FF vs. Crop - which System for UW-pics

The reviews on the 150mm lens indicate a slow auto-focus.

Can you provide references to these reviews?

Individuals saying AF is slow don't mean a whole lot. You have no idea how they are testing, if they are, or what they consider slow.

The shallower the DOF, the slower AF will be and the 150 at f/2.8 is shallower than the 105 at f/2.8 so it is at a disadvantage. In my experience the 150 AF is fine but I use AF to get in range and MF afterward. Alex is certainly a photo pro, he places great emphasis on AF performance, and he didn't mention AF as a problem with the 150 on the D3. He thought the lens quite useful.

If fast macro AF is the first priority a large sensor is probably not the first choice. I'd wonder why any serious photographer would make such a choice. Of course, your original point has nothing to do with AF speed and that point has already been debunked.

Simply stated, I can take the same shot from further away from the subject. Now technically, more water between the camera and the subject degrades the photo but, practically, being farther away allows me to get a better pose from the subject simply because I am less likely to spook the subject.

FF shooters don't have any problem achieving these working distances and they can focus fine while doing so. Not a good reason to drive format choice.

Before deciding on anything consider this:

Canon's new 5D MkII is 21MPixel Full Frame camera. Nikon do not have a camera with a matching specification.

I am NOT suggesting Canon are the better choice, merely indicating that the likelihood is that Nikon will have to compete in the near future. I am rarely an advocate of waiting until the next best thing comes out but given the situation at present I'd be wary just in case current products are short lived - just my personal view.

Regardless of reviews, assertions, etc., all the cameras discussed in this thread are capable of very high quality results - lens availability and choice together with output requirements are as important factors as body choice.

If fast macro AF is the first priority a large sensor is probably not the first choice.

Unless 'pro' AF is only available in a body with a large sensor!

Unless 'pro' AF is only available in a body with a large sensor!

Yes, of course, but...

The longer the focal length for a given f-stop, the narrower the depth of field. The narrower the DOF, the longer it takes to sweep through the focusing range.

The higher the magnification, the wider the focusing range. The wider the range, the longer it takes to sweep through the range.

Larger formats require higher magnifications and longer focal lengths but still need fast lenses for the AF sensors to work. As a result, larger formats inherently have an AF speed disadvantage when all other technologies are equal. All else is not equal, of course. If you were designing a macro system for AF speed, 4/3 would be a better choice than DX or FX. If you were designing an FX pro body system, you'd have more money to spend on faster AF electronics.

The AF speed of the 105VR doesn't have much impact on the Canon shooter.

If a lens provides the right combination of perspective, magnification and IQ then a shooter will learn how to focus it. This is dedicated macro we are talking about!

...lens availability and choice together with output requirements are as important factors as body choice.

That's the important point.

Let me go through this agian Craig.

If I am shooting a macro subject that moves rapidly I can't use manual focus. I don't have the time, or the brainpower, to 1) Find the critter who has just moved 2)Get the eye in the focus rectangle 3) adjust the focus manually and 4) press the shutter. If I am a professional photographer who dive multiple times per year more than I do, then I am able to hang around and wait for the happy circumstance when I can do all four. Not me. I have other places to see on the reef and other critters to photograph.

I would say a large percentage of photographers 1) Don't ususally dedicate a large percentage of their dive to a single subject and 2) Are not capable of using manual focus on a fast moving subject.

So, therefore, for a Nikon shooter (not a pro), I would not give up the AF105VR lens to go to a FF camera for macro. I need the fast autofocus of the lens to get the shots I want. The reviews that I have read indicate that the Sigma 150 is not nearly as fast autofocus.

I continually focus (autofocus) while approaching the subject as you do but, at the critical moment I rely on autofocus not manual focus. Why? The subject will be gone in the time it takes me to manual focus. And, frankly, the lense is fast and accurate enough that the autofocus is much better than my manual focus.

Therefore I would say a D3 with a Sigma 150mm is not as useful as a D300 with a Nikon af105VR.

That's the advice I give Meerseen.

I used the 150mm on my last trip exclusively in AF and it worked well. It's good enough you don't have to use it at an MF lens - I don't know where that myth came from.

Cheers

James

James,

The "myth"

"This is far from the slowest or most-inconsistent autofocusing lens I've used but definitely is not the best in this regard. Fortunately, most macro photography is done using manual focusing which makes any autofocus inconsistencies and speeds irrelevant. This is a really nice 150mm telephoto lens that could be even better for general purpose and sports use if it had fast and accurate AF." --The-Digital-Picture

Actually, I was responding to Craig who indicates he uses manual before the final push. I have no doubt that this is a good lense. However, the reviews indicate it is not as fast in autofocus as the AF105VR and that is importent to me.

Tom,

I think you should either try it, or perhaps read an UNDERWATER focused review before drawing a conclusion like that. If we're ever on a trip together, you're welcome to try mine.

Cheers

James

Tom, I'm glad you like the 105 on a DX sensor. Lots of people do. FF offers that same perspective. The AF issue is red herring. MF is not hard with small subjects that would be typical of a 105+DX setup. The issue is moot as AF works fine with the 150. Curiously, Alex has written that he has mixed feelings on the speed of the 105VR and hasn't switched from the slower 105. Super fast AF is not a requirement. How did anyone shoot macro underwater before the 105VR? How do Canon shooters manage?

I don't use AF as you described. My normal macro lens I use with MF only. With lens-motor supermacro lenses I use AF to quickly set the range then switch to MF. For WA, midrange zooms, and wider macro I use AF only.

Super fast AF is not a requirement. How did anyone shoot macro underwater before the 105VR? How do Canon shooters manage?

It's probably because the Canon 100mm macro already had USM :-)

Sorry I took the bait....

I recently undertook a project to see whether dSLRs could be used to identify gobies in a dark, cold Scottish Sea Loch (in VERY dismal weather). 4 of us shot usin 2 c Canon 5Ds with 100 usm macros, a Nikon D200 with new 60mm macro and a D50 (I think) with an older 60mm macro. We all used sptiing lights (very varied from Kowalski Xenon to small led types). Out of ~1100 images of these small fish (~2cm to ~10cm) very, very few were incorrectly focused - even the moving fish were ok. No-one used manual focus. Now I'm not saying that anyone should not use manual focus but AF is nowadays extremely effective - in case anyone is interested, the aimpoint was to produce images showing face, nape and dorsal in focus if possible so that features could be examined, so focus had to be very accurate indeed. The project worked and we even identified species which we had no idea were there! If anyone wants a copy of the report to see the results (~5Mb Word file) pm me with your email address.

It's probably because the Canon 100mm macro already had USM :-)

 

Sorry I took the bait....

I was not baiting Canon shooters, I was making the point that other lenses besides the 105VR are capable of good AF performance. All macro lenses are slow at AF relative to lenses in general and comments stating such, as can be found for the Sigma 150, are worthless. The Sigma 150 autofocuses faster than the pre-AF-S Nikon macro lenses do.

Also, I don't advocate MF, I am simply saying that it's not difficult to learn. I use MF because my favorite lens does not do AF well. I would prefer, and would always use, AF with MF override if all Nikon lenses offer it like Canon systems do.

Of all the differences between FF and cropped sensor, AF performance is the least interesting to discuss.