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| Pentax Converter A |
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| Pentax Adapter F |
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| Sigma AF Converter |
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| AF-360FGZ Dedicated Flash |
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| Pentax AF280T TTL Flash |
One of the dirty words in photography is "teleconverter" or "converter". Pentax even used the name "Adapter" for one they made. You see 4 of them here--all different. The first 2 were made by Pentax for about 20 years beginning in 1984. One is a 1.4x model and the other is a 2.0x model. The number has to do with the amount of magnification it does to the focal length. Translated, the little one will add 40% to the focal length while the big one is a lense 'doubler' and will add 100% to the focal length--Thus with it a 300mm lens becomes a 600mm lens. Both of these first two 'converters' are '-L' variations. There are also '-S' variations. The dash "L's" are for long lenses--300mm or longer. they won't fit the shorter lenses because of the protruding optical unit you see sticking up. There are not a lot of them around because they effectively dedicated to some very expensive extreme telephoto lenses, but as you might surmise they work quite well with them.
As you might guess they are not a free lunch. They do their thing by by sort of magnifying part of the image collected by the lens as they mount between the camera and the lens. The process degrades the quality of the image by magnifying the optical limitations of your lens, and also reduce the lens speed as they discard part of the image collected by the lens. The 1.4x can be expected to make the effective speed of the lens 1 stop slower while the 2x will take around 2.5 stops of light away. Some converters can be stacked, but these two shown in the first photo mechanically will not stack though either one can be used in conjunction with either of the other two--if you put the 'dash L' one on the lens first.
Stacking them will compound your light loss and image quality issues, but also reach way out there which can be the only solution to small birds and shy animals in the wild. Your own experience may vary and will depend closely on the quality of the optics that you have. The very high quality and fast optics that Pentax custom made in the 1980's are the target market for these converters. Most people report that with the 1.4x-L they cannot see significant quality degradation, so when applied to the 300mm F/2.8 lens, the result is effectively a 420mm F/4.0 lens an extremely useable combination. Like wise the 2.0x-L takes the same lens to a 600mm f/6.3 with pretty minor quality degradation. If you start out with a 600mm base lens, then you see what happens. A possible downside to these converters is that they are designed for the A series lenses, and no auto focus support was ever provided in them, though with the extreme telephotos many prefer to manually focus anyway.
This device is one of the more interesting pentax creations. It's called an AF adapter, but in the process it is also aa 1.7x teleconverter. It is intended for placement between Pentax-A (manual focus lenses) and Pentax AF (autofocus) camera bodies. Nominally,it will increase the focal length of the lens bly 70% and also convert the lens to autofocus. Actually, it doesn't do anything to the lens, as you set the focus of the lens to 'infinity' and it stays there, but the autofocus drive moves the optics around in the 'adapter' which effectively changes the focal point. It's focal range is less than the manual focus range so if the target is too close it won't work. While it has the predictable 'costs' in terms of lost F-stops and optical resolution, it actually works reasonably well if you are photographing 'close to infinity', but gets less happy on the close end of things. You can manually back the manual focus back from infinity, but life gets more complicated. Recently with the resurgence of Pentax and the shortage of new lenses, these 'Adapters' have been much in demand. It has no optics sticking in the back of the lens and will therefore mechanically work on any Pentax lens. It will even work as expected with the new fangled Pentax SDM lenses.
The third photo down is a Sigma full autofocus converter. It has a drive shaft all the way through and will support autofocus lenses. You have to be careful however. The camera has no clue you have done this and still thinks it has the shorter length lens attached. Similarly the readings of the F stop are literal--i.e. where the lens is set, but its a lot darker so it is pretty easy to fall off the bottom of the AF sensitivity range which means that your AF goes bezerk. It is not happy with an SDM lens however. They will need to be focused manually as nearly as I can tell.
Pentax has made a bunch of flash units over the years. They are in 3 classes. The really old ones date to prior to 1981 and are essentially manual units. These old one required you to do some calculating. In 1981 Pentax introduced the fully dedicated flashes that only required that you slip them on the camera and turn them on. They used a TTL system that read the light off the film and shut off the flash unit when enough light had arrived. The lower flash unit is actually one of those, but all the slides and the like on the back make it easy to use in it in the then manual mode for pre 1981 camera bodies.
Beginning with the second generation digital bodies, Pentax has abandoned the TTL mode, meaning that all the flash units made since 1981 will not work on second generation digital cameras such as the Pentax K10D, unless you set it back to the manual mode. The Pentax 280T shown here is a classic of the TTL mode flashes made for around 20 years beginning in 1981.
The latest and Greatest is the AF 360 FGZ model. In Pentax speak, the number in the model has something to do with the power of the flash. Larger numbers are more powerful. Of the letters following the 'F'tells you its a flash model, the second letter tells you of the type of flash it way. Pre-1981 dedicated flashes had an S here to tell you that it would 'sync' the camera with the Flash. A 'T' here tells you that it is a TTL mode camera, and finally if you see a 'G' in the model, that is a code for the current P-TTL technology. Finally a 'Z' in the model tells you it is a zooming flash, which will detect the focal length of the lens and adjust itself accordingly, though there were some manual zoom models as well. The FGZ is backwards compatible and can be set to the TTL mode for TTL cameras, and can even be put in a manual mode. This means that effectively the flash can be used with just about any camera with a hot shoe. This means that if you have an old pentax camera you can buy a new flash, if you wish, and there will be some mode that works with it, as long as it's a camera with a hot shoe.