Pentax-F 1:3.5-4.5 35070mm. Comments please.

Over the past year I have been building up my collection of Pentax lenses using Ebay.

I haven't bought anything very exotic, and have not paid very much. The average price has been under £40.00, for lenses in excellent condition.
Some have been replacements for lenses I used to own, like the lovely 75-150mm zoom (I left my first one in a taxi!), and almost all have been excellent.

The one exception has been the 35-70, which produces muddy, low contrast pictures. I believe this to be the same lens optically as the A version, which gets quite good marks on Stan's site.

If anybody else has this lens I would welcome their comments. It's a useful little zoom, and I'd like to know if mine is a dud, or if they are all like this.

There are a number of 35-70mm zooms, the most useful being the SMC Pentax-A 35-70mm f4 in my opinion. This is because it has a constant aperture value over the zooming range and continuous focusing down to a very useful 1:4 magnification at 70mm.

All the 35-70mm lenses should be sharp, crisp optics and if you have a "muddy" one, then perhaps an element is loose or misaligned or the lens has been subject to some sort of damage.

Thanks John,

Oddly enough the lens was part of a job lot including an SFX, F 75-210, and the 400 flash. None of it appeared to have ever been used. Neither lens has a mark on it of any sort, and the other lens is a cracker. Perhaps the 35-70 has a manufacturing fault of some sort.

George

George

Have you considered my Tamron Sp 35-80 offerd for sale lower down?

Not branded Pentax by very sharp etc. If you are intersted I can e-mil you some pics including enlarged details etc.

Kevin

Many thanks Kevin, but I would really prefer a Pentax lens with AF and auto aperture, so the Tamron doesn't fit the bill, though I am sure it is optically excellent.

Hi George,
Sorry to hear about he 35-70. I haven't used the F version but some years ago I was looking for a 35-70 for the Super A so I could use I as a point and shoot. I came across 3 of the 3.5/4.5 versions and didn't like any of them. The buid quality seemed poor and they all seemed "loose". Then I found an F4 version which I think is cracking. If you are in the market for a cheap mid range zoom, I would recommend the 28-70/F4 FA AL. Constant aperture so it's great for using a hand held meter and the performance is astonishing considering they seem to be about one of the cheapest on the second hand market. I would fully endorse the views on Stan's. At F8 or below, it matches the performance of the 28-70 F2.8 AL and that's saying something. I use mine on the MZ-S almost as a standard lens because the 2.8 is so big to lug around. ffordes have several in at the moment for £50-60 in exc to M- condition.

Failing that I have an FA 28-90/3.5-5.6 in mint boxed condition that's open to offers.

Regards
Kim

Thanks, Kim, that's very helpful.

The 28-70 looks like my best bet.

Rather ominously, I can't find any reviews of your 28-90. I presume it doesn't come up to the standard of the other lens?

George

Hi George,
I have found the 28-90 to be better than the FA 28-80/3.5-5.6. It feels better built and seems to give better results. It certainly isn't as good as the 24-90 (but then it's a good deal cheaper. If you don't mind the shorter range, the 28-70 is the best option IMHO. Guess why the 28-90 going I think one the the reasons there are many reviews around is that it is fairly new and there are so many other lenses in that range that it has been ignored by the more serious individuals rather than any weakness.

I just came across this topic because I was looking to see if there were any comments on zoom lenses in the 35-70mm format.

I have just bought a Pentax-A 35-70mm f3.5-4.5 lens on eBay but I have not yet taken any pictures with it, as I am unimpressed. I cannot fault its condition, as it is excellent-plus. However, it has a loose feel and the front of the lens barrel wobbles when trying to focus. For some reason it will focus on a distant object as much as half a centimetre before the focusing ring gets to the infinity mark. When I turn it all the way to the mark, the image is out of focus. When viewed through the split-screen in the viewfinder a vertical object is completely out of line.

Has anyone else experienced this problem with this particular lens type? I am wondering whether it is a fault with my lens or just a design fault with all these lenses.

You have a potentially excellent lens that sounds as if it is very worn and poor condition. Focusing on Pentax lenses should be as smooth as silk, but not loose and sloppy. Although some very long lenses are designed to focus beyond infinity, usually mirror types that need to be able to compensate for dimensional changes due to temperature, 35-70mm lenses are not.

If you can find one, I have a preference for the SMC Pentax-A 35-70mm f4, not because of quality issues but because it has a fixed aperture throughout the zooming range. This is useful for flash calculations, and for manual matering.

