Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
03-22-2010, 02:33 PM   #1
Forum Member




Join Date: Mar 2010
Photos: Albums
Posts: 68
First Manual Lens

I just got my first manual lens, an el cheapo Sears 50mm f1.7 from eBay. I've taken a few photos and I really like what I see, and here are my observations/questions:

1) I've pretty much just set this thing on f1.7. I have very rudimentary understanding of photography, but honestly, unless I'm dealing with bright sun, is there a reason why I would take it off of 1.7? I got this lens for shooting indoors in low light and for getting the shallowest DOF at all times. Even in sunlight, if the shutter speed can be fast enough (I'm using a K-x, which tops out at 1/6000), I should be able to shoot at f1.7 most of the time, right? (It's rainy today, so I can't test this out for myself until Wednesday.)

2) I'm amazed at how easy it is to use this lens. Even though it is fully manual (no A on the aperture dial), the camera is still able to adjust the shutter speed automatically (unless I leave it on M); I had no idea it would do this. Not only that, it even tells me when the object is in focus (the hexagon, the beep)! I had no idea it would do this, either. And I must say, it's pretty accurate, especially if there's enough light. For a manual lens, it certainly seems like it does a lot of things automatically.

3) Having said that, I miss the ease of the AF. It's tough without the split screen/prism in certain situations. My first SLR was a Canon D50, and I used that prism all the time. For those folks using manual lenses, have you all gotten that replacement screen off of eBay? I'm a bit skittish to mess with the delicate parts of the camera, but if I get any more manual lenses, it might become a necessity.

- Sung




03-22-2010, 05:06 PM   #2
Senior Member
AOShep's Avatar

Join Date: Feb 2010
Location: Eastern PA
Photos: Gallery | Albums
Posts: 293
QuoteOriginally posted by sjwoo Quote
3) Having said that, I miss the ease of the AF. It's tough without the split screen/prism in certain situations.
I installed the Katz Eye split image focusing screen just for that purspose. Even with my AF lenses I find it helpful. Glad you are happy with your purchase, enjoy.
03-22-2010, 06:49 PM   #3
Inactive Account




Join Date: Aug 2008
Location: Michigan, USA
Photos: Gallery | Albums
Posts: 7,485
QuoteOriginally posted by sjwoo Quote
I just got my first manual lens, an el cheapo Sears 50mm f1.7 from eBay. I've taken a few photos and I really like what I see, and here are my observations/questions:

1) I've pretty much just set this thing on f1.7. I have very rudimentary understanding of photography, but honestly, unless I'm dealing with bright sun, is there a reason why I would take it off of 1.7? I got this lens for shooting indoors in low light and for getting the shallowest DOF at all times. Even in sunlight, if the shutter speed can be fast enough (I'm using a K-x, which tops out at 1/6000), I should be able to shoot at f1.7 most of the time, right? (It's rainy today, so I can't test this out for myself until Wednesday.)

2) I'm amazed at how easy it is to use this lens. Even though it is fully manual (no A on the aperture dial), the camera is still able to adjust the shutter speed automatically (unless I leave it on M); I had no idea it would do this. Not only that, it even tells me when the object is in focus (the hexagon, the beep)! I had no idea it would do this, either. And I must say, it's pretty accurate, especially if there's enough light. For a manual lens, it certainly seems like it does a lot of things automatically.

3) Having said that, I miss the ease of the AF. It's tough without the split screen/prism in certain situations. My first SLR was a Canon D50, and I used that prism all the time. For those folks using manual lenses, have you all gotten that replacement screen off of eBay? I'm a bit skittish to mess with the delicate parts of the camera, but if I get any more manual lenses, it might become a necessity.

- Sung
I had one of those lenses for awhile on my K10d many years ago.. The only reason (as you put it) to take it off of f1.7 is if you want sharper images. You'll find yourself going to about f8 for best results if I remember correctly.

A lot of people are happy with the Jinfinance (ebay) screens. It isn't that delicate of a process to change the screen, you just have to be a little careful. I don't think you can beat a Katzeye though (but it is anything but cheap).

Enjoy your new lens.. Take it out and see what it will do in Good light.

