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Author Topic: 25mm 645D lens vs D800  (Read 12377 times)
larkis
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« on: April 06, 2012, 10:04:43 PM »
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I posted this on another forum would like to see what the lula community has to say about this as well.

The following is my dilemma. I own the pentax 645D system and a few lenses in the normal and telephoto focal range, but I need a wide angle for some of the shooting I like to do once in a while. With the D800 being quite a nice camera I'm wondering if it's a better choice to get a D800 body and a wide angle nikon lens. The price for the camera and a lens would probably end up being close to the price of the pentax lens alone. The 645D still provides a nicer image based on samples I have seen online and raw files I have tested. Considering there are not a lot of reviews of the SMC Pentax-DA 645 25mm F4 AL [IF] SDM AW that I can find, it's a hard choice to make.

I'm not sure if going with a D800 and a zeiss wide angle would get me to about the same spot as the 645D with the 25mm offering. The added benefit of going with a D800 would be a backup camera body that is in a comparable resolution range and also the faster autofocus/handling for street shooting.

Any constructive comments for the pro's and con's would be welcome. I would prefer if people who own both medium format and FF slr's comment as there seem to be a few members (trolls ?) on here who are anti medium format on principle and refuse to see any of it's benefits.
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tsjanik
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« Reply #1 on: April 06, 2012, 10:22:07 PM »
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Larkis, I'll be interested in the replies as well since I face the same decision.  The D FA 25mm held the promise of a full frame 645DII, but now the DA version seems not much more than a 35mm lens and at 5K is the cost of a D800 and a 14-24mm.  My own inclination at this point is to use a 35mm on the 645D, stitch when necessary and avoid the 25mm and perhaps use the funds for a D800, a different camera with less apparent (to me) overall IQ, but some distinct advantages.

Tom
« Last Edit: April 07, 2012, 05:45:42 AM by tsjanik » Logged
BernardLanguillier
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« Reply #2 on: April 07, 2012, 02:36:23 AM »
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One first comment is that if you like the rendition of AA filterless bodies then the d800e may be a better option?

On your main question, I have not seen any test results for the 25mm but the Pentax folks I spoke with last year were clearly confident in its performance.

Beyond that it really is a matter if your willingness to manage 2 systems in parallel with the added cost of separate accessories,... And of your ability to become an expert user of these 2 systems, know their limitations and develop the ability to work around them intuitively to deliver results reliably.

Cheers,
Bernard
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DandA
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« Reply #3 on: April 07, 2012, 09:40:47 AM »
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Larkis poses an interesting question and a delema that many of us users of the 645D face.  The advantages in terms of IQ of 645D files is evident but it's hard to say whether it would match a D800 with the 14-24 f2.8 or Zeiss 21mm lenses vs. 645D with the 25mm .

Tom, when you say the DA version of the 25mm is no more than a 35mm, I am a bit confused.  Both the original D FA 25mm and just announced DA 25mm for the 645D would have an angle of view on the 645D of approx 20mm in 35mm full frame terms.  Therefore it would be most like the D800 with the Zeiss 21 or Nikon 14-24 set at 20mm.  Are you saying that if Pentax came out with a full frame 645D body, that the new DA 25mm because of it's reduced image circle (due to reconfigured hood design?) would end up being approx 37.5mm on a full frame 645D (in 35mm FF terms)?  If so, then the original D FA 25mm would be the answer for a purchase now, even if used on the 645D cropped body.  What disadvantages it (the D FA 25mm) might have on the current 645D vs. the DA 25mm, it's hard to know without any definitive test or even a statement by Pentax.

Pentax these days I believe will take it slow in any decisions regarding the 645D and system and it's development.  I think they will be very prudent and cautious and if I was to take an educated guess, the next iteneration of the 645D body will be the same sensor size but with an increase in # of pixels as changing technology (such as those used by Nikon allowing them to use 36MP on a 35mm FF sensor) will extract similar or even better performance from those greater # of pixels.  By using the same sized sensor as so to keep development and production costs down to a minimum and ultimately keep the price/performance advanatge of the 645D in the MF arena, they would hope to keep the system a viable upgrade to FF 35mm (D800 etc.).

