Another Carina, with 100ED

[avandonk]

Before I perform surgery with hacksaw on the tube of the 100ED I thought I would take some pictures to establish the amount of shortening.
Here is one result. With shortening will get more focal reduction.

Details. Canon 5DH in cam. noise reduction on,100ED with Hutech FR/FF so at 765mm @ F7.65,Hutech nebula filter, 5X8min ISO 800, stacked with Registar. Only adjusted curves in PS, no other processing! Vignetting is only a tiny bit at the corners thanks to a 2.7 inch focuser and removing the rear baffle of the 100ED which was causing vignetting!
Larger picture 750k
http://users.bigpond.net.au/avandonk/Car_100ED.jpg

This was the only viable target with the Moon out.

Bert

[Hammerman]

Great photo, Bert! Beautiful color and detail. I was surprised at how little processing you said you did. It looks like you spent hours on it. Very impressive.

So this is the type of results I could get taking photos through my 100ed? Well.... if I had the camera equipment you have.... and if I lived in the Southern Hemisphere...... and if I had talent..... and....

[tornado33]

Howdy Bert
Hope you dont mind but I couldnt resist having a play with this image as theres a wealth of detail on it.
I increased the gamma in Iris, dropped the red slightly to neutralise the sky background then manually drew a ring with 250 pixel feather round the outer area then darkened the inside a bit, removing the outer vignetting. whaddya ya think? That 5D combined with the LPR filter really sucks in the red hydrogen alpha light thats for sure. Cant wait to see how brighter it will be with more focal reduction.
Keep them coming. I await you turning it on things like the Lagoon, Triffid, Swan and Omega nebulas.
Scott

[janoskiss (Steve H)]

Look at the large version Scott if you want to see detail! There is some very intricate structure visible there.
Gentle with that hacksaw now Bert.

[ving (David)]

lordy! so much detail!

[PhotonCollector (Paul)]

Hello Bert (avandonk),

Congratulations on a nice pic of Eta Carina. Very impressive how you have imaged the nebula and kept the sky background so dark, guess that's because of the hutech nebula filter.

On and ... glad to hear I'm not the only one who uses hacksaws to modify telescopes

Paul M

[avandonk]

Thanks for all the comments. I never mind if anyone wants to play with my images Scott. I may (always) learn something. I dont want to turn this thread into cutting telescope tubes 101, but here are a few pictures I hope they are self explanatory.
You are correct PhotonCollector I decided to use the Nebula filter as the Moon was out. The Hutech focal reducer flattens the field beautifully but only has a reduction of 0.85.
The Astro Physics focal reducer also flattens the field beautifully but only at a reduction of 0.8. If you use the AP FR at about 0.7 or 0.6 it introduces field curvature and this is where the Hutech comes in. Place the Hutech FR/FF behind the AP FR the field is flat again. Careful adjustment of relative distances should end up giving me a focal reduction of about 0.6 (or better) and a flat field. I could go into the theory but its better to try it for real.
This turns the 100ED into a 540mm at F5.4, or thereabouts. I hope to get all the distances correct by experiment. Even if I don't get the result I am after at least I still have a working 100ED that performs like an 100mm APO.

My reason for doing all this is the 5DH's huge sensor shows up any optical shortcomings such as field curvature or vignetting and rather than spend a lot of time massaging images to overcome this, I want to stop it at the source as I intend to collect a lot of images.
I hope this makes sense.

Bert

[h0ughy (David)]

Originally Posted by avandonk

Thanks for all the comments. I never mind if anyone wants to play with my images Scott. I may (always) learn something. I dont want to turn this thread into cutting telescope tubes 101,...................a lot of images.
I hope this makes sense.

Bert