New equipment help

[bomberbaz]

COPIED FROM EEVA DISCUSSIONS - EEVA EQUIPMENT

Been thinking of upgrading my eeva gear.

It is apparent to me that the current set up isn't hitting the mark. Trying to use a spotter frac with the ZWO 224MC isn't working at all. 

First I can't get to focus without a barlow and then the barlow reduces the already small fov to levels where resolution and resolving anything but the moon starts to get awkward.  I am often caught preaching that one shouldn't cut corners on visual and one size doesn't fit all and yet here I am trying to do exactly that.

So I was thinking of getting a camera with a larger chip + better resolution and also a dedicated refractor (unless there is a better idea) to use with it. 

Problem is budget. Initially I was thinking around 500 quid but soon realised that wasn't quite enough.

However after doing research and reading various forum/reviews I came to this solution.

Skywatcher 72ED/ F5.8 - ZWO ASI 178 USB3 Camera  - Maybe a Antares 0.7 focal reducer. (Not sure about this as need to confirm it will achieve focus with this in place) Price about £600.

UPDATE to the above: Having done a little extra research I am not convinced I require a new camera so I am having second thoughts about the upgrade, however I think the OTA is something that definitely needs upgrading.

So looking for any feedback on whether the above setup is a realistic one that will provide decent results for eeva.

TIA

Steve

[Peter Drew]

It depends on what class of object you wish to image with EEVA.   Lunar and planetary requires long focus and high resolution, DSO's call for fast focal ratios.  A SCT comes close to satisfying both requirements using Barlows or focal reducers.     🙂

[bomberbaz]

DSO work Peter. I love planetary visual but I want to get more detail out of DSO which your eye simply cannot pickup.

Steve

[bomberbaz]

 

You can see that a 72ED and 224 give a pretty good FOV and a bigger chip is probably not really needed. 

[Peter Drew]

1 minute ago, bomberbaz said:

DSO work Peter. I love planetary visual but I want to get more detail out of DSO which your eye simply cannot pickup.

Steve

A SCT will produce good DSO results with a suitable camera and a F3.3 reducer.  I had a lot of success with a 12" SCT.        

[bomberbaz]

I am weight limited Peter, a 5" mak/sct, 5" reflector or 80mm refractor is my limit I am afraid. 

However I was aiming at lower weight for better stability, hence the 72ED query.

[barkingsteve]

The only other scope i would suggest is something like a skyhawk or starblast ( if you can find one ) 

https://www.rothervalleyoptics.co.uk/skywatcher-skyhawk-1145p-parabolic-reflector-telescope.html

it will give you a slightly  smaller fov with the 224 than the 72 but you will have more aperture and with the money saved you can always get the 178, which will give you a slightly bigger fov. 

Edited July 27, 2020 by barkingsteve

[bomberbaz]

19 minutes ago, barkingsteve said:

The only other scope i would suggest is something like a skyhawk or starblast ( if you can find one ) 

https://www.rothervalleyoptics.co.uk/skywatcher-skyhawk-1145p-parabolic-reflector-telescope.html

it will give you a slightly  smaller fov with the 224 than the 72 but you will have more aperture and with the money saved you can always get the 178, which will give you a slightly bigger fov. 

I wasn't familiar with this OTA but it does look a very good option. Thanks 👍

Steve

[vlaiv]

178 offers only marginal advantage over 224 for EEVA - if you use mono model.

I would personally look into F/5 newtonian, 0.5" focal reducer and 224 as EEVA choice.

130PDS

+

https://www.teleskop-express.de/shop/product_info.php/info/p676_TS-Optics-Optics-TSRED051-Focal-reducer-0-5x---1-25-inch-filter-thread.html

(this one is out of stock, but there is 2" version as well - not sure if there will be any advantage in using 2" version)

and 224 camera.

That should give you about 2.4"/px sampling rate with 130mm of aperture - not bad.

Only drawback would be a bit of coma in the corners perhaps? Here is what F/6 in this arrangement looks like (this was very big scope - 8" F/6 so FOV is smaller):

There is almost no coma in corners. At F/5 there is probably going to be a bit.

