Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
05-02-2011, 11:56 PM   #1
Pentaxian




Join Date: Jan 2011
Location: 5th floor
Posts: 1,328
67 lens crop factor on 645d?

I am stupid and ignorant.

Is there a crop factor to consider when using 67 lenses on 645d?

05-03-2011, 06:13 AM   #2
Veteran Member




Join Date: Feb 2011
Photos: Gallery
Posts: 573
Focal length is focal length. The diagonal of the 645D sensor is 55mm--the format is 33mm x 44mm. Divide the lens focal length by the diagonal to get the angular magnification. So my 67 105mm lens is about a 2x telephoto. It is better to think in the format that you use, rather than in the format you are not using.

Last edited by Yamanobori; 05-03-2011 at 06:49 AM.
05-03-2011, 07:34 AM   #3
Inactive Account




Join Date: Mar 2007
Location: Long Island, N.Y.
Photos: Gallery
Posts: 1,124
The "Crop Factor" is due to the size difference at the other end of the optical path. In it's most common usage, it is because the APS C sensor of our DSLR's is smaller than the frame size of a 35mm film camera. If you were to figure out a way to take a 645 frame size negative in a 67 camera, then you could talk "Crop Factor".

But no matter what you do, a 75mm lens is a 75mm lens, is a 75mm lens.
05-03-2011, 10:27 AM   #4
672
Pentaxian




Join Date: Dec 2010
Location: santa monica
Photos: Gallery
Posts: 417
While the other replies are certainly not wrong in any way, the answer you are looking for is 1.6 . But only if you were shooting those 67 lenses on a 67 camera .

Its a totally different number if you were shooting your 67 lenses on 645 film or 35mm film cameras.

05-03-2011, 12:09 PM   #5
Pentaxian
RonHendriks1966's Avatar

Join Date: Jan 2009
Photos: Gallery
Posts: 8,714
Well look here 120 film - Wikipedia, the free encyclopedia and see that 6x7 is 56 x 70 mm in size. Compared to 645D that is 33 x 44 mm there is a crop size if you want to have the same Field of View (FOV) Field of view - Wikipedia, the free encyclopedia. The crop size is somewhere between 1.6x and 1.7x depending of wich FOV you would like to keep (horizontal, vertical or diagonal).

To compare, the current 55mm lens that is sold with the 645D is comparable with about a 90mm lens on a 6x7 camera.
05-03-2011, 12:47 PM   #6
Pentaxian




Join Date: Jul 2009
Location: Seattle
Posts: 7,089
I believe the OP was simply asking if the crop factor of the 645D's sensor would change from its 1.3 by mounting a lens made for a different format camera. If that is the case, the answer is no.
05-03-2011, 01:43 PM   #7
Forum Member
managger's Avatar

Join Date: Jul 2010
Location: Moscow
Photos: Gallery
Posts: 56
QuoteOriginally posted by Fontan Quote
Is there a crop factor to consider when using 67 lenses on 645d?
Everything is simple - you must divide on 1.27
For example: 105mm 67 lens will be 105/1.27= 83mm in terms of 135 format.
Like 83mm lens on 36x24mm film.

The same operation - for 645 lenses too.
For example: 55mm 645 lens will be 55/1.27= 43mm in terms of 135 format.
Like 43mm lens on 36x24mm film.
05-03-2011, 05:56 PM   #8
Pentaxian




Join Date: Jan 2011
Location: 5th floor
Posts: 1,328
Original Poster
QuoteOriginally posted by tuco Quote
I believe the OP was simply asking if the crop factor of the 645D's sensor would change from its 1.3 by mounting a lens made for a different format camera. If that is the case, the answer is no.
This was it. Yes.

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, crop, factor, medium format
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Crop factor of the 645d WerTicus Pentax Medium Format 16 06-14-2011 04:49 PM
Crop factor cjbroadwell Troubleshooting and Beginner Help 9 01-01-2011 08:52 AM
crop factor again!! adwb Photographic Technique 7 12-04-2010 06:56 PM
Full Frame lens vs DA & crop factor comparison... JayR Troubleshooting and Beginner Help 4 03-02-2010 09:15 PM
wanting to understand- lens distortion and 1.5 crop factor slip Pentax DSLR Discussion 10 03-29-2007 06:59 PM



All times are GMT -7. The time now is 02:39 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