Field Flattener for ST80

[TareqPhoto]

I want to have a field flattener to use with my ST80, i saw this one, is it compatible with ST80?

https://www.firstlightoptics.com/reducersflatteners/skywatcher-field-flattener.html

[Zakalwe]

ST-80 is f5.

The FF specification are from f5.5 to 6

[TareqPhoto]

Just now, Zakalwe said:

ST-80 is f5.

The FF specification are from f5.5 to 6

I did read that, but will that cause a problem? or does it mean that FF won't do the job?

And about FF, if i find any other flattener that is designed for F4 up to F6 refractors will it work on ST80?

[Cornelius Varley]

The ST80 has a 1.25" focuser and the field flattener is designed for 2" focusers so it won't fit the ST80.

[TareqPhoto]

6 minutes ago, Cornelius Varley said:

The ST80 has a 1.25" focuser and the field flattener is designed for 2" focusers so it won't fit the ST80.

Sure it won't as long i keep using that focuser, but i am planning to change the focuser to another one which is 2", so then will it work?

[Zakalwe]

27 minutes ago, TareqPhoto said:

I did read that, but will that cause a problem? or does it mean that FF won't do the job?

It means that it is out of specifications. It might work, it might not. You are asking if something will do a job that it is not designed to do.

27 minutes ago, TareqPhoto said:

And about FF, if i find any other flattener that is designed for F4 up to F6 refractors will it work on ST80?

Possible. ST80 aren't designed as imaging scopes so I'd expect a certain amount of chromatic aberration which a FF shouldn't be expected to cure. What makes you think that you need a FF anyway?

[TareqPhoto]

Just now, Zakalwe said:

It means that it is out of specifications. It might work, it might not. You are asking if something will do a job that it is not designed to do.

Possible. ST80 aren't designed as imaging scopes so I'd expect a certain amount of chromatic aberration which a FF shouldn't be expected to cure. What makes you think that you need a FF anyway?

Ok, pass the first part of the answer, maybe i should look at another FF if this is not designed for F5 anyway.

The question from your answer is, what is the FF used for? i thought that it is used for the field curvature rather than CA, or am i wrong? and for that CA i did read from another forums that using a mono cooled camera and filters will eliminate or reduce the CA at least, so let's say using a mono camera will solve one problem, then i have to look at the other problem which is a field curvature, they told me even an APO triplet or doublet will have this issue so they are coming with FF or need to buy one for them, you have another opinion or idea?

[Zakalwe]

If you are going to the expense of buying a mono camera, filters, replacement focuser and field flattener than I'd question why you'd be opting for an ST-80?

[TareqPhoto]

4 minutes ago, Zakalwe said:

If you are going to the expense of buying a mono camera, filters, replacement focuser and field flattener than I'd question why you'd be opting for an ST-80?

I already have a mono camera, QHY163M, an expensive one, and i have one filter now which is Astrodon Ha 5nm 1.25", but i can't buy another scope yet, because i am still getting more filters and then needing a filter wheel, those expense will prevent me from buying a scope until next year, also even if i want to buy another scope it is likely i have 5 options, and only the expensive ones are in my mind which is difficult to get soon, so i just keep my hope for ST80, i can't make it as a quality triplet for sure, but i never asked to make it as one, all what i wanted to do is just to replace its accessories for improvement in taking images or dealing with lights, didn't ask for making quality images, i may also ignore about flat flattener for now, i just asked if i can find it may help slightly, but it is not a big deal, if those expensive scopes refractors needing one then this cheap must need one regardless about its design or quality, so i can't buy a scope in favor to get more filters and accessories, and i did test my QHY camera with this scope and the results is very surprising and promising, given that i didn't do good polar alignment and no guiding and let someone stack/process for me but sounds he didn't stack, so i can imagine if i did good PA and got longer exposures and better guiding and added more filters i may get really acceptable nice results until next year the time i can afford an APO triplet FPL-53 scope, even with this triplet if i buy it now i will be forced myself to buy filters to have colorful images but then i can't, so think about it as a practice test with cheap scope until i am ready for a chosen APO triplet scope.

