SLR to Telescope?

[Rednut05]

Is this easy to do?

I haven't a Telescope, but I have a 20D. I wanted to have a bang at taking photos of the moon like shown in a recent post.

I have a 70-300 Sigma, DG, APO or something added to the end of it. Would this be any good or no where near long enough?

So I wondered how cheap a telescope I can buy/ beg/ borrow and how, if you can attach an SLR to it to get my desired picture?

Cheers.

David

[viper_larry]

Get yourself one of these for £0.99p (+ £30 delivery) - you will NOT be disappointed. Mate bought one before Xmas and I was amazed at the quality - he got his for £0.11p. Glass optics and metal casing. The seller also does camera mounts - simply use the telescope as a lens. I do that with mine with varying results.

[RobDickinson]

I was supposed to get a telescope sight -> SLR conevrtor thing with my telescope, wasnt in the box, was only $60 tho (20quid) so wasnt to worried, 'scope is shockingly bad as you could expect but I'd get an OK shot of the moon. Usefull for checking out the surf at the beach tho...

[jmorgan]

Could look in here
www.warehouseexpress.com/

We spent a lot of time looking up () on scopes before we dived in. Found out a lot like getting it right as much as possible first time around, good optics and tripod etc. Think we have made the right choice. We wanted to attach a SLR as well and a suitable T piece has been bought although I found that to focus the camera on the scope I had to remove it and attach the camera directly to the view finder with the adapter. Only moon shots I have at the moment are from a digital held up to the eye piece. Not tried the SLR properly yet.

Edited by jmorgan on Wednesday 10th January 06:28

[Zad]

You need an adaptor such as one of these: www.astro-engineering.com/Adaptors/adaptorsforteles.html

The precise one will depend on what camera and what telescope of course. Some excellent astro photos are obtained by piggybacking the camera onto the scope to use the tracking mount, and using a fairly wide angle lens. Even 100mm can pull out a lot of detail.

[puggit]

Hi Rednut...

I have a telescope and no SLR and I'm not far away (in Reading). I'd be very happy to join forces (maybe lend one way and then the other?)

Between us we'd need to buy an adaptor and a T-ring, but I can look in to that if you let me know what SLR you have?

I have a Meade ETX-90 scope (with computerised tracking!)... I also have a filter for viewing the Sun and I'm desperate to get some good shots with that!

Edited to add - oops you've got a 20D... I'll do some research later and post up what kit is needed

Edited by puggit on Wednesday 10th January 09:29

[VxDuncan]

You basically need a telescope that takes standard 1.25" eyepieces (not the smaller .965". THen you need a camera adapter for 1.25" to t-thread (about a tenner). Lastly a t-ring apadter for your camera mount to t thread. These are about a tenner from jessops.

Selection of the mount is far, far more critical than the scope. You need something solid as by far your biggest issue will be focusing, which is a lot harder than you think. With my big scope (5" 1200mm FL refractor at f9.8) there isn't much depth of field - even getting the whole of the moon in focus is an issue!

Let us know if you need any more help or pop along to ukastroimaging.co.uk but be aware that it's a slippery, expensive slope!

Take a look at the moon shot in my pbase gallery - the focus on this wasn't great and I had to USM the hell out of it to get an image. www.pbase.com/duncan_c/astro

[_dobbo_]

VxDuncan said:

Take a look at the moon shot in my pbase gallery - the focus on this wasn't great and I had to USM the hell out of it to get an image. www.pbase.com/duncan_c/astro

Some crazy images there, do you mind if I ask a question. In the shot:

M42 Great Orion Nebula - 15 x 3 minute & 12 x 1 minute exposures, unmodded 300D @1600 ISO. 15 x 3 minute darks (Guided)

I'm not sure I understand the explanation - is this 27 exposures put together? Doesn't everything move too much to make that possible?

[jmorgan]

"I also have a filter for viewing the Sun and I'm desperate to get some good shots with that! "

Helps when there is some activity on the sun as its a right royal sod to focus. Worth having a look on www.nascom.nasa.gov/sunspots/">here otherwise its a tad white on black (with Baader filter at least)

Usual disclaimer DO NOT VIEW THE SUN WITHOUT THE RIGHT KIT OR FILTER!, sorry, not aimed at you in-particular puggit.


This is good
www.astro-nut.com/sun.html

[puggit]

Here's one I took of Venus transiting the sun a couple of years back - literally just stuck the lens of a compact digital on to the telescope viewing lens!

Yes, I've posted it on here a few times...

[jmorgan]

Ah, way ahead of me. What filter is that? I have only just got me first Baader filter. Sorry if it sounded an bit sucking eggs thingy.

Out of focus sun spot with a 350D straight on the adapter. The T piece had to be removed as I was unable to focus down enough. Baader filter over the end of the scope, very securely so it does not fall off. I need to get more practice in on the focusing.

