First attempt with 7Dmk2 on Celestron 11 Edge HD

Been struggling with getting my scope setup and go to function properly aligned. Got closer Last night with what I would consider about a 70% hit on getting it aligned.. a slightly breezy night with some thin high clouds but this is a single 60sec exposure 1250 ISO with the camera directly on scope with T-ring.

since the stars are not too elongated for 60 sec... I wonder if is it the high clouds, or a general focus issue keeping it from being tack sharp. possible the breeze???? I used liveview at 10x and thought I nailed the focus.

comments, thoughts?

Thanks guys a complete noob, but this forum has been a huge help.

Definitely looks like a focus issue, to me.

I highly recommend Backyard EOS. It's got a great focusing tool (among many other great features) and is very inexpensive. Also has a 30 day free trial, so you can be sure you like it.

I use a Bahtinov mask, but still find I get my best focus through the software.

Only problem I've found is that since purchasing BYE, I've had very few nights. It's been a really cold and windy winter...

BTW, which mount do you have? I have the Edge 800 with the CGEM mount. The GOTO is excellent when properly aligned.

Thanks Andicus... yep playing with the trial version of EOS right now and will be all over it tonight... another clear night here in the N.W. on a new moon.... so I'm on it like a cat on velcro

my mount is the CGEM DX but I think it was all user error.... as not getting the calibration star center in both the finder scope and eye piece.

also have Orion SAG and will be trying that tonight again.

Same as most this winter, a clear night has been rare....

If you don't already have one, I'd recommend an illuminated reticle eyepiece for easier centering. I normally add 4 calibration stars, which seems to do the trick.

I see blur stars.
No tail.
No zigzag jerky motion due to wind/unstable leg.
There is a tad of CA that seems corrected in pp but by no means even close to my old lens.
And finally, It is OOF. That is your main issue.
Whatever is your method of focusing, something is going wrong and needs revision. Everything else looks good.

Made another attempt the other night, down out of any wind, used 2 additional calibration stars, and backyard EOS. not sure it was any better than my 10x liveview method. I worked and worked on getting the smallest number in the focus/framing menu, but even the slightest touch of the scope focus knob made huge jumps, took several shots (below) even when using the scope for visual, it is a huge challenge to get objects in perfect focus, the sweet spot seems so incredibly small.

still trying to learn the best approach on the focus knob... if it is best to come at the focus point from the left direction or right direction, and if there is any effect on the mirror.

wonder is it slight constant vibrations from the CGEM mount due to improper balance?


Thanks for the comments and help on this guys.....

couple straight from EOS

Pixel Perfect wrote in post #17438980
I worked and worked on getting the smallest number in the focus/framing menu, but even the slightest touch of the scope focus knob made huge jumps, took several shots (below) even when using the scope for visual, it is a huge challenge to get objects in perfect focus, the sweet spot seems so incredibly small.

Still OOF and guess you know why.

The pitch angle on your focuser is probably too large, good for visual rapid focus but not good for fine focus on sensor. If you have the option of changing the focuser into something more refine, I suggest you go down that route. Otherwise try to "Bracket" your focus, the same way you bracket exposure or WB.

Pixel Perfect wrote in post #17438982
couple straight from EOS

Let me add two cents if i may please . Actually this image is not really bad at all . I have taken tons of images of M42 at the heart with exposures as short as 2-3 secs trying to get the best image with best star results and i think 99% of the time i get this same results . I really believe it mainly has to do with using a DSLR . No DLSR can take the perfect DSO image with perfect stars . What i see here is the 4 main stars in the heart grouped tightly and that's the goal is being able to actually seperate these 4 stars. So far i have only seen that happen with dedicated DSO cameras that cannot be used for anything else but some costing upwards 10K . Where this will improve your image is to back off to a smaller image , copy and paste this into a full image of M42 and edit it where it cannot be seen with any stacking evidence . Jerry Lodriguss has a quick short lesson you can see what i'm talking about: http://www.astropix.co​m/HTML/J_DIGIT/COMP2.H​TM

But you might notice how his stars look, just like yours do here .

Thanks so much for all the tips guys... Think we have a couple clear nights in my future so going back at it.... Reading my manual for the scope I guess after you are in focus for astrophotography you should tighten the two mirror lock to reduce vibration. Duh. Guess we will see if this helps.... Also what is everyone's thought on using my auto guider with PHD instead of the the mounts goto function. Have had problems in the past getting the Orion SAG to lock in and track, but most likely user error... Just wondering if this would provide better tracking/drift etc..... I have gotten 90 sec exposures with limited trails but not much past that... Is that a sign of poor alignment.

Sorry for so many questions. But there is a wealth of knowledge here

Thanks for the help

You're off to a great start.

There are several things here that are likely issues contributing to blur.

1) Critical focus. This is something that requires careful attention, especially at these focal lengths. I would suggest a focus aid, either on your laptop or as an attachment in the focus process. A Bahtinov mask is an inexpensive tool that you can make yourself or buy in the US for under $20. I use a Stiletto unit but they're no longer available.

2) Accurate tracking. Just like shooting any type of photography, any motion equals blur when shutter speed isn't adequate. You're obviously working on this and can take some effort to get up to the accuracy needed at high focal lengths. Auto guiding will definitely help but alignment and scope/camera balance are still prerequisites, regardless if guiding or not.

3) Seeing conditions. If the atmosphere is very unstable it won't matter how well you focus, your results will be less than optimal. The higher the focal length the more evident the poor seeing becomes.

I battled these things early on in the hobby when using large SCTs. It took lots of patience and persistence to see improvement but it'll come.

Here's a look at the trapezium of M42 through a 10 inch SCT. Probably the best I ever did with focus and dealing with all the things I outlined. Like mentioned above I had to layer in the core of the nebula in photoshop since a much shorter exposure is needed in that area to resolve those four core stars. I didn't want to post a live image in your thread so here's a link:
http://i3.photobucket.​com …43coretinker.jp​g~original

Also remember there is actually more than 4 stars in the Trap but unless you have high magnification they are hard to pick up . In my C8 using high power i can actually see all the stars of the trap which is really neat but when imaging there is a couple so close that it makes it look like only 4 stars in the final image . It's very hard to split two of the stars in the Trap . Here is an image showing all four main stars and two companion stars . This explains what i'm talking about .

http://www.samirkharus​i.net/trapezium_finder​.jpg

I'm pretty sure I have 5 in mine but I'll have to look for the high rez image to see if the 6th is visible. The overlap of the larger and smaller is tough to hold.

The autoguider shouldn't be a replacement for good alignment, as it can't compensate for field rotation. It can certainly help you get longer exposures, but you still want to get the best alignment you can manage.

Your other question about focusing direction... It is recommended, with SCTs to do your final focusing in a counter-clockwise direction as that is pushing up on the mirror. Then use your mirror locks.

As for the sensitivity of the focuser, I agree that it is very tricky. I'm considering getting a Feathertouch MicroFocuser. I'd also consider a stepper type focuser, but they get very expensive, very quickly.

I agree with the focuser also . I have a Auto-Focuser i bought and attached to my C8 and i have never regretted it . Trying to focus with your fingers is very hard but an AF works great .