Dave (D&A)

« Last Edit: April 07, 2012, 10:46:31 AM by DandA » Logged
theguywitha645d
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« Reply #4 on: April 07, 2012, 11:17:59 AM »
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Are you saying that if Pentax came out with a full frame 645D body, that the new DA 25mm because of it's reduced image circle (due to reconfigured hood design?) would end up being approx 37.5mm on a full frame 645D (in 35mm FF terms)? (D&A)



Huh A 25mm on a 645 camera would be the equivalent to a 15mm on 35mm. On a 44x33 format camera, it is similar to a 19mm on a 35mm FF. image circle is just going to limit the format, not the focal length. Or am I not understanding your post?
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theguywitha645d
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« Reply #5 on: April 07, 2012, 11:19:59 AM »
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Larkis, why not a 35mm on the 645D? The 25mm is really wide. It is a really hard focal length to use.
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DandA
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« Reply #6 on: April 07, 2012, 12:38:25 PM »
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Huh A 25mm on a 645 camera would be the equivalent to a 15mm on 35mm. On a 44x33 format camera, it is similar to a 19mm on a 35mm FF. image circle is just going to limit the format, not the focal length. Or am I not understanding your post?

All you wrote is correct. I came to the same figures as you did and stated pretty much the same.  What was just trying to figure out (and why I mentioned the "cropped" statement regarding use of the new DA 25mm on a potential full frame 645D) was based on what Tom expressed in his post (above), where I thought he was saying that the new Da 25mm wouLD end up being like a 35mm lens on full frame 645D?  If one mounted a cropped lens like the DA 25mm on a potential full frame 645D and cropped the image in post processing whereby all vignetting is removed, I supposed the lens might end up being an approx 22mm lens (in 35mm FF terms), not 37.5mm as I previously stated or something thereabouts.

Guess I will wait for Tom's clarification as I'm sure I'm simply not understanding his statement.

Dave (D&A)
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larkis
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« Reply #7 on: April 07, 2012, 01:31:50 PM »
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I'm not sure of the performance of the 35mm lens. Are there any samples out there ? Plus I do want something that is about 20mm equivalent on a FF 35mm body which the 25 on the pentax comes close to.
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DandA
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« Reply #8 on: April 07, 2012, 01:54:29 PM »
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Hi Larkis,

You might be interested in looking over my review of most of the Pentax FA AF 645 lenses that I used and tested on the 645D, including the FA 35mm f3.5 lens.  The manual focus version of the 35mm is very similar in performance to the Af version with perhaps a bit more sharpness on the sides/edges/corners but with some additional CA present at the wider apertures.  The link to my Penatx 645 lens testing is:

http://forum.getdpi.com/forum/medium-format-systems-digital-backs/35577-comprehensive-testing-results-observations-pentax-645-lenses-used-645d.html

Thanks!

Dave (D&A)
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tsjanik
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« Reply #9 on: April 07, 2012, 01:59:38 PM »
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Dave:

Sorry for the confusion Dave.  I said "..not much more than 35mm.." and I meant it as a hyperbole.  The D FA will be useable on a full frame 645 sensor and is usable on the 645N now - an extremely wide MF lens and perhaps worth the 5k price.  The reduced coverage DA version is restricted to use on a cropped sensor.  Is it larger than 35mm? Yes of course, but not all that much. I find it difficult to justify the price versus 35mm equivalent lenses, e.g. the Nikon 14-24 for 2k or the Zeiss 21mm prime.  Were I to buy the 25mm, I would get the D FA, which will continue to be available in Japan (who knows why?)  If the only difference between the lenses is the extended shade, and I suspect it is since the lenses have the same specs, one has to wonder why Pentax has done this modification for lenses outside Japan.

Larkis the 35mm A is terrific lens for landscapes , you won’t be disappointed.  Very sharp, some barrel distortion but easily fixed.  The FA gets mixed comments; Dave has more experience with it and may add his thoughts.  Here are two examples of the A version.  EDIT: Just saw Dave's response

Tom


_IGP41693 copy 2++ by tsjanik47, on Flickr.


