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02-19-2011, 04:10 PM   #1
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55mm lens comparison on 645D

I did a lens comparison with 645D and various lenses, all at 55mm. Taken at different times so the lighting is a little different. All from the same spot at f/8, on a tripod.
Full image with this post, then crops from the following in a 2nd post: 645 55mm A, 45-85mm FA at 55mm, 67 55mm (late) and the 55-100mm 67 zoom at 55. All lenses were sharp in the center. Crops are from lower left corner. The 645A lens falls apart, the 45-85 zoom does very well and the 67 55 and 55-100 are superb. Little to choose between with the 67 lenses.

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02-19-2011, 05:06 PM   #2
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Don't keep us hanging...
02-19-2011, 05:09 PM   #3
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Sorry I thought I had posted the rest. Sorry for the sizing differences. Too much of a hurry, I should be doing other things
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02-19-2011, 05:15 PM   #4
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Very interesting. I am assuming difference in image scale is object distance. But it certainly illustrates the differences.

Oddly enough, Michael Pollen had come up to speak in Maine last year as well.

02-20-2011, 03:07 PM   #5
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55mm on the 645D

I did the same sort of testing, but with printed (HP-Z3200) 2ft x 4 ft test patterns using the Electronic Still Camera Picture Test Chart (ISO 12233 Test Chart). I found that the 55-100 zoom is so good that I can sell my 55mm, 75mm, 90mm and the 105mm and not look back.

I can't upload all the images (there are several hundred), but I will upload the 55mm f4 (SMC Pentax 67 late version) and the 55-100 zoom cropped images. Both are at f8, and you can see that there is little to choose between them. A full sized chart is included for reference crop size reference.

The top image is the 55mm f4, the middle image is the 55-100 zoom at 55mm.

I repeated this for the 75mm f4.5, 90mm f.2.8, 105mm f2.8, 135mm f4,165mm f4 and 200m f4 and the results are the same: the two zooms are the equal or better of the any of the primes in terms of sharpness and detaill (no 75mm f2.8 AL, sorry) at their respecitve best apertures. With the 645D, the best apertures were f8-f16.

I could not compare the 300EDIF directly because of the difference in focal lengths compared to the zooms.

materialsguy
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Last edited by materialsguy; 02-20-2011 at 07:59 PM.
02-20-2011, 06:19 PM   #6
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When the 55-100 was introduced, I bought one and tested it wide open. I was shocked at how sharp it was. I had used the 75 Takumar for 10 years before that and thought it was the benchmark for 6x7 lenses (along with a couple of others). The 55-100 is just amazing and I just no longer used my 75mm anymore and sold it. The zoom can easily match the 75 Takumar and now from what I've seen above, can match the 55mm latest as well. Impressive-
02-23-2011, 02:22 PM   #7
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I said the very same thing years ago (experiences / tests on film), but not many believed... I sold my 75mm, 90mm, and 105mm primes too (the 55mm was kept for another use).

Last edited by leping; 02-24-2011 at 08:28 PM.
02-23-2011, 03:21 PM   #8
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The 55-100 performs amazingly well, but it's such a beast to carry! Maybe not when compared with carrying all the lenses it may replace, but I usually just go out with one lens, rarely two, so that is lighter, and the primes are faster. (I've never had the 75 Tak, just the ASPH) Still, the zoom is more versatile except for the max aperture. Nice to have such tough choices!

02-26-2011, 11:17 AM - 1 Like   #9
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I just compared the P645 FA 55-110 (note: not the P67 55-100) with the P645 FA 45-85 and the P67 55 (latest) on the P645D.

At 55mm and f5.6 (wide open), the 55-110 is good in the center, but soft at the edges. At f8, the edges sharpen up and are similar to the P67 55mm at f5.6. By f11, the 55-110mm is the equal of the P67 55mm at f8, across the whole frame.

When the FA 55-110 is compared to the FA 45-85, at 55mm, the 55-110 is softer at f5.6. At f8, both lenses are good across the frame, but best at f11 for critical sharpness. Comparing these same zooms at 80mm and f8, the centers are similar, but the edges are better on the 45-85 lens. However, at f11, both are very similar across the frame.

The FA55-110 is definitely a good lens: light weight (about 500 grams) and compact, but needs to be used at f11 for best quality as f5.6 is not critically sharp, which is what using a P645D is all about.
02-26-2011, 03:54 PM   #10
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Interesting comments, rlj, thanks! I've been curious about the 55-110 which seems to be rarely seen.
03-29-2011, 06:58 PM   #11
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Does'the 55-100 67 zoom lens when used with the 645d does focus confirmation work?
Is it accurate or you have to focus as best as you can with your eye

Steven
03-30-2011, 02:51 AM   #12
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QuoteOriginally posted by kuau Quote
Does'the 55-100 67 zoom lens when used with the 645d does focus confirmation work? Is it accurate or you have to focus as best as you can with your eye
the AF system in the 645D is the same as what is found in the smaller APS-C cameras so yes you do get AF confirmation. However, sometimes the focus screen can ever so slightly be out of kilter with the sensor plane - and that can potentially cause problems because if the AF module is saying you are in focus but the focusing screen says you aren't, it is going to be hard to know which to trust. This is a big problem with the phase one-mamiya cameras - where the AF or the focus screen(and sometimes both) can be so out of whack that it is impossible to get things right. Personally I think Pentax putting AF correction function on the 645D is f*cking brilliant because then you can bring the AF into line with what you are seeing on the focusing screen, getting the focus screen in the right place can be tricky but at least it's doable, and thanks to pentax adjusting the AF is possible too.
03-30-2011, 06:01 AM   #13
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Well for FA lenses yes an excellent feature to have, but on MF lenses the adjustment does not work so for me I guess checking into the 67 55-100mm is out of the question. Accurate focus on a matt screen for me is almost impossible and I doubt even if I sent in my body to pentax they could adjust the focusing screen. A hit and miss proposition. The 645d like 99% off all modern digital cameras are meant to be used primarily in AF, hense the reason you hardly see from any manufacture an optional split prism micro focussing screens.

Oh well

Steven
03-30-2011, 07:25 AM   #14
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Steven:

I tested my copy only once and at f/8, but no problem with focus. Based on my tests with other lenses, if you need to shoot wide open, a Pentax 2x magnifer is essential. The 67 zoom is a great lens, but so large and heavy, I doubt I'll use anywhere more than 5 feet from the car.

Tom
03-30-2011, 07:42 AM   #15
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Thomas,
Yep, Sounds like the 67 Zoom is a winner and huge, I was hoping that it could replace my 45-85 FA,
yet I really like shooting at 45mm and there is no replacement for that 45mm lens. The FA45 is not good, I even tried the 67 45mm, that also was not good. I guess after looking at the comparisons done at 55mm the FA 45-85mm zoom is really not that bad, and the size it right.

On another note, I am still debating on whether to try the 150-300mm FA zoom. I own the 150, 200, and 300mm 5.6 FA primes now, lots to lug around, and since I am a "F11" kind of guy, I may give it a go.

Steven
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