Pentax primes are only slightly better than low-rated 3rd party zooms - what am I doing wromg?

[l_plate_driver]

I am new to SLR photography - having used a trusty Nikon TW-20 P & S

followed by an Olympus 80G and Pentax 140M, I simply could not pass

up the chance to buy a MZ-10 several months ago. It came with a Sigma

28-80 AL Macro - the results were a mixed bag and only slightly

better than my previous P & S's...

 

Since then, I have bought via Ebay a Sigma 28-70mm 2.8-4.0, Takumar

(non-SMC) 28-80mm 3.5-5.6 and Tamron 28-80mm 3.5-5.6. None were very

good...

 

Thus began my search for pentax primes; having researched the usual

sites exhaustively (stan's, bd's, photozone, etc), I bought the

following - 28mm f2.8, M & K 28mm f3.5, M 35mm f3.5 and A 50mm f1.7.

 

I have compared all my lenses, primes and zooms, using a tripod,

release cable, hood and ISO 200; all photos were taken with an

aperture of 11 to maximise optical performance and at all times,

speeds were faster than 1/focal length. I don't have any filters...

All photos were blown up to 8 x 12.

 

Primes are better than zooms but all seemed somewhat over-rated. The

28mm f2.8 is actually not very good at all...

 

My questions are these:

 

1) What am I doing wrong? I would like to improve...

 

2)Should I be using filters, and if so, which types and brands - in

fact, besides protection what else do filters do? (Such dumb

questions - hence my choice of name!)

 

3)Are my expectations to high - I see many poster-sized photos at

work and hey man, they are so big yet their details (such as the

leaves) are clearer than on my 4 x 6's!!! Different format film or

simply just better technique?

 

Please help; any advice would be gratefully appreciated...

 

L-Plate Driver

[matt_needham]

The poster size prints may be taken with medium or large format gear. I personally rarely enlarge 35mm beyond 8x10. For fantastic 16x20"+ prints I grab my Pentax 67II or 4x5 view camera.

[paul_quirk]

Sometimes, the quality of the film has a lot to do with the quality of the picture. I personally find that when using primes, the difference in quality when compared to zooms is much more noticable when I'm using, say, Fuji Velvia 50, or high quality 100 iso film. When shooting 200 and up, the grain becomes noticable, and the lens quality is not as important. I like to use Fuji 800 for a fast film myself, but the pictures taken with my zoom look about as good as when I'm using one of my prime lenses at that film speed. Especially considering that the Sigma's and Tamron's aren't exactly terrible lenses, and decent point-and-shoot cameras generally also don't have terrible lenses. Those "Lesser" lenses are well-matched for iso 200 film and up.

 

Another thing to consider when using high quality, low ISO film is you'll tend to get better latitude. However, I would suggest investing in a tripod (if you haven't already) and a remote shutter release before considering going with such a slow film. The results of Velvia 50 are stunning, and can only be fully appreciated with a slide projector and a sufficiently large screen.

[paul_quirk]

By the way, Matt, at 16x20, you'll be hard-pressed to tell the difference between one made from a 35mm picture shot on Fuji Velvia 50 using a good quality prime lens and one made by a medium format camera. The Fuji Velvia 50 is that good.

[jbq]

You want to actually compared the lenses at f/5.6. That's the sweet spot for many primes. If at all possible, shoot slide (consumer ISO 100 slide film will do) and compare with a 10x loupe on a light table.

 

There aren't any secrets for high details. Beyond about an 8x magnification the film resolution starts to be a limiting factor if you want critical resolution, even if you shoot with good film, good lens and good technique. I wouldn't think about going further than 12x. You figure it out, in order to retain critical resolution on a 30x40 poster you need to shoot on a much larger piece of film, at least 4x5.

[robert_davis2]

I agree that it's likely those primes are likely better at wider F/stops. One thing to understand is if you stop down far enough you can make even a really bad lens look good. That means the difference between lenses isn't that great.

 

It's possible you've gotten bad samples. While I doubt it's likely since you are testing so many different lenses but sample differences do exist.

 

Something people forget about enlargement with 35mm film is that you have to start by shrinking the image down to fit the tiny negative. The negative only contains so many possible spots.

 

Filters filter light. They remove the light they are designed for. That ranges from a simple UV filter that is supposed to cut down on UV. To a filter to correct tungsten lighting to daylight. To various special effect filters. Then you've got all the B&W filters. Mostly filters are artistic choices.

