Bigma 50-500mm, D300's, TC's, & AF - Need Answers

Canon EF 100-400mm f/4.5-5.6L IS

09/20/2008 01:24:09 AM · #1

I have searched the net looking for information on this with no luck. I'm buying a 50-500mm Bigma, I have a D300, I already own the 1.4x Sigma APO TC but read that the Bigma will only work in Manual Focus with this TC. I then read that when using a Tamron TC 1.4x the autofocus works, although a bit slower and over 100mm only... however I am unsure if this works with my whole set-up. So.. my question is, D300 + Bigma HSM + Tamron 1.4x TC = AF??? For a fact? If so, I am going to sell my APO TC as its still in the box and buy the Tamron... and if its true, can someone provide a link for me to the Tamron TC, with MFG# so I make sure to get the right one.

THANKS

Strikeslip

Canon EOS-5D

09/20/2008 07:27:23 AM · #2

I don't have an answer for you, but...

I was thinking about getting a TC for my 100-400, but after a conversation with a sales guy at Henry's decided the cost to quality would be too great and I'd be better off digitally cropping to get that extra bit of zoom.

Just an FYI.

Ann

Olympus OM-D E-M1

Olympus 12-40mm f/2.8 Pro

09/20/2008 10:55:23 AM · #3

Autofocus doesn't work (at least not well) if the max aperture of the lens is smaller than f/5.6, because it's too dark for the autofocus to work. A 1.4x TC reduces the max aperture by 1 stop, and a 2x TC reduces it by 2 stops. I believe the bigma's max aperture, at least when it's extended, is already f/5.6. So, plunking a 1.4x TC on it would make the max aperture f/8. My experience with my D300 and a setup like that is that it will attempt to focus, but will take 10 seconds or more to lock focus, effectively making autofocus useless.

edit: punctu,ation

Message edited by author 2008-09-20 10:56:17.

09/20/2008 08:12:47 PM · #4

bump

Nikon AF-S Nikkor 70-200mm f/2.8G ED VR II

09/21/2008 03:58:39 PM · #5

no one knows if bigma + TC = MF with all TC's??? :(

MattO

Nikon D4

09/21/2008 04:58:31 PM · #6

Originally posted by aerogurl:

no one knows if bigma + TC = MF with all TC's??? :(

If you can find a non-reporting TC it might AF very slowly. But I'm going to be honest and tell you upfront. The IQ of the Bigma is borderline anyway, as is the AF speed. Adding a 1.4 you might as well shoot yourself in the foot. Not trying to suggest you are making a poor decision in buying, just telling you the truth as I have experienced it with that lens. I used the bigma+1.4 on a 1 series camera which will AF with that setup, and it was about as impressive as watching paint dry.

Matt

Canon EF 100-400mm f/4.5-5.6L IS

09/21/2008 10:22:14 PM · #7

well i found out that with such an aperture at max focal range, adding the tc is going to be pointless anyway.. it would seek and seek in AF... so thanks everyone :)

MelonMusketeer

Nikon D7000

Nikon MF 50mm f/1.4

09/21/2008 11:23:51 PM · #8

Originally posted by aerogurl:

well i found out that with such an aperture at max focal range, adding the tc is going to be pointless anyway.. it would seek and seek in AF... so thanks everyone :)

I think you made a good decision.
Even if you were able to get AF, camera shake would be a major problem, as I have found with long tele's and extenders. If you are going to already be at 500mm and 5.6, then adding the TX will make shutter speed so slow that camera shake will likely cancel any gains from the TX.

Faster shutter speed without the TX is better, even if you have to crop to 1/2 the original file size to get the crop that you would get full frame with the 1.4 or 2X. The 2X would increase exposure times by a factor of 4, so instead of 1/500 with just the lens at 500mm, it would be 1/125 and 1,000mm with the TX/lens combo with the same light on the subject. I have a 1,000mm f11 Meade mirror lens, but almost have to put it on a sandbag to get clear shots if there is any breeze at all.

Manual focus is also difficult at apertures smaller than f8, unless the subject is brightly lit and not moving much. Try the stop down preview button with the D300 and aperture set at f11, and you can see how it would look in the viewfinder with the 2X. I have a couple of 2X's, both manual, and I use them very rarely.

Good luck with it, any way you choose to go.

Strikeslip

Canon EOS-5D

09/22/2008 08:52:48 AM · #9

Originally posted by Strikeslip:

...better off digitally cropping ...

Hey, that guy may not be so stupid afterall!