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11-01-2010, 07:20 PM   #16
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QuoteOriginally posted by Todd Adamson Quote
Thanks! I'll try some shots at 2.8 next time, just to judge sharpness and keeper rate. Since I am accustomed to shooting f/2 and wider on a FF body, the DOF I get from a crop sensor at 50mm and f/1.7 is somewhere in the ballpark, but ultimately this won't be my go-to portrait lens. I have a 77/1.8 coming at the end of the week, and that's what I plan to use most often for this kind of studio work.

I may try a KatzEye one day, but I reeally don't want to. Though I could probably get used to it, my limited experience with them has been no great pleasure.

I don't know what the functional "aperture" of the stock K-7 screen is, but watching things pop in an out of focus through the VF, it seems like it's better for manual focusing than the D3's VF, so I have high hopes for getting to the point where I can shoot MF lenses without changing screens.
Hi Todd, I agree with the others in that the first shot appears to be slightly misfocused.

For critical focus without using a 3rd-party screen, you can use live view (zoomed-in). The live view on the K-7 is quite good for this purpose.

11-01-2010, 07:22 PM   #17
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QuoteOriginally posted by Todd Adamson Quote
Thanks! I'll try some shots at 2.8 next time, just to judge sharpness and keeper rate. Since I am accustomed to shooting f/2 and wider on a FF body, the DOF I get from a crop sensor at 50mm and f/1.7 is somewhere in the ballpark, but ultimately this won't be my go-to portrait lens. I have a 77/1.8 coming at the end of the week, and that's what I plan to use most often for this kind of studio work.

I may try a KatzEye one day, but I reeally don't want to. Though I could probably get used to it, my limited experience with them has been no great pleasure.

I don't know what the functional "aperture" of the stock K-7 screen is, but watching things pop in an out of focus through the VF, it seems like it's better for manual focusing than the D3's VF, so I have high hopes for getting to the point where I can shoot MF lenses without changing screens.
I find it easier for me to nail focus with a FF probably because of the bigger and brighter VF. I find it the opposite with the crop sensor. for me, a splitscreen + magnifying eyepiece combo made life a lil easier.
11-01-2010, 07:34 PM   #18
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I'm not familiar with the M50/1.7, but the first shot looks slightly out of focus, even looking at the first posted image. I recommend getting the O-ME53 magnifier loupe - it helps with manual focusing.
11-01-2010, 07:37 PM   #19
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QuoteOriginally posted by Laurentiu Cristofor Quote
I'm not familiar with the M50/1.7, but the first shot looks slightly out of focus, even looking at the first posted image. I recommend getting the O-ME53 magnifier loupe - it helps with manual focusing.
I'll probably give that a try, thanks. Looking back now at those two web-sized images, the tip of her nose looks sharper in the first, so I'm thinking I was probably front-focused.

11-01-2010, 07:46 PM   #20
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QuoteOriginally posted by Todd Adamson Quote
I understand stopping down for better sharpness, but I like to control my DOF, and I plan on using this lens wide open often, as I do with all of my fast lenses. So I'm just trying to determine if the less-than-expected sharpness here is me, or just the norm for this lens at 1.7.

Thats not why I said what I said
11-01-2010, 09:39 PM   #21
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QuoteOriginally posted by Todd Adamson Quote
I'll probably give that a try, thanks. Looking back now at those two web-sized images, the tip of her nose looks sharper in the first, so I'm thinking I was probably front-focused.
The difficulty with focusing such fast lenses with the standard focusing screen is there is a huge discrepancy between the the DOF you are seeing and the DOF you actually get, and it gets worse with lenses faster than f/2.8. Focusing a 50mm f/1.2 @ f/1.2 with the standard screen is a tough challenge, and a skill few have the patience to develop.
11-01-2010, 09:44 PM   #22
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When I am shooting below f2.8 on my k-x I use this method :

-Hit the Liveview button
-Magnify the LCD screen image to *6-10 times (keep pressing the INFO button)
-focus
-shoot

You will nail focus everytime. Very good method for portraits or if the subject is still. I have a k50 f1.2 an this is the only way I can get anywhere near correct focus at f1.2
11-01-2010, 09:45 PM   #23
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QuoteOriginally posted by Digitalis Quote
Focusing a 50mm f/1.2 @ f/1.2 with the standard screen is a tough challenge, and a skill few have the patience to develop.
Tell me about it

11-02-2010, 12:02 AM   #24
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FWIW: I think the sharpness is on the tip of her nose instead of her eyes. I tend to shoot wide-open portraits too (and I'm quite good at it) but I find it a lot harder with ~50mm lenses than with ~75mm lenses.

