purple fringing

[Tom Barry]

Diver, there is an excellent Nikon users website called Nikonians, which has a forum specifically for Nikon D40 and D50 cameras; there is a thread on all known fully-compatible lenses for the series, and a 50mm f 1.8 is not among them. I suspect a combination of factors is at work here and the result is that you are getting purple fringing or chromatic aberration as Steve says, possibly by a combination of the incompatible lens' aperture staying at f1.8 rather than stopping down sufficiently to give any depth of field plus the use of the close-up diopter attachment. The lens also could be faulty, with one or more elements knocked out of alignment. You might post a query on that website to see if anyone has experience with your particular camera/lens combination. Sorry you're having such difficulty.

[Scott D]

Hey Diver,

Do you have it in manual mode? Did you match the camera aperature to the lens? I remember having some issues at first with mine too. I'll get the camera out tomorrow & see if I can remember what I did and post it.....

[Steve]

the lens being set at f/22 is what I don't get, the camera would not operate unless this was done

That sounds like a problem to me...

[JBHII]

What you're seeing is known as "chromatic abberation". It's most prevelant in areas of black and white; or, as seen in your photo, an area where there's a lot of reflection.

In my experience, this is almost always caused by the lens. The quality of the optics has the single biggest influence on this.

Another thing I notice is that your white balance appears to be off quite a bit. What type of lighting are you using? You might want to compensate for that, as that could have some impact, as well...

Hmmmm...I don't think the white balance is off by that much....I'm seeing the photo is heavy on cyan in some of the white areas, which is not at all uncomon when shooting with daylight temperature florescent light sources...and it's easily correctible with post photo editing software.

What amazes me more is that Terry indicates (if I'm reading correctly) that his photo was taken at an f-stop of 22! That's a pretty narrow depth of field I'm seing!

[JBHII]

Here's what I was able to correct in about 30 seconds with Photoshop:

Here's Terry's "before" photo:



Here's the "after" photo where I selectively removed some of the cyans and magentas which were problematic:

[Scott D]

hey John, I was thinking the same thing on the F-stop. The DOF seems awfully shallow for that high a F-stop.

Terry,
How close was the camera to the watch? And did you confirm if you have a lens adapter on it? Those will definitely limit the DOF as they usually curve at the outer edge of the adapter. Try it without the close up adapters & also try moving the camera further away & using the crop to get closer. It makes focusing a bit harder, but I saw better results in mine when keeping the camera about 20-24" away.

[Tom Barry]

Yep, the aperture appears to be wide open at f 1.8. Were you able to talk to someone at the store yesterday?

[diver88]

:):) Mr Barry,

I called and they told me things did not sound just right, to come in and they would help... well, as you probabaly know it rained cats, dogs and goats yesterday so I did not venture from the shed. so no help there as of yet.


Mr Scott and Mr John....

I am really new to this so....
on the new lens there is a moveable f/stop ring as manual.
my camera says on the display no matter what mode or anything that the f/ring must be set and locked at f/22 before anything will operate..

doesent that decrease the size of the aperature mechanically on the lens?
so no matter what I do with the camera from then on the aperature is no wider open (lower number) than the physical opening on the lens?

the photo I posted showed this info,
f/5.6
shutter speed 1 second
1.'6"
manual focus
camera setting on Priority
ISO @200

I do think the 2 element Nikkor close-up 3 diopter was on the lens at the time
(I'm guessing)

I will play with the lens again today to see what happens..

thanks guy's you are teaching me... I'm learning

diver88:):)

[JBHII]

Wow Terry...the short answer is, I agree the lens your using probobly isn't the best choice for your camera.

The longer answer is, that sounds like a lens designed for a 35mm film camera....I'm going to show my youthful age here (and relative innexperience with film based cameras) but I've never worked with a lens that featured an "f ring."

Clearly the metadate indicates the shot was taken at f5.6 which makes sense looking at the DOF on the photo. If by "priority mode" you mean Aperture Priority, then the f stop could have been adjusted in camera.

Really, I should just shut up....I've never really played with a Nikon.

[Scott D]

Hey Terry,

So the lens should work for you. I do believe it should auto-focus for you too. According to Nikon's web-page it is compatible with the D40. So here's what I did on the D80. This seems to work best for mine at least.

1) set the lens on F22. I believe it must be on F22 for the camera to be able to control the aperture. That's why it won't allow you to take a picture on anything other than F22. it can't control the aperture on the other settings (I assume those are for non-auto cameras).

2) set the camera to "A" mode (Aperture of course.. ) ).

3) Using the front scroll-wheel (in front of the shutter release) set the camera to the F-stop you want. You'll see the setting change on the LCD display. You can scroll from F22 - F1.8. The exposure time will auto adjust (assuming you've locked in the ISO).

Here's 2 sample shots I took using the above steps. On a tripod, exact same camera position, using the exact same lens, no flash - just inside light, and set to ISO400. I loaded them at 1024x768 to give you a better view. Note, I have done zero corrections, both are straight off the memory card. These are the exact same shot. Nothing except Aperture was changed.

Set on F1.8:


Set on F22:



As you can obviously see, the depth of field is far better in the one taken at F22. While the lens was set for F22 on the 1.8 shot, you can see the camera did adjust the lens down to the 1.8 setting. I think if you do that, you'll see the camera is adjusting the F-stop. Give that a shot & see if it helps. For testing purposes, try something similar to what I did, taking a frame down a long board with items on it so you can truly guage how the setting are locking in. Once that's done, then move back to the macro stuff. Now when you do, try moving the camera farther away from the watch. I had a heck of a time getting it to work at minimal distances, so I moved it back & cropped on the PC & it worked far better.

Try that & let me know...


BTW, exposure times were of course very different. The F1.8 exposure was 1/60 while the F22 exposure was 3 seconds.