Two f6.3 reducer adventure

[kon1966]

Was mucking around with my 8se today and usual setup is celestron 6.3 reducer with celestron T adapter , T ring and eos camera. I just decided to string 2 reducers together so one screws into the back of the other and then used a short T adapter from bintel 2 inch diagonal.

Shock horror, it works with only slight corner vignetting with the eos i the corners only. I calculated turned the f10 sct into approx f4 to f5ish. If clouds do not cover I will test on easy target.

[Atmos]

I’d be curious as to what the coma/field correction is like.

[Slawomir]

An interesting investigation Kon.

Here is a link to someone doing a similar stacking of reducers:

https://www.cloudynights.com/topic/551155-experiences-using-compound-focal-reducers-with-a-lodestar/

I thought it might help with your experiments.

[ChrisV]

Yes quite a few stack these reducers for live imaging - have a look on cloudynights EAA forum. Just a matter of getting camera-reducer-reducer spacings right. They work them down to x0.33 or so.
They often do it as the 3.3 reducers are hard to come by

But I'm amazed you get it to work OK as most use them with 1/2" or smaller 1/3" sensors.

[kon1966]

Interesting articles, thanks. Not sure what exact spacing to sensor from second reducer but looking at side of house brick wall today there was only a very small dark triangle in each corner which is the cone of light.

The sides, top and bottom view was full view. So I think I guessed the spacing nearly spot on. Will also be interesting on sharpness and coma as more glass. I will take photo with 1 reducer then 2 reducers and post.

Regards
Kon

[blink138]

haha very interesting
pat

[kon1966]

Results from last night, just quick setup so no proper alignment. Wanted to see what is possible. I set max iso but usually do not go that high, no collimation check or let scope cool down and iso was max so much noise.

Moon photo from sept 25th with 1 reducer and last night with 2 reducers.

Sculptor and triffid was 1 shot for 15 secs at iso 6400 in sydneys light pollution with eos cls filter. Usually have to go for longer exposure time.

I need to experiment with the spacing though.

Regards
Kon

[ChrisV]

You could try using astrotoaster and stack live from your dslr. Have a look at Howie's youtube
https://www.google.com.au/url?sa=t&source=web&rct=j&url=%23&ved=0ahUKEwi0vZTNn4rXAhWENJQKHQelBy oQwqsBCCgwAA&usg=AOvVaw0VTJzWxrN8ZFOD4xbU2nov

He uses a dslr and has some vignetting. Toaster has built in stuff to balance out the vignetting and gradients. Is like a built in flattener - kind of. But it's surprising how well it works.

[kon1966]

Had a look and will give it a go. Like the idea of live stacking.

[ChrisV]

He has a few videos on youtube. Have a look. Even if you do single shots the live processing although simple can really improves the images

[Peter Ward]

Just 'cause you can....doesn't mean you should.

Gotta say the coma/astigmatism is out there big time. I doubt you'll be able to fix that, but sure, have fun tinkering :thumbsup: