SMC Pentax-A 35-105mm f/3.5 Macro - How about more data?

[celasun]

<p>(I had posted the below message at another forum earlier and there was no response. I hope shared members of the other forum do not mind my re-posting it here as well).<br>

I have read quite positive remarks on this now long discontinued lens, the SMC Pentax-A 35-105mm f/3.5 Macro.<br>

Its image quality seems to be higher than expected, to say the least. Slight drop in performance reported at image corners is probably irrelevant for cameras with an APS-C sized sensor. However, some information still seems to be missing. Below are my questions to uncover them for future Internet visitors (and for myself, of course):<br>

- What was the original price like when this lens was on the market?<br>

- Does it share its optical design with other lenses of different brands? Anyone particular?<br>

- The ability to keep the focus while zooming in and out is a nice one. Do you know other Pentax zooms sharing this feature?<br>

- The ability to shoot (semi-)macro "throughout" its range is a nice feature. Do you know other lenses like this? And, is there a name for this design feature? (Most, if not all, current macro-zooms go macro-ish at the long end only).<br>

I somehow feel that this lens was quite "different" from the rest. Is it, really?<br>

And, yes; I am expecting one tomorrow :)</p>

[andrewg_ny]

<p>This was and remains a very good lens; above-average optically, solid build. I don't know the original retail price but I'll bet it was somewhat pricey. It's a bit large and front-heavy on a small body; feels better on a body with a grip like a Super Program or LX, a little less comfortable on a ME Super for example. As you probably know, f/3.5 at 105mm isn't super-common in standard (wide to short tele) zoom lenses, this is faster than average. The lens was made in an era when f/3.5-constant were 'pro zooms' instead of the f/2.8 more common today. I'm not aware of any lenses with the same design, I believe it's unique to Pentax.</p>

<p>Most zoom lenses maintain focus reasonably well when adjusting focal length though some will shift a little bit. I think you may be right that the A35-105/3.5 does a pretty good job at this. There are some notable exceptions, like the Vivitar Series I 28-90/2.8-3.5 which I consider an interesting alternative to the lens you mention--it is similar in size (also takes 67mm filters), is also faster-than-average, but has a varifocal design which does not even attempt to maintain focus when you zoom--zoom even a little, and focus needs to be re-adjusted. Since it is a one-touch (push/pull) design however with practice you can start adjusting the focus as you zoom. The Vivitar is available in many mounts, including Pentax-A. Some attribute its 'prime-like' performance--particularly at wide angle--to this less-convenient-to-use varifocal design.</p>

<p>Not all lenses had their 'trick' macro (close focus) modes at the long end, some were at the short end as well. Basically the distinction is that once you enter these 'macro modes' something else is lost--either you can no longer focus to infinity, or focus is no longer held when zooming, etc. On this lens you need to push/pull the focus ring to switch into & out of macro mode at the minimum focus distance. I recall that with the A35-105/3.5 it can focus significantly closer (possibly reaching highest magnification) at the <em>short</em> end of the zoom. Perhaps someone else here can confirm that, I don't have the lens with me now. Unfortunately (and this is a drawback of the relatively long 105mm reach), at the long end of the zoom minimum focus is rather long (1.5m) unless you enter the macro mode. Workable, but somehwhat less convenient. </p>

<p>Pentax basically stopped building lenses with these macro modes with their FA series of autofocus lenses--many of the first-generation AF lenses (Pentax-F) shared designs with the A series, inheriting features like these macro modes. With the next generation, FA, the lenses usually allowed closer focus at any focal length without having to enter any special macro mode...so many of us are spoiled now...but back in the day, this wasn't a given, so for example with many lenses you might not be able to focus closer than 1 meter unless you're at the long end of the zoom. The A35-105/3.5 is notably more flexible than that but perhaps still less flexible than a modern close-focusing internal focus lens.</p>

[miserere_mei]

