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Snareguy78 · 11-01-2022, 12:34 PM

I bought a 6x7 and possibly Jameson helped me buy several lenses but still have a 45 f4, 55 f3.5, 105 f2.4 and a 90-180 f5.6... all of them I'm having focus issues with. How do you tell what diopter is in there...

I'm seeing zero markings for anything

Last edited by Snareguy78; 11-02-2022 at 02:10 PM.

garywakeling · 11-01-2022, 10:59 PM

Unfortunately the diopter if in the viewing path has no markings on them, try removing it and taking it to an optometrist to measure or a cheaper alternative is at the local drug store and go to the magnifying glasses with 0.5 1 1.5 2 diopters and see which one looks closest to the one in your camera

**kaseki** · 11-02-2022, 09:20 AM

Or use it to focus a distant light onto a surface. The power in diopters is the inverse of the focal length in meters.

Snareguy78 · 11-02-2022, 02:13 PM

Well that will do it. Looks like it has a +2 diopter in it. I was losing my mind... 4 wasted rolls testing with each lens but at least now i know. Luckily seems like i can buy a replacement on ebay.

garywakeling · 11-03-2022, 03:29 AM

Originally posted by Snareguy78

Well that will do it. Looks like it has a +2 diopter in it. I was losing my mind... 4 wasted rolls testing with each lens but at least now i know. Luckily seems like i can buy a replacement on ebay.

Glad you worked it out before getting too frustrated with the camera results

**kaseki** · 11-03-2022, 10:49 AM

It may be worth noting that the young have sufficiently flexible lenses in their eyes to easily accommodate 2 diopters thrown into their visual path. When one reaches geezer age, however, or have lenses replaced due to cataracts, this flexibility is no longer present and focusing on the reticle plane of the camera sight might be difficult unless their prescription happens to match the lens power inserted into the eyepiece.

Addendum to my earlier comment. The direct measurement of focal length that I noted applies to positive diopter lenses. It can be used with negative lenses if a known power positive lens (of greater power) is used to find their combined focal distance, and then the positive lens contribution removed from the measured diopter value to yield the negative lens power.

11-01-2022, 12:34 PM	#1
Snareguy78 New Member Join Date: Aug 2022 Posts: 12	I bought a pentax 6x7 mlu I bought a 6x7 and possibly Jameson helped me buy several lenses but still have a 45 f4, 55 f3.5, 105 f2.4 and a 90-180 f5.6... all of them I'm having focus issues with. How do you tell what diopter is in there... I'm seeing zero markings for anything Last edited by Snareguy78; 11-02-2022 at 02:10 PM.

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11-01-2022, 10:59 PM	#2
garywakeling Moderator Join Date: Jul 2011 Location: Melbourne Photos: Gallery \| Albums Posts: 1,774	Unfortunately the diopter if in the viewing path has no markings on them, try removing it and taking it to an optometrist to measure or a cheaper alternative is at the local drug store and go to the magnifying glasses with 0.5 1 1.5 2 diopters and see which one looks closest to the one in your camera

11-02-2022, 09:20 AM	#3
kaseki Loyal Site Supporter Join Date: Dec 2017 Photos: Gallery \| Albums Posts: 1,139	Or use it to focus a distant light onto a surface. The power in diopters is the inverse of the focal length in meters.

11-02-2022, 02:13 PM	#4
Snareguy78 New Member Join Date: Aug 2022 Posts: 12 Original Poster	Well that will do it. Looks like it has a +2 diopter in it. I was losing my mind... 4 wasted rolls testing with each lens but at least now i know. Luckily seems like i can buy a replacement on ebay.

11-03-2022, 03:29 AM	#5
garywakeling Moderator Join Date: Jul 2011 Location: Melbourne Photos: Gallery \| Albums Posts: 1,774	Originally posted by Snareguy78 Well that will do it. Looks like it has a +2 diopter in it. I was losing my mind... 4 wasted rolls testing with each lens but at least now i know. Luckily seems like i can buy a replacement on ebay. Glad you worked it out before getting too frustrated with the camera results

11-03-2022, 10:49 AM	#6
kaseki Loyal Site Supporter Join Date: Dec 2017 Photos: Gallery \| Albums Posts: 1,139	It may be worth noting that the young have sufficiently flexible lenses in their eyes to easily accommodate 2 diopters thrown into their visual path. When one reaches geezer age, however, or have lenses replaced due to cataracts, this flexibility is no longer present and focusing on the reticle plane of the camera sight might be difficult unless their prescription happens to match the lens power inserted into the eyepiece. Addendum to my earlier comment. The direct measurement of focal length that I noted applies to positive diopter lenses. It can be used with negative lenses if a known power positive lens (of greater power) is used to find their combined focal distance, and then the positive lens contribution removed from the measured diopter value to yield the negative lens power.

I bought a pentax 6x7 mlu

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