AND the finder scope removed as I did not want to accidentally lose my sight or burn a hole in the top of me head.

Edited by jmorgan on Wednesday 10th January 11:37

[puggit]

jmorgan said:

Ah, way ahead of me. What filter is that? I have only just got me first Baader filter. Sorry if it sounded an bit sucking eggs thingy.

I don't think you can warn people enough about the dangers of the sun. One direct observation through a telescope and you've lost your eyesite - no warnings given!

It's a screw on filter like this one:


from www.astro-engineering.com/ETX/meadeetx6070atac.html

[jmorgan]

Ah. I bought the sheet for around £14 and made one up to fit the end. Then I found a generic one that would fit for around £30 I think, it will save all the phaffing around doing the Blue Peter bit. When the this one gets damaged then off the shelf for me.

[VxDuncan]

dobbo said:

M42 Great Orion Nebula - 15 x 3 minute & 12 x 1 minute exposures, unmodded 300D @1600 ISO. 15 x 3 minute darks (Guided)

I'm not sure I understand the explanation - is this 27 exposures put together? Doesn't everything move too much to make that possible?

You are spot on - there are 27 exposures and the subject does move. THis is where things get extremely complicated and expensive! The simplest way of getting decent shots of deep sky objects like this is to use a tracking mount, that is one that is aligned with polar north and has a motor to drive it at the correct rate. This is however an open control loop and is only good for shots of a minute or so even with very expensive mounts. The shot you mention was taken guided, that is with another telescope alongside the main one (on the same tracking mount) with a webcam in it. The webcam is pointed to a nearby star and using some cunning software looks for any errors in tracking and issues corrections to the mount for closed loop control. It can be a bit of a nightmare to set up - usually at least an hour before I can press the shutter! The system is sensitive enough that if a truck goes past on the main road 40m away it will notice thema nd try and correct..

The reason for the stacking of 27 images is to reduce noise Try taking an hour image with a 300D and have alook waht you get! Instead lots of shot images are taken and then averaged (stacked) to reduce the random noise inherrent in the sensor. Then a Dark frame is subracted (that has also been stacked to increase s/n ratio). This removes the dead pixels and amp glow. Once you have this master image you can pull the levels alot. Which is good 'cos you need to, usually an image will start out only in the first 10% or so of the histogram.

Astroimaging is complex and expensive. Take my advice and don't try it. It will make your brain and your wallet hurt.

[_dobbo_]

Thanks for the info. Sounds far to complicated and expensive, I already have too many wallet crippling hobbies without adding another!

[Rednut05]

When is the best time to take pictures of the moon? I'm sure this will get a lot of sarky answers...

By that I mean;

Midnight or slightly earlier, gets dark at 5ish?
Best to take them away from light pollution, say in the country, middle of a field?
How long should the exposures be?
What mode etc?

Just want to make suer I get the correct settings.

David

Oh and cheers for the help and interest so far

[VxDuncan]

The image on my website was taken from my backgarden which is really light polluted in the city. LP doesn't matter for the moon as it's so bright. If using a scope you have no aperture control so you're best in manual mode as it wont matter anyhow. Exposure-wise it's trial and error -start around 1/60 sec at 100ISO (with a decent support) and see where you are on the histogram. Keep iterating till you get the best exposure. You'll be focusing manually on the really bright subject-get close and then zoom in on the LCD to get it as good as possible (after a few iterations.

Best time is anytime other than a full moon -you want the sun to be cross lighting the craters at the terminator. so a week or so before or after full moon is good. For best results wait till the moon is highest in the sky (so you are imaging through less of the atmosphere.

[jmorgan]

Nice pics there. Working my way to it, practice and all that. Itching for the motors for the mount and reading elsewhere that certain filters yield good results with street lighting.

[VxDuncan]

My light pollution is awful yet isn't really an issue for most stuff. With the Astronomik CLS filter I use most of the LP is cutout - thought the sensor will flood in a 15min exposure. I live on the border between solihull and brum-it's pretty bad, though I am quite lucky that the orange glow is old skool street lights-ie single wavelength so easy to filter. If the council swaps to the white light street lamps i'll be screwed! Far more of an issue is moonlight - with a bright moon you can forget being able to see anything, and as the light is white it can't be filtered.

[jmorgan]

Still getting used to finding my way around. OK in the back garden to some extent but a few street lights come in. I have seen the filters and think I am going to shell out for one. Biggest annoying thing, being new to it and all, is being able to see the pole star, but not getting it in the scope and using the rings to pin point objects. Must try more in hopping around from ones I can recognise. More practice needed. But its been a pain the last few months with work and weather etc.

Have found the moon fascinating. I used to use binoculars, still do, but a whole lot better through the scope.