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03-11-2012, 02:55 AM   #1
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Pentax 645 120mm macro and Pentax 645 35mm lenses and Pentax 6x7 45mm lens.

My knowledge of Pentax 645 lenses is minimal (I'm new to Pentax) so please could someone advise.

Firstly with the 120mm macro, the Pentax lens roadmap shows it as an f/2.8 lens, but all references I can find to the lens shows f/4. Is there an f/2.8 version, or is that a plan for the future?
Is the f/4 version still available new, or is it now withdrawn? Is a used f4 lens a good option, and what would be a reasonable price to pay for a good copy?

Secondly 35mm lenses. From my research there is an A version (manual focus) and FA version (autofocus). Is the FA version still available new, or is it withdrawn now? There are a couple of retailers still showing it on their websites, but I haven't phoned to see if they have it in stock (I'm not at the buying stage yet anyway). In any case which is considered to have the best optical quality on a 645d - the A or FA? It is for landscape use, not photographing flat objects etc, but whether prone to flair etc is important. The reviewers on here give the FA versIon great reviews, but one or two comments elsewhere seem to suggest there are some not so good copies of this lens around, and one comment was about back focus (the 645d doesn't have focus micro adjust ... does it?).

Finally are there alternative and potentially better options at around the 35mm focal length, using lens fit adapters or anything?

Thanks for advice.

03-11-2012, 03:07 AM   #2
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The 120mm macro lenses are f4. You can still get them new in Japan (and all other FA 645 lenses), but I don't see how you could go wrong with a used one, either, as long as it's in good shape.

SMC Pentax-FA 645 120mm F4 Macro Reviews - 645 Telephoto Primes - Pentax Lens Reviews & Lens Database

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03-11-2012, 08:57 PM   #3
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35mm

seems like many folks here prefer the A 35mm. I had both for testing on a 645D and sold the FA35 eventually. It was one or two millimeters tighter than the A and had a habit of picking up flares which were easily avoided or supressed by the A. Also i have lots of 77mm filters (A sized) already and no 82mm filters (FA sized).

keep in mind that "af micro adjustment" has nothing to do with back focus, it simply sets the auto focus parameters. Back focus is set by re shimming the lens or sensor.....
03-12-2012, 12:27 AM   #4
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QuoteOriginally posted by 672 Quote
keep in mind that "af micro adjustment" has nothing to do with back focus, it simply sets the auto focus parameters. Back focus is set by re shimming the lens or sensor.....
Thanks, and no I didn't realise that. So back focus is to do with the actual (incorrect) position of the physical components, and not adjusting where the software thinks the point of sharp focus is?

03-12-2012, 06:30 AM   #5
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QuoteOriginally posted by Newmoon Quote
Thanks, and no I didn't realise that. So back focus is to do with the actual (incorrect) position of the physical components, and not adjusting where the software thinks the point of sharp focus is?
No. "Back focus" is really not a technical term. What it is saying is something is not right in the optical train. It could be the sensor position--unlikely in the 645D--or it could be the lens position. Tuning the AF in the camera can cure it.

BTW, the A 120mm Macro has the same optics as the FA version. And I also have the A version of the 35mm. The A has more CA than the FA, but is reportedly sharper in the corners.
03-12-2012, 09:42 AM   #6
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AF micro adjustment only calibrates the af system so that it matches what is seen in the viewfinder.....it wont change anything about back focus......Yamanbori may well have a point that we are using the term "back focus" to mean different things.....
03-12-2012, 11:26 AM   #7
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the f/2.8 lens in that range may be in reference to an announced, but not available 645 FA 90mm f/2.8 lens.

The 645 A 120mm f/4 macro is an amazingly beautiful lens. Rock solid feel and silly sharp. In addition to my 645N I also use it with my Nikon DSLR (and adapter).

The 645 A 35mm is beautiful as well. I had at one point the FA 35mm and the A 35mm - sold the A 35mm and regretted it, so picked up another A 35mm and sold off the lovely FA 35mm. That little A lens is quite spectacular!
03-13-2012, 06:55 AM   #8
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Only disadvantage of the 645 A 35mm is the rubber hood, which is not too useful. Mine broke (after getting stuck on a filter). I thought I had a third-party replacement but it vignettes. I'm now trying a metal screw-in third party version but I do not like metal screw-in hoods much.

03-14-2012, 12:24 AM   #9
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QuoteOriginally posted by Newmoon Quote
Firstly with the 120mm macro, the Pentax lens roadmap shows it as an f/2.8 lens, but all references I can find to the lens shows f/4. Is there an f/2.8 version, or is that a plan for the future?
120/2.8 macro lens on last Pentax Ricoh 645 lens roadmap is mistake. There must be 120mm macro lens with aperture F4 instead of F2.8. There is no such lens as 120/2.8 macro for 645 system.

03-14-2012, 05:13 AM   #10
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Seems to be a 28-45 coming; a replacement for the 45-85/4.5 (the same lens in D-FA style? Or is it a 45-90?); and a 90-200 coming. All great choices!

No other MF systems has so many modern zoom lenses. As the 645 cameras and lenses are relatively large and heavy zoom lenses make even more sense than for smaller formats.
03-14-2012, 09:09 AM   #11
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Depending on plans to create a larger sensor for the 645, a 40 or 45mm prime would really be in order. The current 45 prime options do not work. The zoom is good but a prime is lacking. 40mm would be good for the current sensor, but if the bet is on a larger sensor, the 45mm really requires a modern incarnation.
03-14-2012, 02:10 PM   #12
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I would have to agree with the above post on the 45mm (67). It is an old design that in its day held its own against its other P67 lens siblings. But with the modernization of the lineup, the 45 was left behind, performance wise. A 645D sensor will show its "so so" off axis performance and lateral color.
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