Otis Memorial Pentaxian Registered: March, 2007 Location: Vancouver (USA) Posts: 42,007
2 users found this helpful
| | Review Date: February 6, 2017 | Recommended | Price: $40.00
| Rating: 8 |
| Pros: | Compact, well-built, rear standard clearance, short minimum extension | | Cons: | Neither lower rail nor rear standard are gear-driven | |
It should be emphasized that this is the compact option for K-series bellows. While well-built and robust, everything is just a little more compact and that is a good thing, for the most part.
Design:- Over/under X-type monorail design with HDPE guides with extension scale (mm) on top rail
- Minimum 31mm extension
- Maximum 131mm extension
- Rail will accept accessories such as Slide-Copier K*
- Bottom rail supports friction placement/fix
- Top rail supports geared and friction placement
- Front standard is geared with knob to fix
- Rear standard is friction placement with lever to fix
- Rear standard back face is flush to rear flange**
- NO provision for auto aperture actuation
Pros:- Compact enough for field use
- Well-built with admirable rigidity
- Geared front rail makes magnification adjustment easy
- Adequate rear standard clearance for use with almost all K-mount digital and film SLRs, including clearance for flash bulge and rotation to vertical orientation. Included are Pentax K-1/K-1ii and K-3/K-3II, each of which require a short extension tube to be usable with Auto Bellows K, M, or A.
- Minimum extension is short enough to allow 1:1.5 magnification with both 50mm and 55mm lenses***
- Allows infinity focus with Pentax-A 100/4 Bellows
Cons:- Rear standard is difficult to position when camera is attached
- Tripod foot is difficult to position when bellows is fully set up
- Bottom rail not usable as focusing rail due to difficulty in fine adjustment
Usage Notes and Comments:
As noted above, it is compact enough to be included in a field kit without any compromise in stability and in the field, the mix of "+" and "-" points are quite reasonable, but should be discussed in the context of actual use. Consider the use case for intended 1:1 magnification of a small curio with a 50mm lens. The sequence goes like this:- Adjust the tripod foot to somewhere near the center of the rail (easy) and attach bellows to tripod head
- Position the rear standard at the full rear of the rail to make mating the mount adapter easier
- Position the front standard at the 85mm mark
- Attach the mount adapter to the camera and attach that assembly to the rear standard
- Loosen rear standard lock lever and slide rear standard forward to the 35mm mark to approximate 1:1. Notice that the movement is not easy due to the weight of the attacked camera. Lock rear standard down with lever. Make note to try it next time with the rear standard fixed at 35mm rather than full back.
- Adjust tripod head and notice that the kit is badly unbalanced toward the back. Unlock and scoot the rear standard forward until the balance is better (tough work) and also move the front standard forward the same amount (50mm spread between the two)
- Do fine adjust of the magnification using live view, a scale, and the front standard so that the horizontal field of view is 23.5mm (easy peasy thanks to the geared movement). Note: The front standard is moved to adjust magnification not focus.
- Position subject and camera to frame subject
- Slide the camera/bellows/lens assembly using the bottom rail to attain focus. Notice that this is smooth, but still fairly clumsy. Make note to buy a decent dedicated focus rail and/or subject platform before trying this again.
- Stop down lens and take photo
The lack of an easy movement of the rear standard is a pain as is the difficulty using the bottom rail for focusing. The Auto Bellows K and Auto Bellows M have geared adjustments for both standards and the bottom rail, but at the price of bulk, rear standard clearance, and minimum extension.
Note: Much is made in some reviews regarding the lack of open aperture metering and/or programmed exposure control (body controls aperture) of the various K-mount Pentax bellows. Both would have required very sophisticated mechanical linkages with high likelihood of poor performance. It is possible that new bellows might be designed around the new PLM equipped lenses to allow full lens automation by wire.
* While the rail is rumored to accept the Slide Copier K, there is some question as to whether it will work with APS-C bodies to copy 35mm film negatives and slides. At issue is whether there is sufficient working distance for the copier-side bellows. I don't have a Slide Copier K handy to test, so will have to leave that question open.
** The design of the rear standard support foot on some other Pentax K-mount bellows introduces clearance issues with the lower portion of some SLR bodies. The standard workaround is to put a short extension tube between body and bellows for additional stand-off. This workaround is not needed with the Bellows Unit K
*** The utility of 1:1.5 support is not immediately obvious unless you are wanting to copy 35mm negatives or slides using an APS-C camera. Most bellows have minimum extensions that are too long to allow shorter focal length lenses with reasonable working distances at that magnification.
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Senior Member Registered: December, 2009 Location: East Yorkshire Posts: 120 | | Review Date: December 5, 2010 | Recommended | Price: $30.00
| Rating: 9 |
| Pros: | Well made. Huge magnifications. | | Cons: | Stop Down Metering | |
The bellows unit K is a superbly made piece of equipment. When they say that things are not made as well as they used to be this proves it.
Massive magnifications can be achieved with this bellows unit and focusing is very accurate. There is a measuring scale on the focusing bar so accurate settings and record keeping are possible. The tripod mount can be adjusted independently making it easy to balance the camera, unit and lens, that can be very heavy. I have used the bellows unit with just about every lens that I own and have obtained superb results.
Unfortunately only stopped down metering is possible, but as at these magnifications you are working very slowly anyway this is not a big disadvantage.
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Site Supporter Registered: October, 2008 Location: Vancouver, Canada Posts: 8,092 | | Review Date: July 7, 2010 | Recommended | Price: $110.00
| Rating: 8 |
| Pros: | Very high magnification rates can be achieved. | | Cons: | Stop-down metering is required, not as durable as extension tubes & rail kit. | |
The Bellows Unit K (II) is the first K-Mount version released by Pentax. It has a bellows extension of 32mm to 137mm. It was later replaced by the Bellows Unit III which has a slightly longer extension (33mm – 140mm) and a “Front Plate Clamp Knob” instead of a “Lever”.
The Bellows K is the manual version and does not maintain the full aperture metering mechanism of the attached lens, so you will have to use stop-down metering. I only use my Bellows unit indoors on a tripod, so this is not a big issue. I find the Bellows to camera “mount ring” a little on the unsecured side, so I use extension tubes and my rail kit outside as they are more durable.
You can achieve some pretty high magnification rates with the Bellows K unit and a reversed lens. Using a K28/3.5 lens reversed and the Bellows unit extended fully to 137mm, you will get a magnification of 6.72:1. Unfortunately at these very high magnification rates the amount of light entering the viewfinder in your camera is very low. It’s hard to focus and if you use an old film camera see the metering needles. This gets even worse when you have to stop-down, a spot-meter and magnifier will help.
Overall a good Macro accessory.
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