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04-07-2013, 02:52 PM   #16
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The main problem may be the K5 rather than the lens since they had poor low tungsten light AF from what people said. The K30 works a treat in the low light venues I shoot in. My favourite lens for gigs is the Sigma 50-150. The cheap 35mm f2.4 handles the wider requirements (or if it's really tight I'll use a 24-70 or 20-40).

One thing I've found with the K30 is that when the camera gives up in really low light/low contrast situations using single point AF, switching to 11 point and AF-C nails focus with a lot of success. You just need to watch the focus point illumination and pick your shots.

04-07-2013, 04:12 PM   #17
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Hi Again!

Thanks a lot for all the information posted.

Regarding the focusing screen I have a "Big Screen" split screen focusing screen, bought in a chinese eBay store for 30$. It's still hard to focus using it, the focus confirmation "bip" and red square and my criteria using the split screen give different focuses using the 50mm at f1.4, the big red square and the narrow depth of field are not good friends, in my low experience.

I didn't know about the CiF (Catch in focus or focus trapping) technique, I'm going to try it, let's see if it works. I really appreciate this information you give me guys.

I just bought a FA 1.4 in the marketplace of the forum, I couldn't resist, although I think that I have a lot to learn and a lot to squeeze my manual 1.4 lens.

I just noticed that I'm used to shot in low ISO's, 1600 it's my limit and 800 it's the preferred, even at wide open appertures (1.4 to 2.4) using these ISO's give me a too long exposition times resulting in moved subjects.

I just uploaded a couple of Galleries from yesterday's gig. So you can see my crapy photos.

Here you have them:
Sonic Trash Azkena 2013 - a set on Flickr
Triángulo de Amor Bizarro [Azkena 06/04/2013]álbum nuevo - a set on Flickr

Feel free to coment on anything you want, and by the way, I know I'm a crapy photographer, anyhow, the pictures there cost me a big effort.

All those pictures are taken using my K5 and my Manual Pentax SMC (k) 50mm f1.4 using liveView.

Thanks again!
04-07-2013, 04:39 PM   #18
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QuoteOriginally posted by Baxujolea Quote
Had a look at these shots. Focus is generally OK. Motion blur seems a problem. Your shutter speed was 1/8s-1/15s & ISO was 800-1600. The Light Value ( was 0.9-1.9 LV which is very low, so getting an adequate exposure is a tough ask any time the performers move.

Note: these LVs are appropriate because of the transmission loss with large large lenses on DSLR sensors, due to the insufficiently numerically small f-number of the micro-lenses on each sensel. You're probably loosing 0.4-0.5 stops at f/1.4 with the K-5 sensor, which has 4.75μm sensels. Some cameras will use a different ISO from what they say they are set to, to silently compensate for this loss when you use low f-numbers. But since you are doing this with a mechanical aperture ring setting on the lens, even if Pentax does do this hidden compensation, it won't be doing it here because the camera is not aware of what f-number you're using. See:

I'd suggest going to at least 1/15-1/30s & ISO1600-3200, if shooting JPEG.

If shooting raw, stop at ISO1600 (the last ISO where analogue gain is used and just before raw NR kicks in), but keep the shutter speed up, and accept the darkish captured image. You can boost the rendered image brightness and apply any fancy NR afterwards in PP, but you can't easily fix motion blur.


Last edited by dosdan; 04-07-2013 at 05:14 PM.
04-07-2013, 04:55 PM   #19
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Thanks Dan,

I agree, next time, more iso less exposition time. ;-)

Let's see if I can get the same exposition values doing so, I had isuess because the high contrass on the stage. Light areas tend to burn and the rest tend to darken... The high iso should be compensated with the fast shutter speed... And the subject should not have that motion blur... I need to try it...

Thanks again for the theorical explanation and the "f-stop blues", again I didn't know about that, it's interesting.


Last edited by Baxujolea; 04-08-2013 at 01:12 AM.

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