03-22-2010, 06:58 PM   #4
Pentaxian
aleonx3's Avatar

Join Date: Jul 2007
Location: Brampton, Ontario
Photos: Gallery | Albums
Posts: 3,878
QuoteOriginally posted by sjwoo Quote
I just got my first manual lens, an el cheapo Sears 50mm f1.7 from eBay. I've taken a few photos and I really like what I see, and here are my observations/questions:

2) I'm amazed at how easy it is to use this lens. Even though it is fully manual (no A on the aperture dial), the camera is still able to adjust the shutter speed automatically (unless I leave it on M); I had no idea it would do this. Not only that, it even tells me when the object is in focus (the hexagon, the beep)! I had no idea it would do this, either. And I must say, it's pretty accurate, especially if there's enough light. For a manual lens, it certainly seems like it does a lot of things automatically.


- Sung
Sung, you need to do "stop down" metering if you want to use other aperture other than wide open - if you don't, you only get to use in wide open aperture.

03-22-2010, 07:35 PM   #5
Forum Member




Join Date: Mar 2010
Photos: Albums
Posts: 68
Original Poster
QuoteOriginally posted by JeffJS Quote
I had one of those lenses for awhile on my K10d many years ago.. The only reason (as you put it) to take it off of f1.7 is if you want sharper images. You'll find yourself going to about f8 for best results if I remember correctly.

A lot of people are happy with the Jinfinance (ebay) screens. It isn't that delicate of a process to change the screen, you just have to be a little careful. I don't think you can beat a Katzeye though (but it is anything but cheap).

Enjoy your new lens.. Take it out and see what it will do in Good light.

Thanks, Jeff. Yeah, the Katzeye is expensive...I think those "Chinese" screens would work for me. Has anyone gotten the screen change done at a camera shop? Of course, they'd probably charge as much as the Katzeye to do it...

- Sung
03-22-2010, 07:38 PM   #6
Forum Member




Join Date: Mar 2010
Photos: Albums
Posts: 68
Original Poster
QuoteOriginally posted by aleonx3 Quote
Sung, you need to do "stop down" metering if you want to use other aperture other than wide open - if you don't, you only get to use in wide open aperture.
Thanks, aleonx3. I noticed that the green button, in M mode, operates the shutter momentarily and then adjusts the shutter speed. Is this what you mean by stop metering? In Av mode, it doesn't do this.
03-22-2010, 10:30 PM   #7
Pentaxian
Marc Sabatella's Avatar

Join Date: Sep 2006
Location: Denver, CO
Photos: Gallery
Posts: 10,686
Correct - in Av mode, it ignores the aperture ring and *always* shoots wide open. See the sticky thread in the beginner's forum on how to use manual lenses. It's got to be M mode if you don't want to shoot wide open.

As for why you'd shoot at other apertures, shallow DOF is nice, but plenty of shots are better with deeper DOF. Also, slower shutters speed can allow you to get nice blurring of motion effects. And the 50/17, like virtually all lenses, gets sharper when you stop down a bit.

I'm moving this thread to the beginner's forum as it seems most appropriate there.
03-23-2010, 04:56 AM   #8
Forum Member




Join Date: Mar 2010
Photos: Albums
Posts: 68
Original Poster
QuoteOriginally posted by Marc Sabatella Quote
Correct - in Av mode, it ignores the aperture ring and *always* shoots wide open. See the sticky thread in the beginner's forum on how to use manual lenses. It's got to be M mode if you don't want to shoot wide open.

As for why you'd shoot at other apertures, shallow DOF is nice, but plenty of shots are better with deeper DOF. Also, slower shutters speed can allow you to get nice blurring of motion effects. And the 50/17, like virtually all lenses, gets sharper when you stop down a bit.

I'm moving this thread to the beginner's forum as it seems most appropriate there.
Thanks, Marc -- all great advice. Why is it that most lenses get sharper at higher fstops? I've done a little reading on this:

F-Stop? What's that?

"It has been noted by many darkroom technicians that theoretically when a lens is closed all the way down (set to the highest f-stop number) the entire field of view in the image is in focus. And, it has also been noticed that even though everything is in focus sometimes the image does not appear to have sharp object detail resolution."

Furthermore:

"This has nothing to do with depth of field and everything to do with two factors: possible inferior lens element quality and the known, observable fact that most lenses, when closed down, do not render object definition as sharply as would be achieved if the f-stop setting was placed mid-range for the lens."

Why is this? So for this lens, middle of the f-stop would be around f8. What is it about that midrange that makes for the sharpest photographs?