<p>A short aside on zoom lenses: When using proper lens tech speak, a <em>zoom</em> lens is one that can change its focal length while retaining focus through out the focal range. A lens that cannot maintain focus is called a <em>varifocal. </em>Zoom lenses are harder to design and require more constraints, which is why Vivitar were able to produce multifocal lenses that were quite fast at the wide end. VIvitar pioneered the design of fast varifocal lenses, and as far as I know never built a zoom lens. Varifocals require the use of a single ring so focus can be maintained while zooming in/out. Any of those old lenses with two rings were zooms; those with one ring were most likely varifocals.</p>

<p>Due to marketing ("zoom" sounds a lot flashier and important than "varifocal"), all lenses with a range of focal lengths are now called "zooms". This was already happening in the late 80's because I've read a few owner's manuals (Tokina mostly) where they refer to their lenses as "true zooms".</p>

<p>With the advent of autofocus, it became a design necessity that the focus ring be separate from the focal length ring, and also thanks to AF, proper focus could be maintained by the AF unit while the photographer zoomed in and out. Because of this, varifocal designs flourished amongst consumer zooms, with "true zoom" designs reserved for the pro line of lenses.</p>

<p>Now, an on-topic comment: The only lens that I know of that's similar in specs to the the SMC-A 35-105mm f/3.5 is the Ricoh 28-100mm f/4, which is also a true zoom (as far as I know) and offers a macro mode at the wide end.</p>

[andrewg_ny]

<p>I was also going to mention the Ricoh, I have one of these too. Not sure yet whether it's as good as the others optically, but by spec it's in the same league. It however is not available with a KA mount (Pentax-A compatible, with 'A' position on aperture ring).</p>

<p>Mis, do any severely varifocal autofocus zoom lenses come to mind? I think many may be slightly varifocal but nothing nearly as severe as the Vivitar Series 1 28-90/2.8-3.5.</p>

 

<blockquote>

<p><em>"Any of those old lenses with two rings were zooms; those with one ring were most likely varifocals."</em></p>

</blockquote>

<p>Are you referring mostly to Vivitar or in general? <em>Nearly </em>all manual-focus telephoto variable-focal-length lenses are push-pull, one-touch designs. I assume this is due more to the mechanical design--how far the elements need to move, etc.--than whether or not the lens is a true zoom or not.</p>

<p>Vivitar two-touch: <a href="http://www.bhphotovideo.com/c/product/162972-REG/Vivitar_316194_Zoom_Super_W_A_19_35mm.html#features">19-35/3.5-4.5</a>, <a href="http://forum.manualfocus.org/viewtopic.php?pid=129836">70-150/3.8</a> (particularly unusual example of two-touch tele zoom). True zooms? I don't know.</p>

<p>Also, some Pentax-A one-touch optical designs re-appeared in AF Pentax-F guise as two-touch. Were these varifocal, or were they made one-touch for other reasons (user preference?). Examples: A35-70/3.5-4.5, A35-135/3.5-4.5.</p>

[celasun]

<p>Dear Andrew and Miserere,<br>

Many thanks to you both for providing a wealth of information on my questions; very much appreciated.<br>

I will share my experiences with this lens soon.</p>

[AJG]

<p>I used to own two of these, and they made surprisingly good quality images on my Pentax MX and LX film bodies. When I mounted them on my first Pentax digital SLR bodies I found that they were quite susceptible to lens flare, a problem that I had rarely encountered on film with them. That's why I sold them.</p>

[jeremy_corbin]

<p>My Late 90's Vivitar "A" 28-80 is a two touch (Separate zoom and Focus). It also maintains focus when I change the focal length. It was the first lens I ever purchased (around $100).It's "macro" (read: close focus) is only 1:4 on the long end.</p>

<p>My biggest beef with the lens wasn't the fact that it ghosts a little bit (since this can look nice if used properly) but the fact that the A notch on the aperture ring is fairly useless. It does not communicate any information to the body regarding aperture settings. It didn't work on my ZX-M, and it doesn't work on my *istDS. This often caused some metering issues, which is why I rarely use it, and instead use my Ricoh P 50mm since I know it's sharp.</p>

