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12-22-2010, 12:52 PM   #1
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It this a true statement on lens for the 645D

From what I have seen and read on the net, is there any advantage in purchasing FA lens over the earlier manual focus versions which are selling for a lot less now then the FA series 645 lens.
I just just landscape, and AF is not important to me, I shoot with an M9 also and for work I use a Nikon D3s.
Thanks
Steven

12-22-2010, 01:31 PM   #2
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My experience thus far suggests that manual focus is not sufficiently reliable and accurate to obtain maximum performance from the camera. This is consistent with what all other users of MF systems whom I know have concluded.

Sorry.

I had had similar thoughts to yours, and pounced on a 200 f4 for pennies. I thought its longer focus throw would increase accuracy. Turns out it's darn hard to focus it.

- N.
12-22-2010, 01:38 PM   #3
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Original Poster
So are you basically saying stick with FA lenses only?
I am about ready to pull the trigger on a 645D body
Steven
12-22-2010, 02:07 PM   #4
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For some application you can try focus bracketing. For landscape it shouldn't matter that much, there the DOF if deep enough and often you want to use hyperfocal settings.

12-22-2010, 02:33 PM   #5
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I've begun early experiments with A and FA lenses (I ended up with one of each in the 120/4 macro, as it happens). My take is that it's darn hard to get critical focus with either auto or manual focus. Just really, really hard.

Now, accepting that for a moment, I have not found the autofocus to give me much higher a hit rate than manual so far. Admittedly, my sample size is small, my experience is short, and I am handholding at a lot of close- and mid-range targets so even my own motion will impact the focus. But for the type of walk-around shooting I do, I'm skeptical of both systems, and I predict it'll be necessary to focus-bracket as elho_cid suggests.
12-22-2010, 02:39 PM   #6
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Thanks Nebster for your input.
For me I would never even consider hand holding any 40mp camera, I am a tripod only guy with the MLU, Theses high MP cameras are so sensitive to any thing, this can invalidate any kind of even real world tests, forget about shooting charts..

I guess at the end of the day there are still not enough 645D's out there to get some consistent feedback on what works well and what doesn't

Steven


QuoteOriginally posted by Nebster Quote
I've begun early experiments with A and FA lenses (I ended up with one of each in the 120/4 macro, as it happens). My take is that it's darn hard to get critical focus with either auto or manual focus. Just really, really hard.

Now, accepting that for a moment, I have not found the autofocus to give me much higher a hit rate than manual so far. Admittedly, my sample size is small, my experience is short, and I am handholding at a lot of close- and mid-range targets so even my own motion will impact the focus. But for the type of walk-around shooting I do, I'm skeptical of both systems, and I predict it'll be necessary to focus-bracket as elho_cid suggests.
12-22-2010, 03:06 PM   #7
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See my post regarding an Amateur's take on this issue. I used manual focus and AF lenses focused at various far distances, just as I would do for landscapes. At the "print size" (roughly 23"x31" @240 dpi, the manual and AF lenses look very sharp to me. Only at "pixel level" can you see focus errors, lens softness. I have 5 manual, two AF lenses and intend to use them all. My avice to you is to buy one MF lens (the 75mm f2.8 can be had from $100 to $160, and it is a real gem). You may find, as I have, that for the kind of work you do, the focusing may not be an issue. My way of working has been to focus about 1/3 of the way into the scene, shoot at f13 to f16 for DOF, and the results in 24"x32" prints are, to me, good enough to sell (which I do)....but I am not a Pro, doing high end advertising, etc. A critical pro making bill board prints will not agree with me, I am sure. But I love mine.
Dave
12-22-2010, 03:54 PM   #8
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QuoteOriginally posted by ndevlin Quote
My experience thus far suggests that manual focus is not sufficiently reliable and accurate to obtain maximum performance from the camera. This is consistent with what all other users of MF systems whom I know have concluded. - N.
I can assure anyone that manual focus is far more precise than any AF system on the planet unless you have problems with you eyesight.
You can not test lenses by using AF; then you test the AF system that typically cannot detect anything beyond 40-50 l/mm.


Last edited by Pål Jensen; 12-22-2010 at 04:05 PM.
12-22-2010, 04:39 PM   #9
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I have 2 FA lenses as of right now. My 80-160 needed a -3 adjustment, after I made that it is very precise on focusing. The 75mm f2.8 may need to go back to as it seems to be back focusing bad and the adjustments made little difference.

I have no A lenses so I cannot really say anything about those.
12-22-2010, 07:06 PM   #10
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Hi Steven,

There is no doubt that AF has its place, and is indispensible for certain types of photography, such as at sporting events, or when subjects cannot or do not have the patience to stay still, or in other cases where there is not much time to go thru the ritual of manual focussing. But many modern photographers seem to believe that AF is or should inherently be a superior focussing system. Perhaps this view originated in attempts to manually focus using the viewfinders found on digital cameras with reduced sensor size, together with commercial grade focus confirmation lights.

In those instances where the subject is stationary and there is sufficient time and light, I almost always manual focus, without bracketing, and have enjoyed a very high success rate. Now, I shoot off a tripod, in part to eliminate photographer wobble, and usually confirm using a 2X eyepiece. Through long experience and careful comparisons I have come to believe that AF cannot do better than MF in these instances, and often does worse, especially when shooting faces at close range and wide aperture, where artistic judgement is required regarding what exactly to focus on.

