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06-24-2007, 10:42 PM   #1
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Question re: my dad's old lenses...

I just purchased a K100D last week and am slowly learning the ropes. My dad has an old Pentax Super ME as well as some lenses and he managed to spare me 3 of his old lenses that need a little cleaning... The lens that I am using now is the kit lens, and my question is this:

How do I use my dad's old lenses and what are they for? i.e. wide angle, etc?

These are the lenses my dad gave me btw: a Pentax-M 1:2 50mm, a Vivitar 28mm 1:2.8 and an Osawa 1:45 100-200mm.

Sorry for the uber noob question

06-25-2007, 12:55 AM   #2
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QuoteOriginally posted by leadbelly Quote
I just purchased a K100D last week and am slowly learning the ropes. My dad has an old Pentax Super ME as well as some lenses and he managed to spare me 3 of his old lenses that need a little cleaning... The lens that I am using now is the kit lens, and my question is this:

How do I use my dad's old lenses and what are they for? i.e. wide angle, etc?

These are the lenses my dad gave me btw: a Pentax-M 1:2 50mm, a Vivitar 28mm 1:2.8 and an Osawa 1:45 100-200mm.

Sorry for the uber noob question
You and I have to stop meeting this way LOL

First on a digital each lens will act as a longer lens. The sensor is smaller than film is. so any lens length is multiplied by 1.5
50mm= 75mm on film considered a normal lens and on a DSLR a mid length portrait lens. The version you have is a good but entry level lens. Still very sharp though.

28mm = 42mm so this would now be your 'normal' lens and is reasonably close to what the human eye sees. quite fast and good in low light.

100-200mm = 150-300mm a fairly long lens good for shooting various things at a distance or close up (not macro) from a short distance. average speed (the f4.5 number which indicates the max aperture)

Now the way yo use the lenses is to set the camera in manual and you first focus the subject. Next adjust the aperture to get the correct depth of field (DOF) the higher the number the more that will be in sharp focus but the shutter speed will have to get slower in relation to the aperture setting. Read the manual on the section about manual exposures and it may shed some light on the subject and how to get the correct exposures. You must also go to the menu on the camera and select "custom setting" on the 3rd page is "Using aperture ring" set that on "2" (permitted) to allow the use of older manual lenses.
06-25-2007, 01:24 AM   #3
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Here's a page on how to use older lenses on new Pentax DSLRs with automatic exposure: Pentax Digital » Pentax Lens Types

depending on which type they are, they'll have more or less limitations compared to new AF lenses.

As for your question of what they're for: there's a good lesson on morguefile.com on optics: morguefile.com Classroom lesson 3

She made a handy chart explaining focal lengths in terms of viewing angles:




If you have any more questions, don't hesitate to ask them

Welcome to Pentax!

Tom
06-25-2007, 04:51 PM   #4
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@Peter Zack: Thanks for coming to my rescue...again! I see now, so which of these lenses is good for "normal" everyday use? Just so I can get the hang of using manual lenses on a digital camera? The 28mm/42mm lens then? Oh, and I want to learn close-up/macro photography... are any of my available lens adequate for me to learn macro shots? Thanks again!

About DOF using manual lenses, I am guessing that to check if I have everything set, I use the digital preview correct?

@TDN/Tom: Thanks for the links! Especially the second one. Learned a lot from it! Though the first link is dead I think, no page is popping up on my browser... thanks again!

06-25-2007, 11:26 PM   #5
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QuoteOriginally posted by leadbelly Quote
so which of these lenses is good for "normal" everyday use? Just so I can get the hang of using manual lenses on a digital camera? The 28mm/42mm lens then? Oh, and I want to learn close-up/macro photography... are any of my available lens adequate for me to learn macro shots? Thanks again!
Take the 50mm out for a walk in a city/town, you'll love it. The 28mm will have a nice field of view on a DSLR aswell.

I don't know about the 100-200mm, I've never heard of it...

QuoteOriginally posted by leadbelly Quote
@TDN/Tom: Thanks for the links! Especially the second one. Learned a lot from it! Though the first link is dead I think, no page is popping up on my browser... thanks again!
you're welcome

Is the link still dead now? it's showing up for me now...and the domain should be stable by now...hmm, maybe it went down for a while during the night...

Tom
06-26-2007, 12:41 AM   #6
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@TDN: Thanks! I'll be taking my camera with the 50mm out for a walk first thing tomorrow! The link still doesn't load with me, maybe something's wrong with my ISP... thanks again Tom!
06-26-2007, 08:42 AM   #7
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QuoteOriginally posted by Peter Zack Quote
First on a digital each lens will act as a longer lens. The sensor is smaller than film is. so any lens length is multiplied by 1.5
50mm= 75mm on film considered a normal lens and on a DSLR a mid length portrait lens. The version you have is a good but entry level lens. Still very sharp though.
That's not quite right. On a DSLR with an APS-C sensor, what you experience is a cropping of the image circle by a factor of 1.5 (actually 1.52, but who's counting ). Your 50mm lens does not instantly become a 75mm lens--there is no magnification of the image. What happens is you have a narrower field of view and are using a smaller portion of the lens circle. Some argue since you are cropping the view, you have the same effect as if you had a longer lens, but there is no optical magnification taking place.

