| Author: | | Forum Member Registered: January, 2015 Posts: 71 | | Review Date: April 16, 2016 | Recommended | Price: $103.00
| Rating: 9 |
| Pros: | Minimal IQ loss | | Cons: | Limited Compatibility, bigger than Tamron-F 2x with more light loss | | Camera Used: K-50
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Mine is of the EX variety (not EX DG) which I assume is a difference in coatings only.
I am using this with the Sigma 70mm f/2.8 EX DG Macro to increase working distance for handheld macro of insects. It is not officially blessed by Sigma to work with this lens but it appears to function 100%. I don't use AF for macro but this combo locks onto distance objects without issue, at least in bright sunlight.
Compared to the Tamron-F 2x used on the same lens:
1) The Sigma is considerably longer
2) The Sigma loses about a stop more light
3) For a given F-stop, the Sigma provides a greater DOF
4) The Sigma provides a 5-10% greater increase in focal length
Everybody knows the rule that using a 2x converter results in 2 stops of light loss, but apparently this is not carved in stone. To get identical exposures (light and DOF), I need to open up by 1 stop with the Sigma 2x compared to the Tamron 2x.
If I compare shots at f/8 with the Sigma to f/11 with the Tamron (apparently the same EFFECTIVE aperture), the Sigma wins in sharpness and contrast. It's not terribly obvious without pixel peeping, but every bit counts when cropping for tiny buggers. The modest gains in sharpness and 5-10% additional working length are worth the trouble. I still never have to go above 1/4 power on my ring flash at ISO 100, even with the additional light loss.
I had less luck using it on my Sigma 400mm f/5.6 APO. AF just searches and searches even in bright sunlight. I could get an aperture reading when in the "A" setting but it would flicker off from time to time. It works fine in full manual mode, and I may use it this way in a pinch, but this is every bit as difficult as you would expect with an 800mm f/14(ish) lens.
This TC only makes sense if you are using a specific set of Sigma lenses in a specific way, but excels at it's narrow set of tasks. I will have this as long as I have the 70mm Macro (my best and sharpest lens)
 | | | | | | | New Member Registered: November, 2010 Posts: 5 | | Review Date: November 9, 2011 | Recommended | Price: None indicated
| Rating: 9 |
| Pros: | No loss of IQ on SMC K 200 f2.5, Aperture Priority mode works on old K lens! | | Cons: | none | |
Because I was able to get this converter below market value, (100.00) I initially purchased it just to resell and help fund my LBA. Then I discovered that even though it had a protruding front element, my SMC K 200mm f2.5 lens would fit on it quite nicely. To my delight, I found that this converter performs like it was made for the 200 K f2.5. There is no degradation of image quality to speak of. It is the first teleconverter that I have tested that is worthy of the 200 K f2.5, and I have tested the Pentax A2-XS, and the Takumar A, along with 2 or 3 off brands like Focal. With every other converter, the image quality of a photo taken with the 200, and then enlarged 2 times, was superior to a 400mm native image made using the teleconverter. That is not the case with the Sigma. Images at 400 are sharper and have more resolution than do enlarged images taken using the 200 alone. I am keeping this converter now because it turns my 200 f2.5 into a 400 f5.0.
After some testing and use I discovered this converter "works" with my K 200 f2.5 as if it is an "A" lens. The converter kept communicating with my Kx, and the aperture setting was showing a setting, like it is with all A lenses. When I normally mount one of my K lenses to my Kx, the aperture setting is lined out. (---). So I set my Kx to auto mode, and set my K lens to f32, and I found I was taking properly exposed photos. The Sigma converter, and my Kx,were automatically controlling the aperture on my K 200 f2.5 lens. After some further testing, I found that the converter would set the aperture as low as f1.2, so I now leave the Kx on aperture priority, and as long as I stay at or above f2.5, it works! My old K lens is now a 400mm A lens when it is on this converter. WOW!
I have attached two photos taken using the aperture priority method described. The lens was set on f32 for both photos. Both photos are unprocessed, downloaded directly from the SD card. Both were handheld. The first photo, 1/180, f2.8, 12800iso. The second, 1/45, f6.7. (A 400mm photo at 1/45 sec. Shake reduction really works on static objects.)