<p>I have an Early 80's Tokina 80-200 push-pull. It maintains it's focus through-out the zoom range as well. It's generally sharp, but I have not done extensive testing.</p>

[andrewg_ny]

<p>Jerimiah, that's odd regarding the 'A' on the Vivitar zoom, I assume it was f/3.5-5.6? Sounds like a mechanical issue with your lens--a contact was not good, either body-to-lens, or inside the lens the contact wasn't being switched properly when the 'A' position was engaged.</p>

[jeremy_corbin]

<p>Andrew, I've never gotten any information passed to any body with this lens. In "A" or otherwise. I'm almost willing to take apart the mount just to see if I've had a loose wire for the past 12 years. The only reason I know that the body (ZX-M) is reporting properly is that when I mount the 18-55 Kit lens to it, it reports the f-stop. Albeit it's a "J" lens and can't do anything but the Maximum aperture, but the information is reported. Curious thing about the Vivitar: It looks like it has two contact styles. One is flat, and the other is a ball bearing.</p>

<p>Here is a shot of the mount on the Vivitar. (Sorry for the quick-n-dirty) In purple is the ball contacts, in blue is the flat contacts...</p>

<div></div>

[jeremy_corbin]

<p>And just for fun, Here is a shot of the Pentax DA 18-55, the Vivitar "A" 28-80, and the Tokina AT-X 28-85.<br>

All 3 are 2 touch zooms.</p>

<div></div>

[jeremy_corbin]

<p>What really gets me is that the DA 18-55 and the Vivitar "A" appear to have contacts in similar places, but apparently not similar enough to make communication with the body a reality... The Vivitar DOES share a similar pin with my Ricoh "P" lens... The one just to the left of 6 o'clock. It has never jammed on my SLR or DSLR.</p>

<div></div>

[jeremy_corbin]

<p>Lastly, if "A" lenses are supposed to communicate data, does that mean that my Vivitar has NEVER functioned correctly? I'd be willing to open it up and take a look, since I rarely use it. On many levels the Tokina is a much better lens although it's got the tradtional TANK build that even outweighs my Tokina RMC 80-200 f/4.</p>

<p>Here's a shot of the Tokina RMC 2x Teleconverter, the Tokina AT-X 28-85 f/3.5-5.6, and the Tokina RMC 80-200 f/4 push-pull I referred to earlier. Again, sorry for the quick-n-dirty shots.<br>

-Jeremy</p><div></div>

[andrewg_ny]

<p>Jeremiah, The Tokina AT-X is 3.5-4.5, right?<br>

As for the Vivitar, check out figure 2 on <a href="http://www.bdimitrov.de/kmp/technology/K-mount/Ka.html">this page</a>, the contact labeled '*' is supposed to extend on the lens to touch its corresponding recessed body contact when you engage 'A'. I suppose its also conceivable that on some lenses the '*' contact is always 'extended' but is connected/disconnected internally? </p>

<p> </p>

[jeremy_corbin]

<p>Andrew, It sure is. It's quite a bit nicer than the Vivitar, but significantly heavier.</p>

<p>I don't have the Vivitar with me, but that contact binary makes perfect sense. Thanks for the link. I'll have to see if the "A" setting makes the * pin reach out to try to touch the body. I should be able to do that tonight.</p>

[jeremy_corbin]

<p>I fiddled with the ball contact on the right a bit. I didn't notice any physical change when putting the lens in and out of "A" but I <em>did</em> manage to accidentally push one of the plastic plugs through and have it fall into the lens somewhere. Bummer. Good thing it's not an SDM lens with moving parts! </p>

