Does nikon disable AF below f/5.6?

[jemini_joseph]

Hi Nikon experts <br>

If I use Sigma 500mm f/4.5+Sigma TC it will report effective aperture

to Camera. The effective aperture will be f/6.3 Does this mean the

camera won't even try AF then? I have the sigma lens and D70. I was

wondering if I get TC it may AF. <br>

<br>

<a href="http://www.wildbackyard.com" target="w-

2">www.wildbackyard.com</a>

[brandonhamilton]

if you go to sigmaphoto.com, i believe their TC compatability chart tells you what TCs with which lenses, affect AF.

[marshall]

I don't know the D70 in particular, but I'm pretty sure that it will try to work, but that it won't work well. AF failure isn't a hard and fast rule, it just doesn't work well if it doesn't get enough light.

[ShunCheung]

As far as I know Nikon wouldn't disable AF, but AF with such a slow lens is pretty unreliable and iffy anyway.

 

On some older Canon EOS bodies such as the EOS 1n film body, if the lens is slwoer than f5.6, the body would disable AF and you have to focus manually. That happens if you add a 1.4x TC on the Canon 500mm/f4.5 AF lens.

[hayward]

Ditto on Shun's comments. The camera doesn't have "shut-off" AF feature or anything like that, it just won't work. The results vary with the lens. I have a D70 and a Tamron 1.4x teleconverter. It works fairly well with my 75-300 f/5.6 Nikon (effective f/8) but comparitively poorly with a Tokina 400mm f/5.6 (effective f/8). Works fine with a 400mm f/4.

[chuck]

There does exist a threshold below which Nikon AF bodies won't even try to AF. It seems to be different for different lens/TC combination. I don't think it's a software limit, I think it's a hardware limit imposed when the split image used by the AF sensors fall outside the width of the sensors themselves. The lowest I've ever gotten any Nikon body to autofocus is at somewhat below f/11, when I attached a TC-16A to a 500mm f/8 mirror lens. The result was much better than you would imagine. D70 definitely would focus at f/8. I've tried with a 300mm f/4 AFS and a 2X teleconverter and it focused like a snap.

[jemini_joseph]

Thanks guys. This answers my question. I know the AF will be slower and most of the times unreliable. As Shum mentioned I know that Canon disables it. I just wanted to make sure Nikon does it or not. I guess all new canon's does that including 10D. Minolta doesn't disable it either. THat's why 10D users tape one of the pin on the lens/tc to 'cheat' the system and let the AF work. <br><br>

Kenko TC with above lens used to work OK on F5 (CAM1300). But on D70 it's just unreliable. If the EXIF data in D70 and data stored in F5 is true Sigma lens is 4.3. I've tested Kenko on 50mm 1.8 lens and thing it takes almost 1.3 stops of light instead of 1 stop. I also read that TC-14E with above lens is better AF. It could be because TC-14E takes only 1 stops. So I just want to try sigma and see if it improves if it doesn't eat 1.3 stops of light.<br><br>

I also read that D2H (Cam2000) does AF with 200-400 Vr+TC-20E (photographyreview.com). If that's true CAM2000 is more capable.

Does anybody else have any experience with this combo? <br><br>

I cannot afford D2X or D1X right now. Hope there will be a D200 with Cam2000

[ShunCheung]

Jemini, you can pretty much forget about Nikon putting any Multi-CAM 2000 AF module on some future D200. Doing so will kill off a lot of the D2H/D2X sales. Nikon is not going to be so stupid to shoot themselves in the foot. Likewise, Canon consumer bodies such as the 20D will always have second-class AF capability.

 

Most likely Nikon will improve the Multi-CAM 900 (currently on the D70, D100, N80, N75, Fuji S2/S3, etc.) to something with 9 or 11 AF points. For most amateur use, it'll be ok. But if you shoot sports or moving wildlife such as bird in flight, you'll need a high-end model.

 

I am sure the used market will be flooded with a lot of used (and abused) D1X when the D2X is available early next year. If you don't mind a fairly out of date DSLR with good AF, that may be an option.

[jemini_joseph]

Shun<br>

I know that it's difficult to guess that Nikon will put CAM2000 on D200. But from the way they came out with D70 over 300D, I would guess so. It's not going to kill D2H much and definitely D2X because of their build quality and many other features. I think if they want to be aggressive and get some market, they have to come out with a camera that's better than 20D. If it's not AF what else? The way they came out with D70 over 300D is an example. I would thing D2X is a real competetion for 1D II. These observations are based on price and features. I know D2X will slightly higher priced to 1D II. Same with D70. To fill the gaps they have to come out with something like F100. They had same AF module on F100 and F5. Did it affect F5? I guess not.

