Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
03-09-2022, 06:12 PM   #1
Site Supporter
Site Supporter
rjm007's Avatar

Join Date: Oct 2015
Location: California
Photos: Gallery
Posts: 217
Pentax 6x7 - The Diopter of Despair

Step One - Order variable diopter eyepiece from eBay. Receive one intended for Leica cameras which doesn't fit.

Step Two - Order Nikon eye piece from eBay - wait weeks. Discover you've ordered the wrong diopter.

Step Three - Order another one, right diopter this time, wait weeks for it to arrive. Hurrah ! It's perfect. Discover despite being same product as previous one it has a shallower thread and keeps falling out.

Step Four - Have bright idea of taking lens out of latest one and replacing it in the standard eyepiece. Rejoice at sense of achievement in thinking of this great idea.

Step Five - Discover that you don't need to apply much pressure to crack new eyepiece lens.

Step Five - Descend into pit of despair.

Anyone found a source for just the replacement lens element ?

03-09-2022, 06:31 PM   #2
Loyal Site Supporter
Loyal Site Supporter




Join Date: May 2007
Location: Flagstaff, Arizona
Posts: 1,371
Step seven (I think you did 5 twice?) - order new eyeball(s) !?
03-09-2022, 06:37 PM - 1 Like   #3
Site Supporter
Site Supporter
rjm007's Avatar

Join Date: Oct 2015
Location: California
Photos: Gallery
Posts: 217
Original Poster
QuoteOriginally posted by AstroDave Quote
Step seven (I think you did 5 twice?) - order new eyeball(s) !?
Might be cheaper getting my eyes lasered. It'll work out cheaper.
03-10-2022, 07:17 AM   #4
Loyal Site Supporter
Loyal Site Supporter
UncleVanya's Avatar

Join Date: Jul 2014
Photos: Gallery | Albums
Posts: 24,475
How painful. My sympathies.

03-10-2022, 07:58 PM   #5
Veteran Member
Abbazz's Avatar

Join Date: Nov 2006
Location: Jakarta
Posts: 650
QuoteOriginally posted by rjm007 Quote
Step One - Order variable diopter eyepiece from eBay. Receive one intended for Leica cameras which doesn't fit.

Step Two - Order Nikon eye piece from eBay - wait weeks. Discover you've ordered the wrong diopter.

Step Three - Order another one, right diopter this time, wait weeks for it to arrive. Hurrah ! It's perfect. Discover despite being same product as previous one it has a shallower thread and keeps falling out.

Step Four - Have bright idea of taking lens out of latest one and replacing it in the standard eyepiece. Rejoice at sense of achievement in thinking of this great idea.

Step Five - Discover that you don't need to apply much pressure to crack new eyepiece lens.

Step Five - Descend into pit of despair.

Anyone found a source for just the replacement lens element ?
You can order a lens of the requested diopter power cut to size by an optician. Normally, any skilled optician should be able to custom cut a lens so it can be mounted inside your eyepiece.

Cheers!

Abbazz
03-11-2022, 05:48 PM   #6
Site Supporter
Site Supporter
rjm007's Avatar

Join Date: Oct 2015
Location: California
Photos: Gallery
Posts: 217
Original Poster
QuoteOriginally posted by Abbazz Quote
You can order a lens of the requested diopter power cut to size by an optician. Normally, any skilled optician should be able to custom cut a lens so it can be mounted inside your eyepiece.

Cheers!

Abbazz
Not mine ! Can't say I've tried any other optician . Just ordered yet another this time from B&H for $24 which I suspect is cheaper than having one hand cut...
03-11-2022, 06:33 PM   #7
Loyal Site Supporter
Loyal Site Supporter




Join Date: Dec 2017
Photos: Gallery | Albums
Posts: 1,095
QuoteOriginally posted by rjm007 Quote
Not mine ! Can't say I've tried any other optician . Just ordered yet another this time from B&H for $24 which I suspect is cheaper than having one hand cut...
There may still be opticians about who care more for the challenge than the process. Opticians providing custom swimming google correction may be examples. They would likely still have old-time lens cutting equipment. Most modern optician establishments carry lines of frames that lens companies such as Fuji cut plastic to fit from molded plastic optical blanks having various combinations of prism, sphere, and cylinder powers, and apply AR coatings to order.

03-12-2022, 02:24 PM   #8
Pentaxian




Join Date: Feb 2009
Location: Arizona
Posts: 1,247
For future reference for anyone looking for similar lenses to what you want, there is always Edmund Optics. They have a huge supply of various lenses. I bought a few items from them many years ago.Optical Lenses | Achromatic Lenses | Edmund Optics
03-20-2022, 09:00 AM   #9
Site Supporter
Site Supporter
rjm007's Avatar

Join Date: Oct 2015
Location: California
Photos: Gallery
Posts: 217
Original Poster
A Circle of Confusion

QuoteOriginally posted by desertscape Quote
For future reference for anyone looking for similar lenses to what you want, there is always Edmund Optics. They have a huge supply of various lenses. I bought a few items from them many years ago.Optical Lenses | Achromatic Lenses | Edmund Optics
I had a look on there but my failure to pay attention while studying optics in my physics classes meant I couldn't understand what I needed when I looked on their site. And they never replied to my email ...

In the end I bought this one from B&H and it works fine and it fits too. No plans to attempt to remove lens from the metal collar this time.

I would still like to get the lens on it's own so I can replaced the current one in the screw in part of the V. I just need to work out what diopter it really is. It say +1 dioptre on the box but I think that is based on the presumption that the VF is by default -1 dioptre. As my RX is +2.5 that sounds about right. Certainly works OK
03-21-2022, 10:30 AM   #10
Loyal Site Supporter
Loyal Site Supporter




Join Date: Dec 2017
Photos: Gallery | Albums
Posts: 1,095
In case this helps, the diopter is the inverse of the focal length in meters. So if the relaxed eye is focused at one meter, then -1 diopter is needed to focus at infinity with the relaxed eye. (Due to both accommodation and depth of field, persons with 20/20 vision can see to infinity fine. They won't notice that their eye muscles are not relaxed when they do so.) To look at 10 cm requires 10 diopters relative to infinity (focal length 10 cm), or 9 from relaxed (focal length 11.1 cm). Usually, myopes (near-sighted) require negative diopter lenses, and presbyopes (far-sighted) positive diopter lenses to see well to infinity.

Now at Edmonds there are also options among convex-convex, planar-convex, concave-convex with the same focal length, and these have different benefits in secondary focusing characteristics that I'm not competent to describe.
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!
645d, 645z, 6x7 the diopter, camera, despair, diopter, ebay, eyepiece, five, lens, medium format, pentax 6x7, step, weeks
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
How Do I Remove Nikon F100 Diopter Lens To Fit In Pentax 67II Diopter Frame? Kristian Wolfe Pentax Medium Format 22 08-19-2021 08:14 AM
Despair louparker Monthly Photo Contests 23 04-14-2021 07:08 PM
Despair cvhennessy Monthly Photo Contests 13 01-12-2017 11:24 AM
I despair to my O-GPS1 with K-3 MilkaSchokoHase87 Troubleshooting and Beginner Help 19 07-13-2016 07:45 PM
Shock, horror and despair: My DA40s aperture blades fell out antipattern Pentax SLR Lens Discussion 23 01-08-2014 05:26 PM



All times are GMT -7. The time now is 07:14 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