Mark1948

As I've had a Canon 2x extender & having never tried the front end variety, I have to admit that they do sound convenient. Can anyone address the tradeoffs?

nicksr1125 Loc: Mesa, AZ

You give up 2 f/stops on your lens and depending on the lens you're putting it behind, you may lose auto focus. Most cameras won't auto focus if the lens is f/8 or slower. I can put mine behind my 70-200 f/2.8 with no problem. When I put it behind my 150-600 f/5.6-6.3 now I have a 300-1200 f/11-13 that won't auto focus. You didn't specify what body/lens you're using. Some lenses move the rear element too far back to allow the use of an extender. I would check the manufacturer's website for compatability.

Peterff Loc: O'er The Hills and Far Away, in Themyscira.

It sounds as though you are talking about supplementary lenses. The rear and front ones serve different purposes. The front end ones are sometimes called close up lenses, that screw in as filters do. They can be very effective, don't restrict light transmission as rear extenders do, but can introduce significant aberrations depending upon the quality. The Canon ones, typically the 250D and 500D are compound lenses and very high quality but also not inexpensive. They can be found on ebay at decent prices periodically.

Apologies if that is not what you meant.

rwilson1942 Loc: Houston, TX

If, as it sounds like, you are speaking of a 2X tel-extender, you do typically loose 2 stops and depending on the maximum aperture of the lens you use it on, you may loose the ability to autofocus. (most cameras will not autofocus at f8 or smaller apertures. Tel-extenders change the effective focal length of the lens they are used on, with a 2X TC, a 200mm lens becomes a 400mm lens, etc. The Canon 250D and 500D referred to above are close-up lenses that allow you to focus closer than the lens alone normally can. However, it sounds like you are talking about the supplemental lenses that are attached to the front of a lens to make a 'normal' lens into a telephoto. The ones I am familiar with generally only work on specific cameras, usually bridge cameras I think, although they can sometimes be use on a different camera/lens. For example I once had one that was designed to fit a specific Sony bridge camera but I was able to use in on my Sony NEX-7 and 55-210mm zoom. You didn't say what camera/lens combo you wanted to use the front end lens on but I suspect that you will not have a lot of luck finding one that will work with many modern combinations. Both tel-extenders and the supplemental lenses are compromises. Any time you add glass to the light path you risk loss of image quality and adding various aberrations. I use a 1.4X TC on my macro lens regularly and get good results but they are made by the same manufacturer and are more or less 'matched' to each other.
I hope I understood you question correctly and that my response helped.

Peterff Loc: O'er The Hills and Far Away, in Themyscira.

Checking Mark's prior posts, he seems to have a Canon T6s now. Perhaps that will give us a clue...

rwilson1942 Loc: Houston, TX

Unfortunately ,I suspect that for front end supplemental lenses, the lens he wants to use it on is more critical.
I found this: http://www.cs.mtu.edu/~shene/DigiCam/User-Guide/FZ-30/Converters/Lenses/Telephoto.html
and this: http://www.amazon.com/gp/offer-listing/B00009V4GD/ref=dp_olp_0?ie=UTF8&condition=all
hope it helps.

Peterff Loc: O'er The Hills and Far Away, in Themyscira.

I agree. I've used this type of lens in the past on old Sony camcorders, they were very effective. I wouldn't really consider them for a still DSLR camera, but I haven't tried them myself. The rear tele-extenders are useful in the appropriate cases, but do have limitations. I do have both the close up lenses and they are very good in the appropriate circumstances.

Perhaps we just need Mark to clarify his requirements and specific lenses a little...

LarryFB Loc: Depends where our RV is parked

I've tried both but in very different years and cameras. The standard tele-extender fits between the lens and the camera. It typically does what it says but sometimes degrades the lens and certainly degrades the f/s (makes the effective f/stop smaller in diameter). This means that your lens may not auto focus. Of course you have to have a tele-extender that matches you camera, otherwise the camera cannot communicate to the lens.

The ones that attach to the front of the lens are usually called supplemental lenses and they come in various flavors to make you lens act like a wide angle or even a fisheye lens, or the make your lens act like a longer telephoto lens. The telephoto ones have the same problems as the tele-extenders, loss of light, inability to focus, plus, optically, at least the ones I've tried, they are much worst then the tele-extenders.

The supplemental lenses that make your lens into a wider angle lens seem to do better for certain aspects of Image Quality, but often can provide a lot of distortion.

My recommendation is to go with a longer or shorter focal length lens, depending on what you are trying to do.

A tele-extender may help in certain cases but could also create signigicant problems.

Understand your camera. Todays auto-focus camera may not auto focus at f/stops smaller than f/5.6 or f/8 depending on your camera. If you are trying to put any tele-extender on a f/5.6 lens and you camera requires at least f/5.6 to auto focus, you are asking for the impossible.

