Thread mount 1.5X telephoto adapter ?

[Narniaman]

**EDIT**
Topic split from EOS T-Con Sticky (http://photography-on-the.net/forum/showthread.php?t=41922)
**EDIT**

Simple question here. . . .


I have a Canon 20D with a 75-300 US zoom lens. The lens uses 58 mm filters.

I have tried using a Canon 1.5x teleconverter -- normally used with a Canon powershot Pro-1 - with this lens. Just like for the Powershot Pro-1, it attaches to the front of the lens -- in this case, my Canon 75-300 lens.

Grabbing a commercial site at random, You can see this type of teleconverter at:

http://pcworld.pricegrabber.com/search_getprod.php/masterid=2411181/

It seems to work superbly, and I don't lose any f-stops with this approach. I now have a 112-450 mm lens -- but its still a f4-f5.6 lens. In addition, the autofocus continues to work nicely.

I can also use it with my Canon 50 mm f1.4 lens, and wind up with a Canon 75 mm lens -- but still with a f-stop of 1.4.

The pictures I've taken with it seem to be quite sharp.

But I've never heard anybody discuss using this combination. What I am missing here?

[robertwgross]

The item that you are talking about is a (cheap) telescopic diopter that goes on the front of the lens. The real teleconverters that should be used are teleconverters that are applied to the rear of the lens.

---Bob Gross---

[Narniaman]

"The item that you are talking about is a (cheap) telescopic diopter that goes on the front of the lens. The real teleconverters that should be used are teleconverters that are applied to the rear of the lens."

I'm not disagreeing with you, but I am wondering if you are making this statement on 1) first hand knowledge -- ie, you have seen, handled, tested the device in question, 2) secondhand knowledge -- you have read a review by somewhat knowledgible in the field who has evaluated the lens, or 3) third hand knowledge -- front lens mounted teleconverters are cheap because that's the way it is and everybody show know that.

I also wonder at the description "cheap" for a $250 lens marketed by a reputable company, Canon. Of course, if that's true than the transitition from cheap to real occurs somewhere between $250 and $284, with the latter figure being the internet price for Canon's "real teleconverter" -- the 1.4X -- at least on the internet.

So with the knowledge that Canon did sell me a cheap, unreal teleconverter for $250, let me humbly rephrase my question.

Assuming that it is possible for some reputable company (such as Canon) to manufacture a quality front mount teleconverter -- why would that lens perform just as well as a rear mounted teleconverter?

[robertwgross]

why would that lens perform just as well as a rear mounted teleconverter?

It's not apparent that it does, for any price.

---Bob Gross---

[Narniaman]

Quoting Bob Gross regarding front and rear teleconverters:

It's not apparent that it does, for any price.


Actually, I meant to say, when comparing front teleconverters to rear teleconverters, "Why wouldn't a front mounted teleconverter work as well as a rear mounted one?"

I'll take your word for it that the $280 rear mounted Canon teleconverter is a "real teleconverter" while the $250 front Canon teleconverter is a cheap, telescopic diopter, albeit a four lens diopter.

But why, for any price, shouldn't a front mounted teleconverter be just as good as a rear mounted one?

There are two real advantages to using a front mounted lens (at least the Canon 1.5x one): 1) You don't lose the overall speed of the lens, and 2) the auto-focus on the primary lens still works just dandy.

I can certainly understand that each additional piece of glass that is put between what you're shooting and your camera's sensors will degrade quality, but why should a front mounted system be any worse than a rear mounted system? More chromic aberration? Good quality larger lenses more difficult to make?

I guess I find it ironic that on the one hand Canon will market the Powershot Pro-1, as an eight megapixel camera with a "L" quality lens --- and on the other hand market a cheap, $250 1.5x telescopic diopter specifically designed. . . . . to complement the L-series lens.

[robertwgross]

I guess I find it ironic that on the one hand Canon will market the Powershot Pro-1, as an eight megapixel camera with a "L" quality lens --- and on the other hand market a cheap, $250 1.5x telescopic diopter specifically designed. . . . . to complement the L-series lens.

Don't confuse an "L" quality lens with an L-series lens. You just did.

---Bob Gross---

[Narniaman]

Bob Gross wrote:


Don't confuse an "L" quality lens with an L-series lens. You just did.


Thanks for pointing out my mistake. I should not have said that Canon was marketing the Powershot Pro-1 camera as having an "L" - quality lens.

I should have said that Canon is marketing the Powershot Pro-1 camera as having an actual "L" lens. At least that's what they claim at their website:

http://consumer.usa.canon.com/ir/controller?act=ModelFeaturesAct&fcategoryid=144&modelid=9823&pageno=1

The lens is described as using "fluorite and UD (Ultra-low dispersion) glass for clear, sharp image delineation with an absolute minimum in chromatic aberration. Also incorporated is an Aspherical lens, precision-manufactured to within 0.1 microns, which corrects spherical aberrations and curvilinear distortion while keeping the zoom lens compact."

They even go as far as to put the legendary red ring around the lens.

So my questions remain

1) Why would Canon, world reknown for quality in camera lens, chose to market a "(cheap) telescopic diopter" specifically designed for use with their "L" series lenses?

2) Why shouldn't a teleconverter work just as well when mounted in front of the lens as behind the lens?

[robertwgross]

Look, you claim that you are using this on a 20D, right?

Canon 20D uses EF or EF-S lenses only.

Does this thing fit into the EF or EF-S lens family? No.

If you want to use it on a Powershot, then that is a different thing.

---Bob Gross---

[Thomas Mårlund]

Actually it will fit on EF and EF-S lenses as it's mounted on the filter-threads. I have never tried it (and I won't now, as I've sold all of my G3-accessories) but it certainly is doable. I would be a bit cautious about putting too much weight on the front of the lens though. Especially if it is an extending lens (did that amke any sense?).

