Customer Reviews

Bower SX4EOS MC4 2X AF Teleconverter for Canon EOS EF Lenses

5 star:		(1)
4 star:		(3)
3 star:		(4)
2 star:		(3)
1 star:		(1)

 

 

Some people have complained about autofocus problems. After reading a little about this, people must understand that for most autofocus systems to work the aperature must be 6 or greater (that means a number smaller than six). But, a 2x converter adds two f-stops to the aperature (decreases the aperature) so you must have a lens that goes no lower than f/4 for the aperature. Most zoom lenses go to somewhere are 5.3 to even higher numbers and that means that as you zoom in on a subject the autofocus will quit working. The answer is that with a teleconverter expect to use manual focus when using a zoom lens.

First off let me say that South Bay Camera handled my order very well. I really chose a teleconverter based on price. With that in mind I am very satisfied with the product. I confirm what other reviewers mentioned that the AF "hunts" for a focus at higher magnifications so I had to use manual focus. Other than that, I had no other problems with it. FYI, I used the converter on my Canon 75-300mm f4-5.6 III and my kit lens (18-55mm). It worked on both.

I use this teleconverter with the Canon rebel XTI and the Canon EF 75-300 f4-5.6 III USM lens. The image quality is fine but the autofocus is poor. The lens (with the teleconverter) focuses very slowly at focal lengths under 270mm and at full 300mm it will not autofocus at all. Manual focus works just fine.

Excellent bang for the $$. Using it with my Canon EF 70-200 mm f4 L the auto focus works fine which surprised me from what some of the reviews indicated. The uploaded photo of the hummingbird was 15 ft away on Auto focus! The ants at pixel level on the bird feeder were very sharp on my monitor. However the edges of other images did have some edge softening on my Canon EOS 30D. On a full frame camera I can see this may be a huge issue. Overall very satisfied.

Update:
I just received my Canon EOS 5D mk2 and with the same lens mentioned above does show a "ton" of softening with the teleconverter. So I'll not be using it on my full frame camera.

Does not give you the feel of 2 x zoom but it does help.

If you are using an image stabilized lens you will lose the Auto Focus abilities of the IS lens

I am please that the Bower 2X lens mounted to my EOS Rebel XT and performed well with my Canon EF 70-300mm zoom lens. But when my Canon EFS 18-55mm lens would not mount to the Bower 2X, I was very disappointed. The extra 1/8" of rubber-like material on the inner Canon EFS 18-55 lens will not allow it to fully seat in the Bower mount.

I usually don't like to write poor reviews. But this really requires it. I was OK with the idea that the focusing was poor in low light. However, I can never use autofocus with this extender. It simply won't work. And while I was expecting some degradation in quality of the image, practically all pictures using this are unusable. I would not recommend it.

I have had this teleconverter for several years. It does work, however as others have mentioned, autofocus is troublesome. Every auto-focus lens I have tried will endlessly hunt if your in medium to low light situation and you ultimately have to manually focus. Previous reviews have explained "why" it happens, however it also slows down an otherwise fast autofocus lens in bright daylight which limits its use. One thing I did notice is if you get everything just "right" the images still are not as sharp.

I would recommend using a different name-brand teleconverter.

Update February 13, 2011:
I ordered a Sakar teleconverter for a friend and I can confirm that it is pretty much the same as the Bower. The one I received said "Digital Concepts" on it but was distributed by Sakar. I will say that after doing this modification again that you have to have a pretty good Dremel and a sharp knife. I used the Dremel (with a small engraving bit) to cut the main donut out then I used my knife to whittle away the rest of the plastic until the EF-S lens fit inside (with a little play so as to not tear up the EF-S part of the lens) the hole I made. Also have to be very careful not to cut / break one of the screw posts on the teleconverter as it is pretty much the far limit of where you will have to cut. I can also confirm that you will have to move the teleconverter lens back some so that the EF-S lens will fit. Threads are tight, so be careful. I found it easiest to screw the lens back (using the lens cap as grip) making my adjustments and then re-tightening the lock collar.

Original Post:
First off, this should be a review for the Sakar teleconverter, but the shipper sent me a Bower so I am writing a review about that. They look similar in construction but I am not sure. If you have a Sakar, then the modification I list here might work but I am certain that it will work for a Bower teleconverter.

I did not want to spend $200 on a hit or miss teleconverter and decided to go cheap. Based on other reviews, both the Sakar and Bower did well with EF lens for the price so I decided to give it a shot. I have a Canon T2i with a EF-S 55-250mm lens (all of my lenses are EF-S).

If you have canon EF-S lens (I used a 55-250mm telephoto) and want a cheap teleconverter then this is a fairly easy mod and will not make any changes to you lens! It will however make some changes to your teleconverter. First mod you can do will only allow you to use your lens on manual focus and requires that you take all the contacts out of teleconverter. If the contacts touch the camera contacts it confuses the camera and will not allow you to take a picture. So with those removed (several screws - watch out for the TINY springs in case you want to put it all back together again) next loosen the screws on the front bayonet assembly (where the lens connects) almost all the way out. Then keep attaching/detaching your lens and making the screws tighter until the lens is snug. You can now use your lens and teleconverter in manual focus mode (keep in mind that you will have no aperture control). You do not want to get the lens too tight on the teleconverter because if you notice it will slowly wear away to rubber portion of the lens back (it actually makes a mark on the teleconverter if you look closely).

The second option is what I did after trying the first one. I noticed that there were marks left by the EF-S lens back on the teleconverter and decided to take the whole thing apart (watch out for the TINY springs and contacts!!!!) and dremel out the portion on the teleconverter that the EF-S lens was touching. I used a small bit to make a fine line/cut and removed just enough so that the lens back fit (i did not want it to scrape the sides but I did not want anything getting inside either). I tested out the 2x lens piece a time or too (had to move it back a little) to make sure it did not hit the back of my lens (you can do this by loosening the outer collar that holds the lens assembly in place then adjust the 2x lens and then retighten). Put it all back together, do a couple more fitting checks and you should be good to go! Plus you get full use of your lens autofocus and aperture settings!!!

I agree with some of the posts here and on the Sakar teleconverter that autofocus can be iffy at long range, but I do not mind using the manual focus if I get more control over my lens.

I posted some pics of the teleconverter and the lens I am using as well as pics of a lamp taken with, then without the teleconverter. For some reason Amazon loaded them up out of order.

Thanks to all who previously wrote reviews listing information about this lens converter for Canon EOS digital. I really needed and wanted a 2x converter for my Canon Rebel XT to use with my 75-300 telephoto lens. I got conflicting information prior to coming to Amazon site. Previous comments really helped!! I am very satisfied with this product. Like it stated you have change two f-stops - but hey - using the camera on manual is the only way to go. The converter is auto-focus so no problem. Great photos!! Bower is a local company in the USA with products made in Japan, what else is new.!! Thanks!!