[mskovacs]

Maybe they will install F100/F5 AF at some point now that the new system is out in the D2H (D2X, F6?).

[don_cooper]

My Sigma 500 F4.5 HSM will NOT even try to autofocus with the Sigma 1.4X converter regardless of the aperture used or scene brightness when used with my D70 or Fuji S2. Don't know why, but it don't!

[jemini_joseph]

Don<br>

That's was 1/2 an hour late!!<br>

I've already bought it :)<br>

I saw a used one for 100 dollars. If it doesn't even try, then it was a stupid decision :( <br>

Does this mean Nikon disables it if camera gets correct aperture?

Kenko tries it because camera still thinks it's a 4.5 lens. I heard TC-14E is better than Kenko. I also noticed one problem with Kenko. D70 loses the contact at times. Then the entire exposure will be screwed. I was hoping to correct this issue too. Anyway I've lost the hope...

[don_cooper]

Give it a try, it might work. The combo is quite good despite not having autofocus, pretty sharp.

[jemini_joseph]

Don, I don't think it's going to work. Since with USM and AF-S it's the lens do the focusing, it's possible that Sigma is disabling this. Anyway I'm going to try it because I have choice. I have bad luck with MF on D70. Since the view finder so small, it's hard to say if the subject is in focus. I used to get very sharp images with F5 and TC-20E. With D70 and Kenko If I focus first and then change to MF and put the TC I'll get sharp images. Here's an example (100% crop)<br>

<img src="http://www.color-pictures.com/images/sigma500/DSC_3290_HeronCloseTC.jpg"><br>

Anyway thanks for the info..

[eric_meseroll2]

See the Sigma link. The Sigma TC doesn't allow AF to be used only MF. The correct aperture will be set on the camera if in P,S modes.

http://www.sigmaphoto.com/Html/faqs.htm

 

Eric

[joseph_wisniewski]

Shun - Don't be so quick to say what Nikon won't do. Two years ago, when rumors started circulating about how Nikon was going to put a 1005 zone RGB matrix meter from an F5 into a $1000 DSLR, I thought the rumors had to be false, for the same reasons you laid down for not putting CAM2000 in the D200. Then D70 came out.

 

Don't forget, Pentax *ist D has something rather like CAM2000. Even if you've got the high end module, if you don't have a big AF motor in the camera, and massive batteries, you're not touching the AF speed of a D2H/D2X. I have trouble seeing Nikon launching D200 with an AF module that has 1/2 the zones and worse zone placement than Pentax *ist D or Canon 20D.

[joseph_wisniewski]

Jemini - The Nikon cameras won't disable AF if they see a lens slower than f8. I've put a (Kenko) 2x TC on a Nikon AF-S 3.5-4.5. It correctly reported f9 to the camera at the telephoto setting, and the camera valiently (but not particularly successfully) tried to focus.

 

But it's not just up to the camera. When you mount the lens, the teleconverter CPU and lens CPU engage in a doalogue, and they finish their negotiations before the lens begins talking to the camera. So, the lens can look at the teleconverter, and say "hey, I'm, an f5.6 lens on a 2x TC, I'm going to report f11 to the camera, and just to save everybody a bunch of embarasment, I'm not even going to try to autofocus".

 

Supposedly, some SIgma HSM lenses do exactly that on Sigma teleconverters.

[ShunCheung]

Joseph, the RGB matrix metering Nikon puts into the D70 is from the 8-year-old F5 design. Today, the D2X uses an improved version of it so that what is in the D70 is no longer state of the art. Moreover, you still don't see the 8-year-old Multi-CAM 1300 in the D70.

 

Nikon is not going to put a Mutli-CAM 2000 into a consumer-grade DSLR in 2005 because they need to distinguish it from its top-end models. Otherwise, they will kill their own top-end sales. That is simply business 101. Frankly, if I can get Multi-CAM 2000 in some $1500 D200, I wouldn't pay $5000 for a D2X. I'll just buy two or three D200 still for less money and it'll overcome any reliability concerns. And with AF-S lenses, AF motor in the body is irrelevant.

 

There is a big difference between the AF capabilities between the EOS 1D2 and 20D, even though the 20D is 6 months newer. Just try them both and it should be immediately obvious. Instead of their 45-AF-point system common to their top-end models, Canon developed a 9-AF-point system for their consumer-grade DSLRs such as the 20D.