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12-24-2011, 11:57 PM   #1
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Advice using the k135 f2.5 with the K5

I recently purchased a Pentax smc 135mm f2.5 K lens for a good price.

On first use I found it very difficult to get an image in focus hand held wide open. Is this normal for this lens?

Has anybody had problems relying in the focus indicators using manual lenses with the K5?

Later I did use a tripod and managed to get some sharp images. So that must mean the fault is the operator not the lens.

Images are here. kaedepics: Galleries: Digital Photography Review
First 5 images. Sorry for the boring subjects.

Is it possible to get a hood for this lens?

12-25-2011, 12:13 AM - 1 Like   #2
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To get really accurate (manual) focus is harder than you think. And do not use the focus indicator - in my experience (with a K-m) it's absolutely hopeless as a focusing aid (certainly with my 135 lenses). The best thing you can do get lots of practice (with static subjects). A lot of people will change the focusing screen if they foresee a lot of mf work, but, in my view, this is a lot more trouble (and expense) than its worth.
12-25-2011, 12:20 AM   #3
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I've just noticed the shutter speeds you're using for some of these photos: they're far too slow for sharp results, hand-held and with this focal length (even with SR switched on, which I assume you have)! I would recommend no slower than 1/90 sec for best results.
12-25-2011, 01:47 AM   #4
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Thanks for the quick response. 3 of those images were indoors using a tripod and the other 2 were out doors using a fence post. My handheld efforts were utterly useless. Get some practice I will!

Thanks again

12-25-2011, 01:59 AM - 1 Like   #5
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Actually, based on his original post, I believe all the shutter speeds were more than adequate as they were done on a tripod. <- typed before above reply :x

You're just going to have to practice to get good results with manual focus. I agree with m42man that the focusing indicator (green hexagon, not red indicators) aren't useful, at least to a degree. They have a bit too much range, especially at f2.5. However, in my experience with manual shooting I notice if I "over focus" towards infinity and then return I'll have better results. Going the opposite way usually results in missed focus.

Of course you can get a hood for the K 135mm. The original may be available sometimes, and, of course, there is everything from rubber hoods to diy paper ones. Me, I prefer to use empty filter rings (4 I believe) and a 58mm to 49mm step down ring. This then gets me down to a 49mm lens cap.
12-25-2011, 02:23 AM   #6
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Thanks for the response. I will look for a rubber hood tomorrow and practice.

Thanks again
12-25-2011, 03:15 AM   #7
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I have never tried it, but others have written that you can use live view to do manual focusing. Another thing is using tethering and a small netbook type of laptop, thus providing a larger screen to use. There is no tethering officially supported by Pentax, however there is an open source.
12-25-2011, 03:26 AM   #8
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Focus indicator may not be useful in all cases of manual focus; it checks against the focus point(s) selected.
When you are looking through viewfinder, open both the eyes and then it gets a bit easier to judge the focus (I got this tip from a magazine and it works for me).

12-25-2011, 05:52 AM   #9
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I've found no amount of of practice will help much when manually focusing an older lens on a modern DSLR. There may be the odd individual who can manage it but for the rest of us there are KatzEye focusing screens. I believe they are available for all Pentax DSLRs from the IST to K5. See link below.

KatzEye

The split prism/microprism ring makes manual focusing a snap. Just like the old days with film cameras. Depending on options these screens can run over $200 but are well worth it if you have a lot of older manual focus lenses. It made a world of difference when I got one for my old K10. I'll be getting one for my K5 in the new year.

There are cheaper manual focus screens out there as well. I believe there is a thread or two on the topic in the forum someplace.

In any case I think you will find a replacement focusing screen is the answer to your manual focus issues.

Tom G

Last edited by 8540tomg; 12-25-2011 at 10:12 AM.
12-25-2011, 10:29 AM   #10
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What they said...
  • Don't use the focus confirm (pretty worthless)
  • Do use some sort of focus aid (aftermarket screen or Live View)
  • Do consider a tripod or monopod, particularly with a longer lens
DOF decreases as focal length increases and critical focus is hard to manage with the stock focus screen on Pentax (and most other brand) dSLRs.


Steve
12-25-2011, 02:26 PM - 1 Like   #11
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I shoot the Takumar Bayonet and S-M-C Takumar 135/2.5s with no problem on my K20D. Is it just me? With my continually delaminating eyeballs, I depend on these aids when shooting wide-open handheld (in ascending order of help):

4) a cheap katzeye-clone focus screen - for contrasty, well-lit subjects
3) focus-confirm, to tell me I'm pretty close to focus
2) CIF (catch-in-focus) to nail the shot
1) continuous (spray-n-pray)
+) fast shutter

If SHARP images are desired whilst shooting handheld, a fast shutter is vital, even using SR. With SR on, set the shutter to at least 1/FL -- so with a 135, shoot at 160th second. With SR off, go 1/(3FL) or 1/400-500. Of course, turn off SR when tripodded.

Last edited by RioRico; 12-25-2011 at 11:17 PM.
12-25-2011, 06:07 PM   #12
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I have an M 135 f3.5 which I haven’t used on the K5 but on the K10d and K20d had no problems manually focusing at f3.5 using focus confirmation with or without catch in focus. I will try both on the K5 today. Perhaps the K lens at $90 dollars wasn’t such a bargain after all. Superficially it looks great but perhaps there is an internal fault.

I need reading glasses so I can’t rely on my eyesite.
12-26-2011, 12:16 AM   #13
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QuoteOriginally posted by everydaylife Quote
I have an M 135 f3.5 which I havenít used on the K5 but on the K10d and K20d had no problems manually focusing at f3.5 using focus confirmation with or without catch in focus. I will try both on the K5 today. Perhaps the K lens at $90 dollars wasnít such a bargain after all. Superficially it looks great but perhaps there is an internal fault.

I need reading glasses so I canít rely on my eyesite.
I doubt if you have a fault with your lens (especially if you get sharp results on a tripod - and don't forget to keep that shutter speed high when hand-held!), so at $90 it seems to be a real bargain. I find that the focus indicator accuracy varies from lens to lens, particularly with the longer lenses like the 135s. I have several 135s, and they all provide a very "snappy" focus indication (giving the illusion of accuracy), but each will have its own level of inaccuracy (some will focus reasonably well, others will front or back focus wildly). DON'T blame the lens!

Assuming you don't suffer too much from astigmatism, needing reading glasses shouldn't prevent you from having a sharp viewfinder image: just use the dioptre adjustment. I need reading glasses, and do have a little astigmatism, but still find focusing reasonably straightforward (but it certainly needs a lot of concentration, and it's no good for moving subjects - that's where you'd be better off with your M135/3.5 and catch-in focus).
12-26-2011, 07:18 AM   #14
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M42man You are absolutely right I should not blame the lens. It is fine. Had a another go with it today and as you say moving objects are a struggle but otherwise I found relying on my eyesight was the best way and in end I began to find the little red square extremely annoying.

Thanks again
12-26-2011, 12:03 PM   #15
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QuoteOriginally posted by everydaylife Quote
I found relying on my eyesight was the best way and in end I began to find the little red square extremely annoying.
You know of course that the little red square ISN'T focus confirmation. Red square marks a focus point; steady green hexagon confirms focus. Try CIF and this becomes apparent.
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