Query on 7D + 300mm 2.8 + 2x - does AF work?

Hi,

I currently use a Canon 7D along with a canon 400mm f5.6 prime. A TC does not work effectively on the 400mm f5.6 as AF goes for a toss. Now, I have been hearing that a 300mm f2.8 is one of the sharpest lenses around, but wanted to know about the image quality after adding a canon 2x on it. Also, is the set up even compatible with the Canon 7D where AF still continues to work reasonably well?

I have heard that 300mm is good on a 7D from someone once and also that 300mm works great with a 2x from someone else. But never in the context of it working well on a 7D without compromising on the AF and image quality.

Can anyone of you please post any experiences you have on this set up or please share any advice you might have?

Note: I cannot afford a 500 f4 lens!!

Aj

Ajith the 300 with x2 will work very well, I know many people who have used this combination. If you use a converter there will be a small loss in image quality particularly at full aperture. The quality loss is most noticeable at the periphery of the image which is generally speaking of little consequence in natural history photography, if you step down little the loss is much less apparent. The biggest point for consideration will be to keep the lens and camera still and to be in a position to use a fast shutter speed- if you can manage that then you will not be disappointed.
You may need to consider if you intend to produce large high quality prints as opposed to medium sized prints and images for the web. If the former then occasionally your compromise will show.
I wouldn't get too hung up about the combo working well with the 7D - it will, but it will also work well with other camera bodies, your main limitation will be the aperture going from f2.8 to f5.6, this means the AF speed will work a little slower.
For what it is worth I did consider this combination but I took the general advice over saving and buying a 500mm prime - I didn't regret it for one moment and I have not met anyone yet who has not been very impressed with their 500mm f4 L IS.
As an alternative you may wish to consider the sigma 50 -500mm IS lens, I am currently field testing this lens, it is too premature to say much yet though it does appear to be a flexible lens - perhaps Jack of all trades but Ace of none, but of course a considerably cheaper alternative.
I am sorry to say you pays your money and makes your choice - hope this helps:)

Thanks a ton for quick reply Jonathan, appreciate your response. I have been using a Sigma 170-500 much before I moved over to a canon 400mm f5.6 prime. The image quality and AF difference that I saw in both these set ups is seen to be believed. But the canon 400mm f5.6 with a TC does not have AF on it, that's why I was exploring the option of either going for a 300mm f2.8 prime or even a 120-300 f2.8 sigma.

I would love to go for the 500mm, but its not just the lens, you would still need to get additional good quality equipment like a sturdier tripod, a gimball head, etc. This could easily set one back by another 2000 USD. The combined expense is way above my budget :(
I have shot with a 500mm borrowed from a fellow bird watcher and the results are there to see. Its a stunning piece of equipment which eases many issues that I have had before in using some slow lenses. Check this pic out for example: http://picasaweb.google.com/rainwash...71772705269762 (note: pics heavily optimized for size to upload, the raw ones are way better!)

But given the limitations around cost and since I have already invested in the 7D, I was wondering if I can get away with a 300mm 2.8 prime on the 7D with a 2x converter. That was the crux of my question. Your response to that has helped alleviate some of my concerns :)

Would also appreciate any other member's experience with a similar set up using either a 300mm prime or a 120-300 sigma lens with a 2x on a 7D.

Ajith, I only can tal about the 300mm/2.8 IS mated with either the 1.4 or 2 times converter. Yes it works and it works very well. Af is a good deal slower with the 2x but still usable even for BIF and the Image quality is still in the good; or if you stop down just a little in the very good range.

For a light and very versatile setup nearly nothing tops the 2.8/300 which without converter is simply stunning. Something I really like about the combination with the 2x is the min.foc.dist. of 2,5m ... which is great with a 600mm lens the same is true for the 2.5m with the 1.4x ... better than the 3.5m of the 400mm 5.6.

Easy to recognize I really like this lens maybe even more than my 500mm

Regards Geraldo

Good comments - nice thread.

The 300 2.8 is suppose to be one of Canon's sharpest lens and great for wildlife. Might not have the correct reach for birding but many use it and produce great Avian images with the 1.4 and 2.0 (do not see too many here). I am researching the 300 2.8 vs. the 400 DO. Artie loves the DO, light weight and with the 1.4 killer combo and easy to carry. Look around in the Forums and see what others are using hope this helps.

Would just save for a 500 ... makes a difference. The price for the 300 2.8 is way up there also !!

Quality wise it is fine even with converters and on its own might be the sharpest lens in the line up !! I feel even with a 2.0X you will be short more often than not.

The 7D is a solid camera and has a fine AF system, you won't be disappointed !! That camera with a 400 5.6 will give you 600mm without a converter !!! In a pinch you can use a 1.4X manually focusing for static subjects !! No best combination just figure what will work best for you !! Its all a compromise all the way to the top !!

This is solid advice, as i did the same, saved for the 500mm, and now i'm a happy camper, the 300 is an awesome lens.. but converters do present there share of differences, at least in my expereince they do.
Don

Forget the 300 for BIFs and go for the 500 f/4 you will not regret it

Thanks a ton all for the info! Seems like the 500 wins hands down with the main arguments against 300 being the lack of reach and loss in quality due to converters. I might actually end up saving up for the 500, might take some time though (sigh!)

You will not regret it! the 500mm f4 is about as good it gets for weight,to reach ratio... of course the 800mm is lighter.. but you'll need a lot longer to save your monies.... man i dream of a 800mm oneday!
Don

I will tell you, from personal experience, that the 300/2.8 + converters is no slouch! I used it for about a year with a 40D and a 1DMk3 and it delivered superb shots.... It's a great "stepping stone" to the 500, and a lot less expensive. This was taken with a 40D and a 300+2x

Aj, I often use the 300/2.8 and 2x tc on the 7D. The AF obviously slows a little but it is well usable (especially if you use a focus limiter). For perched birds I would say the AF with this combo is good but for flyers it is somewhat limited to slow to medium flyers.
IQ with a 2x is very good, especially if you can stop down one to f8. For birding purposes I consider the lens to be a 600/5.6 and not a 300/2.8 LOL.

BTW I stepped up to the 300/2.8 from the 400/5.6 and have never regretted it.