 

The simplest way to improve is to go up in size. Bigger formats shrink the orginal less and then need to enlarge the negative less. Both mean better results.

[paul_quirk]

Good point, Jean-Baptiste. I almost forgot. On some Pentax lenses, the sweet spot for the lens is marked in orange. For instance, on my 3.5 28mm lens, it's F8 with the focal length set at 3 meters (10 feet); that also puts it in hyperfocus, meaning everything from 1.5 meters on will be in focus. So for that paticular prime lens, I'll want to try to stay at or near F8.

 

There is no such marking on my 50mm prime lens, however. Perhaps it's good at any aperature setting, not having any paticular sweet spot.

[paul_quirk]

"The simplest way to improve is to go up in size."

 

Simple only if money is no object. Medium format is expensive, and it's the cost that makes it complicated. For those of us who are on a budget, the simplest way to improve is to go with slower, good quality slide film. Nothing is simpler than dropping in a roll of the best film, Fuji Velvia 50. No new gear to learn about, no 2nd mortgage to buy the gear, etc...

[robert_davis2]

Larger formats are expensive if you make them. Used TLRs aren't that much money. In todays market even some newer MF cameras aren't too expensive. For the cost of a *ist film body you can buy a used 4x5 camera and a lens.

[fred_mueggelhopper]

You need to be more specific here, to address your quality

issues. What part of the results are you unhappy with,

sharpness, contrast, colors? You state that you are new to SLR

shooting, but have bought 7 lenses to improve. Have you read

any SLR instructional books, or taken the time to learn to use the

camera? Try Shooting the 50 or 28 only for a month or two until

you become thoroughly familiar with them.

Now about F11....it is not always the optimum aperture. It is

good for depth of field, but optimum sharpness can usually be

achieved at 2 or 3 stops down from maximum aperture. your

28/2.8 will be very sharp at f/5.6.

Do not buy anything else. Pick one slide film and one lens.

Read some books, and learn. Record your exposures. Enjoy!

[Troll]

It's possible that the camera focus is off, and there's nothing the matter with your lenses. Have it checked by a competent repairman.

[keith_merrill]

I can't beleive that you have a print quality issue with the 50f1.7. I have this lens and find it amazing, sharpness, resolution, bokeh, flare resistance, build quality. I haven't heard a good thing about the 28f2.8 lenses, but I haven't had one, so I can't comment directly, but I can tell you that the build quality of the older k and m lenses is better than sigma and tamron offerings, even current ones.

 

If your not getting good 4x6's, then something is wrong with your film, development, printing ect... and its not the lenses. If you are taking this stuff to a lab, then try a different one, or as others have said, shoot chromes and then judge.

[lacey_smith4]

ok, much of what has been said is correct. So, I will limit what is really a long diatribe.

 

f11 is terrible for testing. It is not so much that with stopping down to f11 the bad lenses get better (they do, to some degree), but the good lenses get worse (diffraction errors worsen with stopping down, and if you say that the theoretical target of 35mm is in the vicinity of 100 lpi, f/11 is around that border of diffraction error (estimated by 1500/fstop). And, that is the BEST you can do, even theoretically, and before optical quality is factored in, and certanyl before film/production issues are considered. (Nonetheless a good lens at f11 is better than a bad lens).

 

This all has to do wiht optimal performance, at the plane of focus, and nothing to do with depth of field, hyperfocal distance, etc. That has to do with getting the best compromise on depth of field and focus, not resolution/contrast/etc.

 

So, a prime, at f1.4 or 2.0 or 2.8, may indeed be better stopped down 2 or 3 stops, and its "best" may well be f2.8 to 5.6. In other words, they are best where the zooms are at their worst -- the zooms' widest apertures. So, the usual f4 zoom is not even getting into its prime, until f8 or 11, and thus approaching its downhill performance cycle. So, for "optimum", they have a fairly limited range of a couple stops (understand, I am not saying they are unuseable, but not at their personal best).

 

Couple more comments. One, modern zooms, computer designed, are really heads and shoulders above those of 20 years ago, and the prime vs zoom difference is indeed less than was true 20 years ago, maybe even 15 years ago. On the other hand, many primes, however good they were, have not really been updated, or redesigned in decades. There simply is not much market, and their performance already optimized. (Unless you get to the Very Fancy Professional levels -- the Pentax 85 f1.4, the 45 or 77 special editions, which are pushing envelopes. Here the competion is the Expensive ones Leica, Canon L, Nikon upper crust, etc. -- not the consumer grades).

