I would like input on buying a used version I versus waiting for a while and saving up for version II. What are the real world differences aside from weight? Thanks in advance.
I would like input on buying a used version I versus waiting for a while and saving up for version II. What are the real world differences aside from weight? Thanks in advance.

If you can afford it I'd go for series II. In addition to the lighter weight, the AF is also faster when coupled with the series III extenders, right now this is only true with the 1DX but it will be eventually the case with all new cameras. Warranty and service is another issue, at some point Canon will stop servicing the old lenses and that's when the price usually drops significantly so series II is a better investment too.
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John, Arash is spot on in his reply, with an investment like this you need to think long term, so if you have to wait, wait. As parts will soon disappear for the older model and you are then left with something you cannot off load, the MKII is far superior and you will not regret purchasing it.
Thanks, that is the feedback I was looking for. I searched but could not find a direct comparison.
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You can also factor into your decision as to how old you are and how long you will have to wait until you can afford the new version.
I had both, the new one is sharper and of course lighter.
There is also a trend among bird photographers to go for the new 600 instead and use it with a full frame camera.
I would add, if your wait might be long, like a year, you might buy a good, used Series I with the knowledge that you can likely sell it for 90% of what you paid for it. If the wait is a few month, then I'd wait and get the S-II. Not only is the S-II considerably lighter, with better Image Stabilization, but the Image Quality is noticeably better. Going from S-I to S-II, I noticed improved IQ and so did others viewing my images.
Oh, I forgot, if you live in the USA, consider buying from CameraCanada.com The savings vs. a US online dealer is between 20% and 30%, due to US vs. Canadian dollar exchange rates. The warranty is the same North America warranty that you receive with a purchase in the US.

there isn't really any difference is sharpness between the old lens and the new lens. they are both pretty darn sharp (in the right hands). The only difference in optics is when the lens is coupled to a 2X extender (MKIII). The new lenses were design-matched to the new extenders and in the case MKII lens + MK III TC 2X the output is sharper, i.e. at 1000mm f/8.
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My experience is different from Arash's. My Series II 500mm has noticeably better IQ than my SI had.
My personal experience showed a difference comparable to what I see in the comparison at The-Digital-Picture.com
Last edited by David Stephens; 01-21-2016 at 12:54 PM.

I am afraid the tests on TDP are quite inaccurate and not re producible as the tester is often not careful with critical focus and lacks proper long lens technique. I have seen many funny results on that site.
Maybe your old lens was defective, I can post (and have in the past) many tack sharp samples form my 500 IS I which I am sure will "jaw-drop" many of the internet experts as Artie says :)
Last edited by arash_hazeghi; 01-21-2016 at 06:26 PM.
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Here's one:
http://www.the-digital-picture.com/R...ns-Review.aspx
This one gives reasons why optical performance "should be better" but doesn't test that theory:
http://kenrockwell.com/canon/lenses/500mm-f4-is-ii.htm
Here's one with comparison images:
http://www.juzaphoto.com/article.php...00_f4ii_review
Here's another, but with no images or real discussion:
http://www.naturephotographers.net/a.../rb1012-1.html
I can no longer find the mtf chart for the Series I, but I remember seeing them side-by-side back in 2011 or 2012, with the S-II showing improvement.

Hi David,
Thanks but none of this provide any convincing evidence. BTW, Ken Rockwell is probably one of the worst sites on the net packed with misinformation and stuff that's just plain wrong, it should be avoided.
One of the links does have some samples but they are lousy, first the reviewer is shooting JPEGs! second the focus is off in a few of his samples. In fact none of them are really sharp to my liking but it could heavy noise reduction that the camera applies to JPEG.
In order to compare lens A vs. B you need to carefully adjust the focus (I use 200% LV) to make sure it is perfect and then shoot a subject under uniform light on solid tripod. One has to shoot in RAW only and then compare the 100% crops with no sharpening applied. I am afraid anything other than that doesn't hold much value.
best
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Great tip, I just bought the 100-400 II from them and going to try it out today. We have snow in Georgia!
Hi Arash - so assuming I use either on a tripod, will I have any trouble with BIF if I get the older version (wrt your comment on AF). I may have a line on a lightly used v1, but if it falls through I will probably wait to save up a little longer for v2.

It's less productive to shoot BIF off a tripod. If that's your goal make sure you can hand hold the old lens first. If you are serious about birds and wildlife I would return the 100-400II and put that money towards a MKII big white.
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