Crop factor is an annoying thing because it doesn't help you in the long end and it definitely impairs you on the short end. Where a 24mm lens was once a decent wide-angle, you now need a 16mm or shorter to frame the same shot.

BTW, those old Pentax 50's are still very good performers if you don't mind using your camera in manual mode. The good thing about them is you will actually learn a few things about photography instead of just pointing and shooting with an auto-* lens.

Enjoy.
06-26-2007, 10:27 AM   #8
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QuoteOriginally posted by leadbelly Quote
@TDN: Thanks! I'll be taking my camera with the 50mm out for a walk first thing tomorrow! The link still doesn't load with me, maybe something's wrong with my ISP... thanks again Tom!
Hmm, strange. I'll copy-paste the part about M lenses (the type you have I think) here aswell then:
QuoteQuote:
# K Mount - “K” or “M” lenses:

This is the first, original mount Pentax used on the K-series of film cameras.
In-house (this is: Pentax made) lenses made by Pentax for this mount are usually labeled “SMC Pentax-M“, “Takumar (Bayonet)” and there are also a few early “K” lenses, labeled “SMC Pentax” (note the -M or -A is missing)
Third party (not made by Pentax) lenses using this mount are usually just noted as “K mount” or “PK mount”. This mount is identical to the Ricoh XR mount (beware! only XR mount! The “A” mount for Ricoh causes problems on Pentax DSLRs).

These lenses will only work in the M-mode (Manual) of your Pentax DSLR. Since these lenses were made before Autofocus (from now on referred to as “AF”) was invented, they only offer Manual Focus (from now on referred to as “MF”)
However, your Pentax DSLR offers ways to use these old lenses in an automatic way:

- By selecting the aperture on the lens itself, using the ring, and pressing the “AE-L” button (stands for: Auto Exposure-Lock), your camera will select the proper shutter speed for the aperture you’ve selected, giving you a correct exposure.
You will notice that when you have selected anything else than the maximum aperture of your lens, when you hit the AE-L button, the viewfinder image will become darker for an instant. This is caused by the camera actually stopping down the lens to the aperture you’ve selected (it was keeping it open using the lever inside the mount, to provide enough light for you to focus), and metering the light coming trough the lens that way.

- When in manual focus, your camera will give you a confirm “beep” and green light in the viewfinder when it thinks you have focused correctl, very useful.
If your camera does nto do this, check if under Menu>Set-up “Beep” is checked ON. Whether this is on or off, the camera will always give you a focus indication in the viewfinder.

Things to check when using lenses of this type:

* Under Menu>Custom Setting, make sure “Using Aperture Ring” is set to “2 - permitted”, this is OFF by default.
* Also under Menu>Custom Setting, make sure “AE-L bttn on M expsr” is set to “1 - Program Line”
Tom

06-26-2007, 03:46 PM   #9
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@ericc: Thanks for the reply! I am hoping to use the manual lenses since these are more fun than AF ones, for me anyway.

@TDN/Tom: Thanks again for the reply and for copying and pasting the info about using K-mount lenses! BIG help! I was actually fiddling with the AE-L button yesterday, not kowing how it works exactly, seems like a good button to make friends with! Especially with manual lenses! Thanks!
06-27-2007, 04:12 PM   #10
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@TDN: Tried out my old lenses last night, and it worked! Hahaha! Thanks for everything man!

By the way, my lenses are a bit cloudy and have some mold on them, I expected it to affect whatever picture was taken, but after testing the lenses, the pictures that came out were clear! Clearer than my kit lens even... isn't it supposed to be that when the lens is cloudy and has mold, the picture will turn out cloudy with some specks? What gives? Just weirded out, but happy...
07-03-2007, 06:51 PM   #11
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QuoteOriginally posted by ericc Quote
That's not quite right. On a DSLR with an APS-C sensor, what you experience is a cropping of the image circle by a factor of 1.5 (actually 1.52, but who's counting ). Your 50mm lens does not instantly become a 75mm lens--there is no magnification of the image. What happens is you have a narrower field of view and are using a smaller portion of the lens circle. Some argue since you are cropping the view, you have the same effect as if you had a longer lens, but there is no optical magnification taking place.
Enjoy.
Several months ago I had an epiphany and realized the lens could not possibly become longer. The camera companies do not want to say, "Our digital sensors are smaller than film SLRs" since that sounds bad. So they say the lenses act longer since that sounds like a good feature.
07-09-2007, 09:58 AM   #12
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QuoteOriginally posted by LeoTaylor Quote
Several months ago I had an epiphany and realized the lens could not possibly become longer. The camera companies do not want to say, "Our digital sensors are smaller than film SLRs" since that sounds bad. So they say the lenses act longer since that sounds like a good feature.
I might also mention: In general, the middle of the lens is the sharpest part. Since the smaller sensor "crops" the edges, the full image you get is probably sharper edge-to-edge than it might have been on a full frame sensor, which is also expensive.

Of course, it's easily cropped, depending on MP count. Just thought I'd mention one of the other positives to the situation.
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