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03-25-2015, 07:02 AM   #1
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Craving Medium Format

I never had interest in purchasing a full frame DSLR, and am very satisfied with my K5II. The low light focusing problem on my K5 angered me so much, though it is fine for manual focusing, so I now use it for astro-photography. I converted a K10D with its CCD sensor for IR and UV photography that works quite well.

As the prices of used medium format DSLRs are now in a reasonable range, I am craving for that super thin DOF. Even my Sigma 30mm f/1.4 on my K5II doesn't quite cut it, there is something different compared to the FOV and DOF of medium format images I see..... Then again, maybe I shouldn't be blowing away so much money..... Let me think some more.

One thing I am very pleased to see is that Pentax has been a game changer in the medium format arena.

03-25-2015, 08:58 AM   #2
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Buy a 6x7 with a waist-level finder and the 105/2.4. The body will be trivially easy to find, the lens less so, but the whole outfit for under $500. You'll buy and process a lot of film before coming anywhere near the cost of a used MF DSLR. And you'll get that medium format thin DOF look to a much greater degree than the 33x44 sensor will do.

Or go large format.
03-25-2015, 09:07 AM   #3
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baro-nite's suggestion makes good economic sense. You could (via scanned negatives) get medium format digital - full frame 6x7 for a very decent price, but with a much longer workflow (develop film then scan) than pixel peeping/chimping on a 35mm DSLR. Then if you like the results, keep shooting with this setup and/or pick up a Pentax 67 - Pentax K adapter and use it on your K5II.
03-25-2015, 09:22 AM   #4
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6x7 is as wide as you can get with Pentax, and you can get a fair amount of gear for $1000.
That leaves a lot of budget for film before it adds up to a 645D body.
Also, 67 & 67ii bodies seem to be increasing in value, while the 645D body is still decreasing in the market. Not a bad time to go wide.

03-25-2015, 10:59 AM   #5

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QuoteOriginally posted by Eric Seavey Quote
...I am craving for that super thin DOF
Are you talking about the a 645D/Z medium format? If so, the normal lens for that is sold as a 55/2.8. Now I don't see that producing thinner DOF than a 50/1.4 or 50/1.2 on a FF.
03-25-2015, 11:00 AM   #6
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the digital 645 is a 'crop mode' of film 645.... if your whole purpose is to get thin DOF.... it might not work very well as you wish, as the fastest lens you could get is an adapted 67 105mm lens (unless you adapt other lens like Hassy 110mm f2 or Mamiya 80mm f1.9), or use extension tube or closeup filter. I believe the 67 105mm f2.4 DOF, is about f1.2 in 35mm term, so I think 67 is the way to go.

A company called "The Bokeh Factory" convert faster lenses to use on Pentax body, you can take a look if you want super thin DOF.
03-25-2015, 11:02 AM   #7
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the current lenses of the pentax 645z are not optimized for thin dof. If you want shallow DOF the pentax 67 system will be your cheapest option. They have relatively inexpensive manual focus prime lenses in f2.4-2.8 range, which will give you a depth of field similar to f1.4 on a full frame camera.
03-25-2015, 10:10 PM   #8
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The thing I like the most is how the bigger formats capture tonal changes and colours. It just looks more 'real' to me. The OoF elements fall in and out smoother and hold more detail in the sharp bits, the 105 2.4 has a perfect 3d look thats worth trying out regardless imo.

03-26-2015, 12:36 AM   #9

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Any body who thinks the depth on the 90mm DFA wide open is not razor thin has not shot the 90mm DFA on a 44x33 MM chip........
03-26-2015, 01:28 AM   #10
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QuoteOriginally posted by 672 Quote
Any body who thinks the depth on the 90mm DFA wide open is not razor thin has not shot the 90mm DFA on a 44x33 MM chip........
Depends on your focal length of choice. 90mm f/2.8 is like a 70mm f/1.8 in FoV and DoF on 35mm, which is decent, but not quite up to par with 85mm f/1.4 lenses. The 150mm f/2.8 has an extra 60mm with the same aperture, and while it likely isn't as sharp, it'll definitely qualify as a blur-factory.

What is currently missing for the digital 645 line are faster lenses at shorter focal lengths, the smaller sensor could easily allow for something like a 55mm f/2 lens or even 1.8, just looking at the tiny rear element shows how much leeway there is for expansion.

In any case, 35mm DSLRs still have the edge in maintaining a sharp picture wide open, a D810 with 85/1.4 Otus shot wide open will produce more real detail, fewer aberrations and a shallower DOF... you do lose autofocus though, in which case the Sigma 85/1.4 ART is 95% as good, with AF and a fraction of the price.

Last edited by Kolor-Pikker; 03-26-2015 at 01:37 AM.
03-26-2015, 04:36 AM - 1 Like   #11
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QuoteOriginally posted by Kolor-Pikker Quote
Depends on your focal length of choice.
Indeed. If you want really thin DOF, try the 600/5.6 wide open. But there's nothing quite like the look of a normal or wide perspective with ultra-thin DOF on a larger format. I think that is what the OP is after.
03-26-2015, 08:23 AM   #12
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Thanks all for your suggestions. Since I have been thinking of getting a polaroid camera for the effects, that I am having a hard time reproducing digitally, perhaps I could also add a medium format film camera.

Let's see regarding the DOF, the sensor is about 4 times the area than that of the K5 (about twice the size in each dimension. So when shooting f/2.8 45mm with a 645D, the field of view appears more like what you would get with a 23mm on a K5. The DOF is what it is for each focal length and aperture, so if I took a 45mm f/2.8 lens and shot a panoramic photo on a k5, covering the field of view of a 23mm lens, I would have to scale the panoramic shot down by a factor 2 to fit the same print size as what I get in a single 23mm shot, thus also scaling the DOF. So would shooting with a 645D 50mm f/2.8 produce similar images to k5 23mm f/1.4? OK... I am just thinking here. I'll open my books on optics tonight and run some calculations....

What are other differences shooting with a digital medium format? What am I seeing in the photos posted that make the photos somehow seem different than those from aps-c cameras? Dynamic range and resolution are different, those shouldn't make that much visible difference on a resized image right? I attached an HDR photo from my vacation using my K5II, cropped and resized it. Aside from resolution, it is not bad.
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K-5 II  Photo 
03-26-2015, 10:07 AM   #13

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Well, for this sort of landscape shot get used to shooting right up to the edge of the diffraction limits, and maybe just over, or focus stack. It's one thing I forgot a bit (cuz I'm a dummy) when I moved back into medium format, especially after some years with crop frame digital cameras. I made the adjustment when I moved to FF, but now again with another jump up to MF.

The other thing I'd say is that what's a bit hard to describe, and you really have to see (and that on a larger monitor and larger print, plus working with the files in post)---but that's that files from smaller sensors seem more "brittle" somehow, a look that some have I think erroneously deemed "digital"----although there is definitely also a digital look to digital----sort of the same situation as the difference between jpg and raw, and as you move up in sensor size there's definitely more malleability to the file. The larger files are just more lush in every way, not just resolution. This sounds like I'm talking mystically about Leica, LOL....but anyway I think it's real, and a lot more obvious than the "Leica look" versus the "Zeiss look" , for instance, when talking about lenses.

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