Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
02-26-2011, 01:10 PM   #1
Forum Member
JJD2500's Avatar

Join Date: Sep 2009
Location: Charlotte, North Carolina
Photos: Gallery
Posts: 63
Focal length conversion

I have been using a K2000 for about 2 years now.
I have a Pentax 50mm 1:2 (prime) lens from my old 35mm film kit.
I'm a little confused about the conversion ratio when using this lens on the DSLR body. Although is works just fine, I don't feel like I'm getting optimal images from the lens.

When I attach it to the DSLR camera body, I'm asked to input the focal length via the camera dial but I'm not certain what the correct setting is?

Any thoughts, comments, or help would be greatly appreciated.

Thanks,

JD

02-26-2011, 01:13 PM   #2
New Member




Join Date: Feb 2011
Location: North East England
Posts: 19
I have been putting in 50mm
Mand
02-26-2011, 01:27 PM   #3
Inactive Account




Join Date: Aug 2008
Location: Michigan, USA
Photos: Gallery | Albums
Posts: 7,485
FL=FL=FL...

It May be the lens. On a dSLR, I've never been particularly impressed with the f2.0 50mm. Maybe that's just me as I'm sure a lot of people use them. Were I you, I'd sell the 2.0 and find a 1.7 to replace it. Infinitely better IMO.

02-26-2011, 01:28 PM - 1 Like   #4
Ash
Community Manager
Loyal Site Supporter
Ash's Avatar

Join Date: Mar 2007
Location: Toowoomba, Queensland
Photos: Gallery | Albums
Posts: 22,681
The exact focal length of the lens (50mm) is what should always be entered, but I would wager there's another reason for the unacceptable results. Would you post some examples of these?

02-26-2011, 01:33 PM - 1 Like   #5
Veteran Member
RioRico's Avatar

Join Date: Jun 2008
Location: Limbo, California
Posts: 11,264
Oh boy, the crap factor confusion again. Forget you ever heard about 'equivalent' focal lengths and FL conversions. A 50mm lens is a 50mm lens, not matter what it's mounted on. Moving a lens from one camera to another, with a different frame size, does not change the lens. The amount of the image circle that the lens projects changes -- that's the 'crop'. But your camera's SR'bot only wants to know the actual focal length. It doesn't care what the field of view (FOV) is.

Back in the day, I had a 135 half-frame SLR, an Olympus Pen-FT, with frame size about the same as your APS-C dSLR. I got a Spiratone 400mm lens with a T2 adapter, and I thought, OH BOY, IT'S 600MM ON THE OLY! But it wasn't. It was just a 400mm image with the sides cut off. That's all. And that's all that happens when you put any FF or MF or other lens on your dSLR. Part of the image is cropped off.

Have fun!
02-26-2011, 01:39 PM   #6
Veteran Member
twilhelm's Avatar

Join Date: Feb 2009
Location: Florida
Photos: Gallery | Albums
Posts: 393
RioRico, you couldn't be more right. (though I think I've seen you write this before)

To the OP, it may be the lens itself. Though I will add that my 50 1.7 and 55 1.8 give me much better pictures than my 50 f2.

But if you think you should be getting better pictures from it, post some. There are many on here with the experience to let you know what is going on!
02-26-2011, 01:44 PM   #7
Veteran Member
causey's Avatar

Join Date: Feb 2009
Location: Arlington, VA
Photos: Albums
Posts: 3,758
What JeffJS said. Buy a 50mm 1.7, M or A. (The A version might help you with the focus.)
I'm also surprised the 50mm 2 is held in high regard by others.
02-26-2011, 01:50 PM   #8
Forum Member
JJD2500's Avatar

Join Date: Sep 2009
Location: Charlotte, North Carolina
Photos: Gallery
Posts: 63
Original Poster
OK, I get the picture. A 50mm lens, is a 50mm lens regardless of the body.
Thanks for the comments.
I'll consider the 1.7, as the 2.0 seems to be standard issue "kit" lens from back in the day.
Special thanks to Ash for giving the strait answer to my question.
I'll post some example shots from this lens tomorrow.

JD

02-26-2011, 03:30 PM   #9
Veteran Member
RioRico's Avatar

Join Date: Jun 2008
Location: Limbo, California
Posts: 11,264
QuoteOriginally posted by twilhelm Quote
RioRico, you couldn't be more right. (though I think I've seen you write this before)
Reiterate? Moi?

Before I were a software engineer, I were a broadcast engineer. Before that, I were a liberal arts major, and I had to write thangs, and stuff like that. I learnt some stuff and thangs. One thang I learnt: REDUNDANCY IS THE SOUL OF COMMUNICATIONS. Repeat forever.
02-26-2011, 05:12 PM   #10
Site Supporter
boriscleto's Avatar

Join Date: Dec 2009
Location: Liverpool, NY
Photos: Gallery
Posts: 12,483
QuoteOriginally posted by RioRico Quote
Reiterate? Moi?

