Canon dioptric adjustment lenses

[cokinut]

Hello all. I have a -4.50 prescription and found out that canon sells these adjustment lenses. I know that the eyepiece that came with the kit is around a +1.00 -> -3.00 diopters. Now, If i get the -4.00, will that mean the max i can adjust the diopters is only to -4.00 or can it get stronger - for example, does the "starting point" of the diopter dial zero out around -1.00 and then i can add the -4.00 to get a total of -5.00 diopters. I hope i'm not confusing anyone.

thanks

[RDKirk]

Hello all. I have a -4.50 prescription and found out that canon sells these adjustment lenses. I know that the eyepiece that came with the kit is around a +1.00 -> -3.00 diopters. Now, If i get the -4.00, will that mean the max i can adjust the diopters is only to -4.00 or can it get stronger - for example, does the "starting point" of the diopter dial zero out around -1.00 and then i can add the -4.00 to get a total of -5.00 diopters. I hope i'm not confusing anyone.

thanks

It's -4 all by itself. However, a bigger question is, "do you really want it?"

I'm -8.75 myself, having dropped from -3.75 when I first started photographing more than 30 years ago. Four years ago I had to add presbyopia (age-related farsightedness) to the prescription.

But I've never found a use for diopter correction to supplement my nearsightedness. I found that it's far more of a pain to take my glasses off for the viewfinder, then having to put them back on when I pulled the camera from my eye to be far worse than simply keeping my glasses on to see through the viewfinder.

The mild dioptic correction that comes with the camera is suitable for people whose correction is slight enough that they can see fairly well without glasses, but want the sharpest vision when looking through the viewfinder. The viewfinder itself presents a virtual image 1 meter from your eye (when the camera diopter setting is centered, which is at -1.0). I find it best to use the camera control to focus on the AF marks while wearing the eyeglass correction that's best for seeing 1 meter from my eyes.

[DocFrankenstein]

Maybe we've discovered a new market: the camera headstrap for the visually impaired. Just strap the camera to your face and you never have to remove the camera.
With the crappy viewfinders of today, the market would be limited to pro minolta users... :lol:

[cokinut]

hah.

well, so if i get a -4.0 correction, that'll be it - just -4.00 and no addition to the -3.00 + -4.00 = total of -7.00 diopters? blah.

[chap]

hah.

well, so if i get a -4.0 correction, that'll be it - just -4.00 and no addition to the -3.00 + -4.00 = total of -7.00 diopters? blah.

I'm not an optics expert, but I think that with the -4.00 diopter lens the zero setting on the viewfinder provides a correction of -4.00. When you change the setting on the viewfinder to -3.00 the effective correction should be -7.00. The correction on the camera should continue to operate with the added lens and allow fine tuning of the adjustment.

chap

[DocFrankenstein]

I'm not an optics expert, but I think that with the -4.00 diopter lens the zero setting on the viewfinder provides a correction of -4.00. When you change the setting on the viewfinder to -3.00 the effective correction should be -7.00. The correction on the camera should continue to operate with the added lens and allow fine tuning of the adjustment.

chap
It doesn't really add like that, but works similarly. You won't get -7 but should be close enough.

[cokinut]

thanks for all your help. it's true that taking my glasses on and off is harder, but i since i have the EP-EX15 with the lenses removed, i need to have my eye pressed against the cup to see the entire viewfinder, plus, i hate having grease marks on my glasses and the sun's glare killing the contrast when my eye isn't pressed up agains the eye cup.

[lostdoggy]

Quoted from EF Lens Work III:
"...The numerical values printed on EOS dioptic adjustment lenses indicate the total diopter obtained when the dioptic adjustment lens is attached to the camera..."

[chap]

Quoted from EF Lens Work III:
"...The numerical values printed on EOS dioptic adjustment lenses indicate the total diopter obtained when the dioptic adjustment lens is attached to the camera..."

Lostdoggy, thanks for digging that up. I shouldn't have posted speculation without having some sort of source.

[cokinut]

ahh. thanks.

in that case, what's the point of having a -3 dioptric lens when the "stock adjustment" goes from +1 - -3 already?