<p>After messing with the ball contact, I remounted the lens on the ZX-M and it now displays the F-stop in the VF. Interestingly enough, it displays an f/4 constant (zoomed out, when it's dark) instead of displaying 3.5. It does meter differently depending on where the zoom is (80 versus 50 versus 28) It seems that the assumption on Table 1 of the link you sent is correct and there is no distinction on variable max aperture lenses. When mounted on the *istDS the aperture was selectable on the body, and metered accordingly. If the lens is set to anything except "A" the lens does not report the f-stop.</p>

<p>Anyway, that was a fun experiment. I can use the "A" as an "A" now. But it was quite strange.</p>

<p>Bulent, what's the word on your new-to-you lens?</p>

[andrewg_ny]

<p>Yes, a KA lens will report only one max aperture to the body. The KAF (Pentax-F) lenses added digital information that included both focal length and current aperture-ring-set aperture, both variable, and taking into account variable-aperture when zooming. The accuracy of the aperture reported to body shouldn't be terribly important unless you're using non-TTL metering such as auto-flash (flash has built-in meter) or a handheld meter. I guess by reporting f/4 it would only be off by +/- 1/3 stop when using flash (most cameras did not have TTL flash back then) which I guess isn't terribly important when shooting negative film or given all the other vagaries of auto flash.</p>

[celasun]

<p>Jeremiah,<br>

My lens also displays its maximum aperture (f/3.5) on the viewfinder.<br>

I have used it for a few test shots.<br>

The resolution and contrast seems to be fine but its color rendition is noticeably different.<br>

A "quick'n dirty" shot showing its contact(s) is attached.</p><div></div>

[ed_yuen]

<p>If you're getting one of these lens, treasure it. I can't attest to all that has been stated by other members of this forum, but I my experience with it is that it is a great workhorse lens. I still shoot film, and have used it alot for mostly family photos and such with a bit of scenic and wildlife stuff (okay critters in and around the yard). the separate focus and zoom functions can be annoying to some but given that it will not lose its focus when zooming in and out is a definite plus. <br>

Now, what am I trying to get at? A while back I managed to pick up two of these lenses in barely operating condition, one with a badly scratched front element and another which had a stiff, poorly functioning zoom. By swapping the latter's front element out and replacing it into the first I got an intact lens that worked. No aberations, no fuzziness in the corners or anything else that would indicate that the lens was in less than satisfactory condition. <br>

Now, maybe I got lucky but it shows me that the lens in question is a well engineered and manufactured piece of optics. I have since given that lens to a cousin of mine who was getting into photography and he has yet to say anything bad about it. I still have three of them, one of which is a spare should something 'bad' happen to the other two. </p>

[celasun]

<p>First Impressions:<br>

I have tested the lens for its macro range using K20D on a tripod. My overall impression is positive.<br>

Most notably, the image quality is practically the same at the center and the borders. This is nice for close range photography.<br>

The lens starts performing nicely at f/4.5. At f/3.5 and f/4 (they are almost the same) the image quality is still acceptable but not "special" in any way (on A K20D). Practically speaking; the resolution is still fine but the contrast is lower and some purple fringing (especially towards the tele end) is present.<br>

Both the contrast & the resolution increase slightly as one stops down from f/4.5 on up until about f/8. Thereafter, the image quality is very good and remains so at f/9.5 and f/11. I did not go further.<br>

My conclusion for this range (<1.50m) is to use it at f/4.5 for portraits and at f/8 for other critical works. For real macro, I have a dedicated lens.<br>

The bulging center of the front element of this lens is at almost the same level as the rim of the filter thread (recessed about 2 millimeters, I guess). So, I believe it must always be used with a hood; even a tiny one made of discarded filter rings would be fine. At open air, the lens will receive much "non image forming" light from about everything in front of the photographer. Althought this may not be a big concern for interior / controlled environment use, the presence of a hood does not harm anything ;)<br>

Compared to digital zooms, it is heavy. Compared to similar lenses from the same era, it is just fine. Overall, I would not refrain from using this lens because of its weight.<br>

I will report my experience with field use later, after my hood arrives.</p>