extender

Recently upgraded my Canon 550d for a full frame Canon 6d & for the bulk of my shooting, the full frame together with my range of lenses (24-105mm, 50mm, 85mm & 70-300mm) will be perfectly adequate for me, however once or twice a year I go to an airshow & often use the long end of my 70-300mm.

Now on my 550d, this would of equated to 450mm or more & I'm considering bridging this gap as I do love to get in close & fill the frame.

I do crop my images where I have to, but my requirement here is to find a solution in camera. Purchasing anything with a larger focal length is out of the question as it would only be used a few times a year. Renting a lens is also out of the question due to the cost.

I don't think this leaves me with many options than to consider an extender to sit between the body & lens. I'm aware that this affects both IQ & light hitting the sensor. With regards to the light, I think I could cope with this as the times of the year I'd likely use this should be quite bright. For those that have (or have used in the past) an extender, I'd like to know how much the IQ changes when it's used.

Alternatively, what other options might be available?

Rent one and find out what it does to your IQ on your lens.

Generally, I will use a TC only when forced to, and, specifically, that means when something will be so far away that cropping a result will just fall apart.

They do impact both IQ and AF -- and, if you are hand holding, you'll notice that camera shake is amplified.

Heya,

Yea, a teleconverter is pretty much it for you if you're not willing to get more lens, or completely just use a crop sensor. The nice thing is, with the 6D, you can throw ISO up really high and it handles that without producing excessive noise really well, so you can throw higher shutter speeds for fast moving things like at the air show to freeze them. This helps overcome the loss in aperture light, due to teleconverter use.

Otherwise, you could get an inexpensive crop sensor camera as a backup for this stuff that also functions all the time for other tasks too.

Very best,

Yea, consider a prime when the budget allows -- a good start is the 400 f/5.6

Your 70-300mm is a variable aperture lens so f/4 at the wide end and f/5.6 at the long end. Your 6d will only AF to f/5.6 and when you fit a TC (the 1.4) you lose a stop of aperture. This will make your lens a 98 to 420 f/5.6 to f/8. So in theory, you should get AF at the wide end but have to MF at the long end. Less than ideal, especially for what you want. In practice, I don't know whether it would AF all the way, I haven't heard of anyone using this combination, best to try before you buy.

Extenders on that lens is a lost cause.
(It likely won't AF at any zoom setting fyi)
Your saying you need longer focal length, but longer focal length is "out of the question"
So really we can't offer you any sound advice without giving you advice that's out of the question.
By all means be the 10,001st person to try to live with an extender on a lens that works terribly with an extender.. But the only practical solution is a longer lens.. Or live with 300mm and dont fill the frame.
If it was that easy that tossing an extender would solve your problems, there would be no long lenses.

S.Horton wrote in post #16510498
Rent one and find out what it does to your IQ on your lens.

They do impact both IQ and AF -- and, if you are hand holding, you'll notice that camera shake is amplified.

not a bad idea that - thanks. True with hand-holding although I'm only aiming to be the same focal length as i used to have so should be used to it

MalVeauX wrote in post #16510500
Heya,

you can throw higher shutter speeds for fast moving things like at the air show to freeze them. This helps overcome the loss in aperture light, due to teleconverter use.

Otherwise, you could get an inexpensive crop sensor camera as a backup for this stuff that also functions all the time for other tasks too.

yeah i was thinking of overcoming the loss of light by doing that so that's cool, and ive still got the 550d so using that would still be an option, however if im away for a few days i like to travel as light as i can

S.Horton wrote in post #16510503
Yea, consider a prime when the budget allows -- a good start is the 400 f/5.6

the budget allows now, but as i mentioned in the original post it doesn't warrant the cost for how little id use it

2slo wrote in post #16510508
Your 70-300mm is a variable aperture lens so f/4 at the wide end and f/5.6 at the long end. Your 6d will only AF to f/5.6 and when you fit a TC (the 1.4) you lose a stop of aperture. This will make your lens a 98 to 420 f/5.6 to f/8. So in theory, you should get AF at the wide end but have to MF at the long end. Less than ideal, especially for what you want. In practice, I don't know whether it would AF all the way, I haven't heard of anyone using this combination, best to try before you buy.

the loss of any AF would be a big issue for me, some of the stuff id be shooting would be fast moving so this might be the nail in the coffin for the converter maybe, unless renting one first perhaps as someone else has mentioned

CyberDyneSystems wrote in post #16510522
Extenders on that lens is a lost cause.
(It likely won't AF at any zoom setting fyi)
Your saying you need longer focal length, but longer focal length is "out of the question"

it's only out of the question because 50 weekends of a year i wouldn't be using it - just doesn't make sense or warrant the cost if (and of course it is an "if" which im exploring here in the thread) there are other options


anyway, thanks a bunch for all the responses in just a few hours, ive got some research to do to try & track one down to rent at a sensible price locally i think

An extender is unlikely to work well on your 70-300mm. The Canon extenders are probably out... they have a protruding front element so won't even fit unless your 70-300mm is the L. So that leaves third party teleconverters, such as the Kenko Pro 300 1.4X DGX or MC-4. Those will fit.

But, even then, teleconverters generally don't give great image quality on a zoom lens. They usually work much better on a prime.

And, does the 6D even focus at effective f8 aperture? I suspect you'll lose all AF, putting even a milder 1.4X TC on an f5.6 lens. Even if you just manual focus, your viewfinder will be dimmed down quite a bit, too. Even with cameras that can handle f8 aperture (5DIII and 1DX, among current models, and older 1D series models), you are limited to only the center AF point or a very small central group of AF points.

Alternatives:

1. Shoot with what you've got and crop your images in post processing. The problem with this is that a 20+MP image quickly becomes an 8MP equivalent image with a lot less detail, with heavy cropping (down to the 15x22mm size of an APS-C camera).

2. Get a crop camera to use for longer shots with your 70-300mm. A used or refurbed 60D or T5i really isn't very much more expensive than the Canon extenders. As you know, this is like having a "free" 1.6X teleconverter (no loss of light to a TC or dramatic drop in resolution due to cropping).

3. Trade your 70-300mm in on a longer lens such as Canon 100-400mm. Or, considerably more affordable are the Sigma 120-400 OS and 150-500 OS. Depending upon what you get selling your 70-300mm, one of the Sigma lenses might end up about the same or even less expensive than keeping the 70-300 and adding an extender to it.

4. Start saving up to add a focal length, such as the 400/5.6 or a 300/4 IS + 1.4X.

5. Rent a lens for the rare occasions when it's needed.

amfoto1 wrote in post #16510988
2. Get a crop camera to use for longer shots with your 70-300mm. A used or refurbed 60D or T5i really isn't very much more expensive than the Canon extenders. As you know, this is like having a "free" 1.6X teleconverter (no loss of light to a TC or dramatic drop in resolution due to cropping).

3. Trade your 70-300mm in on a longer lens such as Canon 100-400mm. Or, considerably more affordable are the Sigma 120-400 OS and 150-500 OS. Depending upon what you get selling your 70-300mm, one of the Sigma lenses might end up about the same or even less expensive than keeping the 70-300 and adding an extender to it.

5. Rent a lens for the rare occasions when it's needed.

these seem the best ideas - 2 would be easy as im sitting on my 550d still & have no intention of getting rid of it. the sigma models seem very reasonable, maybe a thought for the future & 5 isn't a bad idea either - thank you for the comments