[erik-nl]

An important reason for not wanting glasses between you and your viewfinder is that ambient light will find its way into the camera because of the gap and screw up the light metering!
Just move your face away from the camera in bright sunlight and keep looking at the readings for aperture and/or exposure, they will change. Underexposed shots are the result of this leak.

Taking off your glasses and holding on to them somehow whilst manipulating a camera, putting them back on, taking them off etc. etc. is a serious pain however.

[jessieanchor]

Quoted from EF Lens Work III:
"...The numerical values printed on EOS dioptic adjustment lenses indicate the total diopter obtained when the dioptic adjustment lens is attached to the camera..."

I know what you are saying, BUT.....

......many (well most) of the Canon EOS SLR's (certainly all but the EOS 1 series) up to (say) 5 years ago came WITHOUT dioptric correction 'wheels'.

Therefore, if you stuck a -4.0 dioptre lens on the camera, then that's what you got...

Surely it then follows (being as Canon have not changed the design of the dioptric correction lenses) that if adding a -4.0 dioptric correction lens, ON TOP of the dioptric correction you can 'dial in', then you can (with a camera giving +1.0 to -3.0 dioptres) get an equivalent of -7.0 dioptres??

I think the quote is printed in lens work probably refers to the -1.0 dioptre already included (made that way) in the standard Canon EOS viewfinder - therefore, in the little equation above, you would get a MAX of -6.0 dioptres....

Canon EOS magazine (is this available to you?) do a service where you can TRY the dioptric adjustment lens that suits you (free - you try one at a time and then return), you then purchase the one that suits you best.... Not sure if it's available (this is in the UK) to overseas.... will check for you.

[jessieanchor]

Yup, have just gone through my 'back stash' of EOS magazines....

.....it confirms that the dioptric correction lenses DO INCLUDE the -1 dioptre that is BUILT-IN to the EOS SLR. Goes on to say that should the image in the viewfinder become blurry therefore, you could even need a +1 dioptre correction lens to bring the view BACK to "0"....:)

.....it assumes (these magazines go right back), that you are using a EOS SLR without a dioptric correction wheel. So you stick your -4 lens on, and that's what you get - but it is -1 plus -3 = a minus 4 dioptric lens. Early EOS's (with the exception of the EOS 1) didn't have a dioptric correction wheel. I have/have had most of the early EOS models, and the only one that has the wheel is the EOS 1.

So with the newer models HAVING the wheel, you can add what you have 'dialled in', and add that dioptric correction to the strength of the correction lens you have got, then DEDUCT one (for the standard view that is incorporated).

So if you need -4.5, then you can dial in -3, buy a -2.5 dioptric correction lens, gives a total of -4.5 after taking off the -1, and you should be 'bang on' as they say here in the UK....:D

Sorry I waffle :o Hopefully that makes sense....! :lol:

[jessieanchor]

P.S.....


Canon EOS magazine can be subscribed too from overseas....:)

But the "try before you buy" for the Dioptric Correction lenses is only available to UK subscribers :(

www.eos-magazine.com (http://www.eos-magazine.com)

[Nicholas Ivan Barnes]

It seems I am able "top up " my built -in dioptric adjuster with the attachment.By the way I can`t find an eyepiece attachment in case I want to keep my glasses on.I had one which fitted my EOS 50E film camera but it doesn`t fit my 300D
Any suggestions?

[DavidW]

It's an old thread - but worth posting some answers that I think are missing.

As has already been mentioned, the powers printed on E series dioptric adjustment lenses include the -1D built in to the camera (with the adjuster in the central position if the camera has an adjuster). I wanted a -2D lens on my 20D to give me enough range in the adjuster to use my glasses or not use them, so that meant I wanted an E -3 lens. With the E -3 lens fitted, I still have the same plus and minus 2D adjustment available; it's just that the central position has moved.


Nicholas - the eyecups and rubber frames are different for different camera ranges. The 300D, 350D, 20D, 30D and I think all the recent digital SLRs apart from the 1 series use Eb bits. You want an Eyecup Eb if you don't use a dioptric adjustment lens, and a Rubber Frame Eb if you use a dioptric adjustment lens.



David