Dielectric Diagonal, ED 2x Barlow vs Standard Diagonal & 2x Barlow

[Aussie Dave]

This maybe a stupid question but I haven't tried mine yet. Would I get better single shots imaging with a 2" Dielectric diagonal and 2" ED Barlow compared to my standard 1.25" diagonals and standard 1.25" 2x Barlow that I've been using up to now?

I don't often use a Barlow but I need to on one of my scopes to reach focus and the resulting images are not very good.

Will the image quality be noticable better?

Also are there any comparisons here or online with images to compare the quality differences?

I think I should of switched over a long time ago.

[Ruud]

Hello Dave, have you already tried the camera without the diagonal? If you don't have enough in-travel on the focuser that might help.

[Aussie Dave]

G'day Ruud. I'm sure I have tried a couple of times. It's better without a diagonal but it's still not reaching focus. It's the Saxon Mak203 that I'm having difficulty with. The Saxon seems to be a difficult scope to image with and the better results that I have saved didn't turn out that great, an example 15 image stack is below. I expected much more from the Saxon.

I'm quite sure this was a standard 1.25" 2x Barlow. If not it was EP projection with low magnification Celestron Plossl EP. Sorry I haven't saved any imaging info with the Saxon yet apart from number of stax.

In regards to my first post, just curious of image quality with a Dieletric and ED Barlow compared to the standard diagonal and Barlow. Just wondering if it will be a noticable difference with my other scopes for imaging.

Looks like I'll need to do more testing when the weather clears. I'll check again without a diagonal.

[Steve Ward]

There should be more than enough travel on the Mak's mirror to bring anything into focus ... ?

Personally I'd be looking to fit a crawford to the back of the 'scope to allow for fine and accurate focusing , I did this to my Mak180 and it transformed it from very good to excellent , moving the primary just doesn't cut it as far as crisp , consistent imaging is concerned.

[michaelmorris]

If you need to extend the point of focus, a good extension tube will be better than any diagonal simply because there are no extra optics.

[Aussie Dave]

Ok guys cheers. Next clear night I'll try again minus the diagonal and Barlow. Like you say Michael, the less optics and mirrors to image with the better.

The Saxon has a Crayford style 1 speed focuser (2") as standard gear Steve and is a very nice focuser. I'll remove the 2" to 1.25" EP adapter from the diagonal and fit that directly to the focuser drawtube, then the Nikon. I'm racking my brain trying to remember if I've already done this...

I have found another adapter in my bits and pieces that fit's my Nikon T2 ring that has a bigger inside diameter of almost 1.5 inches. That adapter screws straight on to a 2" visual back for my other SCT's, not sure what camera it's from. The 1.25" ring adapter is fine for imaging and I don't think there's any gain from getting a 2" ring adapter now, was thinking about it.

[ollypenrice]

If you need to extend the point of focus, a good extension tube will be better than any diagonal simply because there are no extra optics.

Absolutely. A diagonal is the worst possible way to extend the chip distance. A tube is all that's needed.

Olly

[Aussie Dave]

I've used an extension tube, a short 2x Barlow in fact with the lens removed imaging with a webcam. Also have a longer 3x ED Barlow that I can do the same with.

Will re-think the way I'm doing things in the future for imaging.

[michaelmorris]

The most important thing when using an extension tube is to make sure it is very firmly held in place and that it holds the camera orthogonal to the light path. I splashed out on Baader click lock fittings. They are pretty pricey, but to me, well worth it.

[Aussie Dave]

I got to do about 4 hours of visual last night after days of cloud and rain but I didn't get the Saxon out to test. It was a clear cool still night and I was itching to do some imaging as well. I tried the SW Pro 150 without a diagonal on Jupiter from about 1am with the longer 3x ED Barlow with lens removed. It was a similar length if I had the diagonal attached. To be honest, I couldn't tell if it was any better without the diagonal. Logically thinking it should be.

Patchy cloud tonight but the next clear night I'll get the Saxon out.