1-17_IGP6821_9757 by tsjanik47, on Flickr
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Lacunapratum
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« Reply #10 on: April 07, 2012, 09:15:40 PM »
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I recently posted a similar question here, trying to make sense out of Pentax's medium format strategy.  In the meantime I have decided to get one in the next couple of months.   Here are some of my thoughts.   

For me it is one more albeit expensive item on top of a long list of existing P645 lenses and accessories.  While it may be one of the most expensive items on that list, its cost is still minor compared to what else I have.  The complete system with telephotos, macro, and soft focus options is so valuable that it makes sense for me to add this one. 

I went into medium format at a time when MF was vastly superior over 35mm in terms of tonal values.  Today, I am not so sure whether "vastly" is still true.  These 40MP sensors pretty much do what I have been dreaming for decades ago.  Ricoh appears to have its plans, but I'd be pretty happy if they keep on making the 645D, perhaps a wide angle and a standard zoom, but that would be all I'd need for the perfect high resolution system for myself.  I am not sure whether I’d be terribly disappointed if they wouldn’t make a full-frame successor, even though it might be a nice option.  Thus, either one of the 25mm options would make sense for me. 

Investing into a new system is always an ordeal, since it isn’t limited to the camera or the first lens.  When you go on a trip you need so much more.  Then there is the different handling and different color processing.  If I (ever) was to once more go back to 35mm (I have 4/3 and m4/3) I'd invest in a Canon system as their lens line-up seems to fit the 35mm philosophy even more.  To me, the D800 and the P645 are so close in terms of creative value that it wouldn’t make sense for me to own both. 

Having a Hy6 system and a Horseman frame, I got one of those 24mm Schneider XL lenses.  There have been some discussion about this lens on the net, but mine is top notch and likely beats any retrofocus alternative, including the Pentax 25mm.  My particular setup is also very usable, even without tripod.  Thus, if I need fast maneuverability, the Pentax 25mm will be my choice; for best image quality the 24mm Schneider will be a nice alternative. 
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DandA
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« Reply #11 on: April 08, 2012, 12:48:27 AM »
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Tom Wrote >>>"The reduced coverage DA version is restricted to use on a cropped sensor.  Is it larger than 35mm? Yes of course, but not all that much."<<<

Hi Tom,

I'm sure it's me (as I'm a bit slow in picking up concepts at times), but I still can't quiet figure out what you mean by the D FA lens used on the cropped sensor 645D, is larger than 35mm but not by much.  Still trying to work out the math in my head regarding this statement.  The use of the full frame DA 25mm lens on the 645D is approx 20mm (in 35mm FF terms).  The D-FA 25mm on the 645D should also be the same, 20mm (in 35mm FF terms).  So my question is even if the D-FA 25mm is ued on the cropped sesor 645D, how can it have the field of view of slightly larger than 35mm (in 35mm FF terms).  I must be missing something???

As for the design changes to the D-FA 25mm vs. the DA 25mm, the longer hood certainly makes it unusable on FF 645, but hard to believe this is the only change, otherwise why would Pentax bother.  At the very least, maybe there are addition coatings to prevent flair and reduce CA and also since they mentioned the full frame 25mm was labor intensive in assembly due to the necessity of precise alignment of all the optical elments on such a wide angle when used on FF 645, that maybe the D-FA 25mm can have the precision of assembly and alignment a little more relaxed, due to its eventual use on on  something smaller than full frame 645.

Dave (D&A)
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pjtn
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« Reply #12 on: April 08, 2012, 03:09:22 AM »
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By the little I have seen of the D800e, under ideal circumstances it will do 90% of what the Pentax will do. It does also have a much more expandable system with more lens options, including those fantastic Zeiss.

