what do you think

[micp]

would a scope

102mm F/11 Refractor be any good for astrophotography.

[rowan46]

It would be fine with a webcam for planetary work but no good for long exposure work unless you have a very high end mount. for deep space you need about f6 or less

[micp]

could you tell me what you think of LYRA OPTICS are there scopes any good.

thanks

[micp]

high end mount,would a Heq5 be ok

thanks

[rowan46]

not for an f11 scope and long exposure I wouldn't have thought. There is a reason why imagers tend to use fast scopes and it's not just because of field of view. I imagine it would make a decent guidescope though.

[rowan46]

f11 is really a planetary scope the long focal length helps control the ca and it takes magnification well. field of view will be quite restricted. not to say it won't work visually on deep space I imagine the views if the optics are as nice as the scopes seem to look will be nice but It doesn't seem to be a deep space imagers scope

[John]

could you tell me what you think of LYRA OPTICS are there scopes any good.

thanks

Lyra Optics don't make the scope - they import it. Here is a report on the same scope under different branding:

Telescope Reviews: Astro Telescopes 102mm f/11 - first light report

[Ad Astra]

F/11 is great for lunar and planetary photos, not for deep sky though. Too slow.

Modern digital cameras can compensate for this somewhat by jacking up the ISO to 1600 or more, but not what you want for deep sky work at all.

[hubalkj]

It would be fine with a webcam for planetary work but no good for long exposure work unless you have a very high end mount. for deep space you need about f6 or less

A properly adapted single shot digital camera would work as well!

[hubalkj]

f11 is really a planetary scope the long focal length helps control the ca and it takes magnification well. field of view will be quite restricted. not to say it won't work visually on deep space I imagine the views if the optics are as nice as the scopes seem to look will be nice but It doesn't seem to be a deep space imagers scope

I couldn't disagree more with your statement about a scope such as this not being a deep space imager's scope. I've taken several deep sky photographs through instruments such as these and they were much sharper, espescially at the edges of the field than any fast apochromat I've owned or used.

[hubalkj]

I couldn't disagree more with the statements about slower refractors not being suitable for deep sky imaging. I've accomplished this task with ease many times over the years with such instruments! This is simply an old wives tale that is incorrect!

[Ad Astra]

Refractors vary quite a bit more in image quality than newtonians do these days. 2, 3, or 4 element lenses, Achromat, Apochromat, and 'super-apochromat' variations are all available, and the quality will affect your visual and photographic work.

That said, an F/11 scope, like an F/11 lens on a camera is far slower than a F/4 - F/6 designs common on scopes designed for photographic work. The need for prolonged exposure times puts a severe burden on the mount, and the tracking capability of your system. The longer your exposure needs to be, the more precise your mount and tracking/autoguiding system needs to be. We used to improve this by "hyper-sensitizing" camera film (treating it with chemicals to increase sensitivity to light - cutting down exposure time!) Now-a-days, we either jack up the ISO on our digital camera, or take several shorter frames and use computers to "stack" them into a single image.

Stacking and high-ISO digital cameras have greatly transformed astrophotography, but the "Long F/ratio = Longer exposure = tougher tracking requirements" dogma hasn't changed. No matter what camera you have, an F/11 scope will be more of a challenge to photograph DSO's through than a F/4 scope. Not that the challenge isn't worth it, a good Apo can give you wonderful images - but you may bankrupt yourself buying a mount and autoguider to match.

If you doubt that, take a look <HERE>, and see what I did with my 133mm f/12 scope to get it properly mounted!

I hope that helps,

Dan

[rowan46]

I couldn't disagree more with the statements about slower refractors not being suitable for deep sky imaging. I've accomplished this task with ease many times over the years with such instruments! This is simply an old wives tale that is incorrect!

I can't dispute your assertions from any great experience, all I know about imaging ( which isn't much) is that I have not got my f10 to be any good for imaging this is due to me not having a mount good enough which I think is what I said in my first reply. Anything can be imaged if the mount is accurate enough but the general opinion of the "old wives" who image on here is that for the less expensive mounts a fast apo gives the best results on dso's. If you have cracked it I would love to be proven wrong as I cannot afford a fast apo or a high end mount and consequently would love to see some of your pics and perhaps a methodology would be useful as I am interested in doing some imaging

[Ad Astra]

Hi Rowan,

All the images I shoot are single exposures on my DSLR, and they turn out ok - but not in the 'spectacular' class that some of the folks here put up!

I find that increasing the ISO (film speed) on my camera helps me to keep the exposures shorter - which gives me a little slack on the tracking and guiding end.

Apart from that... practice, practice, practice! (It used to be a lot worse with film when we had to PAY to develop all our shots - even the rotten ones!!!)

Dan