Desperately trying to fit the sun's entire disk into my images...

[Larry V]

Hello everyone,

I am currently trying to prepare, for the upcoming total solar eclipse in August.  I tried imaging the sun a few weeks ago and quickly realized that I was in need of a focal reducer, to widen my field of view and subsequently fit the entire sun in my images.  I just received the focal reducer on Monday and waited until I had a not so cloudy day to test everything.  Today was that day, but it proved to be quite a disappointment.  I am still unable to image the son's full disk, even with a focal reducer.  I started off by connecting my camera to the T-Mount and inserting it in my Baader Click-Lock star diagonal, which was of course connected directly to my focal reducer.  I realize that I most likely should be connecting my T-Adapter directly to the focal reducer, rather than going through a star diagonal, but when I do this, it places my camera's sensor closer to the focal reducer, hence I fit even less of the sun's disk into my image.

The image I provided seems to be the very best I can do.  In order for me to even produce the attached image, I had to completely bottom out my focus, which is not good.  Even with doing this, it is evident that I am still not in perfect focus.  I have listed all of my equipment below, in my current sequence for the optical train.

If anybody can PLEASE provide some insight, I would be most appreciative!  I am an avid researcher of information and think I am on the right track, but I am also VERY new to all of this.  I am hoping that my camera's sensor is not too small for me to pull this off.  

 

Thank you so much in advance.  I look forward to your advice!

 

Larry

 

Equipment:

Celestron Edge HD 11"

Celestron .7x Focal Reducer

Baader Click-Lock Visual Back

Baader Click-Lock Star Diagonal

T-Adapter

Canon T5i DSLR (Full Spectrum Modified)

 

[Davey-T]

Your problems are related to the focal length of your scope.

If you look in the FLO link at the top of the page under help and support / astronomy tools / FOV calculator you can enter your equipment and experiment to see if any combination will get you a full disc.

Done a couple of examples, your scope, my Meade and a 120mm refractor

Dave

 

[Davey-T]

Had a play around and a .5 reducer would appear to work.

Dave

 

[Peter Drew]

Hello Larry, welcome to this forum.

Wrong telescope for the job to be honest. For a total eclipse image you really need much more than just a full disc in the frame. You can photograph the Sun any day with the method you have been trying. For totality you need a wide enough frame to take in the extensive corona, the one and only chance you get to do this. A much shorter focal length telescope or a telephoto lens should do this well. Fortunately there is enough time still to get this right. 

[johnfosteruk]

Another option is lenses, what lenses do you have? For example if you have a 400mm, pop a 2x teleconverter on it and you have 800mm giving a similar FOV to the second screenshot in Dave's post. Doesn't need to do AF so that and some solar film won't cost you too much and you'll capture a good portion of the corona.

[Larry V]

16 hours ago, Davey-T said:

Had a play around and a .5 reducer would appear to work.

Dave

 

 

16 hours ago, Davey-T said:

Your problems are related to the focal length of your scope.

If you look in the FLO link at the top of the page under help and support / astronomy tools / FOV calculator you can enter your equipment and experiment to see if any combination will get you a full disc.

Done a couple of examples, your scope, my Meade and a 120mm refractor

Dave

 

Thank you so much for taking the time to put all of this information together for me!  I think I am going to go the piggy-back route, and use my telescope to track for my Canon T5i camera.  I am planning to purchase the Canon EF-S 55-250mm F4-5.6 IS STM Lens, as it is well priced.  I also use Backyard EOS, something I probably should have mentioned in my description.  When photographing planets, I make use of the 5X feature of the software, which allows me to get a 1:1 pixel aspect ratio in my images.  This definitely enlarges my planetary views and I am thinking, with 250mm of zoom, it should get me where I want to be with the sun as well.  I am going to keep my fingers crossed!  If you have any thoughts, please let me know.  Thank you again for your reply!

[Larry V]

8 hours ago, johnfosteruk said:

Another option is lenses, what lenses do you have? For example if you have a 400mm, pop a 2x teleconverter on it and you have 800mm giving a similar FOV to the second screenshot in Dave's post. Doesn't need to do AF so that and some solar film won't cost you too much and you'll capture a good portion of the corona.

Thank you so much for taking the time to reply to my message.  I currently have the STM lens that came with my camera kit.  It has a maximum zoom of 55mm.  I think I am going to go the piggy-back route, and use my telescope to track for my Canon T5i camera.  I am planning to purchase the Canon EF-S 55-250mm F4-5.6 IS STM Lens, as it is well priced.  I also use Backyard EOS, something I probably should have mentioned in my description.  When photographing planets, I make use of the 5X feature of the software, which allows me to get a 1:1 pixel aspect ratio in my images.  This definitely enlarges my planetary views and I am thinking, with 250mm of zoom, it should get me where I want to be with the sun as well.  I am going to keep my fingers crossed!  If you have any thoughts, please let me know.  Thank you again for your reply!

[Davey-T]

Sounds like a plan Larry, enjoy your eclipse, wish I was going.

Dave

[Larry V]

8 hours ago, Davey-T said:

Sounds like a plan Larry, enjoy your eclipse, wish I was going.

Dave

I am a 7th grade science teacher and plan to blow off the very first staff meeting of the upcoming school year, just to have the chance to photograph this event.  It will be am amazing event for sure and honestly, I NEED some good photos to place down before my principal, just in case I get dinged for it.  lol  

My overall plan is to create a presentation that all of the schools in my district can reference for use in their classrooms.  Soooo...if I do get in trouble, at least it will be for the glory of science.

[johnfosteruk]

Taking one for the team. You're a hero ?

[Owmuchonomy]

15 hours ago, Larry V said:

Thank you so much for taking the time to reply to my message.  I currently have the STM lens that came with my camera kit.  It has a maximum zoom of 55mm.  I think I am going to go the piggy-back route, and use my telescope to track for my Canon T5i camera.  I am planning to purchase the Canon EF-S 55-250mm F4-5.6 IS STM Lens, as it is well priced.  I also use Backyard EOS, something I probably should have mentioned in my description.  When photographing planets, I make use of the 5X feature of the software, which allows me to get a 1:1 pixel aspect ratio in my images.  This definitely enlarges my planetary views and I am thinking, with 250mm of zoom, it should get me where I want to be with the sun as well.  I am going to keep my fingers crossed!  If you have any thoughts, please let me know.  Thank you again for your reply!

Just be careful with a zoom lens that you don't get 'zoom creep' during your session.  It would be prudent to make sure once you are set that you fix the lens zoom (and focus) rings so they can't move.  Alternatively, buy a fixed focal length lens.