I'm attempting to dial in my new 17-40L. I have asked three well respected shop folks for a setup recommendation and I got four different answers. (The treasure remains elusive) I've had it in the pool with the Sea & Sea recommended configuration and the corners are a tad soft. While that might work for open water dolphins I'd really like to dial it in if I can. Is there a simple, readily available tool/method for creating a lens test that I can pull together. I've got four different configurations I'd like to try for a trip in a couple of weeks. Any pointers would be greatly appreciated.
In digging around in the old posts I saw Mr. Loftus had some sheets he printed up for testing the Tokina 10-17 back when it came out but they are no longer on the website and I'm too far from Fl to go steal Mr. Frink's great setup.
One of the reasons I like it, is because it is designed as an autofocus depth chart, and I think can be helpful if one want to see depth of focus in the corners which I think is helpful sometimes. Good luck.
Crikey Steve you are going to be in the pool hours playing with that!
Having said that guess that the pool is probably the coolest place to be in AZ this time of the year!
Paul C
Thanks Jeff,
Do you have any sample shots of how you used this to test your corner sharpness. I'm not sure how I would rig it up.
Hey Paul,
It is a tad bit on the warm side here, nice and cosy. Air temp today 38 or so and the pool is 32.
Cheers!
Steve
Thanks Jeff,
Do you have any sample shots of how you used this to test your corner sharpness. I'm not sure how I would rig it up.
Hey Paul,
It is a tad bit on the warm side here, nice and cosy. Air temp today 38 or so and the pool is 32.
Cheers!
Steve
Steve I just pointed my dome port horizontally down lying on the side of the pool over an area where the pool bottom was not slanted. I placed the charts where I wanted them using the pool net to move them around. One chart in the center of the FOV and one at the periphery. Turn off the filter or creepy crawly. Of course it's easier if you have help.
Thanks partner, I'll give it a go and let you know how it turns out.
Have fun,
Steve
i've got similar test issues and have been thinking of getting a large - say 3x4 ft sheet of white plastic and drawing a grid with sharpie and straight edge
i've got the lens about as well posititoned in the dome as practical and want to find out if a diopter helps or hurts
Hi Steve,
I went to the store and bought a sheet of linoleum that has a pattern on it. That works pretty well for corner sharpness testing. That's how I tested the 10-22 when it came out.
Cheers
James
I've found that it's a lot easier testing in a big tub of water. Get a large Rubbermaid container & something with fine detail in the corners (like a couple of signs with text & bar code in corners). Since you only need to get the dome wet, 6-12" of water is all you need. Adjust for lens being tested. Shoot at 2 or 3 different f-stops (f4,5.6,8). If you get sharp results up close, then more distant shots will also be fine. Much quicker changing setups this way & very little actually gets wet.
Thanks Jim, do you have any pictures of your setup you can share?
Hey James, do you have the link to what you discovered on the 10-22? A shot of your setup would be helpful too if you can lay your hands on it.
I'm thinking of building a pvc frame I can sink in the pool that will hold the camera and the target/reference images. Anybody ever try that?
Overthinking again,
Steve
Steve:
I hang an aluminum yard stick over the edge of the pool and shoot it diagonally. This gives me the ability to see lens sharpness cornor to cornor and in the middle.
Nice to meet you at Long Beach. Sorry we didn't have more time to BS; It was a busy day!
Allan
Hi Steve,
My lens test is in the Library here.
Cheers
James
I like the yardstick idea.
Would a simple light colored sheet with a checkerboard pattern work? Weight the bottom edge and hang the top edge over something straight, like the pole for your vacuum head or leaf skimmer (in case your pool edge is curved). With the pool pump off, I'd think that would stay pretty 'vertical' and be a nice big target to let you test corner sharpness further off for mid- to wide- angles.
I have not tried this myself, however.
Thanks for all the advise guys, I tried a simple approach but I found the differences in the test conditions needed to be controlled a little closer so I could make sense of what I was seeing. It turns out the best configuration in terms of sharpness in the corners and less distortion varies quite a bit by f stop. I built up this little test rig out of some pvc I had laying around, so I could try to understand the differences. Here is what I ended up using;
(The treasure remains elusive) I've had it in the pool with the Sea & Sea recommended configuration and the corners are a tad soft. While that might work for open water dolphins I'd really like to dial it in if I can. Is there a simple, readily available tool/method for creating a lens test that I can pull together. I've got four different configurations I'd like to try for a trip in a couple of weeks. Any pointers would be greatly appreciated.
