Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
10-27-2011, 07:26 AM   #1
New Member




Join Date: Jul 2011
Posts: 24
"input focal length" on af lens...yeah.

Okay, so here´s a question.

I have the k-7 with the 18-55 wr and the 50-200 wr... and i love it a alot.
I also have several manual lenses that i love, that when attached makes the camera promt me for focal length.
But the deal is, i have a 0.70 screw on "lens/filter", VLC-MHG07, and when i attatch it to my 18-55wr lens, i would LOVE to be able to ajust the focal length to lets say 12.. or 13 (or something around that area)

But of course when the 18-55 wr is attached the "change focal length" is greyed out in the menu. is there anyone out there in pentax-land how know of a hack or similar that would make this work for me.


Sorry if this is a bit vague, english is my second language.

Best wishes.
a pentaxian in love with his camera.

10-27-2011, 07:56 AM   #2
Veteran Member
jolepp's Avatar

Join Date: Oct 2010
Location: Finland
Photos: Albums
Posts: 3,196
You could probably fool the camera into thinking your lens is 'A' type with the trick mentioned here: https://www.pentaxforums.com/forums/pentax-dslr-camera-articles/51036-how-use...tml#post490997. This would mean using manual focus though. If there is enough light so that you don't have to depend on SR you might just turn that off: the camera needs to know the focal length for its SR calculations (and to use as EXIF info).
10-27-2011, 08:05 AM   #3
Inactive Account




Join Date: Mar 2011
Photos: Gallery | Albums
Posts: 302
So, you want your photos to show 12mm in the EXIF data for image stabilization and such? To remove the focal length information from the shot (to be replaced with your input value), the data pin (the contact closest to the autofocus shaft) would have to be isolated. You would also lose the distance to the subject, exact absolute f-stop value, and (pretty sure) distortion correction ability.

Now, what to isolate it with? To test, scotch tape would probably work, but it might leave a residue. Anyone else have any ideas that are long lasting but non-permanent?
10-27-2011, 08:16 AM   #4
Pentaxian
Lowell Goudge's Avatar

Join Date: Jan 2007
Location: Toronto
Photos: Gallery | Albums
Posts: 15,401
Sadly there is no correction for this in the present software, apparently because pentax does not seem to be willing to support add-on or accessories that are manufactured by thrid parties.

The same issue has been present from the onset with respect to shake reduction and exposure issues when using a teleconverter. Most teleconverters simply pass through the lens data, and as a result, all automatic functions use the wrong aperture and focal length in the calculation.

this impacts not only SR, but also P-TTL flash, Program exposure lines, shutter speeds in Av mode when using flash, etc.....

It would be nice if there was an entry, just like focal length for manual lenses, at start up for "Using TC Y/N" with several options

Input / select multiplication factor
Correct for Focal length y/n
correct for aperture y/n
correct for both y/n

Are you listening pentax?

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, dslr, k-5, k-5 ii, k-5 iis, k5, length, love, pentax k-5, wr
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
"Focal length" sebberry Pentax SLR Lens Discussion 2 07-04-2011 05:20 PM
"A" lens and SR and focal length? slow2focus Troubleshooting and Beginner Help 2 12-27-2009 02:41 PM
What focal length input DutchAus Troubleshooting and Beginner Help 3 12-24-2009 09:15 AM
Input focal length for a manual lens jpzk Photographic Technique 11 01-14-2009 08:50 PM
which focal length(s) are considered "fish eye"? slip Pentax SLR Lens Discussion 3 12-13-2006 10:51 AM



All times are GMT -7. The time now is 06:12 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