[Mystic]

I have the opportunity to buy these lenses,
according to Pentaxforums lens reviews 28-70 is better than 28-105, is it really so? is the price difference is taken in consideration? at which price 28-105 becomes better that the 28-70? does it become a better?

can anyone having both of them comment please..?
which is better optically?
can you post any pics taken with any of the mentionned lenses?
thanks.

[jslifoaw]

I owned both at one point. If you get a good copy, both are very good.

Both of mine were awful, with one corner super blurry at certain focal lengths. They have really good colour too which appeals to me.

I use an FA 24-90 instead, and I find it to be much better, but if you can make sure they're good copies, I would choose the 28-105, and consider paying up to $175 for one.

[Mystic]

thanks jslifoaw, for your shared knowlegde.

any other opinions?

[Marc Sabatella]

I've never used either, but most owners of the 28-105 in question are very happy with this lens - it was a very popular kit lens alternative before the superzooms (18-125, 18-200, 18-250) started showing up on the market. I don't see how the 28-70 could possibly be enough better to not want to go with the greater range of the 28-105.

[jslifoaw]

I actually bought it (28-105) on the recommendation of a well-known DPR member and I wish I had used the cash for something else (the FA*24 was only $380 back then for example). After realizing it was a bad copy, it took me considerable effort to get it corrected under warranty, and only after telling the repair shop that they were spouting BS about film lenses not working well on digital. They then took over four months to get it back from Pentax.

I would not buy a zoom unless I got to hand pick my copy. I have had four lenses that were noticeably subpar, even using my mark I kit lens as a benchmark. Incidentally, three of them were highly regarded so maybe they're just "fad" lenses supported by the reputations of well-known forum posters.

[creampuff]

Well I had two copies of each of both lenses. Both my FA 28-70mm were used but were pretty sharp, one a little more so than the other. Both my FA 28-105mm lenses were mint but they do vary a little in sharpness wise. Of the two lenses, if you can find and test a good copy, you can't go wrong with either. Preference would go to the FA 28-105mm for the zoom range, but the FA 28-70 is very compact. Both focus very quick and if you can get over the polycarbonate body construction, make fine walkabout lenses.

[Marc Sabatella]

Of the two lenses, if you can find and test a good copy, you can't go wrong with either. Preference would go to the FA 28-105mm for the zoom range, but the FA 28-70 is very compact.

That's the thing, though - the 28-105 is virtually the exact same size and weight, which is part of what it so attractive to so many. Assuming we're talking about the f/3.2-4.5 version, as the OP is - the f/4-5.6 version is actually considerably bigger and over twice the weight, according to Dimitrov's site.

[creampuff]

Marc, the difference in size between the 2 lenses shows up when they are zoomed to the longest end of the zoom range. The FA 28-105mm is noticeably much bigger because of the barrel extension. There are several f/4-5.6 versions of the 28-105mm and they are mediocre by most accounts.

[Spock]

I had a 28-70 f4 and now I have a 28-105 f3.2-4.5.

28-70f4

The 28-70 was a very sharp lens with minimal distortion but I did feel short zoom range was a bit limited.

The most annoying thing however was the vignetting it suffered at 28mm with a standard thickness filter. I had to buy an expensive ultra-thin filter to avoid vignetting. For this reason, polarising filters could not be used (in any case the end of the lens rotates) and any sort of lens hood was completely out of the question.

A good thing was that the lens hardly changed its length during zooming.

28-105 f3.2-4.5

The 28-105 is comparable in weight size and image performance but has a much more useful range. It's perfect for portraits, pet photos, and as a walk round lens. The large flower shaped lens hood is a nice bonus and the end of the lens doesn't rotate which allows for polarising filters.

It does extend quite a bit at the long end but that's not a problem at all - unlike lenses that extend at the short end (like the DA16-45) which impact on the effectiveness of cameras' built in flashes. In any event, the lens is so light and compact that even at full extension it hardly feels like there is a lens fitted to the camera at all!

I looked at the Tamron-built but Pentax-badged 28-105 f4-5.6 or the earlier Pentax power zoom 28-105 f4-5.6 and they were bulky, clunky and clumsy compared to the f3.2-4.5 version which is faster to boot!

I think the 28-105 is a perfect lens for a digital SLR when used as part of a 2 lens kit along with a wider lens such as a 12-24. I find I use it almost exclusively for day to day or holiday photos only removing it when I specifically want a wide angle effect.

I have the black version which, while made of plastic, looks to be of quality construction. I considered the silver version but decided it looked like a poor copy of the silver 'professional' lenses and was likely to end up looking pretty tatty once the paint started chipping or flaking off.

[Marc Sabatella]

Marc, the difference in size between the 2 lenses shows up when they are zoomed to the longest end of the zoom range. The FA 28-105mm is noticeably much bigger because of the barrel extension.

Good point! Although I wonder (kind of!) how they compare at equivalent focal lengths?

[Spock]

Good point! Although I wonder (kind of!) how they compare at equivalent focal lengths?

Unfortunately I didn't have any overlap in my ownership of these lenses but my 'seat of the pants' impression is that they are 'much of a muchness' optically.

I suspect you'd be hard pressed to spot any difference in a side by side comparison of image quality but there is no doubt the 28-105 is a better overall package.

[Mystic]

thanks for everyone's input, I already bought 28-70f/4 for about 75$ and if everything's alright I will buy 28-105 f/3.2-4.5 along with MZ-6 film camera for about 180$..

do you think it's a good decision?

28-70 seem a good copy, sharp and no front-back focussing.

[EsBee]

I purchased an extremely used copy of FA 28-70mm f4 recently for a bit more than what Mystic paid. It looks and feels quite used but man it takes some sharp pictures wide open, especially on the low end of FL. Currenly it is my mostly used lens on a day-to-day basis.