[luftfluss]

An outstanding and extremely relevant comparison! Thank you so much for providing us with this.

The 4th set of comparison photos (where the blue sky dominates) is really interesting to me. My Pentax M 28/3.5 would render the sky similarly to the Zeiss, while my Pentax 15 Ltd would be more similar to it's 31mm sibling, and would my 18-55 for that matter. Is this "improvement", or a philosophical difference in lens design between different decades?

[taurus9]

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However, there is one significant danger when the screws are to be removed. Make sure to have a very small, sharp-ridged screw driver, and make sure to press very firmly and turn slowly when removing the screws to ensure the screw is actually turning and not being stripped. On mine three of the four screws came out fine, but one stripped because I was careless about applying pressure (I finally got it out though).

Because the lens is made in Japan, the screws are JIS type, not phillips. So, I would recommend buying JIS drivers, and not attempt to unscrew using regular philips drivers or jewellers screwdrivers. On my copy of the Zeiss 28mm 2.8, the screws were glued down, and required heating from a soldering iron to loosen up.
I guess that's reassurance that the lens has never been tampered with!

Great review though; I think I'll start using the Zeiss again to try it out, but unfortunately I tend to use a different lens I dearly love, the Leica R 35mm Summicron type 2. Trying out alt-lenses is extremely addicting - another path to the road of LBA!

[audiobomber]

The 4th set of comparison photos (where the blue sky dominates) is really interesting to me. My Pentax M 28/3.5 would render the sky similarly to the Zeiss, while my Pentax 15 Ltd would be more similar to it's 31mm sibling, and would my 18-55 for that matter. Is this "improvement", or a philosophical difference in lens design between different decades?

I believe it's due to coatings. Newer lenses tend to show a cooler (more blue) colour balance. I don't like the blue tinge, but it's a worthwhile tradeoff for improved flare resistance and sharper contrast.

[ricolek]

Zeiss looks much better.

[paperbag846]

Zeiss looks much better.

+1. Deeper blues and greens. Really beautiful.

[les3547]

Because the lens is made in Japan, the screws are JIS type, not phillips. So, I would recommend buying JIS drivers, and not attempt to unscrew using regular philips drivers or jewellers screwdrivers. On my copy of the Zeiss 28mm 2.8, the screws were glued down, and required heating from a soldering iron to loosen up.
I guess that's reassurance that the lens has never been tampered with!

Thank you for the info . . . if you don't mind, I'm going to copy your advice and post it in another edit note at the end of the opening post.

[interested_observer]

Because the lens is made in Japan, the screws are JIS type, not phillips. So, I would recommend buying JIS drivers, and not attempt to unscrew using regular philips drivers or jewellers screwdrivers. On my copy of the Zeiss 28mm 2.8, the screws were glued down, and required heating from a soldering iron to loosen up.
I guess that's reassurance that the lens has never been tampered with!!

Since I was thinking about converting the mount on my newly acquired Contax 85/2.8 and needed a better screwdriver set - your recommendation came in just the right time.

[Frogfish]

This is a superb review Les (and a big nod to Gordon too). Far more 'real world' and applicable to my photography than many more technical reviews.

As you know the Zeiss is one of two lenses I was considering (the other being the Leica 28/2.8 R) and this has sold it to me. I was also looking at the Zeiss 25/2.8 but the 28/2.8 has better borders though sharpness on both of those lenses is stunning. I'll be getting the Zeiss next week and then looking at getting it converted at my local lens repairer, as lens conversions seem to be very common here.

So it comes down to an extra 10% wider (25mm) or added sharpness across the frame (28mm) and since I want this mainly for landscapes then the 28mm wins. I should add that I will be keeping my Sigma 30/1.4 because it does a fantastic job in low light (almost 2/3 stop faster than the 31 Ltd), for low DoF and is cut-your-throat sharp .... therefore perfect for an entirely different purpose in my new favourite focal length range (28-31).

One question, does the Zeiss retain any information connections with the K5 / K7 ? I was using my Voigtlander 50/1.8 today (Pentax mount) and found that it works perfectly with catch-in-focus even though there are no electrical connections.

[interested_observer]

... One question, does the Zeiss retain any information connections with the K5 / K7 ? I was using my Voigtlander 50/1.8 today (Pentax mount) and found that it works perfectly with catch-in-focus even though there are no electrical connections.

