nikon d750 and 500mm f 6 lens or camera and telescope for astro

[iwols]

hi all just wondering what would be the difference between my camera on a sigma 500mm f6.3 lens(which i already have) and my camera on a skywatcher 80ed/100ed scope,daft question but not sure the advantage of purchasing the ed 80/100 or would the camera on the sigma 500mm be just as good for astrophotography any thoughts welcome,on a heq5 goto mount

[happy-kat]

As you already have the lens why not try it then you will have some output to review. Does the lens show any imaging issues like excessive comma etc. Which you won't know until you try it.

[iwols]

thanks for that, will do when weather permits just wondered if anyone had a similar experience with similar equipment

[michael8554]

Hi iwols

Not aware of a Sigma 500mm F6.3, do you mean the 50-500mm F6.3 Zoom lens?

It's Apo like the 80ED (which is 600mm F7.5) so the Sigma has more glass, but is faster, so it's swings and roundabouts.

Like happy-kat suggests, try it and judge the results.

Michael

[Thalestris24]

hi all just wondering what would be the difference between my camera on a sigma 500mm f6.3 lens(which i already have) and my camera on a skywatcher 80ed/100ed scope,daft question but not sure the advantage of purchasing the ed 80/100 or would the camera on the sigma 500mm be just as good for astrophotography any thoughts welcome,on a heq5 goto mount

Hi

I imagine that lens is quite heavy... I expect you'll have to take some care to make sure the camera + lens balances ok (in RA and DEC) on your heq5. If it has a collar/tripod mount then that will help. Most lenses work better if stopped down 1 stop but that will obviously slow it a bit. Some lenses are better than others for AP so, as mentioned, you'll have to try it out and maybe post what you can get here. Getting sharp focus of stars is important in AP but lenses can be difficult to get just right, and get to stay in focus position.

Look forward to seeing what you can get.

Louise

ps remember to put the lens and camera in Manual mode and you'll need to set the camera to Bulb mode

[iwols]

Hi iwols

Not aware of a Sigma 500mm F6.3, do you mean the 50-500mm F6.3 Zoom lens?

It's Apo like the 80ED (which is 600mm F7.5) so the Sigma has more glass, but is faster, so it's swings and roundabouts.

Like happy-kat suggests, try it and judge the results.

Michael

yes its the 150-500mm

[iwols]

Hi

I imagine that lens is quite heavy... I expect you'll have to take some care to make sure the camera + lens balances ok (in RA and DEC) on your heq5. If it has a collar/tripod mount then that will help. Most lenses work better if stopped down 1 stop but that will obviously slow it a bit. Some lenses are better than others for AP so, as mentioned, you'll have to try it out and maybe post what you can get here. Getting sharp focus of stars is important in AP but lenses can be difficult to get just right, and get to stay in focus position.

Look forward to seeing what you can get.

Louise

ps remember to put the lens and camera in Manual mode and you'll need to set the camera to Bulb mode

yes the lens is quite heavy but does have a tripod mount,will post if weather ever permits

[iwols]

maybe ide need the 

Skywatcher Startravel 80T Optical Tube

if i dont go down the telescope route

[Thalestris24]

maybe ide need the 

Skywatcher Startravel 80T Optical Tube

if i dont go down the telescope route

I'd avoid the ST-80 for imaging with, if that's what you were thinking of.

Louise

[iwols]

no its just to use to set alignment up on the mount and locating objects

[Thalestris24]

no its just to use to set alignment up on the mount and locating objects

I think a Skywatcher 9 x 50 finder would actually be better for that - just my opinion. It is fl =170mm vs 400mm for the ST80.

Louise

[iwols]

thanks just not sure how i would mount to my wedge

[Thalestris24]

I've n

thanks just not sure how i would mount to my wedge

I've never actually tried it but I imagine you could probably secure it in the same way as a dovetail. I have one that I use for guiding with but it's been taken out of it's holder and attached to an aluminium bar via a couple of pipe clamps. Nice and rigid  :

Louise

[iwols]

thanks all food fro thought cheers

[Thalestris24]

It's on an ST80 on a Heq5! Would prob be better attached via a dovetail to mount directly on the heq5.

Louise

[iwols]

thought i could fit on the long wedge next to the camera  that came with the heq5

[Thalestris24]

thought i could fit on the long wedge next to the camera  that came with the heq5

You mean a dovetail bar?? The finder wouldn't fit directly to it - it normally mates with a vixen style finder shoe, located on the scope. With a bit of DIY you could get a finder shoe and screw it to a dovetail (might be tricky) or get a couple of 54mm pipe clamps like I did.  Or you could attach it alongside a rectangular aluminium bar or short piece of wood which would allow you to clamp the finder's foot in place. Or, you could get an ST80...

[RichM63]

I find focusing a lens much easier than focusing an insensitive telescope.

I have an ST80 and a 200-500 zoom, 99.9% used in daytime. The zoom wins out every time, both for ease and IQ. Remember a telescope has no real means of controlling aperture even with a chipped adapter.

However this fuzzy pic will give an idea for mounting with a telescope.

Rich

[iwols]

so are you saying the live view through my  camera would be better than the Skywatcher 9 x 50 finder for aligning the mount when using just the camera and 500mm lens,thanks for the advice by the way,its a vixen type bar as well that came with the mount

[iwols]

really need some clear sky to test  out

[Thalestris24]

Talking of focussing...

Here's another view of my ST80 showing a SW autofocusser attached  The ST80 R+P isn't the best for focussing but the 'autofocus' motor attachment gives you much finer control.

Also an image of a TS microfocusser on a Canon lens. This is a great device for fine focussing a lens and holding it there.

I think you probably need something widefield for locating sky objects. You could use your camera viewfinder/500mm lens for finer adjustments though the crosshairs in the SW finder are probably good enough for aligning on. Liveview doesn't work very well unless you're pointing at a bright star. Also, using it for any length of time makes the sensor temperature go up (bad!) and drains the battery, if you're using one. Actually, thinking about it, you have a zoom lens so you could indeed use the viewfinder starting at 150mm for finding and aligning with. All this would be made much easier with a laptop running Ascom, backyard Nikon, Stellarium and eqmod... But it's the start of a slippery slope!

Louise

[iwols]

thanks would it make sense to get the 9x50 and some how attach that along with my camera ,not sure how though cheers