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04-15-2016, 12:29 PM   #1
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DA 50mm 1.8 Advice.

So I just got this lens and am committed to really trying to become proficient with it. I was wondering if anyone has any advice concerning this lens. It's pretty much gonna be my walkabout lens for awhile, and whilst I understand it's limitations (poorish macro, not great for landscapes etc) I was wondering what some 'optimum' settings might be for certain scenarios etc. Like for example, in good shooting conditions, is sharpness vastly improved above Aperture 4 etc, is there a cap, should you try not to shoot too high etc. I understand there is no 'fixed optimum' settings as the camera must adjust to the environment condition, but I am just trying to understand if there is a 'good zone' to use for some easy scenarios, such as a landscape shot on a sunny day etc. If possible and conditions allow, should the user try and shoot above the 1.8-2 range, is the trade off in bokeh worth it in terms of extra sharpness gained at a higher value, that sorta thing.

Maybe this post is an oxymoron lol

Well... anyway if anyone wants to wade in with their 2 cents feel free and go ahead

04-15-2016, 12:33 PM   #2
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There'll be some useful information in here about what aperture is sharpest, etc:
Pentax-DA 50mm F1.8 Review - Introduction | PentaxForums.com Reviews
04-15-2016, 12:44 PM   #3
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QuoteOriginally posted by bertwert Quote
There'll be some useful information in here about what aperture is sharpest, etc:
[url= 50mm F1.8 Review - Introduction | PentaxForums.com Reviews[/url]
Thanks Bert!
04-15-2016, 01:19 PM   #4
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I know the advice always says that you should stop down for the best results, but personally I've gotten very good results wide open, and I found the lens very versatile handling any scenario I've thrown at it. I hope you enjoy it as much as I have!

The only thing I might recommend is that particularly close up 1.8 is very shallow so you have to be careful with your depth of field.

04-15-2016, 01:21 PM   #5
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QuoteOriginally posted by jabbershort Quote
I know the advice always says that you should stop down for the best results, but personally I've gotten very good results wide open, and I found the lens very versatile handling any scenario I've thrown at it. I hope you enjoy it as much as I have!
Hi, I'm still new to all this and the lingo, when you mean 'stop down' and 'wide open' what exactly are you meaning by this? I take it that's aperture talk?
04-15-2016, 01:40 PM - 1 Like   #6
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QuoteOriginally posted by BruceBanner Quote
not great for landscapes
I wouldn't say that--if you look you'll find that there's been some very nice landscapes made with this focal length. And you'll find the 50mm to be an excellent choice for portraiture.

QuoteOriginally posted by BruceBanner Quote
'stop down' and 'wide open'
Stop down = use a smaller aperture - more depth of field, more things in focus from near to far.
Wide open = shot with the widest aperture - often a little soft, very restricted depth of field

Often the optimum aperture for lens IQ is somewhere in the middle between wide open and minimum aperture. f4, f5.6, f/8 generally give excellent results.

On my old manual 'K' series lenses, f8 is my default.
04-15-2016, 01:49 PM   #7
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QuoteOriginally posted by johnyates Quote
I wouldn't say that--if you look you'll find that there's been some very nice landscapes made with this focal length. And you'll find the 50mm to be an excellent choice for portraiture.



Stop down = use a smaller aperture - more depth of field, more things in focus from near to far.
Wide open = shot with the widest aperture - often a little soft, very restricted depth of field

Often the optimum aperture for lens IQ is somewhere in the middle between wide open and minimum aperture. f4, f5.6, f/8 generally give excellent results.

On my old manual 'K' series lenses, f8 is my default.

So Stop Down would be a high aperture value (F22 is max on this lens) and Wide Open low value (F1.8 on this lens)? It's just that we use reverse terms when talking about aperture, such as a 'high' aperture lens is like 1.4 etc?

I understand that the lower the aperture value (1.4, 1.8 etc) is great for low light situations, and even when the lighting is good but you deliberately want a very small thing in focus and lots of bokeh everywhere else, but for day to day portrait use I wondered if 4 was recommended, or slightly higher etc. As you mentioned the optimum IQ would be somewhere in the middle this makes sense, so cheers for that

04-15-2016, 01:51 PM   #8
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QuoteOriginally posted by BruceBanner Quote
I am just trying to understand if there is a 'good zone' to use for some easy scenarios, such as a landscape shot on a sunny day etc. If possible and conditions allow, should the user try and shoot above the 1.8-2 range, is the trade off in bokeh worth it in terms of extra sharpness gained at a higher value, that sorta thing.
Probably the easiest way to find out is to mount the lens up, go out, and take some photos. It may help to write up a script ahead of time indicating the questions you want to answer and then jot down the exposure numbers for each question. Even something as simple as running an aperture sequence on a set subject should answer most of your questions.

BTW, while macro with your DA 50/1.8 due to incompatibility with most extension tubes/bellows is not really possible, landscape is certainly something that can be done at the available field of view.