You can use the lens in both Manual and Av modes. It is a purely mechanical lens with no electrical contacts, or should I say that I would expect them to be all shorted (which should make Catch in Focus work also). Anyway, I have the nasty habit of changing lenses with out turning the camera off. In doing this, I have found that the body does indeed remember the focal length if the lens was first mounted when tuned on. I have not experimented if you swap two different focal length manual lenses.

[les3547]

One question, does the Zeiss retain any information connections with the K5 / K7 ? I was using my Voigtlander 50/1.8 today (Pentax mount) and found that it works perfectly with catch-in-focus even though there are no electrical connections.

Okay, I deleted my former post because I changed the answer twice. I just double-checked the K-7 and focus confirmation and catch-in-focus work, but you lose electronic aperture control (and AF of course). If you look at the EXIF data, all f stops are recorded as f2.4, which is strange since the lens only opens to f2.8. Since stopping down also darkens the viewfinder, in low light you have to open the aperture to focus, and then stop down to the aperture at which you wish to shoot. I don't mind that much, maybe a little . . . The camera metered through the Zeiss just fine, and exposed accurately in Av mode.

[civiletti]

You are welcome . . . and I had it set on AWB.

Nice comparison! I think using AWB, though, may have increased the color difference between the lenses. I'd like to see a landscape comparison shot with, daylight, cloudy, or skylight [whichever is appropriate] color balance. That would, I think, show the relative color rendition of the lenses.

[interested_observer]

Okay, I deleted my former post because I changed the answer twice. I just double-checked the K-7 and focus confirmation and catch-in-focus work, but you lose electronic aperture control (and AF of course). If you look at the EXIF data, all f stops are recorded as f2.4, which is strange since the lens only opens to f2.8. Since stopping down also darkens the viewfinder, in low light you have to open the aperture to focus, and then stop down to the aperture at which you wish to shoot. I don't mind that much, maybe a little . . . The camera metered through the Zeiss just fine, and exposed accurately in Av mode.

Afternoon Everyone,

I guess I should have written a complete response, however I really did not want to go off in the the weeds. About a month ago I was looking at a number of images I had taken between the Contax and 31 Ltd, and the shutter times of the Contax appeared to be much faster than those of the 31 Ltd. I posted here about the observation...

• https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/151332-lens-ef...-vs-zeiss.html

The thread produced a lot of interaction - 35 posts, and the conclusion that was arrived at was as follows:

• The 31 Ltd being a Pentax lens that communicates with the camera in Manual and AV modes indicates that its wide open aperture is f1.8
• For any of the all manual lens, the Pentax body will automatically default to f2.4 as the wide open aperture (Av and Manual modes), due to their inability to communicate with the body.

I'll leave it to everyone to read through the thread, however the bottom line is, the f2.4 default is somewhat of a red herring. The manual aperture is set (on the Contax), the body meters the shot, and the most important aspect of all is the image comes out just as intended.

My takeaway from all of this is that in the Av mode, the shutter times when compared to a Pentax lens (that communicates with the body), may look a bit off. This however does not affect the image in any way, since the body meters through the lens with the manual aperture set, the images comes out just perfect (but in the EXIF the aperture is recorded as f2.4 the default value, with the shutter time recorded as shot).

[vrrattko]

You can see the true "potential" of the FA31 wide open from this full size picture (FA31 wide open photo - Alan Chan photos at pbase.com) when it works right. However, I suspect many samples being pumped out of the factory aren't as good as they should be due to loose QC. And by just looking at the OP's pics, it might suffer slightly from this misalignment too if only slightly.

But that image of rendered wall hardly reveals anything of fa31's potential, only hints that corner sharpness might be decent.

[selar]

I don't know how to fix the discrepancy . . . I suppose everyone will have to take my word for it on the lenses' resolving strengths/weakness and handling of DR, or acquire the two lenses and see for themselves!

How about loading full size originals to Skydrive, similar to what I did in the FA31 vs FA35 shootout?

[Frogfish]

Thanks Les & Gordon for the info on CIF this was quite important to me, although I can manage quite well without it I just love it, almost as good as AF and with my poor eyesight and MF lenses it enables me to get so many more keepers. I usually use my MF lenses in full manual anyway so stopping down if needed isn't an issue.

Today I bought both the Zeiss Distagon 28/2.8 in beautiful condition and a Zeiss 85/1.4 in pristine condition (I had my little repair shop guy check them out for me) and I'm now having them both converted to PK mount (reversible), they should be back in 7-10 days - all for less than the cost of a 31 Ltd. Now I'm like a child with Xmas just days away