Help with hot spot...

[Grevolorio]

Hi guys,
Thanks to Teerex's advice, I decided to get me a D70. Man am I a happy man...
I instantly loved the camera. Since I still havent got my 67mm R47, I started with a Sigma 28-70 ( I already had a 58mm Hoya R47). Unfortunately I'm getting horrible hot spots in the center, if it wasn't for those hot spot, photos would be great. Can you give me some advise on how to avoid them if possible of howto handle them in photoshop? I've seen in other posts and it seems like it is easy to fix them or am I getting the wrong idea?
Thanks in advance, Gus

 

[teerex]

Hi guys,
Thanks to Teerex's advice, I decided to get me a D70. Man am I a happy man...
I instantly loved the camera. Since I still havent got my 67mm R47, I started with a Sigma 28-70 ( I already had a 58mm Hoya R47). Unfortunately I'm getting horrible hot spots in the center, if it wasn't for those hot spot, photos would be great. Can you give me some advise on how to avoid them if possible of howto handle them in photoshop? I've seen in other posts and it seems like it is easy to fix them or am I getting the wrong idea?
Thanks in advance, Gus

Another proud owner of the D70. You will love it for a long time to come.

Which lens is giving you the hot spot? Seems some lenses of certain focal length give hot spots. Try shooting with the kit lens and see if you get them.

What's the R47? Does not sound familiar.

 

[deadpixel]

Hi guys,
Thanks to Teerex's advice, I decided to get me a D70. Man am I a happy man...
I instantly loved the camera. Since I still havent got my 67mm R47, I started with a Sigma 28-70 ( I already had a 58mm Hoya R47). Unfortunately I'm getting horrible hot spots in the center, if it wasn't for those hot spot, photos would be great. Can you give me some advise on how to avoid them if possible of howto handle them in photoshop? I've seen in other posts and it seems like it is easy to fix them or am I getting the wrong idea?
Thanks in advance, Gus

Gus,

The D70 is pretty good all round camera and can give you very good results when used for IR or UV, however, you do need to watch out for hot-spots as it is quite prone to being troubled by it. The extent of the hot-spot is determined by the camera, lens, the focal length and the aperature you set the lens to.

With prime (fixed focal length) lenses, the usual way to avoid hot-spots is to widen the aperture. The AF 50mm f/1.8 for example has visible hot-spots when the aperture is set to sizes above f/8. This is evident even in non-IR photos; try shooting a bright blue sky with the lens set to f/16 and auto-leveling the photo. With zoom lenses, hot-spots are usually more evident when the focal length is set to the widest, for example 28mm on your 28-70mm. To counter this, open up the aperture more. You can see evidences of this in the test I did with the Tokina 12-24 thread. The hot-spots become less evident as you open up the lens or increase the focal length.

As to whether it can be corrected with PS, I would say that it is possible but it would be better if you could get it right the first time. PSing may be fun at times but correcting issues such as these are chores you should try to avoid.

Cheers

 

[Grevolorio]

What's the R47? Does not sound familiar.

Can't you tell I'm excited? I meant the R72, I don't know where I got the R47, my bad.

Now that Deadpixel mentions it, I used f11 or f13 for my shots trying to increase the DOF, I used a Sigma 28-70, at 28mm. I thought it was because it was a cheap lens. I'll try opening it up and let you guys know. I ordered my 67mm Hoya R72 (not 47), but I'm still waiting for it.

Now about the Photoshop part, of course I'd like to shoot it right the first time but I imagine that eventually you will end up with photos with a hot spot that you cannot retake and would have to try to save them, that it why I thought it would be nice to know how to fix them.

Any other ideas would be greatly appreciated.
Thanks again, Gus

 

[deadpixel]

Now about the Photoshop part, of course I'd like to shoot it right the first time but I imagine that eventually you will end up with photos with a hot spot that you cannot retake and would have to try to save them, that it why I thought it would be nice to know how to fix them.

Hmm, well if you're really determined to try, here's a rather clumsy and tedious, but quite effective, method I use when I really need to.

I'm assuming you're using PS CS:

1. Using the elliptical select tool, select an area slightly larger than the hot-spot.

2. Identify the color/shade of the hot-spot and using the Hue/Saturation tool, adjust the area of the hot-spot till you get a color/shade similar to the surrounding area. Save the settings and cancel the Hue/Saturation tool.

3. Open the Hue/Saturation tool again and load the settings that were previously saved. Click OK.

4. In your History palette, click on the History Brush Source box next to the Hue/Saturation. Click Edit->Undo (to undo the Hue/Saturation) done on the entire photo.

5. Select the History Brush in the Tool Palette, set mode to normal and opacity to 30%. Right-click and set the brush to a size about a third of the hot-spot and set Hardness to about 10%. Moving out from the centre of the spot, CLICK AND HOLD to brush on the previously undone Hue/Saturation ALL THE WHILE PRESSING DOWN ON THE CLICK. Once you've reached the outer limit of the spot, repeat the process but stop when you're two-thirds out and repeat a third time when you're a third out. The hot-spot is brightest in the center so this process gives the change a more even look.

6. If it is still too bright, click on the Clone Tool, set Mode to Darken and Opacity to 40%, Alt-Click on a darker area to set the area of referrence and then click on the area to darken.

Look at the two before and after photos below. I hope the change is obvious enough.

#1 - Before:

#2 - After:

Hope this helps.

Cheers