I have since discovered I can mount a Panagor 90mm f2.8 macro lens to my Sigma converter. The aperture priority method I describe was intermittent with the Panagor. It came and went when I handled the lens a certain way, or jiggled it just so, which can't be all that good. In a test, I covered the contacts on the front of the coverter with thin tape, and the aperture setting on my camera lined out, and reverted to standard manual exposure setting using the green button. So I guess my 200 and this converter working together might be a fluke specific to my particular lens. Even if I end up covering the contacts, and using the green button to set exposure, I will still have a tack sharp converter to use with my 200mm lens.
A further update. This converter will work with the Tokina AT-X PRO 80-200mm 2.8 zoom lens. The zoom has a receased rear element so the converter mounts perfectly. I can not discern any significant loss of IQ when using the converter. Even at 2.8, the images are sharp. The reviews of the Tokina say it is sharp at 2.8 and I would agree. The AF with the converter works smoothly and locks quickly when the subject is in daylight. It gives you a 160-400 5.6 telephoto zoom.
| | | | | Pentaxian Registered: August, 2009 Location: Wandering the Streets Posts: 1,411 | | Review Date: April 29, 2010 | Recommended | Price: $280.00
| Rating: 5 |
| Pros: | Nicely built | | Cons: | Doesn't work as advertised on website | |
This really isn't a review of the teleconverter since I can't use them. It is actually a review of Sigma and the fact that their website doesn't provide the necessary information.
I purchased this TC (as well as the 1.4x TC) to use with my Sigma APO 70-200mm f/2.8 EX DG HSM II lens. Unfortunately I found that they did not work. When I reviewed the paperwork provided with these teleconverters my lens was not mentioned. Needless to say I am disappointed, particularly when the Sigma website was not clear about this at all. So, to help anyone else who may be considering picking up either of these TCs, the following lenses are listed in the paperwork as compatible.
- Sigma APO Macro 180mm f3.5 EX IF - Manual Focus = Both
Sigma APO 300mm f2.8 EX - Autofocus = Both
Sigma APO TELE MACRO 300mm f4 - 1.4 = Autofocus - 2 = Manual Focus
Sigma APO TELE MACRO 400mm f5.6 - Manual Focus = Both
Sigma APO 500mm f4.5 EX - Manual Focus = Both
Sigma APO 800mm f5.6 EX - Manual Focus = Both
Sigma APO 50-500mm f4-6.3 EX RF = Manual Focus = Both
Sigma APO 70-200mm f2.8 EX
= Autofocus = Both
| | | | | Junior Member Registered: April, 2008 Location: Stockholm, Sweden Posts: 36 | | Review Date: April 4, 2010 | Recommended | Price: $360.00
| Rating: 9 |
| Pros: | Much less weight and price with this converter than buying another big lens | | Cons: | The converter does not seem to fit other lenses than the Sigma teles | |
I bought the 2x converter to complement the Sigma 70-200 EX/2.8, giving me a 140-400/5.6 which is an attractive tele zoom length and maximum aperture.
When using it with my K20D, I have not noticed any bad effect on the exposure level, demanding the introduction of any positive or negative EV correction. As regards my K-7, I have not tested adding the converter yet. The screw drive AF works flawlessly also with the converter on.
Not least, the picture quality with this converter does not diverge significantly from the quality of the main lens without it. Thus, I am very happy with the results.
 | | | | | | | Site Supporter Registered: January, 2007 Location: Toronto Posts: 17,886
1 user found this helpful
| | Review Date: May 30, 2008 | Recommended | Price: $200.00
| Rating: 9 |
| Pros: | No noticible loss oif IQ | | Cons: | rear element interferes with many lenses | |
This TC works well with the SIGMA APO 70-200 EX zoom lens, but has the same interference issue with the rear element of many other lenses. It is reallly only intended for long sigma lenses.
The TC is physically longer than some other 2x TCs which have the front elements much further recessed from the lens mount.
It should be noted that the TC passes all lens data directly through the contacts, and as a result, focal length and apature reported are those of the prime lens, not the resulting combination. This leads to incorrect focal lenght setting for shake reduction, and on the K10D an error in metering, where it overexposes consistently by 1-1.5 stops. This can be managed by using exposure compensation or manyal exposure settings.
Exposure is NOT impacted when this is used on the *istD. No commnet as to exposure accuracy on other cameras as these are the only 2 I own
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