However I would stay with the 645D and get the 25mm lens, personally. The viewfinder alone is a compelling reason to stay. It seems as though Ricoh will continue development of the 645D platform so who knows what the future may bring, Nikons cards are on the table already, Pentax remains to be seen.
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tsjanik
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« Reply #13 on: April 08, 2012, 08:47:06 AM »
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Tom Wrote >>>"The reduced coverage DA version is restricted to use on a cropped sensor.  Is it larger than 35mm? Yes of course, but not all that much."<<<

Hi Tom,

I'm sure it's me (as I'm a bit slow in picking up concepts at times), but I still can't quiet figure out what you mean by the D FA lens used on the cropped sensor 645D, is larger than 35mm but not by much.  Still trying to work out the math in my head regarding this statement.  The use of the full frame DA 25mm lens on the 645D is approx 20mm (in 35mm FF terms).  The D-FA 25mm on the 645D should also be the same, 20mm (in 35mm FF terms).  So my question is even if the D-FA 25mm is ued on the cropped sesor 645D, how can it have the field of view of slightly larger than 35mm (in 35mm FF terms).  I must be missing something???

As for the design changes to the D-FA 25mm vs. the DA 25mm, the longer hood certainly makes it unusable on FF 645, but hard to believe this is the only change, otherwise why would Pentax bother.  At the very least, maybe there are addition coatings to prevent flair and reduce CA and also since they mentioned the full frame 25mm was labor intensive in assembly due to the necessity of precise alignment of all the optical elments on such a wide angle when used on FF 645, that maybe the D-FA 25mm can have the precision of assembly and alignment a little more relaxed, due to its eventual use on on  something smaller than full frame 645.

Dave (D&A)

Dave:

The statement was an intentional exaggeration, sorry if that wasn't clear.  My only point is that the D FA 25mm is not a full format 645 lens and should not be priced as if it were.

Tom
« Last Edit: April 08, 2012, 09:06:41 AM by tsjanik » Logged
DandA
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« Reply #14 on: April 08, 2012, 03:11:13 PM »
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Dave:

The statement was an intentional exaggeration, sorry if that wasn't clear.  My only point is that the D FA 25mm is not a full format 645 lens and should not be priced as if it were.

Tom

Tom, I couldn't agree more with your statement although if the D-FA is simply the same lens as the DA 25mm lens except with an extended hood, then both lenses would cost Pentax the same amount of $$ producing both.

I still though can't believe the only difference is the hood, otherwise as someone else stated, why then not modify the original hood to be a "sliding type" to meet the needs of both cropped and full frame format.  There must be something else to all this and the whole story isn't clear yet in my opinion, so hopefully we'll receive some clarification from Pentax soon.

Dave (D&A)

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Lacunapratum
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« Reply #15 on: April 08, 2012, 09:17:58 PM »
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I asked a similar question earlier.  How could we get that sort of a response from Pentax? 
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larkis
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« Reply #16 on: April 08, 2012, 09:58:24 PM »
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Perhaps the people who run pentax forums have some contacts with the company ? I would like to hear more from pentax on this lens and what it can and can't do. Keeping your customers in the dark is not a great strategy especially if they are spending thousands of dollars on the products you make.
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« Reply #17 on: April 08, 2012, 11:04:52 PM »
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Tom,
Nice photos!
Eric
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tsjanik
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« Reply #18 on: April 08, 2012, 11:25:48 PM »
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Tom,
Nice photos!
Eric


Thanks Eric.  BTW the first image is a stitch of two exposures; although the clouds of the front were moving very quickly, there was no problem combining two shots.  Of course if I'd had the 25mm, I wouldn't need to stitch Grin.

Tom
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DandA
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« Reply #19 on: April 09, 2012, 10:38:52 AM »
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Perhaps the people who run pentax forums have some contacts with the company ? I would like to hear more from pentax on this lens and what it can and can't do. Keeping your customers in the dark is not a great strategy especially if they are spending thousands of dollars on the products you make.

My thoughts exactly! This is a $5000 lens just recently released and there is hardly an explanation from them? This really surprises me, especially that 645 customers are not generally newbies entering photography for the 1st time. Regardless of the price point of this camerA, medium format users generally expect both significant and proper communication regarding a manufacturers medium format equipment, especially when such an important running change is made to a new $5000 lens. This is one particular case where Pentax should tread their customer base carefully and try to address concerns in my opinion.

Dave

Dave
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