HD Pentax D FA 28-105

I take it all back ....

Yes, I was one of those who saw Pentax's new 'Full Frame' zoom, the D FA 28-105mm 1:3.5-5.6, as ... well ... a 'full frame kit lens' . And now I own one!

I did my research and realised that my initial impressions were wrong ... based on a few early sample shots that were probably unfairly representative of what the lens was capable of. Thanks to the SRS Bank Holiday Sale I am now the happy owner of this beautiful lens ....









OK, I'll come clean ... its not in the box! I took those shots WITH the new lens

What a lovely item .... The immediate impression is of quality and good design. It is solid without being 'heavy', an excellent size for the focal range, and considering its a 'Full Frame' lens, and has very secure and even feeling zoom and focus rings.

These few were taken with the little F35-70mm, which sadly might be getting less use from now on (its focal range having been well and truly absorbed by its new brother .... although its 'macro' feature, used for these shots here, will still be very useful) ......

















I have already seen some good results from the lens, and I'll be posting some example shots here over the next few days, but its obviously a clear jump up from the 18-55 AL WR, which is already a very good 'kit lens'. I made this purchase as a long term 'investment' into the system, as I hope to get a future K1 or other FF model, and the deal was an opportunity. I see the focal length as still very helpful to me on APS-C in the meantime ... of course, I'm only able to assess the sweet spot areas of the optics, but reports based on K1 use indicate the edges are impressively sharp, with the main issue being vignetting ..... but that is fairly simple to deal with I think.

Handling is excellent ..... what I really like is the new placement of the focus ring behind the zoom ring, and its very easy to flick the fingers over to the focus ring for a bit of quick-shift. Focussing is smooth and very easy, but secure, and the zoom ring is solid and resistant to move, but reassuringly so, and very easy to grip and precisely set. Overall its a impressive piece of ergonomics I must say!

The autofocus is, perhaps inevitably for me, a revalation ..... my first move away from screw-drive, and it is clearly quicker ..... locks on in an instant ... and the lack of noise is amazing! Admittedly, apart from the DA18-55 my lenses are older and noisy anyway, which just makes the new DC motor even more of a pleasure to experience. I doubt the autofocussing could be heard more than a few feet away, and only then in very quiet conditions.

So ..... first thoughts very good indeed ..... I need more time to process some example shots, and I'll post some soon. Please add here any of your own impressions or questions about this new zoom lens ......

Nigel

It is a lovely lens and it maintains its performance through the range very well. Now you really need that K-1 to go with it!

Ah yes, the next step .... Any winning numbers for me John?

I bought one too but my initial impression is it over exposes slightly and tends to lead to burnt out highlights. Other lenses at the same focal length i compared it too didn't over expose the same shots. If I dial in a bit of underexposure its OK but I don't think I should have to do that by default with what is still a pricey lens. I'm debating whether to return it.

I wonder how a lens can 'overexpose' .... Isn't it a camera that determines exposure?

The only thing that comes to mind specifically about these new lens types is that the HD coating is described as having a higher 'light transmission'. Could this be interacting differently with the metering sensors and algorithms....I wonder if firmware can resolve this?

Anyway, a half stop or so compensation isn't an issue, surely? Isn't it part and parcel of everyday photography to need some exposure compensation, for most shots?

I suppose that's true. Just odd though. If the lens isn't closing the aperture enough it will, of course, over expose so it could be a mechanical problem. I mainly got it to use when the weather's poor to avoid lens changing and it's WR to boot so shouldn't suffer problems used in isolation.
The other lenses I was using to compare the exposures were the FA50mm 1.4 prime and Sigma 24-60mm zoom, both of which had identical exposures judged by the flashing red over exposure warning. Indeed the f stop, speed and ISO indicated were the same for all three lenses, it was just the exposures that were inconsistent.
With the new Pentax zoom most of the sky ended up flashing red, not so with the older prime and zoom which rendered the sky quite well. A further test at around 100mm comparing it to the DFA100mm macro produced a similar result. If this is the effect of the HD coating rather than a mechanical problem I'll avoid HD versions in future, but suspect it is a problem that could be dialled out in a service.
If I had the K-1 with only this 28-105 I wouldn't be too happy with the combination. The only other time I've experienced anything like this with the K-1 is with a Tamron Adaptall lens with the 'A' mount. Perhaps that's the common link, Tamron?
I'll try some more comparisons before I decide whether its a keeper or not.

My 55-300 also has a tendency to over-expose in comparison with my other lenses. I have to pull it back 1/3 of a stop to get the expected results. Not sure why this would be but it's the same on my K-5iis and K-3. Also, it doesn't happen with any other lens I own.

Well done on the purchase Nigel, hope you get good results from it and I look forward to seeing some K-1 images at some future time.

Regards
David

Thanks David You may have to endure a fair few more from the K7 in the meantime .... But, yes, I feel rather well prepared for a leap to Full Frame now, when it does eventually come.

John, I'm not sure I would reject a lens, and certainly not an entire coating technology, because of a (what sounds like a consistent) small overexposure issue .... Surely the other qualities of the lens overpower that particular concern, which after all just needs that small compensation adjustment? . You can even set exposure compensation to be retained as you set it every time you switch off in the Memory section of the Rec menu .....

Lets see if anyone else sees this issue with other copies of they lens .... I'll certainly keep a close eye on my exposures with it and report back here.

Thanks Nigel. If it is a Friday afternoon lens it would be best to get it replaced while new. Shame one can't dial in exposure compensation per lens like one can do with focus. Obviously dialling in under exposure would affect all the others so I wouldn't want to leave it set to under expose as a norm.
Anyhow I'll try it again another day before I make any rash decision about it and I'll try it on my K-3 as well.
I'm not short of good quality lenses so if this one's a puck I'll either get it replaced or go without. I've got 30 days to reject it if I decide to go down that route; maybe I'll think differently tomorrow!

According to Which I have a 30-day right to reject. (Under the Consumer Rights Act you have a legal to reject goods that are unsatisfactory quality, unfit for purpose or not as described and get a full refund - as long as you do this quickly. This right is limited to 30 days from the date you buy your product. After 30 days you will not be legally entitled to a full refund if your item develops a fault, although some sellers may offer you an extended refund period. )

However SRS are saying this has to be done in 7 days. They need to get up to date with the 2015 Consumer Rights Act. So I'll have to make that decision quicker than anticipated. If it's faulty I thought I had a year or two??

Of course, if its something that's just a small annoyance it can be enough to put you off using it, especially the niggling doubt about a fault ....I fully accept that in that situation it is probably best to send it back, think again and try again.

Someone else has said something similar about it here:
https://www.dpreview.com/forums/post/57704912

Thought you might like to know that I've given the lens another go. I turned the settings from bright to natural which reduces the contrast and it seems much better. Last night I also had a play with the raw files where it had burnt the sky out and managed to recover good cloud detail in them. Repeating some of the shots I took yesterday don't look at all bad today. Maybe it's redeemed itself, fingers crossed!
If the problem reoccurs the answer might be to create a settings parameter for the lens with a lower contrast as perhaps the lens gives more contrast than others.
I've noticed some of the Ricoh example shots show the syndrome I was getting, no doubt for the same reason. So if anyone else experiences apparent overexposure with the DFA 28-105 try dialling back the in camera contrast setting before rejecting the lens.

Good points, thanks ....I have looked at a few of my first shots now and processed them (from RAW), and I have also seen some burnt out highlights. I do check the histogram when shooting, and I thought it was only touching the right edge, but the burn out is more than I expected and more than I get on other lenses .... So it looks like its a ' thing' for this lens.

You could be right, perhaps it's something to do with high contrast caused by the HD coating? Could it fool the camera into overexposing somehow?

In any case, John, how do you find the other aspects of the lens, handling , and optical performance etc?

Nice buy Nigel. I have one too and am very happy with it. Sure, it could be wider, longer or faster but given that it isn’t it is indeed compact and light for a FF lens and it feels very decent, much like the DA 16-85 (which is a step above the DA 18-135).

I find it very dependable in every way (colour, contrast, sharpness, af speed and accuracy, etc.). Vignetting is not really an issue, it’s actually less than many older FF primes. I haven’t noticed an over-exposure tendency myself, actually I been pretty spot on if I recall correctly. I’ll double-check my originals. Sharpness, across the whole frame, is really high. K-1 landscape shots have a lot of detail. Here are two I made a few weeks ago in France.

Enjoy your lens!

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I don't get any over-exposure either, but i routinely dial in -0.3EV compensation with most lenses. With centre weighted metering this works out very exactly for me.