Anything "wrong" with eyepiece projection?

[Macavity]

As I (do little more than) experiment with my budget imaging equipment, I cannot help but wonder: [is there] Anything "wrong" with eyepiece projection... As a methodology?

For some reason, my attempts to stick a Webcam on the back of my MAK127 produce 'orrible vignetting - Albeit with a 1/3(?)" cheap chip. But, if I use my NICE Baader eyepiece projection adaptor, I get (relatively) FINE images. Also, with a variety of eyepieces (and extension tubes), I can easily access a wide range of image scales - The focussing seems snappier too!

What's not to love? More seriously though, eyepiece projection seems rather seldom used - I guess because of the additional "glass" involved? I was just wondering, if it has it's protagonists here or even it's (legitimate!) critics...

[jgs001]

I've used it Chris, for close ups of the lunar surface with my 450d. For that it's not ideal as the SLR is single shot, slow frame rates, but it does work and works quite well... if you're lucky enough to catch a moment of steady seeing. I'd expect with a webcam it ought to work well.

[brianb]

? More seriously though, eyepiece projection seems rather seldom used - I guess because of the additional "glass" involved? I was just wondering, if it has it's protagonists here or even it's (legitimate!) critics...

When film was king, eyepiece projection was more popular - this had lots to do with needing more magnification because of the relatively poor resolution of film compared with small pixel webcams. Working at f/60+ was commonplace ... needed excellent seeing, of course.

EP projection simply doesn't work as well with small ratios as it does with large ratios, because the correction of the optics isn't right unless the virtual image plane is at infinity. Barlows / tele-extenders are designed for small ratios, which is why they're now more popular.

Nothing to stop you trying EP projection. No reason why it shouldn't work, well, but probably best to try with a short EP giving a large magnification and a short focus scope to reduce the working f-ratio to something reasonable.

[Macavity]

Thanks folks - Brian, for the little bit o' history! I only really want to grab a few half-decent white light solar (occasional lunar?) images. I think I'm slowly winning. I sense my initial ambition to grab full disk images of these may now be contrary to the spirit of eyepiece projection, but hey...

I think it was useful to rediscover (and motorise!) my moth-balled EQ3-2. A MAK127 is going to be inherently too small for a "solar overview", but on reflection, MOST of the white light solar dish will be inherently blank - Sometimes ALL of it?

Next up (funds permitting!) replacement of my Orion Mk.II SSCI. Much as I try to ignore it's deficiencies (and extremely frustrating bundled software!) it becomes a serious vexation.

That's the way the money goes... <sigh>

[brianb]

but on reflection, MOST of the white light solar dish will be inherently blank - Sometimes ALL of it?

Indeed - my fault I'm afraid - new Lunt solar wedge arrived with me on Monday, greyed out on Monday but sun has been blank ever since - a variant of the usual "new equipment curse"!

[Jove]

Hi Macavity... I;ve been looking at getting a few bits to do EP Projection with my Skymax 127 - mainly Lunar shots, and perhaps some planets too. I'd be interested to hear what kit you use to attach your camera to the scope. Also, how sturdy is the EQ3-2? I am using the SW "Supa trak" mount (The alt-az mount that came with the scope) and wonder if it is a bit bouncy when I release the shutter (using a remote!)

Thanks!

[MikeD]

I use EP projection, not sure if powermate ect would be better but EP projection is cheaper.

Heres a mosaic I shot ep projection with my 10" newt and DMK21

Mike.