Ghost image in solar photos

I'm just getting started with solar photography, preparing for the August solar eclipse that will be partially visible in northern Ontario. The solar filter is a Thousand Oaks Optical Type 2 + glass. Some of my photos have a second disk in them as in the sample and I'm wondering what that could be. Thanks!

I did get some clear photos as in this sample. It was partially cloudy, so I was dodging clouds. I also learned that it is VERY difficult to see the Live View display when taking solar photos. I appreciate your tips and advice.

Bobby49 wrote:

With most unwanted light reflections like that, the original light is entering the front of your lens. Then it is reflecting off some intermediate layer and bouncing back outward. Sometimes the ghost shows up there on an outer layer and then the sensor sees it.

With a really premium lens, you often have anti-reflective coatings on those intermediate layers. They absorb the reflections. Evidence of that is if you look down into a lens and see green, blue-green, or brown.

I'm going to take a wild guess that your filter might be doing that to you.

If you shoot more directly at the target, the reflections should be aligned with the target, so they may not be quite so objectionable.

Thanks. This is definitely not "pro" gear. I will take a look down the barrel of my lens to see if I can eliminate that as the cause. Next time, I'll line up the main image with the ghost.

Gollan wrote:

Bobby49 wrote:

With most unwanted light reflections like that, the original light is entering the front of your lens. Then it is reflecting off some intermediate layer and bouncing back outward. Sometimes the ghost shows up there on an outer layer and then the sensor sees it.

With a really premium lens, you often have anti-reflective coatings on those intermediate layers. They absorb the reflections. Evidence of that is if you look down into a lens and see green, blue-green, or brown.

I'm going to take a wild guess that your filter might be doing that to you.

If you shoot more directly at the target, the reflections should be aligned with the target, so they may not be quite so objectionable.

Thanks. This is definitely not "pro" gear. I will take a look down the barrel of my lens to see if I can eliminate that as the cause. Next time, I'll line up the main image with the ghost.

This is typically a problem with uncoated glass filters.

How far from the optical axis (nominally the center of the image) was the sun when you got the ghost image? If you can't fix it any other way, you should be able to intentionally place  the sun sufficiently far from the opitical axis that to have a clean separation of the image and the ghost, then remove the ghost in photoshop.

hha

hha wrote:

How far from the optical axis (nominally the center of the image) was the sun when you got the ghost image? If you can't fix it any other way, you should be able to intentionally place the sun sufficiently far from the opitical axis that to have a clean separation of the image and the ghost, then remove the ghost in photoshop.

hha

Thanks! For these tests, I tracked the sun manually on a gimbal head, much the same as I do with lunar photography, so I didn't pay much attention to where it appeared in the frame. Looking at the images from the session there does appear to be a pattern with the distance from the centre of the frame:

I'll do more tests to see what I can do to keep the ghost either behind the sun or far enough away to be removed.

Gollan wrote:

hha wrote:

How far from the optical axis (nominally the center of the image) was the sun when you got the ghost image? If you can't fix it any other way, you should be able to intentionally place the sun sufficiently far from the opitical axis that to have a clean separation of the image and the ghost, then remove the ghost in photoshop.

hha

Thanks! For these tests, I tracked the sun manually on a gimbal head, much the same as I do with lunar photography, so I didn't pay much attention to where it appeared in the frame. Looking at the images from the session there does appear to be a pattern with the distance from the centre of the frame:

Another though occured to me:

Is you solar filter a one side aluminized glass plate? If so, the aluminized side has to be on the outside (= first surface the sun hits).  If the alumized side is on the inside, you will reflect a ghost from the reflection of the reflected light from the  uncoated glass surface.

hha

That is so disappointing. There was me expecting to see a decent picture of a ghost, rather than those crappy, blurred ones you see on TV 

Seriously though, very nice solar images. I have had the same problem at times and I use very high quality glass. Just try to narrow down the cause by taking lots of images & seeing what works best.

hha wrote:

Another though occured to me:

Is you solar filter a one side aluminized glass plate? If so, the aluminized side has to be on the outside (= first surface the sun hits). If the alumized side is on the inside, you will reflect a ghost from the reflection of the reflected light from the uncoated glass surface.

hha

The filter is a 95-mm screw in type. I just checked and the reflective part is definitely on the inside of the filter. So the clear glass is on the outside. (Easy to tell by looking at dust on the filter). I checked on the Thousand Oaks Optical website and they state that their threaded glass filters, "can be used as a lens protector since uncoated surface faces out". So it is the way they intend it. Hmm...

Trollmannx wrote:

This is a well known issue.

Tilt the filter slightly and the reflex will be grown outside the image of the sun. This is how we have used glass solar filters since they were introduced.

The ever so slightly quality loss is no issue (unless wanting one of those long running academic discussions leading nowhere). Have never been able to see the difference between a plane parallell and a slightly tilted solar filter even when pixel peeping.

So - tilt the filter ever so slightly to get the reflex outside the inage of the sun - and happiness is restored...

Thanks for the info. I'm learning a lot from this experience. The filter is a 95 mm screw in type. Now that I understand the situation a bit a bit more, I will either have to line up the reflex with the sun or place it in one corner of the frame by placing the sun in the other corner. I will also look for ways to tilt the screw in filter a bit.

Gollan wrote:

hha wrote:

Another though occured to me:

Is you solar filter a one side aluminized glass plate? If so, the aluminized side has to be on the outside (= first surface the sun hits). If the alumized side is on the inside, you will reflect a ghost from the reflection of the reflected light from the uncoated glass surface.

hha

The filter is a 95-mm screw in type. I just checked and the reflective part is definitely on the inside of the filter. So the clear glass is on the outside. (Easy to tell by looking at dust on the filter). I checked on the Thousand Oaks Optical website and they state that their threaded glass filters, "can be used as a lens protector since uncoated surface faces out". So it is the way they intend it. Hmm...

If the uncoated surface is on the outside you will get an undesired  4% reflection of the sun from the front surface, which is then attenuated by the aluminum coating. Make a homemade adapter to revere the sides and convince yourself.

hha

I have say that this thread is reminding me to start practicing as well.

Thank you to everyone to offered advice. From the Thousand Oaks Optical Website:

Pinholes and minor surface scratches are common in solar filters; however, our multi-coating technique keeps them to a minimum. A "bright" pinhole in the coating may cause "ghosting" due to scattered light. If this is seen during observation, the pinhole(s) should be blocked out. Block out any pinholes on inside surface facing telescope.

Once I found a suitable light source, there were a few bright pinholes. I blocked some of them with a Sharpie marker and the ghosting *seems* to be reduced, but not gone. I will check for more pinholes and in any case, I can work around the remaining ghosting. On the first sunny day since I took my last photos, I got out again:

I still have a lot to learn, particularly about post-processing, but I'm happy with this start in solar photography.

hha wrote:

Gollan wrote:

hha wrote:

Another though occured to me:

Is you solar filter a one side aluminized glass plate? If so, the aluminized side has to be on the outside (= first surface the sun hits). If the alumized side is on the inside, you will reflect a ghost from the reflection of the reflected light from the uncoated glass surface.

hha

The filter is a 95-mm screw in type. I just checked and the reflective part is definitely on the inside of the filter. So the clear glass is on the outside. (Easy to tell by looking at dust on the filter). I checked on the Thousand Oaks Optical website and they state that their threaded glass filters, "can be used as a lens protector since uncoated surface faces out". So it is the way they intend it. Hmm...

If the uncoated surface is on the outside you will get an undesired 4% reflection of the sun from the front surface, which is then attenuated by the aluminum coating. Make a homemade adapter to revere the sides and convince yourself.

hha

I'm having the same issue with the Thousand Oaks Optical 95 mm filter (glass) on the Nikon 200-500 f/5.6. I tried "reversing" the filter (the front is not threaded so I used gaff tape) and it seemed just as bad. Both side are quite reflective. I also tried putting a high quality polarizer (with anti-reflective coatings)  between the solar filter and front of lens to see if it would help--it did not.

Does anyone know if the reflections as bad with other filters (other brands or just putting solar filter film in front of the lens)? Do other options have only 1 mirrored side?

SoupOrPhoto wrote:

hha wrote:

Gollan wrote:

hha wrote:

Another though occured to me:

Is you solar filter a one side aluminized glass plate? If so, the aluminized side has to be on the outside (= first surface the sun hits). If the alumized side is on the inside, you will reflect a ghost from the reflection of the reflected light from the uncoated glass surface.

hha

The filter is a 95-mm screw in type. I just checked and the reflective part is definitely on the inside of the filter. So the clear glass is on the outside. (Easy to tell by looking at dust on the filter). I checked on the Thousand Oaks Optical website and they state that their threaded glass filters, "can be used as a lens protector since uncoated surface faces out". So it is the way they intend it. Hmm...

If the uncoated surface is on the outside you will get an undesired 4% reflection of the sun from the front surface, which is then attenuated by the aluminum coating. Make a homemade adapter to revere the sides and convince yourself.

hha

I'm having the same issue with the Thousand Oaks Optical 95 mm filter (glass) on the Nikon 200-500 f/5.6. I tried "reversing" the filter (the front is not threaded so I used gaff tape) and it seemed just as bad. Both side are quite reflective. I also tried putting a high quality polarizer (with anti-reflective coatings) between the solar filter and front of lens to see if it would help--it did not.

Does anyone know if the reflections as bad with other filters (other brands or just putting solar filter film in front of the lens)? Do other options have only 1 mirrored side?

Couple things.  I've tested both TO Solarite (reflective side out) & Baader (both sides reflective) film filters in home made holders & have never gotten anything like this.  One problem causing these flare images is the longish exposure, 1/60", required because the TO glass filter seems to be darker than OD 5.  If memory serves?, Baader gives me 1/1000" & Solarite 1/250".  Baader is susceptible to loss of contrast from light leaks from the back of DIY holders.