Which +2 diopter for Tokina 12-24

I Was thinking B&W, but there are a ton of them out there.. Has anyone used the Adorama branded diopters? are they any good? Any suggestions as to which brand is gonna have a good balance between optical quality and price?

THanks

Phil

dual element diopters are better than single element. the only dual element +2 i know of is the Canon 500D which is fantastic, albeit a little pricey (i think about $250). I use it all the time on my 17-55mm with excellent results. cheers,

chris

edit: my mistake, $140 at b&h

A 77mm Canon 500D (a +2) will run you about $125 + shipping. The 500D is really better for lenses longer than 100mm focal length though.

I'd stick w/ the B+w personally - I think they're excellent.

Cheers

James

A 77mm Canon 500D (a +2) will run you about $125 + shipping. The 500D is really better for lenses longer than 100mm focal length though.

 

I'd stick w/ the B+w personally - I think they're excellent.

 

Cheers

James

hi james,

what makes it better on longer lenses vs a b&w +2 (single element?) on a wide?? this is new news to me but i'm no expert. would love an elaboration. cheers,

chris

Canon has two excellent close-up filters - the 250D and 500D - both aimed at slightly different focal lengths. From the product descriptions:

"The 250D is suited for lenses with a focal length anywhere from 30 to 135mm. The 500D and 500 are geared for lenses with a focal length anywhere from 70 to 300mm."

IIRC, the 250D is the equivalent of a +4 and the 500D is the equivalent of a +2 - so they're not always interchangeable pending the lens, port and application.

I use the Tokina 12-24 behind a S&S fisheye dome and haven't found the need to use a diopter. What system are you using it with and what are you finding that leads you to want the +2?

Mike

I use the Tokina 12-24 behind a S&S fisheye dome and haven't found the need to use a diopter. What system are you using it with and what are you finding that leads you to want the +2?

 

Mike

Im using it with an Ikelite 20d setup with 8" dome.. Im noticing that the center is super sharp, but the edges tend to fall off a little bit.

Phil

Im using it with an Ikelite 20d setup with 8" dome.. Im noticing that the center is super sharp, but the edges tend to fall off a little bit.

 

Phil

Yes, in CFWA situations it is possible that close objects in the corners can be a little fuzzy. Let us know how if the +2 helps.

Mike

Canon has two excellent close-up filters - the 250D and 500D - both aimed at slightly different focal lengths. From the product descriptions:

 

"The 250D is suited for lenses with a focal length anywhere from 30 to 135mm. The 500D and 500 are geared for lenses with a focal length anywhere from 70 to 300mm."

 

IIRC, the 250D is the equivalent of a +4 and the 500D is the equivalent of a +2 - so they're not always interchangeable pending the lens, port and application.

I remember reading that when I bought my 500D to do topside macro with my tele zoom, before I had a housed uw camera.

I could be wrong, but that seems to me to be a reccomendation based on the power of the diopter, saying a +4 250D (250mm max focus) is more suitable for medium focal lengths giving similar macro repro ratios as the weaker +2 500D (500mm max focus) on long lenses. This makes it easier for the average Joe Shmoe to choose a diopter for his lens. That's assuming there isn't some other design element in the diopters optimizing them for the given focal length range.

We already know what power we need (+2 or +3 for a 20cm/8in dome) and therefore canon's reccomendation seems invalid in our situation. Just a guess, i'm not really sure about that. Cheers,

Chris

Be careful in your choice of dipoter.

I've got a Nikon 12-24 which is a little soft at the corners used behind a dome port. I bought a diopter to see if that helped and found the depth of the filter ring caused vingnetting so the cure was worse than the disease.

I have no personal experience in this, but in his book Underwater photography Paul (pgk) recommends the use of a simple dioptre. He explains that the virtual image is curved (that’s why there is corner fuzziness, the sensor is straight), and using a simple dioptre (with curved front) counteracts this end results in a flatter image on the sensor. Use of a two-element dioptre might not yield this particular advantage.

I have tried both simple (Hoya, Subal, B&W and others) and compound or doublet (Canon and Marumi) diopters and to be perfectly honest all worked fairly well with the exception of the Canon which was fine over most of the image but actually appeared to produce somewhat softer image quality in the extreme corners with very CFWA shots. (Being a 'real' thick lens fitted directly in front of the camera lens, it may be that it caused a change in the overall optical configuration and might require the dome to be moved outwards slightly - easier said than done!).

But all this said, diopters do need to be used with the dome and lens in correct relationship to each other and may well make things worse if the drome to lens distance is already incorrect, when all sorts of abberations can cause flaring, fringing, etc.. Cerianthus points out the other effect of using a diopter which is that it tends to counteract the image curvature but the diopters which reverse this MOST have one curved surface (front) and a flat one (rear) as these, the most simple of diopters, apparently have inherent image curvature in the opposite direction to that caused by an in-water dome. I'm not sure that these very simple diopters are even available now though and they would probably cause as many problems as they solve - it would be interesting to find out if anyone can source one..

But to answer your question, if you can get a B&W, Hoya or similar it should be fine!

Be careful in your choice of dipoter.

 

I've got a Nikon 12-24 which is a little soft at the corners used behind a dome port. I bought a diopter to see if that helped and found the depth of the filter ring caused vingnetting so the cure was worse than the disease.

Good point. When I got the 12-24, I slapped my circular polarizer on it and went out shooting (topside). All the pictures had vignetting. I ended up having to get the thinnest one I could find (a Nikon) and that helped a lot. With really wide angle lenses, you need to make sure you get a filter with a thin ring.

Mike

I finally got in the water with the b&w +2 dipter and it didnt really seem to make any difference at all.. Im going to check to make sure I have the correct extension for my dome port as that is the only thing I can think of that would cause the softness in the images.. On the surface this lens is sharp so im hoping that I can get it to work underwater as well..