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03-13-2009, 02:28 AM   #1
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DA 35mm Ltd questions

Hi guys, I got my first Ltd lens (which is my first fixed focal length lens) on Monday. I am really excited about the build quality and the colour rendering and the macro capabilities. I am going to try it out to the moors tomorrow and I am really looking forward!

Anyway, there is couple of things I am not very sure about. If there are any DA 35 Ltd owners, who could give me couple of answers, I will be more than happy :-)

1) DOF scale
When shooting landscapes, I would like to focus hyperfocally. But the DA 35's DOF scale is pretty... narrow. I am not sure, how to use it, say compared to other Ltds, which have probably more usable DOF scale.
So guys, the question is, how do you do your hyperfocal focusing with DA 35?

2) AF macro focusing in 1:1 distance
I tried to use AF focusing (AF-S), when shooting the subject really close in front of the lens - but the AF was desperately hunting. When I set the focus to manual, set the lens to the 1:1 ratio manually and tried to focus by changing the distance of the camera and subject, everything was ok.
Do you use AF for 1:1 photos? Or how do you actually focus in those cases?

Thank you!

03-13-2009, 05:40 AM   #2
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QuoteOriginally posted by Jet Quote
Hi guys, I got my first Ltd lens (which is my first fixed focal length lens) on Monday. I am really excited about the build quality and the colour rendering and the macro capabilities. I am going to try it out to the moors tomorrow and I am really looking forward!

Anyway, there is couple of things I am not very sure about. If there are any DA 35 Ltd owners, who could give me couple of answers, I will be more than happy :-)

1) DOF scale
When shooting landscapes, I would like to focus hyperfocally. But the DA 35's DOF scale is pretty... narrow. I am not sure, how to use it, say compared to other Ltds, which have probably more usable DOF scale.
So guys, the question is, how do you do your hyperfocal focusing with DA 35?
Yes, the DOF scale is very close, unlike a wide angle lens. If you require a large DOF, then you really need to get to f11 or f16 and use that hyperfocal distance. The DOF scale is not any narrower than any other lens of that focal length as the DOF is focal length and sensor size dependant.

QuoteQuote:
2) AF macro focusing in 1:1 distance
I tried to use AF focusing (AF-S), when shooting the subject really close in front of the lens - but the AF was desperately hunting. When I set the focus to manual, set the lens to the 1:1 ratio manually and tried to focus by changing the distance of the camera and subject, everything was ok.
Do you use AF for 1:1 photos? Or how do you actually focus in those cases?
I focus as you have done. If I require 1:1, I set that on the lens and then move the camera back and forth to obtain critical focus.

Thank you![/QUOTE]
03-13-2009, 06:56 AM   #3
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I love this lens, but find it much more usable in manual focus mode, both for landscapes and macro. The focusing for lanscapes is really tricky (I think this should be expected from a 1:1 macro lens), since a single millimeter turn could be cruical. Once you nail it though, the resolution is stunning.
03-13-2009, 10:53 AM   #4
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The spacing of the f/numbers on the DOF scale is tight *because* it's a macro lens. In order to focus all the way down to 1:1, the entire focus scale has to be compressed. But in terms of actual depth of field it is identical to any other APS-C 35mm lens, and the DOF scale is accurate. (If you have a FF lens you'll find the DOF scales to give slightly different results, that's because this lens is designed for APS-C and it takes into account the additional enlargement required to get an image at the assumed viewing size.)

The DOF at 1:1 is VERY shallow, and this makes it difficult for the AF system. It's very common when shooting at that close a distance to set the camera to manual focus mode, leave the focusing ring alone, and move the camera or subject to achieve best focus.

03-14-2009, 08:38 AM   #5
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For DOF you can use an online calculator to make some choices before you go out or you can download a Photography calculator to your iTouch or iPhone if you own one and have it with you in the field.