- Sung

03-23-2010, 06:44 AM   #9
Ira
Inactive Account




Join Date: Mar 2009
Location: Coral Springs, FL
Photos: Gallery | Albums
Posts: 5,218
I never understood how it can actually ignore the aperture ring.
03-23-2010, 06:59 AM   #10
Veteran Member
RioRico's Avatar

Join Date: Jun 2008
Location: Limbo, California
Posts: 11,264
QuoteOriginally posted by sjwoo Quote
So for this lens, middle of the f-stop would be around f8. What is it about that midrange that makes for the sharpest photographs?
Search on DIFFRACTION LIMIT. But here's an overview: basically, when light hits the edge of an opening, it gets deflected, diffracted. As you know, aperture is measured in f-stops, which are the RATIO of the focal length to the size of the aperture opening. So f/1, the aperture and focal length are the same. At f/2, the aperture diameter is half the size of the focal length. Et cetera.

If the focal length is long, even a small f-stop is still a rather large hole. But on a short lens, that hole is pretty small. So, when a short lens is stopped down, a noticeable portion of the light passing through the aperture has bounced off its edges. It's deflected, diffracted; it's no longer going where it should on the film or sensor, so the image is a bit fuzzy.

Frame size has a major role here too, as your DIFFRACTION LIMIT research will show. Ansel Adams and crew worked with 8x10 inch (20x25cm) view cameras, with apertures down to f/64. But they also used 320mm lenses, where f/64 is a 5mm hole. With a 50mm lens, f/64 is only 0.78mm across. The combination of small frame and small hole makes for increased diffraction.

But is that important? If you're shooting ultra-macros or detailed landscapes that will be greatly enlarged and closely inspected, then yes. If you're shooting snapshots, grab shots, street scenes, life around you, and you're not intent on 30m blowups, then no. But try it yourself: Put camera on tripod, set to Av mode. Aim at something nice. (Don't tell us her name.) Shoot at entire range of f-stops. (Depending on the lens, you may need to bracket the shutter speeds.) Now view the pictures at a normal distance, looking for objectionable fuzziness. Unless you're pixel-peeping, you may have a hard time finding any.

Why is midrange considered best? Because you avoid the softness of wide-open, and the diffraction of closed-down. But lensmakers set their smallest apertures so that, with normal usage, diffraction ISN'T a problem -- unless you're doing extreme blowups that will be closely inspected. That 30m blowup probably won't be gone over with a magnifying glass. So don't sweat it.
03-23-2010, 07:10 AM   #11
Site Supporter
Nowhere Matt's Avatar

Join Date: Nov 2007
Location: Nowhere Land
Photos: Gallery | Albums
Posts: 2,312
Yes but do not over look what has been mentioned in this thread. Understand that a manual lens such as this one, when used on a digital body, turning the aperture ring will do nothing to the aperture. With M lens and the mount to digital bodies, the mechanism is put into a position so that the lens's aperture remains fully open and cannot be adjusted. Using features of the camera will allow the camera to account for lighting and then set controls such as shutter speed and sensitivity to try to properly capture the image given the factor of maximum aperture opening.

Now an A lens... That's a little different.
03-23-2010, 07:12 AM   #12
Pentaxian
aleonx3's Avatar

Join Date: Jul 2007
Location: Brampton, Ontario
Photos: Gallery | Albums
Posts: 3,878
QuoteOriginally posted by sjwoo Quote
Thanks, aleonx3. I noticed that the green button, in M mode, operates the shutter momentarily and then adjusts the shutter speed. Is this what you mean by stop metering? In Av mode, it doesn't do this.
Yes, for K-mount manual focus lens, it does not work in Av mode (only wide-open) and in M mode (use stop down metering for other aperture setting). However, in M42 lens with switch set to M, you can use Av mode without stop down metering in addition to M mode with stop down metering. Therefore, m42 lens has a slight advantage over k-mount lens in this regard.
03-23-2010, 07:22 AM   #13
Site Supporter
Nowhere Matt's Avatar

Join Date: Nov 2007
Location: Nowhere Land
Photos: Gallery | Albums
Posts: 2,312
And in a few months perhaps, you can search the forum for reverse mounting threads.
03-23-2010, 08:03 AM   #14
Forum Member




Join Date: Mar 2010
Photos: Albums
Posts: 68
Original Poster
QuoteOriginally posted by RioRico Quote
Search on DIFFRACTION LIMIT. But here's an overview: basically, when light hits the edge of an opening, it gets deflected, diffracted. As you know, aperture is measured in f-stops, which are the RATIO of the focal length to the size of the aperture opening. So f/1, the aperture and focal length are the same. At f/2, the aperture diameter is half the size of the focal length. Et cetera.

