Wide Field Finder Scope - Help...

[Spacedout]

Hello All,

I'm looking at various scopes at the minute to use with but that will give me a wider field of view than the current C11.  I do use the Mallincam MF5 reducer with the C11 but with the Mallincam Xtreme to FOV is still pretty tight.  The problem I find is that if my Goto accuracy is having a bad night it is pretty tough to find certain targets.  The idea is if I use another scope with one of my other cameras (CR6) I may be able to use this to see roughly where the target is.  I can then nudge to mount in the right direction to get the target centred onto the main OTA and camera.  As I have the AZ EQ6 I can mount two separate telescopes so this is currently what I'm looking at:

http://www.firstlightoptics.com/startravel/skywatcher-startravel-120t-ota.html

Any thoughts or advice very much appreciated.

Regards

Karl

[allcart]

I would also consider the ST80. Its still f.5, cheaper, and makes a very nice finder/guider scope, with a slightly wider FOV.

[Spacedout]

Thanks Allan,

I had looked at that and saw the review on astronomy shed.  I guess I started worrying about aperture and light grasp    Sorry for the dumb question but if both are F5 why does the ST80 have a wider FOV?

Regards

Karl

[Steve Ward]

A better solution might be to refine your alignment set-up and procedure , properly set-up the Synscan system is very accurate and reliable .

By avoiding the issue by going for a wide-field finder you are not getting the best from a very good mount ... 

[Spacedout]

Hi Steve,

Thank you and yes it is a good mount though I have had as have others issues with goto accuracies.  There was talk of Sky-Watcher coming out with a 3 star alignment for Alt Az though this is yet to materialise.  That said, I am using a video camera which is equivalent I'm told to using a 6mm eyepiece.  Therefore the Goto does not need to be too far off for me to miss it.   

Regards

Karl

[JamesF]

The ST120 is really quite big.  I wouldn't want to use it for a guidescope or finder.  The ST80 (or the ST102 if you really must have the extra aperture though I don't think it's really necessary) would be far more reasonable.

James

[Spacedout]

Thanks James, The ST80 is looking good so far though the 102 with the mount may also be useful as it could double quick set up option.

Cheers

Karl

[Steve Ward]

But a wider FOV in the finder won't help , there will a much smaller target to see to start with , and the finder will have to be perfectly aligned for you to stand much chance of putting the target on chip.

I find that when using the Mak180Pro with an SPC900 a good initial alignment is paramount , and even then the 9x50 finder is too wide to be accurate enough (similar chip/FL combo as yours) even crossing the cross-hairs is enough to lose sight of the target.

[Spacedout]

Thanks Steve,

You are right I guess I need a re-think and start looking at better alignment again!

Thanks

Karl

[shirva]

Can see where your coming from karl..with a wider field of view I do the same with my set up its easy..in my opion...to miss targets with a 6mm eyepiece/camera..to be honest we can go too techy more scopes with more cameras...ive went back to mk1 eyeball and my finder scope supplied and wondered why I was wanting to spend more money on more tech when you can keep it simple.....America spent a million quid developing a pen to write in space....the russians used a pencil...

[Spacedout]

Thanks Davy,

I know what your saying but the remote set will always need tweaking and that is part of the fun for me.  Learning and trying out new things

Cheers

Karl

[Dwight]

Hi Karl:  I see that you want to continue with the remote setup.  Several setups that I have seen on NightskiesNetwork use the QHY5ii guide camera and the 50mm guide scope.  Given that the guide camera has only the 1/3" chip, the image scale is more than enough to centre up objects when used as a finder.  It actually shows some objects better than the main scope d/t the larger field.  If you get a chance, catch "HeavensDeclareGodsGlory" 's broadcast by Don.  He uses this exact setup to good effect.  It doesn't have to be the QHY camera either as other guide cameras work too.  Don can see the finder image in PhD and centre it up.  Easier on the mount too as payload is less and you probably already have a finder.....Dwight

[Spacedout]

Thanks Dwight,

I will take a look and yes this makes sense!  I have a couple of other CCTV cameras with 1/3" chips I was planning to use for the finder but I'll also take a look at the QHY5ii.  I'll watch out for Don too as ultimately I would like to broadcast once the set up is where I want it. 

Thanks

Karl

[Dwight]

You're welcome Karl. The QHY is a great little camera with a very sensitive CMOS chip. I bought the color version with the accessory kit which includes a photo tripod adapter, parfocus ring, finder lens, and all sky lens. The finder lens gives a very wide field and would be too wide for your purposes. I bought it primarily to use as a solar system imager. For your purpose I would recommend the mono version as it is more sensitive (80% QE) and two seconds will easily show all but the dimmest and smallest objects....Dwight

[DoctorD]

Hi Karl

FoV is determined by focal length only, the focal ratio will affect light gathering capability, so two F5 scopes should see the same stars, however an 1000mm focal length 200mm newtonian will have a very different field of view to a 400mm 80mm refractor.

For a given chop size you need to decrease the focal length to get a wider FoV. 

Have you considered using a camera lens in combination with your camera as a finder?

