide greater magnification, and a shorter lens-to-subject distance than the same tube mounted on a 50mm lens.

I'll see if I can find one on eBay.

So compared to a 50mm, a 43mm lens with tubes will give me greater close up but I just have to get closer to the subject. Correct? I can also try the tube my other lenses.

[BrianR]

I'll see if I can find one on eBay.

So compared to a 50mm, a 43mm lens with tubes will give me greater close up but I just have to get closer to the subject. Correct? I can also try the tube my other lenses.

Generally, yes. See the calculator here:

Macro Extension Tubes & Close-up Lenses

Note the "New Closest Focusing Distance" is the distance from the subject to the sensor and not the working distance (the distance from the subject to the front of your lens). Magnification does depend on the lenses 'built in' extension as expressed by it's magnification at minimum focusing distance - e.g. a 50mm macro on tubes will give higher magnification than a standard 50mm on the same tubes. Also note that the calculator will be an approximation, especially for more complicated lenses, but should give you a good idea what to expect.

[Sage97]

Generally, yes. See the calculator here:

Macro Extension Tubes & Close-up Lenses

Note the "New Closest Focusing Distance" is the distance from the subject to the sensor and not the working distance (the distance from the subject to the front of your lens). Magnification does depend on the lenses 'built in' extension as expressed by it's magnification at minimum focusing distance - e.g. a 50mm macro on tubes will give higher magnification than a standard 50mm on the same tubes. Also note that the calculator will be an approximation, especially for more complicated lenses, but should give you a good idea what to expect.

Great info. Exactly what I needed. Thanks a bunch.