[condyk]

Narniaman, do have any sample shots so that people have a basis to judge the quality? Seems the debate is theoretical at the moment and a few shots might help.

[Huckaback Photo]

Narniaman
"I guess I find it ironic that on the one hand Canon will market the Powershot Pro-1, as an eight megapixel camera with a "L" quality lens --- and on the other hand market a cheap, $250 1.5x telescopic diopter specifically designed. . . . . to complement the L-series lens"

A question for you.
Do you really consider this screw on lens to be cheap ?

I certainly agree that it would work as would any screw on filter or adapter lens, be it tele or wide. However it appears to me that this particular multiplier is vary expensive when you realise the limited number of lenses it can be fitted to ( 58mm filter thread ) or smaller.
I think that totally prohibits the use on any SLR eos L series lenses because none have that small a filter thread (to my knowledge).
If you check out both CyberDyneSystems and my own posts above you will note how many different lenses the Canon extenders can be used with in the L series range.
Now if Canon thought to make screw on the front versions imagine how many different would be needed.
The screw on lens you refer to is specifically made for powershot pro 1, which has a built in lens (non removable) that uses similar glass optics to that found in the (originally 35mm) L series lenses.
without these fittings theres no way longer reach is pos with the pro shot 1.
I do feel the purpose of this Sticky was to inform all about Tele extenders and Tele converters, to that ends CyberDyneSystems has done a great job as I'm sure you would agree.

as Condyk mentions do you have some sample shots, Why not post some in the photo sharing section for us to view.
is there a problem with lens hoods & filters ?
the Canon extenders comunicate to the body you would not have this function with the screw on multiplier etc.

Martin (Huckaback Photo)

[CyberDyneSystems]

Topic split from EOS T-con sticky.. O.T.

[Huckaback Photo]

Well done CDS
Thought this belonged here, rather than the sticky information panel.

Martin

[Andy_T]

I think that a look at sample images might be appropriate.

I tried a similar thing with adding my Olympus WCON-08 (by all means also a very fine lens that performed flawlessly on my G2) to my 18-55 kit lens using a 58-55 adapter.

While it did make the angle wider, the image degradation on the corners of the lens was clearly visible. Of course, wide angle converters on wide angle lenses are normally much more critical than tele converters.

Main reason, of course, is that the rear mounted lens converters are calculated by Canon to work with the EOS lenses, while the front mount converters are not.

Let's offer some kind of common basis here ... Bob, what do you think ... could you bring yourself to the agreeing to the statement 'Adding a 1.5 teleconverter does not deteriorate the image quality of an 18-55 or a 75-300 lens much :wink:'

Best regards,
Andy

[cactusclay]

Interesting.

[Narniaman]

Just a word of explanation. . . .

Before I got the Canon EOS 20D I had a Sony F707. On a Sony forum I discovered I could use the Olympus B-300 front mount teleconverter on the F707. That particular lens has a 1.7 multiplication factor. That was the only option I could find to increase the focal length of the camera, and I popped $200 for it, and felt it worked reasonably well.

When I got the 20D I also purchased the EF IS 75-300. And while I was pleased with it, I still wanted just a bit more to take pictures at college softball games. I wanted to be able to basically get a portrait shot from 250 feet away -- to catch players expressions. The 75-300 can't handle that. I experimented with the Canon L series 70-200 and 100-400, but wasn't convinced that they were that much of an improvement from my 75-300.

I then recalled that the adapter I had for the B-300 was 58 mm, which is exactly the same filter size for both the EF 75-300 and the EF 50 f/1.4. And so I tried attaching the B-300 to the lenses to see what I got. I did take a couple of pics with the Canon 75-300/Olympus B-300 combination.

The first picture is taken from my back porch to give some perspective on the second picture. Picture #1 is using the EF 17-85 lens set at 50 mm.

Picture #2 is the combination with the zoom completely out, giving a focal length of 510 mm. On this particular day I used an ASA setting of 1600, an f-stop of f/16, and a shutter speed of 1/350th second. The house in the picture is about 400 meters from my back deck, at least according to mapquest.

The original pictures were take at "L" resolution, or about 3600 x 2300. Since some detail is lost in both pictures from resizing to 640x480 for bandwidth purposes. In the following post I will show a crop from Picture #2.

[Narniaman]

Here's a crop from picture #2, which was about 1400 x 900 before being transformed to 640x480 for bandwidth considerations.

I should mention that I did purchase the Canon 1.5 teleconverter -- mainly because it is even bigger than the Olympus B-300 1.7 teleconverter, and I thought it would be useful when taking pictures of softball games at night. My initial impression is that it isn't as sharp as the Olympus teleconverter. However, I haven't used it from this particular vantage point. I will try it out when I get home tonight.

And as to the Canon being a "cheap" lens -- my reply was a tongue in cheek response to another poster who stated categorically that front mounted teleconverters were cheap diopter lens.

[Jon]

Was that on a tripod? At 1/350, you're a little slow for reliable hand-holding that batch, and if that was the case it could contribute to the general unsharpness of the picture.

[Narniaman]

They were taken hand held.

Here's two more cropped pictures. The first is from the original picture, cropped down to show the street sign. The total width of the picture is about 200 pixels (resized to 640x480). In this picture the width of a pen stroke (ie, the width of "I") is about 4-5 pixels.

The second is cropped from a picture taken just with the EF 75-300 mm (no teleconverter) set at a focal length of 200 mm. The width of a pen stroke in this stance is about 2 pixels. The width of this picture is about 100 pixels, and again its resized to 640 x 480.