Image quality with teleconverter

[jdbb]

If I was to take a shot of the moon with my 40D and 100-400L fitted to either a Canon 1.4 or a 2.0 teleconverter, how would the image quality compare to the same shot taken without the teleconverter and then centre cropped to see the same amount of detail.

regards

John

[camerasnoop]

Try it and see.;)

[Kym]

You would have more effective pixel density with the TCs.
So unless the TC IQ is really woeful you are much more likely get a better result with the TCs.

This assumes you use a sturdy tri-pod for your moon shot - the stability issue is very significant and the TCs make that even more so.

Eg. 500mm + 1.4 TC ...

http://farm6.static.flickr.com/5202/5354387246_b6fd9934b3_o.jpg (http://www.flickr.com/photos/cypheroz/5354387246/)
Moon 2011-01-14 (http://www.flickr.com/photos/cypheroz/5354387246/) by cypheroz (http://www.flickr.com/people/cypheroz/), on Flickr

[jdbb]

Thanks for the reply Kym. I've asked the question because I'm thinking of buying a TC and wanted to makes sure it would be okay.

Canon have a 1.4 and 2.0 TC. Given they are both the same price, is there any reason why you wouldn't just get the 2.0.

regards

John

[Kym]

In general TCs can introduce some problems, notably chromatic aberration (CA).
The more TC the more CA. So a 1.4 is 'better' than a 2.
But, its one of those things you need to try in practice as the problems are often not noticeable outside a lab.

You do need to hear from a Canon shooter using one of these specific models.

[Tannin]

Very little difference. You would get slightly more detail with the converters IF you did everything right, but only slightly. Even with a fast prime lens designed to be used with converters, the improvement is quite small. With a slow zoom lens like the 100-400, the improvement is marginal, and certainly isn't worth the cost, let alone the loss of auto-focus, colour, and contrast.

A 1.4 converter on a 100-400 (or pretty much any other slow lens) is not worth the trouble. A 2.0 converter is completely hopeless.

[mrDooba]

If you do decide to play it might be a good idea to stop down and not shoot wide open. This will most likely improve your image quality.

[William W]

Canon have a 1.4 and 2.0 TC. Given they are both the same price, is there any reason why you wouldn't just get the 2.0.

Yes.

For all the other times you will use it, and all the other lenses you will use it on: other than taking the moon photo with the 100 to 400L.

WW

[jdbb]

Many thanks for all the replies. I am still undecided about what to do and will do some more research.

I'm trying to understand William W comments above. Is he saying the 1.4 would be more useful because it could be used on many more lenses? If yes, why doesn't the 2.0 work on those same lenses?

regards

John

[unistudent1962]

The 1.4x TC will cost you one stop, the 2x TC will cost you two stops.
Canon's AF system stops being functional/reliable at f5.6, so with either of these TCs you will lose AF at the long end of your zoom range. TCs are ideally suited to Canon's faster L lenses, f2.8 or better.

[William W]

I'm trying to understand William W comments above. Is he saying the 1.4 would be more useful because it could be used on many more lenses? If yes, why doesn't the 2.0 work on those same lenses?

Double posted somehow?
Response is below.

WW

[Bennymiata]

What's wrong with the Kenko Pro extenders?
You could easily get boththe 1.4X and the 2.0X for less than the price of one of Canon's extenders.

I don't own any extenders, but the reports I've read say the Kenko ones work really well and will auto-focus the lens in circumstances where the Canon's may not.

[William W]

I'm trying to understand William W comments above. Is he saying the 1.4 would be more useful because it could be used on many more lenses? If yes, why doesn't the 2.0 work on those same lenses?

Clarification:

In the OP, you mentioned you wanted to take picture of the moon.
It appears you already own the 100 to 400 – and you are thinking of buying EITHER the x1.4 OR the x2.0 Canon tele-extender.
I assumed the tele-extender will be used ONCE for that moon photo.
You then asked “Canon have a 1.4 and 2.0 TC. Given they are both the same price, is there any reason why you wouldn't just get the 2.0.”

What I meant by my response:

Before I bought either one tele-extender or the other - I would consider ALL the other photos I might want to take using the tele-extender I purchased, rather than just thinking about that one “moon photo”.

For example (with the same lens) I would consider if I might want to hand hold that 100 to 400 with a tele-extender on it and shoot Rugby.

Or as another example (with another lens), I would consider if I was thinking about buying a 135/2 and using a tele-extender with it for Judo, or Karate in crappy lit, Gyms.

Does that make better sense?

WW

Addendum: Yes on the other part of your question to me: the x1.4 will "work on" more lenses than the x2.0 - in respect of the fact that the x1.4 only robs 1 stop and the x2.0 robs 2 stops
For example AF will still function, if you had a 70 to 20/4L on a prosumer body - but that wasn't the whole of what I meant.

[jdbb]

Thanks for the reply WW - now I understand.

regards

John