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06-15-2016, 06:57 PM   #1
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28-45 plus 25?

Does anyone own both these lenses and is it worth it? I have the 28-45. Sometimes I want to go wider and my choices are to go to a different camera (ie thinking about a K1) or get the 25mm but does the extra 3mm less make enough difference to be worth the expense of owning both lenses? This is for landscape shooting only.

Unlike the Pentax 15-30 on K1 the 25 does at least have a filter slot for CPL and I assume for ND filters and maybe even GND filter?

06-15-2016, 09:12 PM   #2
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I own both the 28-45 and the 25 (DA version). Whether or not it's worth it is a very personal decision, especially given the relatively high price of the lenses (as an aside, I would suggest that the prime is much worse value than the zoom because it costs much the same, covers just one focal length and is less good optically).

The 3mm does make an appreciable difference, so if your need is often to have a wider angle of view, it does help. But much less than I would wish - a wider prime would be preferable and give better spacing between lenses. If I had not already owned the 25 when the zoom came out, I doubt that I would have bought the prime. But there have been times when I have been glad I have both.

I am an obsessive kind of chap, inclined to think "it's not wide enough, but even a small increase in angle of view gets me closer to what I want, so I'll have it." I'd say it's only worth it if your mindset is similar or if you find yourself with slightly too little angle of view with the zoom. The difference is appreciable but not massive.

As for the quality of the prime, the zoom beats it. But if you stop the prime down and use it carefully, including considering field curvature, it's very good indeed (and certainly good enough to use in preference to a lens that's just too long).

The drop-in filters are fine for polarisers and solid NDs, but not grads. I used a custom holder with the 25 to allow me to utilise big Lee grads; quite possible. But the DR of the Z, together with bracketing, means I don't use grads much any more.

All this would be solved if they launched a lovely, sharp 21mm f2.4 prime! (Sorry - just beating my favourite drum!)

Last edited by Ed Hurst; 06-15-2016 at 09:19 PM.
06-16-2016, 12:58 AM   #3
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I have both the 645Z + 28-45 and the K-1 + 15-30. I actually do not think the 15-30 is all that great, especially using it handheld. The K-1 struggles with accurate auto-focus at the wider end, will get it right approx 50%. It is ok on a tripod, but still no 645 system. Plus filters on the 15-30 are a trouble. In fact I am having my doubts on the K-1 as a whole, I feel at this stage that its a bit of a dog, but I need to spend much more time with it to evaluate as its a picky thing to get optimal results with, a very different beast to the 645z which is a easy to get top quality results with.

I am most likely going to sell the 15-30 and get either a Zeiss ZF.2 18mm f/3.5 and adapt it to ZK with Leitax, or a Zeiss ZF.2 15mm and adapt it, or wait till the new Irix 15mm f/2.4 for Pentax K comes out, as all 3 of them can take screw in filters.

One thing to note, many people had QC issues with the DFA 25 and DA 25 for 645, some of them just falling apart.
06-16-2016, 03:12 AM   #4
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QuoteOriginally posted by 2351HD Quote
One thing to note, many people had QC issues with the DFA 25 and DA 25 for 645, some of them just falling apart.
This is actually what let to the premature discontinuation. Hopefully they figure out what went wrong and re-release the lens!


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06-16-2016, 03:57 AM   #5
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QuoteOriginally posted by Adam Quote
This is actually what let to the premature discontinuation. Hopefully they figure out what went wrong and re-release the lens!
Yes let's hope Adam, would be a treat to have a replacement for it, maybe even a little wider perhaps!
06-16-2016, 04:14 AM   #6
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The difference between 25 and 28 should be somewhat noticeable but not enough to buy a new lens for in my opinion. According to this FoV calculator you increase the horizontal field of view from 76,3 to 82,7 degrees.

