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DPChallenge Forums >> Hardware and Software >> How much quality do I loose with a 2x convertor
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Showing posts 1 - 11 of 11, (reverse)
AuthorThread
 04/03/2005 01:10:35 PM · #1
Hi folks. I am considering getting a 2x convertor but have heard they lose quality. Does anyone use them and if so are they good or bad.
Thanks in advance.

Justin
 04/03/2005 01:14:13 PM · #2
I don't lose quality per se, just speed. Which can result in lower quality if the subject is moving. I sometimes have to bump up the ISO which results in more graininess.

But, its a heck of a lot cheaper than a 160-600 zoom which is what the 2X gives me.

d
 04/03/2005 01:31:52 PM · #3
Converters work best with fast primes, work ok with fast zooms, work so so with slow zooms. If the quality of your lens (prime or zoom) is so so to begin with, the converter will only magnify the flaws. Image quality will degrade a lot more with a 2x than with a 1.4x.
 04/03/2005 01:34:41 PM · #4
Keep in mind that you might also be losing the ability to auto-focus. Many cameras will only auto-focus on a lens that is f/5.6 or faster. So except for very fast lenses, putting the 2x extender on your camera may make it difficult or impossible for your auto-focus to work.
 04/03/2005 01:34:51 PM · #5
I took some comparison photos right after I got my converter. Give me a couple of minutes, I'll resize them and upload them.
 04/03/2005 01:41:54 PM · #6



Both these were taken with a 100-400 IS L lens f/11 or so - full zoom - which is 800mm plus the 1.6X factor hand held - I think it's amazing. Fist one was from about 60 feet away and the second at about 75' away. You will get much better results if you use a tripod and do not require a faster f stop. I can get the exact shot specs on the shot set up if you'd like

Edit : I used the 2X II converter

Message edited by author 2005-04-03 13:43:43.
 04/03/2005 01:47:04 PM · #7
There are really very few lenses that are so sharp as to handle a 2.0x converter wothout visible softening. The 2.0x converter linearly magnifies the image from the lens 2x , meaning the lens needs to be twice as sharp as it would need to be when used by itself to produce sharp output using the converter. That's assuming the converter does not degrade the image at all (a poor assumption). You will also lose some contrast.
I've used the Canon 2.0x II converter on my 70-200, and of course it starts out as a 140-400 f/5.6, but I really have to stop down to f/8 to get it back to sharp. It's a combination for really good light only.
 04/03/2005 01:48:22 PM · #8
ok, here I am. This view from my backdoor is my standard lens tester spot. The good people in the corner always have a flag hanging up - very handy!
I took these photos with the Canon 75-300 mm lens.
Straight out of the camera, no processing. Only thing I did was add the text for comparison.
The photos may not be brilliant, but they give you a good idea of reality.

At 75mm, normal and with converter:



At 300mm, normal and with converter:



Edited to add: eeewww, my quick and nasty resize via Windows powertoy resizer didn't help these photos any :-(

Message edited by author 2005-04-03 13:51:04.
 04/03/2005 02:00:55 PM · #9
Originally posted by ebertdj:



Both these were taken with a 100-400 IS L lens f/11 or so - full zoom - which is 800mm plus the 1.6X factor hand held - I think it's amazing. Fist one was from about 60 feet away and the second at about 75' away. You will get much better results if you use a tripod and do not require a faster f stop. I can get the exact shot specs on the shot set up if you'd like

The shot details are listed on the first photo - the second one had pretty much the same but a faster shutter speed 1/320 if I recall correctly with out looking it up

Edit : I used the 2X II converter
04/03/2005 02:07:56 PM · #10
oops brb

Message edited by author 2005-04-03 14:10:18.
 04/03/2005 02:13:40 PM · #11
I'm using the Canon EF 70-200 mm f/2.8 with a 1.4x, hand-held and with high shutter speeds for wildlife, large birds etc. The image quality is absolutely stellar.

I'm considering adding a 2x to this lens, which would, if I used the full zoom range, translate to 224-640 mm. 600 mm is quite a bit. If I loose two stops under average conditions, I anticiate I'd be shooting somewhere between f/5.6 (at best) and f/8.0 or less.

I would not use the 2x without a tripod and be prepared for an increased depth of field (and a lesser bokeh). I feel, if I can I accept these facts (or make them work to my advantage) without a marked loss of quality, I'd be quite happy to have saved the considerable expense for a prime of an equal reach.
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