Redesign for the 645D 25mm lens

[Shashin]

Pentax has redesigned the F DA 25mm--now the DA 25mm. The specs state it will not work on the film bodies and there is at least a cosmetic change to the front of the lens.

Pentax launches medium format all-weather prime - Imaging Resource

 

[D&A]

Curious! I guess we can all speculate as to why the changes and what this might mean for a full frame 645D. My initial guess is the performance on 645 film bodies might not have been optimal with the original 25mm lens (after all) and Pentax felt by extending the hood and whatever other changes they might have made, tweaked performance for a cropped sensor. It also might have addressed the somewhat excessive CA thats been reported to occur with the original version of this lens.

Since this new version seems to be for 645D only, I'm not sure that means no full frame 645 sensor 645D, since other new lenses on the road map are supposed to be full frame like the new 55mm. Instead I think all it means is this one particular lens is not for full frame and that the FA 35mm f3.5 at this point would become the widest agle lens for full frame 645. Of course the 35mm f3.5 field of view in 35mm terms, would end up being a approx 21mm on full frame 645, so Pentax may believe they have the wide angle focal length covered for full frame 645 with this lens as opposed to the newly revised 25mm.

Dave (D&A)

 

[tsjanik]

Interesting, so will copies of the D FA version become more or less valuable? I was curious to see how that lens performed on a 645 N.

Too bad they didn't use the design change as an excuse to lower the price.

 

[tsjanik]

This report indicates the D FA version will be avaiable in Japan, DA version everywhere else.
Seems a bit bizarre.

The only difference between versions appears to be the lens shade.

www.photoscala.de/Artikel/Kommt-Pentax-smc-DA-645-425-mm-AL-IF-SDM-AW - Translator

 

[D&A]

This report indicates the D FA version will be avaiable in Japan, DA version everywhere else.
Seems a bit bizarre.

The only difference between versions appears to be the lens shade.

www.photoscala.de/Artikel/Kommt-Pentax-smc-DA-645-425-mm-AL-IF-SDM-AW - Translator

Hi Tom,

I couldn't agree more...that decision to possibly market both verions seems very strange. It might be due to the fact that there is some stock of the original version in some parts of the world and they didn't want to leave those dealers with lenses that some 645D users might think inferior to the new version, especially if there are advantage or improvements in the new version.

Either that or they are saying when the newer version is used on the 645D cropped sensor, there are distinct advantages but still left the old one in production for 645 film users. I tend to think my 1st theory may be more likely. Of course Pentax doesn't want to upset the few who purchased the original version just less than a year ago and after such a short period of time, already have an improved version.

Its like Nikon not yet discontinuing the D700 while the D800 is being introduced. Its probably that they want to first clear dealer stock of the D700 before its officically discontinued.

Dave (D&A)

 

[Shashin]

+1 The D FA has been discontinued because of this announcement. Pentax will just let the stock run out. If there are problems with the D FA, this is not really the time for Pentax to be announcing it. However, since the D FA is the only 25mm lens that can be used on a 645 film body (and any future 645D releases), then it might get rather a cult following.

 

[tsjanik]

For me, an important aspect of this lens was the use on a potential full-frame 645DII, I'm disappointed that it's now cropped. It's not clear if the cropping is simply the extended lens shade or a redesign of the lens. At 5k, this move by Pentax makes a Nikon D800 and the 14-24 an attractive alternative.

Shashin: the FA version will be offered in Japan, so it will still be produced; this move makes no sense to me.

 

[D&A]

Hi

I stated this elsewhere but I think it might be germain to the discussion. I don't think this revised lens necessarily means that there will be no full frame 645D. It appears to align the image circle perfectly with the older model lens for use on full frame, might have been a labor intensive effort and many samples initially didn't cut it...so to streamline production and make things easier to adjust in assembly, modifications were made to the lens and the image circle and alignment just has to be a bit greater than that needed for the cropped 645D sensor. Theoretical, the new version should be less expensive but Nikon migth not want to ofeend those that already spent money for the older lens stricty for use on their 645D.

Dave (D&A)

 

[tsjanik]

Dave, yours is a logical explanation for the change in designation, but the people who will be offended are those being asked to pay the same price for a reduced image circle lens, particularly since the D FA version will continue to be sold in Japan.

 

[D&A]

Dave, yours is a logical explanation for the change in designation, but the people who will be offended are those being asked to pay the same price for a reduced image circle lens, particularly since the D FA version will continue to be sold in Japan.

Tom you are right and I previously gave this some thought and some might be OK with this is it can be shown that the newly redesigned model of the 25mm does convincingly show a distinct advantage in performance on a cropped sensor 465D vs. the full frame version of the same lens used on the current (cropped) 645D. If there are any performance differences, a guess on my part is either they are small, or if greater than that, only under very speccific shooting circumstances.

Even if Pentax does fully intend to continue to make the full frame version lens, my guess it will only be if there are sufficient #'s who purchase it to make it worth their continuing it. Of course they could do a short run ever few years, just to keep it available in certain markets. Conversely, they may have already stopped production of the full frame version lens, and what is being sold is simply left over stock.

Since any full frame 645D will need a very wide lens, Pentax may feel that the FA 35mm f3.5 on a full frame 645D as it being approx 21mm in terms of feild of view (in 35mm terms), may then be as wide as needed and that the full frame 25mm lens on a full frame 645D digital camera (being approx 15mm on a 645D in 35mm terms), is simply problematic in terms of getting ideal performance on full frame digital or difficult to be able to align each with regards to it's internal optics and precise image circle, and that the costs of doing so, is just too high to make it worthwhile.