[LightBucket]

Sell the filter and don’t buy anymore or a filter wheel, and buy a much better scope, then in time upgrade and get the filters and associated kit,  that’s the correct way round of doing things, as you can still image..as you have the camera, just maybe get a much cheaper set of filters such as the ZWO offering.

for the price of two astrodon filters you could buy a very nice 80mm refractor...

[vlaiv]

This might be interesting read for you:

http://www.astrophotography-tonight.com/astrophotography-comparing-three-80mm-refractors/

My advice is: don't bother with either changing ST80 focuser nor trying to find suitable flattener - just use it as is - crop frames at point where you find stars to be unacceptable distorted.

This will give you opportunity to improve your imaging skills and also learn much about processing until you gather the money to step up and get your self a proper imaging scope + suitable corrector for it.

If you struggle with 1.25" focuser, and want an upgrade, I would suggest instead of getting 2" focuser for ST80 to actually sell your ST80 (don't know how much used scope market is developed where you live, but in general ST80 should not be hard to sell - it is very versatile item) and buy your self a ST102 OTA- it comes with 2" focuser (also crappy one, but just live with it for now), and it will be a bit more suitable for your camera.

[TareqPhoto]

22 minutes ago, LightBucket said:

Sell the filter and don’t buy anymore or a filter wheel, and buy a much better scope, then in time upgrade and get the filters and associated kit,  that’s the correct way round of doing things, as you can still image..as you have the camera, just maybe get a much cheaper set of filters such as the ZWO offering.

for the price of two astrodon filters you could buy a very nice 80mm refractor...

Sorry, i won't sell my Astrodon and i don't want cheaper filters, i prefer to use cheaper scope over cheaper filters 

[tooth_dr]

6 minutes ago, TareqPhoto said:

Sorry, i won't sell my Astrodon and i don't want cheaper filters, i prefer to use cheaper scope over cheaper filters 

It just seems an unusual pathway to upgrade.  I have an ST80, and would not consider imaging through it.  In fact I tried to image Venus the other morning through it, and gave up very quickly.

[Zakalwe]

6 minutes ago, TareqPhoto said:

Sorry, i won't sell my Astrodon and i don't want cheaper filters, i prefer to use cheaper scope over cheaper filters 

[Dave In Vermont]

1 hour ago, Cornelius Varley said:

The ST80 has a 1.25" focuser and the field flattener is designed for 2" focusers so it won't fit the ST80.

Unless you install something else like a 2" Crayford, which I did with wonderful results! As far as I'm concerned. Crazy I know - the Dual-Focus GSO I went for cost almost as much as the ST80. I just checked out the field-flattener and read this:

A high-quality, non-focal-reducing Field Flattener optimised for DSLR imaging on refractor telescopes with focal ratios around f/5.5 to f6.0. 

Will also provide much improved results on refractors with focal lengths narrowly outside this optimised f/range.

A good match for the Skywatcher Equinox-80 and similar. 

Integral T-Ring adaptor thread. High quality CNC machined body with gloss black anodised finish.

Features standard 2" push-fit barrel for use with 2" focusers. 

So if you're feeling brave, you could roll-the-dice and get one anyway. Maybe look for one on the 'Used' marketplace?

Best Wishes, Tareq -

Dave

[TareqPhoto]

18 minutes ago, vlaiv said:

This might be interesting read for you:

http://www.astrophotography-tonight.com/astrophotography-comparing-three-80mm-refractors/

My advice is: don't bother with either changing ST80 focuser nor trying to find suitable flattener - just use it as is - crop frames at point where you find stars to be unacceptable distorted.

This will give you opportunity to improve your imaging skills and also learn much about processing until you gather the money to step up and get your self a proper imaging scope + suitable corrector for it.

If you struggle with 1.25" focuser, and want an upgrade, I would suggest instead of getting 2" focuser for ST80 to actually sell your ST80 (don't know how much used scope market is developed where you live, but in general ST80 should not be hard to sell - it is very versatile item) and buy your self a ST102 OTA- it comes with 2" focuser (also crappy one, but just live with it for now), and it will be a bit more suitable for your camera.