To get significantly wider angles I think K-1 and the Irix 15mm f/2,4 (100,4 degrees H) looks very interesting. Both considering the FoV, filter possibility and the K-1 pixel shift function.
06-16-2016, 03:54 PM   #7
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QuoteOriginally posted by Simen1 Quote
The difference between 25 and 28 should be somewhat noticeable but not enough to buy a new lens for in my opinion. According to this FoV calculator you increase the horizontal field of view from 76,3 to 82,7 degrees.

To get significantly wider angles I think K-1 and the Irix 15mm f/2,4 (100,4 degrees H) looks very interesting. Both considering the FoV, filter possibility and the K-1 pixel shift function.
Yes I agree the Irix looks very interesting but no news on availability yet. The reason I was asking about the 25 is its the only available super wide for the Z and I had an opportunity to bid on a kit that included it. I think I may pass for now because of the cost of it and see what transpires with the Irix lens or Pentax own roadmap prime wide angle.
06-17-2016, 12:09 AM   #8
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QuoteOriginally posted by 2351HD Quote
I have both the 645Z + 28-45 and the K-1 + 15-30. I actually do not think the 15-30 is all that great, especially using it handheld. The K-1 struggles with accurate auto-focus at the wider end, will get it right approx 50%. It is ok on a tripod, but still no 645 system. Plus filters on the 15-30 are a trouble. In fact I am having my doubts on the K-1 as a whole, I feel at this stage that its a bit of a dog, but I need to spend much more time with it to evaluate as its a picky thing to get optimal results with, a very different beast to the 645z which is a easy to get top quality results with.

I am most likely going to sell the 15-30 and get either a Zeiss ZF.2 18mm f/3.5 and adapt it to ZK with Leitax, or a Zeiss ZF.2 15mm and adapt it, or wait till the new Irix 15mm f/2.4 for Pentax K comes out, as all 3 of them can take screw in filters.

One thing to note, many people had QC issues with the DFA 25 and DA 25 for 645, some of them just falling apart.
The whole filters thing is my biggest reservation about the 15-30 as I use them all the time. I've made a decision to get the K-1 and the 24-70 then wait and consider my options for the ultra wide later - hopefully the Irix pans out well.

The 645Z will remain my core landscape camera which suits about 80-90% of my shots, the K1 is a backup and also gives me some longer focal length. It's also an experiment for me to see how it goes against my 20 year experience with Canon and if I warm to it whether I sell out of canon or keep a foot in each camp. At this point in time I can't see myself getting rid of my 5D3 and 50mm f1.2.

I am curious why you refer to the K1 as 'a bit of a dog'?

06-17-2016, 01:59 AM   #9
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Mainly because I am getting such inconsistent results with it, mainly handheld. Sometimes sharp, sometimes crappy, even at 15mm and 1/250.

It's like the IBIS or autofocus is poor and not consistent.

I am debating keeping it of getting a Sony A7 system. They deliver consistently.

It's funny because I get nothing but superb results from my 645z, tripod or handheld.
06-17-2016, 02:23 AM   #10
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QuoteOriginally posted by 2351HD Quote
Mainly because I am getting such inconsistent results with it, mainly handheld. Sometimes sharp, sometimes crappy, even at 15mm and 1/250.
I think it's down to the spread of your grip on the lens/body. On a Canon 1Dx, I can hold the 200/2 or 300/2.8 much more stable than the 85/1.2 or 50/1.2. As your hands become closer then the whole things approaches a single point of contact/support whereas longer lenses become a double point.

I think that working at portrait distances most detail will cover quite a span of pixels whilst more distant landscape features covering fewer pixels will "smear" more obviously for the same actual movement.

Bob
06-17-2016, 02:26 AM   #11
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QuoteOriginally posted by 2351HD Quote
Mainly because I am getting such inconsistent results with it, mainly handheld. Sometimes sharp, sometimes crappy, even at 15mm and 1/250.

It's like the IBIS or autofocus is poor and not consistent.

I am debating keeping it of getting a Sony A7 system. They deliver consistently.

It's funny because I get nothing but superb results from my 645z, tripod or handheld.
My initial use will be on a tripod mostly but I will certainly be interested in assessing its AF performance in comparison to my Canon bodies.
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