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**Bill_R** · 05-21-2011, 10:46 PM

I'm thinking of getting a DA 55-300 as a reasonable and cheapish starter lens for zoom. I've just noticed in the k-r manual that the focus indicator is only available for lenses with maximum aperture of 5.6 or faster.
Since at 300 mm the DA 55-300 is 5.8 does this mean at 300 the focus indicator doesn't work or, in practice, is it so close it still functions?

gp1806 · 05-22-2011, 07:04 AM

I have a DA L 55-300mm and a K-R. The indicator works for me. You should be OK with that lens.

Poolhall · 05-22-2011, 09:23 AM

Me too -works fine and I tend to leave mine set at f8 in av mode for shooting pics of small birds and focus it manually. No problems from 55-300mm either with the indicator.

**Bill_R** · 05-22-2011, 02:17 PM

Thanks all.
I thought it might have to do with not stopping down to focus and therefore there being not enough light with a max aperture of above 5.6 - what you set it at being irrelevant since it hasn't stopped to that yet. It possibly still does but seems this lens has enough light when at 5.8 and 300 mm - which is good

Might also explain why the lens can hunt a bit at longer focal lengths. Or does it sometimes hunt at all lengths?

Swapnil · 05-22-2011, 02:50 PM

Originally posted by Bill_R

Might also explain why the lens can hunt a bit at longer focal lengths. Or does it sometimes hunt at all lengths?

AF system works on Contrast detection and Phase detection philosophy. Not Sure if K-r uses phase detection but at longer focal length even the slightest shake can cause great deflection. Just think of it as ripples in water, at the origin the ripples are barely visible but at the ends they can look like waves.
Since there is constant change in contrast in AF point. System finds it hard to focus it quickly. Hence, it keeps hunting for sometime.

**Bill_R** · 05-22-2011, 03:50 PM

Originally posted by Swapnil

AF system works on Contrast detection and Phase detection philosophy. Not Sure if K-r uses phase detection but at longer focal length even the slightest shake can cause great deflection. Just think of it as ripples in water, at the origin the ripples are barely visible but at the ends they can look like waves.
Since there is constant change in contrast in AF point. System finds it hard to focus it quickly. Hence, it keeps hunting for sometime.

Thanks for the info Swapnil.

Specs for the k-r gives:

TTL: Phase Matching autofocus
LiveView: Contrast detection + Face detection, Contrast detection, Phase Matching. Phase Matching in LiveView performed by the AF Sensor.

05-21-2011, 10:46 PM	#1
Bill_R Site Supporter Join Date: May 2011 Posts: 262	Focus indicator k-r da 55-300 I'm thinking of getting a DA 55-300 as a reasonable and cheapish starter lens for zoom. I've just noticed in the k-r manual that the focus indicator is only available for lenses with maximum aperture of 5.6 or faster. Since at 300 mm the DA 55-300 is 5.8 does this mean at 300 the focus indicator doesn't work or, in practice, is it so close it still functions?

05-22-2011, 02:50 PM	#5
Swapnil Senior Member Join Date: Apr 2011 Location: Bellevue Photos: Gallery \| Albums Posts: 147	Originally posted by Bill_R Might also explain why the lens can hunt a bit at longer focal lengths. Or does it sometimes hunt at all lengths? AF system works on Contrast detection and Phase detection philosophy. Not Sure if K-r uses phase detection but at longer focal length even the slightest shake can cause great deflection. Just think of it as ripples in water, at the origin the ripples are barely visible but at the ends they can look like waves. Since there is constant change in contrast in AF point. System finds it hard to focus it quickly. Hence, it keeps hunting for sometime. Last edited by Swapnil; 05-22-2011 at 03:40 PM. Reason: grammar

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05-22-2011, 07:04 AM	#2
gp1806 Veteran Member Join Date: Mar 2009 Location: Chicago suburbs Photos: Albums Posts: 848	I have a DA L 55-300mm and a K-R. The indicator works for me. You should be OK with that lens.

05-22-2011, 09:23 AM	#3
Poolhall New Member Join Date: May 2011 Location: Hindley Wigan Lancashire Posts: 6	Me too -works fine and I tend to leave mine set at f8 in av mode for shooting pics of small birds and focus it manually. No problems from 55-300mm either with the indicator.

05-22-2011, 02:17 PM	#4
Bill_R Site Supporter Join Date: May 2011 Posts: 262 Original Poster	Thanks all. I thought it might have to do with not stopping down to focus and therefore there being not enough light with a max aperture of above 5.6 - what you set it at being irrelevant since it hasn't stopped to that yet. It possibly still does but seems this lens has enough light when at 5.8 and 300 mm - which is good Might also explain why the lens can hunt a bit at longer focal lengths. Or does it sometimes hunt at all lengths?

05-22-2011, 03:50 PM	#6
Bill_R Site Supporter Join Date: May 2011 Posts: 262 Original Poster	Originally posted by Swapnil AF system works on Contrast detection and Phase detection philosophy. Not Sure if K-r uses phase detection but at longer focal length even the slightest shake can cause great deflection. Just think of it as ripples in water, at the origin the ripples are barely visible but at the ends they can look like waves. Since there is constant change in contrast in AF point. System finds it hard to focus it quickly. Hence, it keeps hunting for sometime. Thanks for the info Swapnil. Specs for the k-r gives: TTL: Phase Matching autofocus LiveView: Contrast detection + Face detection, Contrast detection, Phase Matching. Phase Matching in LiveView performed by the AF Sensor.

Focus indicator k-r da 55-300

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