Well, the point is, i don't know which ST102 you are talking about, if it is the following i will post then it is cheap one and i can buy it no problem or even same series but 120mm instead of 102

https://www.firstlightoptics.com/startravel/skywatcher-startravel-102t-ota.html

If i saved more i can go with another scope which is this one:

https://www.firstlightoptics.com/pro-series/skywatcher-evostar-80ed-ds-pro-ota.html

As you can see, it comes already with 2" focuser, but then i can't afford to get a flattener which they mentioned as option and sounds it is necessary, and i won't sell my filter and i won't stop my plan for more filters from Astrodon.

[TareqPhoto]

2 minutes ago, tooth_dr said:

It just seems an unusual pathway to upgrade.  I have an ST80, and would not consider imaging through it.  In fact I tried to image Venus the other morning through it, and gave up very quickly.

Imaging Venus with ST80? i am not that much crazy yet, will, for planetary i have an eye on 11" SCT or 7" Mak from SW, but this scope is my plan in next year, i delay visual and imaging of planetry for the future, i will never try to do that with my ST80 even if i bought a planetary camera and 5X barlow, so i wasn't talking about planetary, i was talking about DSO only.

[parallaxerr]

Hi Tareq,

I thought I'd chip in with some info. I find myself in a similar situation to yourself, I have acquired a fair bit of imaging gear, however, I still only have an Achromat (ST120) to begin with. As a result I have read a lot of information on imaging with achros and tried a few little tricks myself to get half decent results.

It can be frustrating sometimes as the overwhelming response to questions regarding achro imaging is...buy an apo. But it needn't be that way.

For a field flattener, I use a Baader MPCC coma corrector. It is only a flattener, not a reducer. I have used it in F5.9 and f5 refractors, in the F5.9 there was still a little bit of field curvature at the edges but in the F5 it gives sharp stars right to the edge of my APS-C sized chip. It is rated for F3.5-F6 so I think it'll work with the ST80 just fine, but would need the 2" focuser. I use a DSLR and the MPCC has a T2 thread so it's a simple connection for me, you may have to investigate adapters/spacers to use your cam, but the point is, it works in fracs at F5 rather well.

Re: CA, it doesn't bother me so much but I have learned to process most of it out and using a UV/IR cut filter along with a yellow 495nm longpass will "almost" kill it to begin with. Have a look at this thread, it references video imaging but the CA reducing technique still applies to stills...

http://astrovideoforum.proboards.com/thread/1079/using-achromats-video

Anyway, you say you have a 5nm Ha filter, well just forget about colour and do mono narrowband, that's something else I'm trying. LOTS of good results on the forums using this method with achros.

I'm sure you'll find a way to get results that make you happy

 

 

[TareqPhoto]

3 minutes ago, Dave In Vermont said:

Unless you install something else like a 2" Crayford, which I did with wonderful results! As far as I'm concerned. Crazy I know - the Dual-Focus GSO I went for cost almost as much as the ST80. I just checked out the field-flattener and read this:

A high-quality, non-focal-reducing Field Flattener optimised for DSLR imaging on refractor telescopes with focal ratios around f/5.5 to f6.0. 

Will also provide much improved results on refractors with focal lengths narrowly outside this optimised f/range.

A good match for the Skywatcher Equinox-80 and similar. 

Integral T-Ring adaptor thread. High quality CNC machined body with gloss black anodised finish.

Features standard 2" push-fit barrel for use with 2" focusers. 

So if you're feeling brave, you could roll-the-dice and get one anyway. Maybe look for one on the 'Used' marketplace?

Best Wishes, Tareq -

Dave

The focuser i looked at or mentioned is already 2" Crayford, so why you think i was thinking about something else? This is the one i linked

https://www.firstlightoptics.com/skywatcher-focusers/sky-watcher-dual-speed-2-crayford-focuser-for-sky-watcher-refractors.html

So isn't this one 2" Crayford already? i just only worried about the diameter of it if matching the ST80 one [~86.7mm], the price is also nice, if it isn't the one then i have to go with GSO anyway, and the price isn't bad either as long it is less than $200, just i prefer the shipping from FLO, that's all.