With the now common use of low dispersion glass, aspherical elements and computer aided design, lens technology on the average is getting better. But modern lens design has its drawbacks too. Design to production time has been drastically reduced to in some cases a matter of months, and designs tend to be developed by teams relying more on numerical optimisations rather than on long experience and prototype field testing. By comparison, the Nikkor 135/2 AIS MF lens was seven years in development having multiple prototypes, and the optical expert in charge had over 20 years previous experience in designing outstanding lenses for Nikon.

There are many older MF lenses whose optical designs and executions are legendary, and it would seem a real shame if the ones that can be mounted on the 645D were to be ignored simply over an issue of MF vs. AF capability. I have now sold all of my 645 FA lenses, because in practice, I rarely used them. The only 645 A lens that I currently own and use is the 120/4 macro. Instead, I use a selection of Pentax 67 and Carl Zeiss Jena (CZJ) lenses on my 645 systems, when I am not using my 67's. I have never felt remorse over selling the FA's, apart from that induced by a Collector's hording instinct, as I closely considered each sale and concluded that I had in my remaining inventory MF lenses whose optics were at least as good as what each sold FA lens had to offer.

I would suggest that before anyone categorically rules out MF lenses, they tryout on the 645D a Pentax 67 55/4, 75/4.5, 100/4 macro, or a 300/4 M*, and maybe a CZJ 50/4 Flektogon or a 180/2.8 Sonnar. I suspect that you will be very pleasantly surprised at the results, and your pocketbook will also be very happy!

Best, Alan

Last edited by ARCASIA; 12-22-2010 at 07:19 PM.
12-22-2010, 08:47 PM   #11
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Thanks Alan, for confirming what I, as an amateur, have found with my 5 645MF lenses.
Dave
12-23-2010, 09:17 AM   #12
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QuoteOriginally posted by elho_cid Quote
For some application you can try focus bracketing. For landscape it shouldn't matter that much, there the DOF if deep enough and often you want to use hyperfocal settings.
If only this were true! I have actually found that the focusing problems occur only at mid to far distances. (This is similar for what other users have experienced with other systems). DOF is a bit of a myth, but one that worked with film. With digital sensors at this level of accutance, its limitations are much more acute.

It is for landscapes in particular that I am not at all yet statisfied that the AF is refined enough. Only time and experience will satisfy me one way or the other.

The point seems to be that with, say a 160mm lens at f8-11, there are probably a hundred, if not several hundred, discrete distances from 30' to infinity. I am not sure that either the AF system, nor more particularly to lenses and their drive systems, are capable of resolving to this level of accuracy. With MF digital, that makes a big difference. The focus throw on my 35mm from 4' to infinity is about half an inch. That might not cut it.


In the studio, AF is great, as long as it's on the right spot.

- N.
12-23-2010, 09:18 AM   #13
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QuoteOriginally posted by Pål Jensen Quote
I can assure anyone that manual focus is far more precise than any AF system on the planet unless you have problems with you eyesight.
You can not test lenses by using AF; then you test the AF system that typically cannot detect anything beyond 40-50 l/mm.
Attempting to focus MF digital cameras manually is a guarantee of a lifetime of semi-sharp images. I didn't believe this either until experience, and conversations with other users and testers confirmed it.

- N.
12-23-2010, 11:30 AM   #14
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QuoteOriginally posted by ndevlin Quote
It is for landscapes in particular that I am not at all yet statisfied that the AF is refined enough. Only time and experience will satisfy me one way or the other.
- N.
Hardly anone use AF for landscape. Hyperfocal focusing is whats used for landscape and for this AF is a roundabout way of doing things.
12-23-2010, 11:41 AM   #15
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QuoteOriginally posted by ndevlin Quote
If only this were true! I have actually found that the focusing problems occur only at mid to far distances. (This is similar for what other users have experienced with other systems). DOF is a bit of a myth, but one that worked with film. With digital sensors at this level of accutance, its limitations are much more acute. - N.
If DOF is a myth, the camera is basically useless for landscape photography. How it can be a myth is a mystery as the laws of optics are the same for film and digital. If you have trouble in near and mid distances, then try hyperfocal focusing - preferable manually as it is faster and more precise. You cannot have problems at mid distances with hyperfocal focusing....
To me it seems that you don't have problems with focus but with DOF.

You comments makes me wonder if you have shot with an MF camera before? If you expect the DOF characteristics of 35mm or APS, you will be dissapointed. 95% of my 645 images are shot at F:16 or smaller in order to not experience "sharpness issues". I remember using the 45mm at F:8 in the beginning being dissapointed with "sharpness" in lansdcapes; I was thinking 35mm. Almost every 6X7 landscape image I have seen are shot at F:22.
Theres only one plane of focus. Everything in front or back of it is technically not in focus regardless. It is a fact of physics you may see while pixelpeeping.

A simple test. Put on a prime lens with DOF scale. Shoot a landscape with foreground. Focus on the closest subject you want in focus. Say this is 2m. Choose the aperture that covers the span from 2m to infinity; say that this is F:11. Turn the focus so that the F:11 DOF mark to the right of the focus point on the lens points at 2m; the left at infinity. This where you focus the image. Then forget about F:11 and set the lens to F:19 - this is because the manufacturers DOF scale are a bit optimistic. Then shoot. Unless you camera and/or lens is bonkers everything from 2m to infinity should be in focus. It works every single time. If you are still not happy; then bad luck - the limitations is the due to the laws of optics.

Last edited by Pål Jensen; 12-23-2010 at 12:17 PM.
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