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04-15-2016, 02:04 PM - 1 Like   #9
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QuoteOriginally posted by BruceBanner Quote
such as a landscape shot on a sunny day etc. If possible and conditions allow, should the user try and shoot above the 1.8-2 range, feel free and go ahead
To directly address this question: 1.8-2 certainly have their place, especially for bokeh or really low light. For landscapes you'll want a deeper depth of field though. Try f8 or so on a bright sunny day, adjust up or down as needed. It should give a good depth of field and be plenty sharp. For close ups, I like to use anywhere between 2.8-5.6, depending on the subject and how much I want out of focus.
I'm still learning, myself. The main thing is, practice a lot and see what you get and what you like. Hope this helps.
04-15-2016, 02:19 PM - 1 Like   #10
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QuoteOriginally posted by stevebrot Quote
Probably the easiest way to find out is to mount the lens up, go out, and take some photos. It may help to write up a script ahead of time indicating the questions you want to answer and then jot down the exposure numbers for each question. Even something as simple as running an aperture sequence on a set subject should answer most of your questions.

BTW, while macro with your DA 50/1.8 due to incompatibility with most extension tubes/bellows is not really possible, landscape is certainly something that can be done at the available field of view.

Cheers, yeh I kinda meant the 50mm aspect of field of view (if that's the right term), the standard kit 18-55 means I can capture more of the scene without needing to possibly do panoramic stitching.


Steve
QuoteOriginally posted by TinaS Quote
To directly address this question: 1.8-2 certainly have their place, especially for bokeh or really low light. For landscapes you'll want a deeper depth of field though. Try f8 or so on a bright sunny day, adjust up or down as needed. It should give a good depth of field and be plenty sharp. For close ups, I like to use anywhere between 2.8-5.6, depending on the subject and how much I want out of focus.
I'm still learning, myself. The main thing is, practice a lot and see what you get and what you like. Hope this helps.
Thank you, that's good advice
04-15-2016, 03:45 PM   #11
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QuoteOriginally posted by BruceBanner Quote
Stop Down would be a high aperture value (F22 is max on this lens) and Wide Open low value (F1.8 on this lens)
You've got it. Both extremes produce less sharpness that the apertures in the middle. The best sharpness on this lens, like many others, is at f5.6 - f8.

Here are some tests that will give you a better idea:
Pentax smc DA 50 mm f/1.8 review - Image resolution - LensTip.com
https://www.ephotozine.com/article/pentax-smc-da-50mm-f-1-8-lens-review-20006
Don't take these as gospel (for one thing, there can be variations in copies of the lens, and also the tests might not have been done correctly), but they show a generally consistent pattern.

As you will see from the charts, with narrower apertures beyond f8, sharpness drops away gradually (due to an effect known as diffraction). But the lens is still plenty sharp at f11 - and that will generally give as much depth of field (DOF) as you could want (e.g. for a vista shot). The difference in DOF between f11 and f16 might not be great enough to outweigh the loss of sharpness (unless you are doing macro). But just try it a number of times and judge for yourself.

At the other end, the lens is adequately sharp in the centre wide open, for those times when you are shooting in very low light and/or you want a very thin DOF (to isolate the subject). Here's an example:

It's not terribly sharp, but I still like the effect and the colours.

For portraits, wide open might not give enough DOF anyway (e.g. the subject's eyes might be in focus, but the nose out of focus.) As a starting point, try somewhere between f.2.4 and f5.6 to get the combination of sufficient area in focus and sufficient subject isolation.

As Steve says, just get out and shoot, experiment and take notes.
04-15-2016, 04:24 PM - 1 Like   #12
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Find yourself a book on photography. It doesn't have to be a new one, because ultimately all photography technique boils down to shutter speed and aperture, and ISO is only the same as being able to put a different film in the camera with every shot. Reading this will set you well on the path to understanding what to do with your camera's controls when you take them off automatic, and why. The great thing about digital is that it costs nothing to learn by making mistakes - no film to buy; no prints to pay for - and you see the results of your endeavours instantly, so you learn to correct them sooner if it didn't work out as you expected.
04-15-2016, 10:54 PM   #13
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+1 to what pathdoc said. My favourite book is 'Understanding Exposure' by Bryan Peterson. Great fundamentals with small tasks every few pages to get you using your camera.
04-16-2016, 06:04 AM - 1 Like   #14
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one thing to practice when doing portraiture/subject isolation is the depth of the subject. like my dog from neck to tip of the nose is about a foot. if i want her whole head in focus i need at least that amount so i can stop down accordingly. you're shooting a 3d world so you need some depth of field. one discussion i learned a lot from was about an ideal f stop to obtain the "3d effect" and the consensus seemed to be just enough to get your subject completely in focus but to still blur the background. dof depends on how clsoe you are to the subject as others pointed out and the f stop. so like f5.6 will have more in focus than f 1.8. usually 1.8 is too thin to get the 3d effect bc only part of the subject is in focus. usually around f4?, depending on how much depth there is, is more of an ideal number. what you can do is set the camera to aperture priority and take consecutive snaps starting at 1.8 and working your way down to like f11 on different subjects and youll see the difference it makes. youll wind up deleting a lot of pictures but its a good visual. also if you only take one shot and its at the wrong aperture you missed a good shot so once u get the relative aperture you think youll want you can take one or two above and below that number and youll have a couple to chose from if the situation allows
04-16-2016, 07:43 AM - 1 Like   #15
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The thing I have found on getting the 3D effect is that it works best when the background is sufficiently far away that it is not at all in focus, with nothing in between. So a line of objects behind the subject can ruin things because it leads the eye into the background and disrupts the subject isolation.
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