Russell Anway

dwijip,
 
That diopter you're linking looks suspicious to me.  A couple things, it doesn't have a brand so there's no way to know what kind of glass it is.  It's in a rotating housing, which is incredibly pointless.  It makes me think its homemade, and someone popped the a polarizer out of its frame and put this piece of glass in.
 
The other thing is that this guy seems to be saying that even though this lens is a singlet it's just as good as the doublets aka achromat's.  In a doublet each of the lenses are coated with different types of chemicals, and when light passes through each of these it has the effect of correcting chromatic aberration because science.  So saying a singlet is just as good as a doublet is just not possible.  They were each designed the way they are for a reason, doublets for quality, singlets for cost.  All that is to say that 70 seems astronomically high.  You can get some good Tiffen series IX diopters for like 10-20 each if you're patient.  And if you need the threads you can get a holder/converter thing that will put your lens into 77mm threads.
 
Here is a (hugely overpriced) example:
http://www.ebay.com/itm/Tiffen-series-9-Diopters-for-SLR-Magic-Anamophot-1-2-3-Diopter-Holder-/161490633136?pt=UK_CamerasPhoto_CameraAccessories_CameraLensesFilters_JN&hash=item25999781b0
 
At this point it is worth noting that the beginning of this thread has a ton of great suggestions.
 
The other thing I'll mention is that you seem to be saying "I can't afford/find the Tokina +.4, so how about this canon +2?" And also you're asking if these would be good for portraits.  Firstly, you don't need any diopters to shoot portraits (unless I'm badly misunderstanding your rig and you have a min focus of like 3 meters, and even then I'd imagine a 135mm taking lens would be close).  One convenient thing about anamorphics is that even though they have poor close focusing, their wide frame means you will likely be further back from your subject for almost everything
 
So for that type of shot, assuming min focus is somewhere within a normal range, you wouldn't want a diopter UNLESS...You were using the Tokina to try and clean up some issues in your image.  Understand that a big part of the reason for the Tokina's appeal is that, in addition to giving you some close focusing, it's low power allows you to put it on a lens and then, in many common shooting situations, you can use the lens as normal with the benefit of the Tokina's achromatic properties (please, someone yell at me if I'm wrong).  There is a convenient symbiosis here because many of the common optical issues with anamorphic lenses and with diopters are the same, and the Tokina, since it's designed to correct dioptric optical problems, conveniently corrects anamorphic issues as well.
 
But, because the primary use of diopters is close focus, and very low power diopters are of limited usefulness to the people who buy most of them (stills photographers for Tokina), there's just not that many options.
 
Now, compare the Canon +2 to the Tokina +.4.  The canon will put your infinity focus at a half meter, while the Tokina will put it at 2.5 meters.  That's the main difference.  So even though the effect that these will have on the quality of your image will be similar, the amount of things that you can do inside their useful range is very different.  Meanwhile, if you wanted to shoot a very close shot of your actor's eye, or pull a shot of a text message off a phone so it takes up the whole frame, then you'll need the +2.  That's really what it's for.
 
Point is, it seems like you're a little confused about what some of this is for, and it seems likely that you're just getting into anamorphic and read you need diopters so you're getting diopters.  My advice would be to borrow/rent a few diopters and try them out.  Then, consider what situations you need to cover with them, and then decide what you need to buy.  For example someone a few posts back said they got a Leica 55mm achromat.  That is a sweet piece of glass.  But its only useful because of the size of the rig its going on, so for them its perfect.  For a lot of other people, useless.
 
Anyway, good luck.

It might be worth emailing redstan.  I emailed him when he was sold out but still was able to secure a +.25 82mm in trade that was not officially for sale (someone bailed on paying him after begging to reserve it so he sold it to me since I had money in hand).

I'll second ceico7.  Stuff I've got from ebay from untested sources has nearly always proved to be a waste of time/money.  So I just pay for that good polish stuff now. 
The one thing I'll point out is that if the pin is out of alignment it won't matter on the foton-A like it does on other anamorphics.  Normally, for example any of the OCT19 lenses, it would skew the image, but that won't be an issues with the foton since it is a two piece lens and the anamorphic portion is aligned to the rails, and not to the mount.  So the spherical will be "out of alignment", but the anamorphic part will be aligned, so you won't be able to tell.
If the lens is out of alignment and it's a single piece, you can also always loosen the PL and then spin it to alignment and then re-tighten.  You just have to be sure and get your back focus correct. 

I've never used the minolta diopter specifically, but I can vouch for the minolta glass of that vintage.  I have a 24mm, a 58mm and the 35-70 zoom and their all really nice lenses, as is their reputation.  It's older so I'm sure standard older glass warnings apply, but i've read on DP review that its a good diopter.  I think its not a terribly prized diopter just because its only 55mm thread (almost all the minolta lenses from back then are 55) and that's pretty small for today.  But if it works for you I'm sure its a fine choice.

