Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
02-01-2007, 09:09 AM   #16
Veteran Member




Join Date: Nov 2006
Location: Westchester Co., NY
Posts: 538
I have some lenses from an old Mamiya 645 and an adapter (Zork) to use them on a K mount body. Have tried one lens, an 80mm f1.8, on my DS.
Have only done some quick test shots and assumed that the effective focal length was +/- 120mm. I thought that I might use it as a fast, short telephoto in low light situations (fully manual).
If I've read these posts right, it really is effectively around 200mm. Might be more useful than I thought.

02-01-2007, 01:23 PM   #17
Senior Member




Join Date: Nov 2006
Location: Portland, Oregon
Photos: Gallery
Posts: 217
boy the crop factor thing is still confusing people.

80mm lens is 80 mm no matter what camera you attach it to. The camera cannot physically change the lens.

The amount of magnification is related to the sensor size, the pixel size the print size etc... effectively, the crop factor of 1.5 for Pentax DSLR's is to translate what you were used to with your old 35m camera.

the sensor on the DSLR is smaller than the 35mm film, so that the image resulting from using your 80mm lens is only coming from the center of the image circle. An 80mm lens on the 645 system is a normal lens right? seems like a 50mm on 35mm systems, or a 35mm on your DSLR?

but an 80 mm lens on the DSLR is not a normal lens, it is a short telephoto ... similar field of view as a (80*1.5=120) 120mm gives on a 35mm camera.

I hope I am helping not hurting...
02-01-2007, 03:04 PM   #18
roy
Inactive Account
roy's Avatar

Join Date: Sep 2006
Location: D/FW area, Tx.
Photos: Gallery
Posts: 1,712
CORRECT!! a 300mm lens is still a 300mm lens no matter how much of the image circle you are using. it'll be the same size no matter what format the lens is made to. that's why the DA50-200 with the crop factor is equivalent to a 75-300 (35mm) even tho it's a digital only 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!
6x7, camera, dslr, lenses, photography
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Pentax Medium Format Resources: 645 & 6x7 Cameras and Lenses, 645 & 6x7 Accessories Adam Pentax Medium Format 9 02-12-2017 03:38 AM
Is 645D compatible with Pentax 6x7 lenses ? Samsungian Pentax Medium Format 41 04-21-2010 12:53 PM



All times are GMT -7. The time now is 05:50 PM. | 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