Mirror slap and star image distortion?

[Robert_T]

Hi All, I haven't been bothered yet using Live View or other mirro lockup to avoid the mirror vibration in my deep sky pics. I'm just wondering for short FL imaging <500mm whether it's liable to show distortion in star images... I see a slight inverted L shape in some stars in the RAWS that I thought might be due to this? What do you guys think:shrug:

Alternatively is this more likely due to guiding corrections?

[Tandum]

I would have thought the scopes you have on that mount would be stable as hell, what's the weight of them plus cameras, about 8Kgs. I know mine wobbles if I look at it, it's around 17Kgs. I tried mirror lock to resolve my problems but that seems to disable remote shooting on the 450D.

Why don't you try shooting with live view on and see if there is an improvement? That would force a mirror lock.

[Robert_T]

Yeh, I'll give live-view a shot. I'm only carrying 6kg with the camera. Probably more likely poor guiding behind my woes ... just hoping for an easy fix;)

[Tandum]

What did happen with your guiding ? You are using ascom guiding and PHD aren't you? If live view shooting doesn't fix it you could play around with the guiding agression settings in PHD.

I bought a GPUSB and use PHD to the guide port. That bit works pretty well for me. tip: I also have a crimp tool if RJ cables are needed and my heq5 is being replaced soon so it will be available.

Damn, it's raining again ... when will it end ..

[Robert_T]

Yeh, I'm using PhD and ASCOM guiding via the autostar controller on the LXD75 so not exactly "direct"... where are the guiding aggression settings founds - are they under the "brain" button?

I thought the HEQ5 had an ST4 port and you could connect direct to that or is there an interface required for that as well? So what are you replacing the HEQ5 with... an EQ6?

cheers,

Bob

[Tandum]

Yes your aggression settings are under the brain button. Have a fiddle if all else fails.

Yes the HEQ5 has an ST4 port, the GPUSB box is basically a USB to ST4 converter which PHD recognises. And yes I have ordered an EQ6GOTO mount which I expect to arrive in August. The HEQ5 is fine with the 8" DOB on it, but I keep adding stuff to it :lol: so a heavier mount is required. I'm already looking at a new scope as well :) Vixen vc200l

[Robert_T]

Now I can pass the blame for the recent and ongoing spate of weather to you...an EQ6 and a Vixen vc200l must be worth at least another fortnight of cloud and drizzle:P

So where does one get a GPUSB from?

[iceman]

From shoestring astronomy.

I got a GPUSB unit to use with my DMK as a guide setup.