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Chromatic aberration ? (1 Viewer)

AZRim

Member
Hi I have a Question. I keep having problems with my pics. I'm using a Casio Exilim 7.2 megapixel cam. I'm using a Kowa TSN-821M scope with the 21wide angle eye piece. I have been setting the cam up like this
anti shake to off and using the two sec delay
iso to auto
auto WB
focus to Macro
metering to center weighted
It seems to me that most of the subjects have blurry edges, can I fix this with the camera? I am VERY new to this so I don't know a lot, I think it might be chromatic aberration or purple fringing.
Here are some of my examples.
Brent:brains:
 

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Hi I have a Question. I keep having problems with my pics. I'm using a Casio Exilim 7.2 megapixel cam. I'm using a Kowa TSN-821M scope with the 21wide angle eye piece. I have been setting the cam up like this
anti shake to off and using the two sec delay
iso to auto
auto WB
focus to Macro
metering to center weighted
It seems to me that most of the subjects have blurry edges, can I fix this with the camera? I am VERY new to this so I don't know a lot, I think it might be chromatic aberration or purple fringing.
Here are some of my examples.
Brent:brains:

Yes that's what it looks like to me.
Your Kowa must be an achromat so is going to show a lot of fringing. This fringing is created right at the objectives of the scope and there is not much to do about it.

There is some software that can get rid of some fringing but is not a big help.

Pics:
1 Your pic showing fringing
2 A picture taken with a properly color corrected APO scope
 

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Brent,

It seems to me that your pictures were taken at high ISO since they show a lot of digital noise. Get the ISO down as much as you can to eliminate this.

Also, the focus is not optimum and this is more difficult to fix - the scope and camera must be in perfect focus and you must avoid shaking the camera when you shoot (stable setup and smooth shutter press). I also have difficulties with focus, I guess it will be better with more experience.
 
Thanks for the info I'll try changing the ISO I've use differnt settings but the result is close the the same.
Brent

I've been thinking a bit more about your problem.

Went to Eagle Optics and read about about your scope. In the description
they say:

" For even truer colors and improved image resolution, choose the TSN
823M spotting scope with Fluorite glass elements."

This confirms to me that your scope is a achromatic rather than a APO
scope so you should expect some CA under certain conditions.
But don't despair. I cut my teeth on achromats and still use them with
good results.

I agree with Jules that you should look towards your
focus, shutter speeds and camera shake. I think your photos may be
suffering more from poor technique rather than from poor optics.
Achromatic glass is capable of much better results than those you posted
here. You do have to learn the limitations and work around them. Avoid
backlighted subjects ( a black crow against a bright sky) and especially
avoid spectral light - the glint of water and chrome for instance it's a
real killer of a image with any scope but especially an achromat. Avoid
taking pictures on very clear days when the light is extremely intense and
shadows are very deep.

Anyway you can do good work with achromatic glass it just take a little
skill and experience.

The following were all taken with an achromatic scope similar to yours.
SF
 

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Thanks for the tips I WILL keep trying I glad you showed me some examples I was beginning to think it wasn't possible to get any better than I got. As far as the clear and bright days thats 360 days of the year in AZ.
 
The acquisition of an Apo or ED will be a vast improvement. Your camera lens is also a source of C.A. but there is not much you can do about the small amount it produces. Instead of using the self timer, why not fabricate a cable release bracket for your camera. I'm attaching a photo of the one I made.
 

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The acquisition of an Apo or ED will be a vast improvement.

Exactly - but even with an expensive ED scope either form of the two different chromatic aberrations may sometimes appear: a) "longitudinal" which comes from the objective or b) "transverse" which arises mainly in the eyepiece. Here is one of my less than successful digiscoping trials that shows nicely *both* the LCA and TCA. And the scope was a Swaro AT80HD & 20-60x zoom.

Best regards,

Ilkka :t:


ps. I think there may have been something wrong with my scope-camera coupling, because I have never since seen such terrible results.
 

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