If the focal length is long, even a small f-stop is still a rather large hole. But on a short lens, that hole is pretty small. So, when a short lens is stopped down, a noticeable portion of the light passing through the aperture has bounced off its edges. It's deflected, diffracted; it's no longer going where it should on the film or sensor, so the image is a bit fuzzy.

Frame size has a major role here too, as your DIFFRACTION LIMIT research will show. Ansel Adams and crew worked with 8x10 inch (20x25cm) view cameras, with apertures down to f/64. But they also used 320mm lenses, where f/64 is a 5mm hole. With a 50mm lens, f/64 is only 0.78mm across. The combination of small frame and small hole makes for increased diffraction.

But is that important? If you're shooting ultra-macros or detailed landscapes that will be greatly enlarged and closely inspected, then yes. If you're shooting snapshots, grab shots, street scenes, life around you, and you're not intent on 30m blowups, then no. But try it yourself: Put camera on tripod, set to Av mode. Aim at something nice. (Don't tell us her name.) Shoot at entire range of f-stops. (Depending on the lens, you may need to bracket the shutter speeds.) Now view the pictures at a normal distance, looking for objectionable fuzziness. Unless you're pixel-peeping, you may have a hard time finding any.

Why is midrange considered best? Because you avoid the softness of wide-open, and the diffraction of closed-down. But lensmakers set their smallest apertures so that, with normal usage, diffraction ISN'T a problem -- unless you're doing extreme blowups that will be closely inspected. That 30m blowup probably won't be gone over with a magnifying glass. So don't sweat it.
Thanks, RioRico. I think I learned more about photography in the last week than my whole life! Your explanation makes perfect sense. It's like Goldilocks -- going for the middle is often the most right thing.

I thought it was going to rain today, but it's actually sunny at times, and I found out something: with this Sears lens, in bright daylight, if I set the camera in M mode, set the lens at f1.7, then the green button stop down metering fails. It always reports 0.3" for the shutter speed. It only begins to work at f8 with the sun out. Is this normal behavior?

BTW, I can still shoot just fine with the lens wide open in Av, the shutter speed climbing up to 4000 to compensate for the f1.7.

- Sung

p.s. For clarification -- my Green Button is on "Program Line" in M mode.

Last edited by sjwoo; 03-23-2010 at 09:16 AM.
03-23-2010, 08:10 AM   #15
Forum Member




Join Date: Mar 2010
Photos: Albums
Posts: 68
Original Poster
QuoteOriginally posted by aleonx3 Quote
Yes, for K-mount manual focus lens, it does not work in Av mode (only wide-open) and in M mode (use stop down metering for other aperture setting). However, in M42 lens with switch set to M, you can use Av mode without stop down metering in addition to M mode with stop down metering. Therefore, m42 lens has a slight advantage over k-mount lens in this regard.
Just a point of clarification -- I can use Av mode with K-mount M lenses -- it's just that it'll always be stuck at the widest aperture, right?

And it looks like I need to get an adapter ring to use M42 lenses. Are there any "A" M42 lenses, or are they all manual? And when you say you can use M42 lenses in Av mode, that means the settings on the aperture ring will be recognized by the K-x in Av mode, right?

Thanks for all your help...

- Sung
Reply

Bookmarks
  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Tags - Make this thread easier to find by adding keywords to it!
camera, ebay, f1.7, idea, lens, lenses, light, pentax help, photography, shutter, time
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
How do I use a 135mm macro lens (manual lens)? justtakingpics Pentax SLR Lens Discussion 6 06-19-2010 08:02 PM
lens question - manual lens won't fire wackymummy Troubleshooting and Beginner Help 7 05-21-2010 10:16 AM
Manual lens mickey93lx Pentax DSLR Discussion 12 11-09-2009 07:31 AM
K100ds and full manual mode w/manual lens dwhopson Pentax DSLR Discussion 10 11-06-2008 10:37 PM
For Sale - Sold: K20D, 16x45mm lens, 50mm (manual) lens, FGZ540 flash pentaxshooter Sold Items 0 09-21-2008 03:21 PM



All times are GMT -7. The time now is 09:27 AM. | See also: NikonForums.com, CanonForums.com part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
register
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]
Top