Photographic Sketch?

[Brasspoodle]

I'm looking for some advice on the best method to get some short exposure single shot images of DSOs that as closely as possible resemble the view through an eyepiece in my 12" Dobsonian telescope: a kind of photographic sketch. I'm still keen to sketch (to get to know the object better) but like the idea of having a variety of images stored away so I can better look back later and be reminded of the night. 

My current plan is to drift align my f7.5 ED80 on a motor driven Eq3 and take images of the objects I'm observing and sketching at the 12" Dob. I have all the gear to drift align and connect my Canon 600D to the ED80 scope to take some basic prime focus shots. I may have some time to start trying things out in a few weeks so....

What kind of DSLR camera settings would be necessary to get a 'visual' image (as you'd see through the eyepiece)?
What exposure length, ISO combo would be generally satisfactory or possible given its not the greatest mount? Some image noise would be perfectly acceptable so long as their is still sensitivity to those averted vision details you can pick up through the EP. 
What else should I be thinking about? Is a focal reducer necessary for such a project (given the mount, useful exposure time, f ratio of the scope)?

I see such wonderful images on this and other forums and realize the time and effort that goes into them. In this sense I'm no photographer and have very little time to spend stacking images or even editing them much, other than cropping them down maybe. I've attached an image of Saturn taken from my iPhone at the eyepiece of my 12" Dob (on a nice night at 300x through my Pentax XW 5mm) and is pretty much the kind of image I'd like to take of various DSOs i.e. not particularly detailed but reminiscent of the eyepiece experience.

Any help, advice, discouragement welcome :-)

[glowingturnip]

i think you'll be able to do a fast & dirty photo of what you can see just fine - when I'm framing shots, max ISO and about a 10 second exposure will show what you're looking for very well - won't win APOD, but it will show you more than you can see with the naked eye

[Brasspoodle]

As an update to my quest I managed to finally try a few ideas. Eventually I got a 20 second exposure at ISO3200 and, although the stars are trailing, the nebula (triffid and lagoon) showed some nice detail. I kept the colour in so less like a sketch but still roughy the same visual content if that makes sense.

Had issues focusing the DSLR at the scope (prime focus) and had to trial and error various shots and couldn't manage to do it through my Canon 600D's "live view". Any suggestions here are welcome! 

[wxsatuser]

Focusing is easy with a Bahtinov mask.

It can be done with Liveview, get on a bright star with a high ISO and zoom in 10x, focus for the tightest star.
It takes a bit of practice and patience but can be done.

[Brasspoodle]

Will do. I think when I tried to focus in live view last night I was no where near being in focus and saw zero on the camera screen. Finally worked out that all I needed was the focal reducer screwed into the T-ring and about a 5cm extension of the focuser tube. Hopefully I'll get another shot at it tonight and I can use my home made Bahtinov mask and zoom in 10x on a bright star. 

[glowingturnip]

download APT (there's a free version, works with your Canon), and you can trial & error to get focus on there, you'll be able to see the result on your laptop screen.

I get critical focus with a bahtinov mask + bahtinov grabber software + APT.  Mind you, that involves dragging the laptop outside, and that's the slippery slope to AP proper !

Nice grouping btw

[Brasspoodle]

Yes, I am trying to avoid the laptop. It's another thing to carry and then that big 'ol slippery slope into AP proper!!! I spent a lot more time tonight drift aligning and got much closer (finally got all the W, N, E and S correctly Identidied) and my homemade Bahtinov worked a treat through live view on the camera. Only real issue is the time this all took (maybe an hour and a half or more) but figure if I have my Dob as well I can get some quality visual time in while I tweak the alignment. Got some shots of Eta Carina but from the moment I turned on the camera the battery warning started flashing: argh!! Still I pushed the exposures to 2 minutes: 4 at at ISO 1600 and 4 at ISO800 to see what would happen. I'll put the results up when the battery recharges. Sadly had only time for two blacks before the camera died so won't be much processing.

[Brasspoodle]

The end result after combining 3 of the ISO1600 with 3 of the ISO800 pictures and subtracting the darks in Nebulosity. 

[Brasspoodle]

Bit more than a sketch now but after drift aligning the rest was kind of easy and I spent about a half hour processing it. Still hit and run so I figure the more efficient I can make everything the better

[glowingturnip]

that's looking rather nice !  definitely on the slippery slope  ;-)

 

[Stub Mandrel]

17 minutes ago, Brasspoodle said:

Bit more than a sketch now but after drift aligning the rest was kind of easy and I spent about a half hour processing it. Still hit and run so I figure the more efficient I can make everything the better

HA! The bug has bitten

See the

and your hobby will never be the same again!

[Brasspoodle]

Thought I'd attach an ISO800 2 minute unprocessed image, which I like more for colour. Colour is probably the area I feel least comfortable with and I'm really dishing up what Nebulosity is giving me. Is the processed image's whiteness due to overexposure? Would it have been better if I stacked more ISO800 images rather than included the ISO1600 frames?

[glowingturnip]

no, it's not over-exposed, you'd have areas of solid white with lost detail with over-exposure.  Processing is a fine art, possibly even more involved than the actual taking of the pics.

What you could try for a quick experiment, if you have Photoshop - load the first image, then post that second image with the colour into a separate layer on top of the first, and change the blend mode for that layer to 'color'.  Then it will use the detail from the first and the colour from the second.

Actually I like the second version better anyway, a little gentle stretching and that would look pretty good.

[Brasspoodle]

Starting to explore the processing side and tried the layering of images in GIMP. Seems like an iterative process of adjusting various sliders to see how they bring out detail, distort certain elements or clean them up. Lucky to have a tiny bit of time to try some things! Anyway below is what I managed to get from the the center of the nebula. The colour helped differentiate some elements is the end. Welcome suggestions though. 

As for being bitten by the AP bug, well the HEQ5 Pro is on its way :-) Still going unguided though....

[Brasspoodle]

This is the bigger image. Saturating the colour seemed to help bring some detail out.