5 replies to this topic

[TheMouseInTheTelescope]

I want to photograph the solar eclipse with my canon t2i DSLR and tamron 18-270 APSC telephoto (roughly 400mm equivalent).

 

I need to find a filter!

 

I came across the Daystar Universal Lens filters (recommended by wirecutter)

https://www.bhphotov...011301119008005

 

Will these be good enough for decent photos of the phases of the eclipse?

 

Are they good enough to double for sunspots as well?

 

What do you recommend if these are not adequate? Anyone have sample images?

Edited by TheMouseInTheTelescope, 19 February 2024 - 12:08 PM.

[SporadicGazer]

With the origami cardboard cell, those don't look like a longterm solution to me.

 

But the Day Star website says they use Thousand Oaks Solar (SolarLite?) film.  That should be OK for snap shots.  And with careful use you should be able to securely and safely attach them to your lens.

 

Generally Baader AstroSolar Film is the preferred white light filter material here.  And a more secure more durable cell (holder) is usually recommended.  The cells from Baader themselves, AstroZap, and Kendrick are well reviewed and use the better film.  (Measure the outer diameter of your optic to order the right size.)

 

Some folks do prefer the Thousand Oaks SolarLite film and Thousand Oaks sells it mounted in aluminum cells, of which I'd also be more confident than the cardboard.

[TheMouseInTheTelescope]

 

Thanks—I received the daystar filter today, I ordered it so I would have SOMETHING. it feels pretty…shoddy…made of cardboard, and the film is clearly warped, not flat/straight as I imagined it would be.

 

I took the test image today in Aperture Priority mode, autofocusing my dslr on the edge of the sun.

 

You can make out sunspots in the crop, but it is not very clear. Not sure if I focussed wrong, or if the bottleneck is the filter. What do you think?

 

Are these results good for this focal length or should I improve my filter? Or should I work on technique instead?

 

(top image is a crop from the bottom image, original, unedited)

Edited by TheMouseInTheTelescope, 20 February 2024 - 12:48 PM.

[SporadicGazer]

  ... I received the daystar filter today, ...

The film filters are often wrinkly, they shouldn't be pulled taunt as that can introduce distortions nor should they be creased.  (They're thin enough wrinkles don't affect the image.)

 

As for the photos, I'm not sure you are focused perfectly.

 

A quick websearch says your lens is f/6.3 at 270mm, that is about 43mm diameter.  Plus there are all the extra elements to make it zoom.  So you may be pushing what that lens can resolve.  (I'm sure experts will be along to offer more experienced opinions on this.)

 

The solar film itself might not be the absolute sharpest, but if it is Thousand Oaks Solarlite, as implied in the listing, it should be very close to as good as possible.  Shoddy cardboard mounting cell shouldn't affect the image, just the long term durability of the holder -- as long as it is secure as you use it.

Something you aren't considering and can have considerable effects on the sharpness of your image is daytime seeing normally... isn't very good.

 

Before changing equipment, I'd get more practice in.  Make sure you nail the focus and consider the seeing carefully, only if / once you are convinced you are maximizing what you've got would I look to changing the equipment.

 

 

ETA: I am visual only.  Your photos are not as detailed as I see with my cheap 60mm (400mm fl) refractor using a cheap Rainbow Symphony black polymer filter.  Your film should be a step, or more, better than mine.  While I should have somewhat better optical resolution than your lens and I suspect focusing for visual is significantly easier than it is for the camera, I would expect better results with what you have now.

Edited by SporadicGazer, 20 February 2024 - 12:54 PM.

[TheMouseInTheTelescope]

The film filters are often wrinkly, they shouldn't be pulled taunt as that can introduce distortions nor should they be creased.  (They're thin enough wrinkles don't affect the image.)

 

As for the photos, I'm not sure you are focused perfectly.

 

A quick websearch says your lens is f/6.3 at 270mm, that is about 43mm diameter.  Plus there are all the extra elements to make it zoom.  So you may be pushing what that lens can resolve.  (I'm sure experts will be along to offer more experienced opinions on this.)

 

The solar film itself might not be the absolute sharpest, but if it is Thousand Oaks Solarlite, as implied in the listing, it should be very close to as good as possible.  Shoddy cardboard mounting cell shouldn't affect the image, just the long term durability of the holder -- as long as it is secure as you use it.

Something you aren't considering and can have considerable effects on the sharpness of your image is daytime seeing normally... isn't very good.

 

Before changing equipment, I'd get more practice in.  Make sure you nail the focus and consider the seeing carefully, only if / once you are convinced you are maximizing what you've got would I look to changing the equipment.

 

 

ETA: I am visual only.  Your photos are not as detailed as I see with my cheap 60mm (400mm fl) refractor using a cheap Rainbow Symphony black polymer filter.  Your film should be a step, or more, better than mine.  While I should have somewhat better optical resolution than your lens and I suspect focusing for visual is significantly easier than it is for the camera, I would expect better results with what you have now.

 

This is a moonshot (cropped) taken with the same lens the other day.

 

it isnt the most high res lens and the sensor is only like 18mp…still think there’s room improvement in technique?

 

maybe im not focussing correctly on the sun. Lens seemed to automatically move into the infinity position when I autofocussed on it

 

the uv filter that fits on my lens is marked 72mm

Edited by TheMouseInTheTelescope, 20 February 2024 - 01:20 PM.

[CreatorsHand]

 

 

 

 

Thanks—I received the daystar filter today, it feels pretty…shoddy…made of cardboard, and the film is clearly warped, not flat/straight as I imagined it would be.

 

I took the test image today in Aperture Priority mode, autofocusing my dslr on the edge of the sun.

 

You can make out sunspots in the crop, but it is not very clear. Not sure if I focussed wrong, or if the bottleneck is the filter. What do you think?

 

Are these results good for this focal length or should I improve my filter? Or should I work on technique instead?

 

(top image is a crop from the bottom image, original, unedited)

 

From everything I have read, it is better to have the film loose than tight, and that isn't a problem. You bought an inexpensive filter that has an inexpensive cell (the cardboard) with good quality film (Thousand Oaks Optical Solarlite). The largest filter offered there in that listing (90-109mm O.D.) is $25. If you are just going to use it for the eclipse, it should work fine if you take care of it. If you went to Thousand Oaks Optical and purchased a filter from them that would fit 109mm O.D., it would come with an aluminum cell for $74, be more durable, and have the same film. The difference is that the filter cell would come in a box to store it in, and likely last longer. Only you can decide which fits your need better. Since you have it, I would say use it, and after the eclipse decide if you want a better one. As an aside, the owner of DayStar filters is the developer and owner of Eclipse Orchestrator.

 

It looks to me like you missed focus a little bit. You might find that you do better with manually focusing, although that might require something to drape over your head and camera and some practice. I just bought a drape on ebay designed for view cameras that I plan to use; a large, dark t-shirt or towel might work almost as well. Even with my 7DII and 5DIV, which have a better autofocus system, I plan to manually focus.

 

I think if I were you I would work on my technique before I worried about the filter. I used a filter from Thousand Oaks Optical with SolarLite film in 2017, and was very happy with the results.

 

Paul