Online Depth of Field Calculator

I own the DA35LTD and I just love the lens. It's on my camera right now.
03-16-2009, 05:19 AM   #6
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Original Poster
Thank you guys for the helpful replies!

So if I understood it properly, where I want to use the hyperfocal focusing, I need to know the particular hyperfocal focusing distance for each aperture, correct?

Than set this distance on focusing ring in manual mode and shoot.

Is it right, or am I missing something?
03-16-2009, 09:59 AM   #7
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QuoteOriginally posted by Jet Quote
So if I understood it properly, where I want to use the hyperfocal focusing, I need to know the particular hyperfocal focusing distance for each aperture, correct? Than set this distance on focusing ring in manual mode and shoot.
When you have a lens with a DOF scale as the DA35 does, it's super easy to set the hyperfocal distance without having to memorize anything. Simply turn the focusing ring so that the "infinity" position on the lens lines up with the f/number you're going to use. Everything from infinity to the distance opposite the same f/number on the other side of the scale will be in focus.

This works best with DA lenses (as opposed to M, A, or FA) because their DOF scale is designed to work with the APS-C sensor size.

Of course when you do this you'll want to put the camera into Av mode (so that you know exactly which aperture will be used) and turn off AF (which would refocus the lens on you).
03-17-2009, 09:17 AM   #8
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QuoteQuote:
Simply turn the focusing ring so that the "infinity" position on the lens lines up with the f/number you're going to use. Everything from infinity to the distance opposite the same f/number on the other side of the scale will be in focus.
Right, I know about that, but if you'll check out this photo of DA 35's DOF scale here https://www.pentaxforums.com/lensreviews/data/34/21730_DA35mmMacro.jpg - I can't see how could I do this use your advice.

03-17-2009, 09:33 AM   #9
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QuoteOriginally posted by Sean Nelson Quote
This works best with DA lenses (as opposed to M, A, or FA) because their DOF scale is designed to work with the APS-C sensor size.
Interesting, I didn't know that. Do you know what the exact criterion is? I mean, if your criterion is "looks perfect when shot with a K20D and viewed at 100%", you get a very shallow DOF compared to if you think it's suffucient that it "looks OK on a small print"
03-17-2009, 01:30 PM   #10
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QuoteOriginally posted by Jet Quote
Right, I know about that, but if you'll check out this photo of DA 35's DOF scale here - I can't see how could I do this use your advice.
Well, the scale works as intended - for example it's telling you that at f/22 you can have everything in focus from infinity to about maybe 3 meters.

I agree that the scale is too coarse at longer distances to be particularly useful. But that means that a table or formula isn't going to be useful with this lens either, since you'll have just as much difficulty setting the lens to, say, 4.5 meters even if you knew that was the correct hyperfocal distance.

Unfortunately this is the nature of macro lenses. In order to get the lens to focus all the way to 1:1 with only a half-turn of the focusing ring, the scale has to be very compressed at the longer distances. Its kind of the nature of the beast.
03-17-2009, 01:41 PM   #11
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QuoteOriginally posted by Sean Nelson Quote
This works best with DA lenses (as opposed to M, A, or FA) because their DOF scale is designed to work with the APS-C sensor size.
QuoteOriginally posted by gazonk Quote
Interesting, I didn't know that. Do you know what the exact criterion is? I mean, if your criterion is "looks perfect when shot with a K20D and viewed at 100%", you get a very shallow DOF compared to if you think it's suffucient that it "looks OK on a small print"
If you're asking me exactly what parameters are used in determining the DOF markings on Pentax's lenses, I couldn't tell you. But it's likely that they're pretty close to what's needed to perceive something as sharp on an 8x10 print viewed at a distance of somewhere between 1 and 2 feet.

The following page has an excellent description of DOF, how it's based on the eye's ability to resolve detail, and how that governs the size of the "circle of confusion" on the sensor which, after being enlarged to get a final print, meets the eye's resolving ability:

Digital Gallery Plus
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