HTH

Paul

[Spacedout]

Hi Karl

FoV is determined by focal length only, the focal ratio will affect light gathering capability, so two F5 scopes should see the same stars, however an 1000mm focal length 200mm newtonian will have a very different field of view to a 400mm 80mm refractor.

For a given chop size you need to decrease the focal length to get a wider FoV. 

Have you considered using a camera lens in combination with your camera as a finder?

HTH

Paul

Thanks Paul,

I learn something new everyday on here!  Yes I'm looking at various options at the minute.  I was thinking of the ST80 as it is cheap and an F5 but I'm also looking at the ED80 as I can use it as a finder, main scope or a quick grab and go.  Decisions Decisions!!

Thanks again

Karl

[hemmi]

Thanks Paul,

I learn something new everyday on here!  Yes I'm looking at various options at the minute.  I was thinking of the ST80 as it is cheap and an F5 but I'm also looking at the ED80 as I can use it as a finder, main scope or a quick grab and go.  Decisions Decisions!!

Thanks again

Karl

Ever considered the astrotech at72ed?  What a fantastic scope for the money! 

[DoctorD]

Hi Hemmi

I have an INED 70 from Teleskop Express (http://www.365astronomy.com/ts-ined-apo-70420mm-carbon-fiber-tube-2-micro-crayford-focuser-p-2561.html), which on paper looks similar to the AT72ED.

I use mine for wide field visual viewing but have also had good results with the SDC435.

You will probably  need an IR filter - I use mine with a 1.25" x0.5 reducer (about F3). 

I took this image of Panstarrs with the INED70 earlier this year:

Focusing was off - I've recently got a Bahnitov Mask that should help with the focusing.

I have also just bought the adapters to allow me to use my F6.3 SCT reducer, however I can only achieve about F4.2 with this because if I use the correct spacing to get the full reduction (F3.78) I cannot achieve focus (not enough inwards travel). Not been able to try this combination out under the stars due to the wether herein the UK.

No such problems with the 1.25" reducer as this sits inside the focus tube.

Note that the £ price is similar to the $ price (and the Euro price is €419) - that's Europe for you!

Mine came in a carry case that also holds a 2" diagonal and a 2" eyepiece (I use a Baader Hyperion Zoom) al you need is a decent photographic tripod and you are ready for visual grab and go!

Clear Skies

Paul

[Merlin66]

May be of interest....

I use an ol' 135mm Zuiko telelens and an ATik16ic as an electronic finder on my C11.

Works very well, no issues, no drama.

[Spacedout]

Ever considered the astrotech at72ed?  What a fantastic scope for the money! 

Hi Hemmi,

That is a very nice looking scope and an even better price!  Not sure if I can get it here in the UK though or at least for the same price.  Thanks for posting it's giving me other ideas

Regards

Karl

[Spacedout]

Hi Hemmi

I have an INED 70 from Teleskop Express (http://www.365astronomy.com/ts-ined-apo-70420mm-carbon-fiber-tube-2-micro-crayford-focuser-p-2561.html), which on paper looks similar to the AT72ED.

I use mine for wide field visual viewing but have also had good results with the SDC435.

You will probably  need an IR filter - I use mine with a 1.25" x0.5 reducer (about F3). 

I took this image of Panstarrs with the INED70 earlier this year:

Focusing was off - I've recently got a Bahnitov Mask that should help with the focusing.

I have also just bought the adapters to allow me to use my F6.3 SCT reducer, however I can only achieve about F4.2 with this because if I use the correct spacing to get the full reduction (F3.78) I cannot achieve focus (not enough inwards travel). Not been able to try this combination out under the stars due to the wether herein the UK.

No such problems with the 1.25" reducer as this sits inside the focus tube.

Note that the £ price is similar to the $ price (and the Euro price is €419) - that's Europe for you!

Mine came in a carry case that also holds a 2" diagonal and a 2" eyepiece (I use a Baader Hyperion Zoom) al you need is a decent photographic tripod and you are ready for visual grab and go!

Clear Skies

Paul

That looks like a good one Paul, carbon fibre too so must be light.  What is the 1.25" reducer that you use for this?

Thanks

Karl

[Spacedout]

May be of interest....

I use an ol' 135mm Zuiko telelens and an ATik16ic as an electronic finder on my C11.

Works very well, no issues, no drama.

Thanks Merlin,

A few others have suggested this and have the same success so something else I'm now looking at.

Thank you

Karl

[DoctorD]

Hi Karl

I use an Astro Engineering x0.6 reducer - actual reduction depends upon the length f your 1.25" nose piece:

http://www.scopesnskies.com/prod/antares/barlow-lenses/focal-reducer/0.6x.html

The whole scope weighs in at 2.1Kg - however the focuser is very heavy and I find I need to add weight to the front to achieve balance on my Minitower.

Hope this helps - and Happy Christmas.

Paul

[Spacedout]

Thanks Paul,

Great price so not surprised it was out of stock.  I ordered one anyway

Thanks again and Happy Christmas to you too!

Karl