Hello,
 
There are far too many tests shot with our anamorphics and far too little work!  And in that spirit I shot a couple narrative bits with my Lomos in the last couple weeks.
 
I shot this with my 35mm and 80mm  Mostly with the 35mm.  The 35mm is an OCT 18 so I also mounted it with a 24mm and a 50mm at times.  Opening shot is 24mm, shots on suspension bridge are 50mm.  Shot on a gh1 (frowny face) and had an arri 650.  I also wrote it and directed it.  First time I've done an ad like this or shot something significant with these lenses.  I used Schneider 4x4 ND's, a tiffen polarizer, and a tiffen +1.5 diopter (closeups to throw that background out of focus).
 
It's an ad for a new app coming out Saturday.  It uses iPhone gps data, and other ambient factors like time/temp to access original artistic content.  So it's a bit like a gallery/scavenger hunt on your phone.  Only available in Minneapolis to at launch.
 

 
I also recently shot a short I will hopefully post here when I make sure it won't cause any problems with upcoming festival commitments.
 
Thanks and let me know what you think!

Hello,
 
There are far too many tests shot with our anamorphics and far too little work!  And in that spirit I shot a couple narrative bits with my Lomos in the last couple weeks.
 
I shot this with my 35mm and 80mm  Mostly with the 35mm.  The 35mm is an OCT 18 so I also mounted it with a 24mm and a 50mm at times.  Opening shot is 24mm, shots on suspension bridge are 50mm.  Shot on a gh1 (frowny face) and had an arri 650.  I also wrote it and directed it.  First time I've done an ad like this or shot something significant with these lenses.  I used Schneider 4x4 ND's, a tiffen polarizer, and a tiffen +1.5 diopter (closeups to throw that background out of focus).
 
It's an ad for a new app coming out Saturday.  It uses iPhone gps data, and other ambient factors like time/temp to access original artistic content.  So it's a bit like a gallery/scavenger hunt on your phone.  Only available in Minneapolis to at launch.
 

 
I also recently shot a short I will hopefully post here when I make sure it won't cause any problems with upcoming festival commitments.
 
Thanks and let me know what you think!

Hello,
 
There are far too many tests shot with our anamorphics and far too little work!  And in that spirit I shot a couple narrative bits with my Lomos in the last couple weeks.
 
I shot this with my 35mm and 80mm  Mostly with the 35mm.  The 35mm is an OCT 18 so I also mounted it with a 24mm and a 50mm at times.  Opening shot is 24mm, shots on suspension bridge are 50mm.  Shot on a gh1 (frowny face) and had an arri 650.  I also wrote it and directed it.  First time I've done an ad like this or shot something significant with these lenses.  I used Schneider 4x4 ND's, a tiffen polarizer, and a tiffen +1.5 diopter (closeups to throw that background out of focus).
 
It's an ad for a new app coming out Saturday.  It uses iPhone gps data, and other ambient factors like time/temp to access original artistic content.  So it's a bit like a gallery/scavenger hunt on your phone.  Only available in Minneapolis to at launch.
 

 
I also recently shot a short I will hopefully post here when I make sure it won't cause any problems with upcoming festival commitments.
 
Thanks and let me know what you think!

That is basically what we're getting at.  "is it worth it?"
 
Some achromat's are worth it others *might not be.   We don't know.
 
I can tell you that we do some macro work with diopters at the studio that I work at and we get some nasty color fringing.  I'm not sure which brand they're using, but its not achromatic, meanwhile I've liked the results from my Tiffen series 9's.
 
It's explained in depth and better some other places, but the basic thinking behind using achromat's with anamorphics is this...  An anamorphic lens of any kind is essentially an adapter, same as a diopter.  There are a number of problems caused by using each of them in common.  Achromatic diopters work to correct those short comings in close photography, but in doing they inadvertantly correct those same flaws in anamorphic photography.  Giving sharper less distorted images (undesireable distortion that is).
 
So you see the point of using achromats on anamorphics often has nothing to do with close photography (though they go well together because you so often use diopters precisely for close-ups when shooting anamorphic).  That's why the low power diopters are popular, such as the tokina +.4 (and now, potentially, the SLR magic +.33).
 
But as to whether or not the SLR magic diopters are "worth it."  That's what I'm asking. They're new so there isn't a lot of information or quality tests available yet.
 
So get shooting and post something!

Get one made...
 
I hope that doesn't sound dismissive, but I've literally never seen one for sale.  And if i sold you one, I'd need one... I'd imagine most people with any sort of access are in the same boat.
 
Also, frankly.  i'm not sure a leather and velvet lens cover that's fourty years old is even a good idea.  Every time i look at my 35mm I'm terrified that there is mold lurking in that skanky old lens cover, then fearfully pack it with more dessicant.