Here is same FOV that you tested with this setup:

 

 

[bomberbaz]

1 minute ago, vlaiv said:

178 offers only marginal advantage over 224 for EEVA - if you use mono model.

I would personally look into F/5 newtonian, 0.5" focal reducer and 224 as EEVA choice.

130PDS

+

https://www.teleskop-express.de/shop/product_info.php/info/p676_TS-Optics-Optics-TSRED051-Focal-reducer-0-5x---1-25-inch-filter-thread.html

(this one is out of stock, but there is 2" version as well - not sure if there will be any advantage in using 2" version)

and 224 camera.

That should give you about 2.4"/px sampling rate with 130mm of aperture - not bad.

Only drawback would be a bit of coma in the corners perhaps? Here is what F/6 in this arrangement looks like (this was very big scope - 8" F/6 so FOV is smaller):

 

There is almost no coma in corners. At F/5 there is probably going to be a bit.

Here is same FOV that you tested with this setup:

 

Would I achieve focus though or would I then need to start moving the focuser to achieve this or am I going to need to get a 130pds?

[vlaiv]

2 minutes ago, bomberbaz said:

Would I achieve focus though or would I then need to start moving the focuser to achieve this or am I going to need to get a 130pds?

Quite right!

You might not be able to achieve focus unless you go for model with low profile focuser or similar. I only managed to achieve focus with mine because I had QHY camera at the time that was 1.25" form factor - so I was able to sink it in focuser together with 1.25" reducer!

I have another crazy idea

It will fit your budget and you will get insanely fast setup - maybe lacking a bit in resolution ...

Initially you were ok with 72mm aperture, right? How about 67.5mm? Would that work for you?

https://www.samyanglensglobal.com/en/product/product-view.php?seq=323

And pair it with 224 sensor.

That lens is F/2 - so very fast. Resolution will be lacking at 5.73"/px but it will provide you with enough FOV to show larger objects nicely:

Or fit Markarian's Chain into FOV

Btw, that lens is very good for wide field AP and will have good resale value because of that.

[bomberbaz]

4 minutes ago, vlaiv said:

Quite right!

You might not be able to achieve focus unless you go for model with low profile focuser or similar. I only managed to achieve focus with mine because I had QHY camera at the time that was 1.25" form factor - so I was able to sink it in focuser together with 1.25" reducer!

I have another crazy idea

It will fit your budget and you will get insanely fast setup - maybe lacking a bit in resolution ...

Initially you were ok with 72mm aperture, right? How about 67.5mm? Would that work for you?

https://www.samyanglensglobal.com/en/product/product-view.php?seq=323

And pair it with 224 sensor.

That lens is F/2 - so very fast. Resolution will be lacking at 5.73"/px but it will provide you with enough FOV to show larger objects nicely:

Or fit Markarian's Chain into FOV

Btw, that lens is very good for wide field AP and will have good resale value because of that.

Erm I think I will stay with the OTA idea @vlaiv, not only is it easier for someone like me to get along with, but it can double for visual if required.

I am going to have a good think and do more research on a 130 P-DS ota as it has got my interest now. 

[barkingsteve]

I use a 130 pds on my evo mount but with a 294 camera, it is a great scope for the price. While it may suite your needs with a 0.5 reducer you will get coma at the edges and you will be close to maximum weight. As you stated in your first post, one size doesn't fit all and you will have to make a compromise somewhere, good luck  

[bomberbaz]

2 hours ago, barkingsteve said:

I use a 130 pds on my evo mount but with a 294 camera, it is a great scope for the price. While it may suite your needs with a 0.5 reducer you will get coma at the edges and you will be close to maximum weight. As you stated in your first post, one size doesn't fit all and you will have to make a compromise somewhere, good luck  

stated wieght is 4kg so yeah, as much as I would be happy going with. Much obliged.

I think on reflection a 130 PDS is going to be the way to go, I will keep my eye on the 2nd hand market.