Mark1948

Sorry for any confusion. Peterff is correct, starting with a Canon T6s & a 70-300IS lens, I was trying to extend my reach with a Newer HD 2.2X 58 mm screw-on telephoto lens. For starters, AF won't work, so I plan on shooting a series of MF pics to see how they look. Having said that, the absence of AF may be a deal killer. Thanks all.

Peterff Loc: O'er The Hills and Far Away, in Themyscira.

Thanks for the clarification. I also have that 70-300IS lens, which on a T6s has a field of view / DOF equivalent to 450mm lens. Longer than that starts to get tricky to use for a variety of reasons. I also have a manual focus FDn 500mm reflex lens adapted for use on EOS cameras. On an APS-C camera ( 800mm equivalent) focus and DOF is challenging. It can get some good results with work and patience, but if you want more reach I would reach into your pockets and get the newish EF 100 - 400 L IS II, assuming your pockets and arms are roughly proportionate!

Good luck.

EF 70 - 300 IS USM

(Download)

Canon FDn 500mm Reflex with Ed Mika Adapter for EOS on T3i

(Download)

rehess Loc: South Bend, Indiana, USA

At one time I had a Canon Rebel and wasn't willing to pay for a 600mm lens, so I tried both a 2X rear extender and a 2X device that screws in like a filter does. Both did increase the effective focal length of my 70-300mm lens. Both did reduce the effective aperture of that lens by 2 f-stops. The image resulting from the rear extender was much much better than the one resulting from the front device {for example, the front extender seemed to create serious chromatic aberration}, so I tossed the front device and used the rear extender until the camera died.

Peterff Loc: O'er The Hills and Far Away, in Themyscira.

That is also what I have found - good close up lenses not included. I still have Canon 2X extender that goes with my FDn 500mm lens, but on an APS-C camera and with no focus confirmation it is almost impossible to use. At least with Canon, I wouldn't consider an extender unless well paired to an 'L' lens or two and the right camera. Without auto focus it adds many complications and limitations. Our modern systems are capable, but they cost a significant amount of money if they deliver the goods.

blackest Loc: Ireland

These are interesting but there is a lot of junk around so you have to pick and choose quite carefully as there is a lot of cheap chinese junk with the optical properties of the bottom of a marmalade jar. The top link is quite good as far as helping to identify potentially useful lenses. Nikon made a good one if I recall and it isn't that cheap. The most interesting ones were made by olympus for their zlr film camera's, these were 35mm almost slr's the almost being they had fixed zoom lens permanently mounted, the technology was ambitious for the time but they made them for a few years.
Because of the limited zoom of the lenses olympus made some front extenders which multiplied the focal length by 1.4 and 1.7 for the fz30 also cursed with a fixed lens these became quite popular. They were quite well made with multiple elements and they do have an interesting property they gather more light than the lens they are mounted on. Optically they give you the extra reach but without the light loss of a teleconverter at the rear. I think it effectively is null so an f4 200mm lens would become an f4 280mm lens.

https://en.wikipedia.org/wiki/Zoom-lens_reflex_camera
https://web.archive.org/web/20070807142920/http://www.olympusamerica.com/cpg_section/cpg_product.asp?more_info_lobby=1&p=11&sc=2&bc=8&product=844

The lens was a 28mm - 120mm Zoom so a 1.4 extender = 168mm and a 1.7x gave 204mm and used as intended they give quite good results.

on the fz30 with a crop factor of 4.87x and a 35mm - 420mm equivalent field of view 1.4 (588) and 1.7 (714) the 420mm was really 86mm

On a DSLR with a modest telephoto they can be quite good but obviously you can buy a 70-200 zoom lens fairly easily anyway. If you use a longer telephoto and attach the extenders the iq goes down usually with a lot of CR and fringing you can recover in post but you may find its better to spend out on a better lens designed for the zoom you are looking for. Oh and if you do decide to get one use it on a lens that is internally focusing or your likely to overwork and damage your focus motor. Best used on bridge camera's anyway, if they have a filter thread.

bull drink water Loc: pontiac mi.

my first dslr came as a kit with a 18-70mm and a 70-200mm. part of the kit was a .05x and a 2.0x front screw on lens. for entry use they were passable.
as I progressed I came to realize that rear mounted extenders were best. HOWEVER, I have found that a good quality .05x or .30x screw on with short focal length lenses can work well for extra wide angle or fisheye shots. as always it's best to try them out for yourself.

billnikon Loc: Pennsylvania/Ohio/Florida/Maui/Oregon/Vermont

The front end variety are cheaper and easier to use than back end. What you are talking about is basically a magnifying glass with threads to fit your camera lens, just like a filter. They come in powers, the downside is they really cut your depth of field, you must really shoot down, F32 would be nice, hold your camera steady and hope for the best, you could also get a reduction in IQ. There are trade offs but no light fall off. These can be fun to use, just under stand the drawbacks.