I hope this all gets sorted out with additional explanations from Pentax.

Dave (D&A)

 

[Shashin]

Dave, yours is a logical explanation for the change in designation, but the people who will be offended are those being asked to pay the same price for a reduced image circle lens, particularly since the D FA version will continue to be sold in Japan.

You do not know the D FA will continued to be sold--they could be waiting for stock to sell out. I am not sure why I would be offended that one lens has a larger image circle than the other when both image circles cover my format.

 

[tsjanik]

Shashin, check the link I included above. A direct quote:

Changes or new features to its predecessor:
There is not a predecessor. Due to the high production effort for a lens with an image field illumination for the analog 645 system Pentax has decided to offer this focal length in two variants.

Version 1 - DFA 645 25 mm due to the large spread of analog 645 system exclusively for the Japanese market

Version 2 - DA 645 25 mm this lens is intended for distribution outside of the Asian market.

 

[Shashin]

Tom, I have seen that, but a company does not announce a product is discontinued until stocks are out. It is not like Pentax continues to sell lot of film 645s in Japan and, at $5K a pop, I am not sure that lens is being snapped up by film photographers. It could also be trying to justify the model change--perhaps there is something ugly in the D FA and this is allowing Pentax to quietly fix it--it is expensive to run two essentially identical lens models (if they are optically identical) at the same time. If the D FA works fine, why bother changing it? Why go into the extra cost of different production lines, packaging, and supply routes?

 

[tsjanik]

Shashin, you may be right and they will simply sell remaining stocks in Japan. It appears that the only change to the lens may be to the shade, if so why not make it removable so the user can decide if whatever the problems are acceptable in the event of a full frame 645DII or for use on a 645N?

Tom

 

[Shashin]

Tom, I have no idea. It is certainly cheaper to keep producing the same lens rather than introduce a variant. Perhaps they are addressing a problem with the D FA. Only Pentax knows.

 

[surfotog]

Would a redesign be such a bad idea? The original exhibited some serious CA. I was disappointed that Pentax would would introduce a $5000 lens that was so poorly corrected. We're no longer in days past when pentax lenses were a bargain. $5k is nearing Leica territory, and for that price we should expect better.
Alas, I doubt this is a meaningful redesign, only a cosmetic one.

 

[D&A]

Would a redesign be such a bad idea? The original exhibited some serious CA. I was disappointed that Pentax would would introduce a $5000 lens that was so poorly corrected. We're no longer in days past when pentax lenses were a bargain. $5k is nearing Leica territory, and for that price we should expect better.
Alas, I doubt this is a meaningful redesign, only a cosmetic one.

I too doubt it's a major redesign and from we've all seen and heard (and I noted in my lens review as you did above), the 25mm does have a considerable amount of CA under certain circumstances. If I had to take a guess (wild or educated), I would say its possible some/all elements might have received a revised coating and along with the slightly longer hood, and both these changes might be an used as an attempt to reduce CA.

Whether they are truly keeping the original version of this lens in production for full frame users (film) or they know there are still stocks of it....Pentax seems to want current users of 645D to use the revised version and if a current film user still desires the 25mm, there should be a copy of the original 25mm available for sale.

Dave (D&A)

 

[Shashin]

Would a redesign be such a bad idea? The original exhibited some serious CA. I was disappointed that Pentax would would introduce a $5000 lens that was so poorly corrected. We're no longer in days past when pentax lenses were a bargain. $5k is nearing Leica territory, and for that price we should expect better.
Alas, I doubt this is a meaningful redesign, only a cosmetic one.

Do you have a 25mm? I understand folks have been very pleased with this lens on a 645D.

 

[D&A]

Do you have a 25mm? I understand folks have been very pleased with this lens on a 645D.

Yes, agree, those I've spoken with have been please except for excessive amounts of CA rearing its ugly head every once in a while.

Tom, if it was simply a revision of the hood design I think they would have offered a retractable hood for both cropped and full frame sensors. I believe its more than this. Pentax spoke about coatings I believe, so I would guess three changes. The first being the hood. The second, additional glass surfaces are coated or multicoated..or maybe used a newly developed coating. Lastly they have hinted about the difficulty of manufacturing the original lens for full frame (labor intensive), due to the limits of element alignment for such an ultra wide angle used on full frame 645....and so the revised lens has some sort of simpler assembly.

The question is if one had the current 645D and hopes that Pentax might have full frame 645D in the future....would they go for full frame 25mm original 25mm lens or the new version...not really knwoing if full frame 645D will or won't ever be produced. Let's assume new 25mm does have a small but real performance advantage when used on current cropped 645D when compared to original version of this lens.

I think Pentax needs to elaborate on all this. It may simply be that the original version will no longer be made and we are simply discussing remaining stocks of the original lens....as Pentax feels once they go to full frame 645D digital, the FA35mm will surfice as a (thee) ultra wide angle lens for this system due to its approx 21mm field of view on full frame 645 (in 35mm terms.).

Why are we stressing over all this? Hasn't the new D800 superceeded the 645D is the performance catogory? Thats what they say over in that other wildy popular forum! (you know I'm just having a bit of fun since both bodies are remarkable performers, with each skewed towards a somewhat different role and application).

Dave (D&A)

 

[Shashin]

Why are we stressing over all this? Hasn't the new D800 superceeded the 645D is the performance catogory?

I am going to wait for the 36MP Nex 9 APS-C camera...