Canon FF, EF 17-40/4L and diopters - is it possible?

I came back from a months trip to Borneo a couple of days ago. I used the 17-40 with the diopter for a number of Sipadan dives. Last year I did the same trip using the 17-40 without dipter. As far as I can see on the pictures I have looked at till now there is a very marked improvement in corner sharpness with the diopter. They are not perfect with the diopter, but mostly usable, which is far from the result without the diopter.

 

/Bent C

Looking through my pictures, I am not really as happy as I was when I wrote the above. The diopter helps, but still most pictures come out with pretty soft corners when at 17 mm. It is a big difference when I compare with the EF 15 mm FE, corners are way better there (which I guess more or less everyone knows already, so no big surprise there). I really have to do some controlled pool tests with the 17-40 to see how good I can make the corners work in a best case scenario. Currently I feel that it will be relegated to subjects with blue water backgrounds.

/Bent C

Bent,

are you using the recommended port for the 17-40 and 8in dome? my understanding is that diopters shouldn't be needed if the right port is used. i too have a 5d, 8in, and 17-40, but my first trip is in a few weeks. from the sounds of it, i need to order a diopter. hmm

Bent,

are you using the recommended port for the 17-40 and 8in dome? my understanding is that diopters shouldn't be needed if the right port is used. i too have a 5d, 8in, and 17-40, but my first trip is in a few weeks. from the sounds of it, i need to order a diopter. hmm

Yes, I am. Of course it depends on how you shoot, but I had an idea of a barrel sponge placed right on one side of the picture and blue water outside it. All those efforts are in my opinion, at least the way I shot them, worthless with my set up. Centered objects are OK, and the closer to 40 the lens is set, the better it gets (which is as expected).The 15 mm FE is way better close to the edges. So, using the correct port attachment, the 8 inch dome, and the 17-40 currently does not give me anything close to what I would like. And I should add that the my 17-40 gets a lot of use above water on a 5D MII, with results that I am perfectly satisfied with, so the lens itself seems to be fine.

However, I should add that I am about to do a pool test to see if it is possible to get reasonable sharpness of corners with my set up. Obviously, there are a whole lot of factors that could influence the result when on a reef, so I would not really dismiss the 17-40 before I´ve done a more controlled testing. Having said that, I really think you should go for a diopter and as small f-stops as possible on your trip.

/Bent C

You may have already said this, but what port and extension ring are you using? How far does the lens tip protrude into the port?

Cheers

James

ok i guess i'll order one. +2 or +4?

on another note, how do you select your focus point? i always use the thumb-joystick which my ikelite housing doesn't support. and most of my subjects are not centered. but since i'm new to underwater photography, it may be better if i center subjects so i don't mess with the dual strobes so much.

You may have already said this, but what port and extension ring are you using? How far does the lens tip protrude into the port?

 

Cheers

James

I use the Ikelite 8 inch dome with the extension ring recommended on the Ikelite website. I am not at home the next couple of days, so I can not really check now how far the lens protrudes into the port, but as soon as I get home I will check.

/Bent C

ok i guess i'll order one. +2 or +4?

 

on another note, how do you select your focus point? i always use the thumb-joystick which my ikelite housing doesn't support. and most of my subjects are not centered. but since i'm new to underwater photography, it may be better if i center subjects so i don't mess with the dual strobes so much.

Most often I use the center focus point (at least for seascapes, for macro I often choose). I realise that in some circumstances this can induce some blurring of edges due to movement of the focus plane when recomposing, however the corner issue shows up on pictures that I do not recompose as well.

I use a + 2 diopter, maybe a + 4 ccould do the job better. I have never tried, so I do not know.

Regards

Bent C

Bent C,

I am in the process of acquiring a 5D/Ike/8inch dome combo; planning to use my 15mm Sig FE for starters, but considered swapping out the 15mm with the thought that the 17-40 maybe a better 'general WA' option if I can only afford one or the other. Do you have any experience with a 15 FE? Do you have links to your pics from Borneo?

Thanks,

tim

I'm learning that the move to full frame can be much more complicated than just sticking to cropped sensors...

Bent C,

I am in the process of acquiring a 5D/Ike/8inch dome combo; planning to use my 15mm Sig FE for starters, but considered swapping out the 15mm with the thought that the 17-40 maybe a better 'general WA' option if I can only afford one or the other. Do you have any experience with a 15 FE? Do you have links to your pics from Borneo?

Thanks,

tim

 

I'm learning that the move to full frame can be much more complicated than just sticking to cropped sensors...

Hi Tim

I use the 15FE more now than I use the 17-40, and with much better results. The major (only?) problem for me with the 15FE is the lack of versatility. When I am on Sipadan, and shooting turtles, I have preferred the 17-40. And, as far as turtle shooting goes, with blue backgrounds, the 17-40 is OK. I have used the 15FE with an 1,4 extender as well, which gives it just a little more reach. So currently, if I was to choose between the two, I would certainly go for the 15FE. However, before leaving out the 17-40 totally, I feel that I have to do some controlled tests. When I look through my latest pictures, the 17-40 has been used on larger openings than the 15FE, so at least they should be compared on similar f-stops before taking a descision. My latest gallery from this years stay is on http://www.pbase.com/borneobent/sipadanmabul_borneo_09 . During my 2008 stay I shot more with the 17-40, which kind of shows in the gallery, as I seem to have kept mostly macro shots: http://www.pbase.com/borneobent/sipadanmabul . If you want to see more examples from the two lenses I have some pictures with both in this album: http://www.pbase.com/borneobent/red_sea_2008

Regards

Bent

You may have already said this, but what port and extension ring are you using? How far does the lens tip protrude into the port?

 

Cheers

James

I use the Ikelite 8 inch dome port with the recommended 5510.24 extension ring. The red ring of the lens is flush with the end of the extension ring, which is exactly aligned with the inner, back part of the Dome structure. Thus, the outer glass of the lense does in reality not protrude into the dome, but is exactly at the back side of the dome.

Interesting. Well if your dome is a complete hemisphere then this is the wrong extension. But I think the Ikelite port is only a chord of a hemisphere so the actual focal point of the dome is back somewhere in the lens - which is good.

That looks about right to me but it's hard to say. There's nothing drastically WRONG w/ that positioning/extension ring.

Cheers

James

Interesting. Well if your dome is a complete hemisphere then this is the wrong extension. But I think the Ikelite port is only a chord of a hemisphere so the actual focal point of the dome is back somewhere in the lens - which is good.

 

That looks about right to me but it's hard to say. There's nothing drastically WRONG w/ that positioning/extension ring.

 

Cheers

James

Thamks, James. Still waiting for some time to do the pool test. I will try with different extensions then.

Regards

Bent

I'm back from my trip. i never got a chance to buy the diopters, but i didn't need it.

i didn't notice any abnormal softness on the edges. i'm quite happy with the 8in dome performance with the 17-40 on my 5d.

at 17mm, there's always some edge softness, but i dont think it is much more than on land. not sure, but the photos are ok for me. i'm always f8 or smaller. i should have tried wider to see the difference, but i didn't get to dive as much as i planned with the camera (surface currents).

for a casual photographer, no diopter was ok for me.

Bent - nice photo of that port. i think mine sticks out about the same. so same port.