 

Second, telling the difference can be a real challenge. There are mtf curves, that hint at fact -- it is not simply resolution, but micro-contrast (and these may be in competition). An example -- for the really fussy, use something like the underside of a fern leaf (with the tiny round spores), shot from about 6 feet (for a 50-100 mm lens). Then, compare with a high power loupe, on a good ASA 50-100 slide (preferably slides, not from a print, initially). If you compare side by side shots, you will find the better lens has recorded the spores aslittle bitty round balls, clearly 3-d in shape. A mediocre lens has nice round discs, but flat in appearance. A bad lens has fuzzy circles. That, in terms of relative size, means the difference is easiest to quantify in very tiny nit-picky details. However, it translates into sparkle and piz-azz in the macro print. Whether a hair strand is not only seen, but if it looks 3-d instead of flat.

 

The whole print issue gets bogged down into other aspects of lens (AND PRINT) personality. But, for instance, color rendition may be subtley different, and, for a while, Pentax optimzed its better primes for superb central performance, risking a (minor) drop-off in the corners (or so it is said). How they handle flare is another BIG area (take a shot with a tungsten light (as a point source) just out of one corner of the frame), also what the out-of-focus rendition is ("Bokeh"). So, any/all of these may also surface in a better lens.

 

Remember the lens is but one step in a cascade 1. subject (contrast/detail/lighting/movement) through 2. LENS to 3. film plane (movement, focus, flatness) to 4. film (grain, etc.), 5. developing (can be destructive), 6. printing (that can cut a 100 lpi lens-film recording to 10-20 lpi), 7. then final presentation/viewing. None of these steps can do anything but DEGRADE away from the optimal -- you controlled for shake, but did not choose optimum f-stop, You used an ok but not great film, and your comparison target, on the final, may be weak.

 

Oh, by the way, one GREAT advantage of primes is their f1.4-2.8 open aperture. In essence, you can gain 1-2 shutter speeds over your zooms in the comparable range -- thus a much "sharper" picture. (regardless of the 1/focal length admonsihemnt, that is only a safety estimate for fastest hand-held speed, and even with a 50mm, the difference between 1/60th and 1/250th is discernible. We may "get away with" 1/30th, or whatever, but to get the most out of the lens, tripod it (you did), or fast shutter speed. Be willing to sacrifice some depth of field for shutter speed (if your target can accept a narrower plane of focus).

 

As mentioned above, some SLRs need focus adjustment. Not a do it yourself thing, but the focus plane of the prism view may not match the film plane. Although I do not know the history of the MZ series, I suspect that modern computerized construction has lessened this error, as it was always an adjustment of tolerances.

 

[david_bradley1]

<blockquote><i>

One thing to understand is if you stop down far enough you can make even a really bad lens look good. That means the difference between lenses isn't that great.

</i></blockquote>

Have right. Half wrong.

<p>

If you stop down enough then all lenses become equally bad because diffraction limits the sharpness of the lens -- any lens.

Therefore it is true that at small aperatures the difference between a good lens and a weak lens is not very great.

The part that is wrong is, "if you stop down far enough you can make even a really bad lens look good".

If fact, just the opposite is true: if you stop down far enough you can make even a really good lens look bad.

[matt_needham]

I have to disagree, Paul. I shoot 99% BW, but I have a buddy who shoots exclusively Velvia and Provia in 35mm, 6x9cm, and 4x5". I agree that they do all look spectacular at 16x20", but there's really no trouble spotting the 35mm work when side by side with prints from the bigger formats.

[John Farrell]

Did you take up photography to make pictures, or to test lenses?

[Sandeha Lynch]

L-Plate ... I don't mean this a joke but quite seriously. Do you wear glasses? Have you had your eyes checked? Glasses will set your eye off-centre against the viewfinder, but a rubber eye cup helps enormously. And even then, just half a diopter off will skew your focus - the image may 'look' sharp to your eye, but in reality it will be off.

<p>

And secondly, have you tried different processing shops? Some are good, some are consistently terrible.

[bill c.]

***"All photos were blown up to 8 x 12"***

 

No, no, no, no, no. Do not ever try to evaluate the sharpness of a lens based on somebody else's prints. What you end up evaluating is the sharpness of the lab's enlarger lens.