Have a look at the shot again. There should be a point where you can see the sharp texture of the fabric of her clothes. If I'm right then the focusing plane is indeed on her nose or just in front of it.

The 2nd shot is superb indeed

This one was shot with a 85mm F1.2, wide open. With a DOF that small it's impossible to have two eyes in focus at the same time unless the person is looking straight into the camera. And that's hard with children

11-02-2010, 12:35 AM   #25
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I've found the VF focus indicator a great help with MF (k-x).
11-02-2010, 05:41 PM   #26
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You can do a series of focus test to find out whether the lens is capable of producing sharp image. Your 1st image is slightly OOF since if it's that soft, hazing would occur as well.
11-02-2010, 09:58 PM   #27
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QuoteOriginally posted by Asahiflex Quote
FWIW: I think the sharpness is on the tip of her nose instead of her eyes. I tend to shoot wide-open portraits too (and I'm quite good at it) but I find it a lot harder with ~50mm lenses than with ~75mm lenses.
Thanks! I suspect you are right on both counts. Front-focused, and it will be easier when I get a longer lens. I hope.

Thanks everyone for your help. I wanted to try the 50 at f/2 or so today, but had to rush my session a bit, didn't want to tale the clients' time for me to experiment.

I can't wait til Friday, when I get my 77. Got my L-bracket today, so I can do some tripod shooting.
11-02-2010, 10:34 PM   #28
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QuoteOriginally posted by Todd Adamson Quote
Thanks! I suspect you are right on both counts. Front-focused, and it will be easier when I get a longer lens. I hope.

Thanks everyone for your help. I wanted to try the 50 at f/2 or so today, but had to rush my session a bit, didn't want to tale the clients' time for me to experiment.

I can't wait til Friday, when I get my 77. Got my L-bracket today, so I can do some tripod shooting.
Thanks Todd for this thread since I had to check and play with my FA 50/1.7 again. eversince I upgraded the firmware to the more recent one, I just noticed that focusing got messed up. mine was perfect before, and no adjustment was necessary up til now. mine now has some front-focus issue and had to adjust the AF to -10. had the same soft focus with the eyes and brows. now they are pretty solidly sharp at f1.7 (wide open).
11-03-2010, 01:32 AM   #29
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QuoteOriginally posted by Todd Adamson Quote
Thanks a lot you guys. I was hoping it was just that I was missing by a bit, and I know I will get better with practice. I will definitely start to explore this lens at f/2 ASAP. Although if what I have been reading about Pentax glass is true, I am not gonna want to take the 77 off my camera once it goes on! LOL
the second shot is spot on and sharp. You first shot just looks out of focus, but it is very difficult to properly focus at wide apertures.

I've recently bought a Pentax A 50mm/f1.2 and a Pentax FA/f1.4 and I'm finding it very hard to focus. takes some practise. I've also had to calibrate the focus indicator for both lenses on my K20D as they were both front focussing to varying degrees. When you've got a DPF of only around of 3mm it makes a huge difference!!
11-03-2010, 01:34 AM   #30
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QuoteOriginally posted by tux Quote
When I am shooting below f2.8 on my k-x I use this method :

-Hit the Liveview button
-Magnify the LCD screen image to *6-10 times (keep pressing the INFO button)
-focus
-shoot

You will nail focus everytime. Very good method for portraits or if the subject is still. I have a k50 f1.2 an this is the only way I can get anywhere near correct focus at f1.2
it's the only sure way. As just said I just bought a 50/1.2 - beautiful bokeh and DOF, but you need a vernier scale to focus. Live view on max mag is the only sure way.
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