Before I were a software engineer, I were a broadcast engineer. Before that, I were a liberal arts major, and I had to write thangs, and stuff like that. I learnt some stuff and thangs. One thang I learnt: REDUNDANCY IS THE SOUL OF COMMUNICATIONS. Repeat forever.
And I would give you more rep if the forum would let me.
02-27-2011, 07:50 AM   #11
Site Supporter
GeneV's Avatar

Join Date: Oct 2008
Location: Albuquerque NM
Photos: Albums
Posts: 9,767
QuoteOriginally posted by RioRico Quote
Oh boy, the crap factor confusion again. Forget you ever heard about 'equivalent' focal lengths and FL conversions. A 50mm lens is a 50mm lens, not matter what it's mounted on. Moving a lens from one camera to another, with a different frame size, does not change the lens. The amount of the image circle that the lens projects changes -- that's the 'crop'. But your camera's SR'bot only wants to know the actual focal length. It doesn't care what the field of view (FOV) is.

Back in the day, I had a 135 half-frame SLR, an Olympus Pen-FT, with frame size about the same as your APS-C dSLR. I got a Spiratone 400mm lens with a T2 adapter, and I thought, OH BOY, IT'S 600MM ON THE OLY! But it wasn't. It was just a 400mm image with the sides cut off. That's all. And that's all that happens when you put any FF or MF or other lens on your dSLR. Part of the image is cropped off.

Have fun!
I think I've agreed with that post before as well.

People really need to dispense with this idea of "equivalence." I learned that long ago when I shot my first medium format.
02-28-2011, 11:44 AM   #12
Veteran Member
RioRico's Avatar

Join Date: Jun 2008
Location: Limbo, California
Posts: 11,264
QuoteOriginally posted by boriscleto Quote
And I would give you more rep if the forum would let me.
What?!?!? There's a rep.limit?!?!? This is outrageous! It's a conspiracy! I blame [political-social rant deleted]

QuoteOriginally posted by GeneV Quote
I think I've agreed with that post before as well.
The same subject arises. The same answers apply. Such is life.

QuoteQuote:
People really need to dispense with this idea of "equivalence." I learned that long ago when I shot my first medium format.
And another tale I've told before: Back in the day, when photography was my job, my colleagues and I variously used 135/HF, 135/FF, 645, 6x6, 6x9, 9x12, 4x5 etc -- and we NEVER spoke of crap.factor nor equivalence, because the marketing geeks hadn't invented the terms yet. With each format, one learned what each lens does, that's all. One started with the 'normal' focal length (frame diagonal) and extrapolated from there: 1/3 shorter than normal is wide, 1/3 longer than normal is long, beyond those are very and ultra, etc. Neither rocket science nor marketing need raise their grumly heads. Learn a tool and use it.
03-01-2011, 03:47 PM   #13
Veteran Member
Lloydy's Avatar

Join Date: Aug 2007
Location: Shropshire, UK
Posts: 1,114
I have dyscalculia, it's dyslexia with numbers, so I just don't do numbers.
Which might be a bit strange considering I've spent my working life as an engineer and chose photography as one of my hobbies.

To me the numbers don't matter because they make little sense, it's a lens. I know what the lens does, I know which lenses are faster than the others. I have a 'picture' in my head that comes from the numbers that somehow makes sense to me. So the 'crop factor' thing, once I had built my picture of it, became meaningless. Which I guess it actually is ?

Screw the lens on and see what the hell it does!

Last edited by Lloydy; 03-02-2011 at 03:45 AM. Reason: sp
03-01-2011, 05:30 PM   #14
Moderator PEG Judges
Kerrowdown's Avatar

Join Date: Aug 2008
Location: Highlands of Scotland.
Photos: Gallery
Posts: 31,374
QuoteOriginally posted by Lloydy Quote
Screw the lens on and see what the hell it does!
+1

It helps if you learn this, it allows you to pre-visualise a situation and put on the right lens.
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!
body, camera, conversion, dslr, length, lens, photography
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
focal length pentax k-x Photographic Technique 9 11-22-2010 12:41 PM
focal length landscaped1 Troubleshooting and Beginner Help 48 05-05-2010 03:04 PM
SLR > DSLR focal length conversion? wedge Pentax SLR Lens Discussion 20 07-28-2009 05:05 AM
What is Focal Length Ole Photography Articles 2 05-15-2009 12:20 PM
Focal Length Jimsi777 Pentax SLR Lens Discussion 2 11-09-2007 06:46 PM



All times are GMT -7. The time now is 09:41 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