 

There is one and only one way to check the sharpness of your lens, and that is with transparency (slide) film. Get the sharpest film you can find (Fuji Provia 100 might do but Kodachrome 25 or 64 would be better), take test shots as you outlined--with the exception of using wider apertures, say f8-- and look at them with a high-quality maginfying loupe (often I use a 50mm lens reversed).

 

I am a working pro who uses both Pentax and Nikon equipment. Once I purchased a cheap Pentax zoom from a friend off the Pentax forum, a 70-210 4.5-5.6. I used it to shoot whitewater kayak slalom racing in bright sunlight, along with my Nikon N90s with a very expensive 80-200 f2.8 Nikon lens on it. When I got the chromes back, I was looking at the shots, and thought, "Wow, that Nikon lens is incredibly sharp!" Then when I was editing through the stack more I realized that those pictures had been taken with the cheap used Pentax zoom! It is one of the sharpest lenses I have ever used, including primes. -Bill C.

[rod_sainty2]

You should be able to get great shots from your existing gear. You don't specify whether the problem is sharpness or colour quality. Bill's answer above is spot on, and I'll add just a bit more:

 

1. For testing lens sharpness, a shutter speed of 1/focal length is too slow. It's easy to get soft shots at 1/60th sec using a sharp 50mm lens until you're more experienced. Plant the camera to a sturdy tripod, use a cable or remote release, or use 1/250th sec at least. As Bill said, testing lenses with anything other than ISO 50-100 SLIDE film is a bad joke. Use a 10X hand lens to compare. Other possible issues are a misaligned mirror or viewscreen, impact damage (should be visible) or yep, your eyes. Eliminate the camera body as an issue by swapping to another Pentax body somehow.

 

2. If the problem is colour, perhaps the exposure is off. are the slides bleached out from overexposure? Vary your exposure on a particular scene by shooting at half-stop increments. As a guide, the exposure for ANY landscape scene illuminated in full sunlight under a clear sky ought be f16 at a shutter speed of 1/ISO (eg 1/60 with K64, 1/125 with ISO 100), though you may prefer f19 or f22 on light scenes like snow or sand.

 

By the way, the Pentax-M 28mm f2.8 often gets a bad wrap on the web, but I suspect the reputation comes from print comparers. Mine was sharp, and I recall that it rated mostly better than the Nikkor 28mm f2.8 in Popular Photography's original test results (March 1978 issue for the Pentax).

 

Regards, Rod

[l_plate_driver]

I would just like to extend my sincerest gratitude and appreciation to all for contributing such thoughtful and insightful answers in response to my posting.

 

With your advice, I am sure I shall improve. I might even be able to call myself P-Plate one day!

 

BTW, I have used the same processor for awhile - doing so after much shopping around. After mucking around with my brother's ME super (I remember he loved the Pentax 135mm) as a young one 20+ years ago, I finally got the chance to take a pic with a SLR when a friend lent me a Nikon EM along with Nikon 35mm and 100mm lenses last year. I remember being literally thrown away by the detail, sharpness and beauty of the images - all this with ISO 200, prints, no tripod and without observation of 1/focal lenght shutter speeds. I still get the same reaction everytime I look at those pics, even now. When I finally got my hot little hands on my own SLR, I suppose I was expecting to take such pictures as well... Admittedly however, for some reason, the images were of appreciably lower contrast. Anyway, I will stay with Pentax - for a start, second-hand wise, it's much better value for money. I would also feel more comfortable blaming myself rather than the equipment.

 

Thanks again!

[imaginator]

Testing lenses can be very tricky... and very misleading. many, many variables! Unless you use a "controlled" experiment approach, you'll never know what caused the results. Not shading the lens would certainly cause reduced contrast, and then there are also film/printing issues. What was the subject? What specific film, and what paper was it printed on? Did you bracket exposures? Did you even look at the negatives to judge exposure (density) Underexposure can make for some crappy prints, add to this printing on the wrong paper, and so on... not to mention your own camera techniques, like focus. Many zooms are "variable aperture" so just because it shows f/11 on the ring, it might be closer to f/16 when the zoom is at the long end, so the exposure won't match a prime at f/11 (I made this mistake once when comparing a 28-80mm zoom and a 70-210mm zoom, both set at 75mm. The 1 stop difference made my test uselss because I used slide film and manual exposure settings. I use a topo map and stuffed animals as subjects, plus some real life subjects. You should look at Bob Atkin's website... good info on lens tests.