Hi,
When Pentax introduced the A series lenses, the 35-70 was an F4 refered to earlier. This was only in the brochures for about a year when it was replaced by the 3.5/4.5 version which lasted for 5 years before giving rise to the F version. The early F4 version is a very good lens and most of these lenses that I have seen have been in good condition. However, I have come across a couple where the zoom/focus mechanism was very loose. With the latter lenses, at least half or more of those that I have seen secondhand have had problems with the zoom/focus mechanism. Whether this is as a result of build or design quality, I am not sure. I do believe that the later 3.5/4.5 version was introduced as a "budget" option. By the mid 80's, Pentax had a number of lenses in this range, notably the 35-105/3.5 and the 28-80. Argueably, there was no need for another "quality" and, therefore, expensive lens in this range.

IMHO, the 35-70/4 is a very useful lens because of it's compact size and very useful macro capability. However, if these are not vital, then the 35-105/3.5 is a much better lens. It's handling is better and it has a faster but still fixed aperture of F3.5. I would always avoid the 3.5/4.5 version of the 35-70.

Kim

I have recently had these three variants of this lens side by side to test, all bought on eBay for about £20 each. So they are used not new samples, though none seemed to have suffered obvious abuse. I used them on my new *st DS so I can't comment about edge or corner performance on full-frame 35mm film.

A 35-70mm f4
A 35-70mm f3.5-4.5
F 35-70mm f3.5-4.5

My conclusion:

The A f4 constant aperture, though (maybe because) its manual focus and the biggest and heaviest, is the winner. The feel of the focus ring is right, not too light, it is smooth. It focusses closer (higher magnification) than the other two on macro. Macro performance is surprisingly good. Sharpness (over the APS sensor size anyway) is a bit soft wide open but crisp when stopped down, no complaints there. Maybe slightly lower contrast compared to a prime. I was never conscious of 'losing' 0.5f at the wide end or 'gaining' 0.5f at the long end compared to the others. Its too small to even think about. I'm keeping this!

The two f3.5-4.5 versions are identical optically. The manual (A) version feels and looks (IMHO) nicer than the F, but you need to like using manual focus. It is a very light one-touch control which is stiffer on the zoom function than the focus function. Focus touch felt sloppy and imprecise. Performance is good but the close focus/macro is not as good as the constant aperture f4, and the adjustment to macro mode feels imprecise. This went back on eBay!

The F version looks and feels cheap and plasticky, though optically identical in results. To use this in manual focus mode you must use the narrow focus ring and overcome aversion to its uneven and imprecise feel. The adjustment to macro mode is however a shorter rotation and a more positive step than on the A series f3.5-4.5. Autofocus is OK in general undemanding use but couldn't cope with macro properly. Undecided whether to resell this or keep it as an emergency backup (for only £18 and so small and light).

This has turned into a most interesting thread, I've a fair collection of lenses myself but as yet, I've not picked up a 35-70.

I think it may be worth pointing out that 35-70's are often considered standard and as such were supplied with cameras. This lens could well be the only lens bought by the original owner or at least the one that spent most of the time on the camera and therefore is likely to have seen a great deal of use, which could explain the relatively high number of worn and sloppy examples.
I've known of AF zooms that seem a little sloppy due to their design but in the case of A series models, I would think it's largely down to wear and tear.

You're right Kimbo, this is an interesting thread.

I have owned both A versions of the 35-70. I was fairly wet behind the ears (still a little dampness there even now) when I owned my first 3.5/4.5 but always felt quietly impressed by the optical quality, not to mention it's compact design, light weight and useful macro facility. All these issues meant that it was almost the perfect lens for taking around the world with me in my backpack and it did a great job. Then on my return I began to hear good things about the f/4 version so I 'traded up'. The f/4 version has impressed me more since I got it and I used it for a month to take a lot of eBay pics. The lens barrel looks virtually unused on it so I was suprised at the looseness of the focusing ring. I accept that there may be a lot of high mileage A35-70 zooms around but these lenses must be especially prone to this problem. Were they quite 'easy' straight out of the box?

I also had the F version and I can't say that I felt like keeping it for long, despite it being optically identical to the A version. It has a slightly cheap feel to it that practically put me off using it at all and the manual focusing ring is not a joy to use. I have also had the M35-70 f2.8-3.5 and thought it was a bit of a cracker, but too heavy and impractical for my purposes.

Any more loose focusing rings out there?

All the best!

Simon

Hi Simon,
The focus ring on my F4 is great but I think I have been very lucky. The 3.5/4.5 are worse but about 90% of the 35-70 I have looked at have been so loose as to be almost unusable. I have also come across a problem with the 3.5/4.5 in that they can also be notchy and uneven. With the F4 a relube should "stiffen" it up nicely.

Kim