About the flattener, i think i will pass it for now, i am not in rush, i emailed FLO about this FF and the focuser and waiting their response, if they confirm it right then i will go with it, if they just replied as no then simply i look for something else, or just live with what i already have.

[parallaxerr]

5 minutes ago, TareqPhoto said:

So isn't this one 2" Crayford already? i just only worried about the diameter of it if matching the ST80 one [~86.7mm], the price is also nice, if it isn't the one then i have to go with GSO anyway, and the price isn't bad either as long it is less than $200, just i prefer the shipping from FLO, that's all.

Unfortunately that one won't fit. There are two synta focuser formats, normal and small. You'll need the small, which you already know is 86mm.

[parallaxerr]

15 minutes ago, Zakalwe said:

You should see the results the guys are getting with Alt/Az mounts!

Breaking the law(s)!!!

[vlaiv]

6 minutes ago, TareqPhoto said:

Well, the point is, i don't know which ST102 you are talking about, if it is the following i will post then it is cheap one and i can buy it no problem or even same series but 120mm instead of 102

https://www.firstlightoptics.com/startravel/skywatcher-startravel-102t-ota.html

If i saved more i can go with another scope which is this one:

https://www.firstlightoptics.com/pro-series/skywatcher-evostar-80ed-ds-pro-ota.html

As you can see, it comes already with 2" focuser, but then i can't afford to get a flattener which they mentioned as option and sounds it is necessary, and i won't sell my filter and i won't stop my plan for more filters from Astrodon.

Yes, Star travel 102 (or 120) - big brother of ST80. I have one and I've done imaging with it to a certain success using OSC sensor, small one, so field curvature was not an issue but CA was, so I used Wratten #8 stacked to UV/IR Cut and stopped aperture and got decent results. If you search this forum there is also a thread dedicated to CA control using this technique - different diameter aperture masks and results with and without yellow filter.

This is all for OSC. RGB filters should control CA a bit better (because you will be focusing to specific part of spectrum with each filter), and for NB filters CA is not an issue.

Focuser on 102 (and I guess 120 but don't know for sure) will need some work / tweaking to get it into shape for imaging. And even tweaked it will not cope with heavy gear. You will need to adjust it so there is no play in it (otherwise it wobbles a bit when focusing, maybe not noticeable on visual but you will see image shift on sensor). I did not do anything special to it. Just disassembled it, cleaned it and re greased it and tightened it properly.

[TareqPhoto]

2 minutes ago, parallaxerr said:

Hi Tareq,

I thought I'd chip in with some info. I find myself in a similar situation to yourself, I have acquired a fair bit of imaging gear, however, I still only have an Achromat (ST120) to begin with. As a result I have read a lot of information on imaging with achros and tried a few little tricks myself to get half decent results.

It can be frustrating sometimes as the overwhelming response to questions regarding achro imaging is...buy an apo. But it needn't be that way.

For a field flattener, I use a Baader MPCC coma corrector. It is only a flattener, not a reducer. I have used it in F5.9 and f5 refractors, in the F5.9 there was still a little bit of field curvature at the edges but in the F5 it gives sharp stars right to the edge of my APS-C sized chip. It is rated for F3.5-F6 so I think it'll work with the ST80 just fine, but would need the 2" focuser. I use a DSLR and the MPCC has a T2 thread so it's a simple connection for me, you may have to investigate adapters/spacers to use your cam, but the point is, it works in fracs at F5 rather well.

Re: CA, it doesn't bother me so much but I have learned to process most of it out and using a UV/IR cut filter along with a yellow 495nm longpass will "almost" kill it to begin with. Have a look at this thread, it references video imaging but the CA reducing technique still applies to stills...

http://astrovideoforum.proboards.com/thread/1079/using-achromats-video

Anyway, you say you have a 5nm Ha filter, well just forget about colour and do mono narrowband, that's something else I'm trying. LOTS of good results on the forums using this method with achros.

I'm sure you'll find a way to get results that make you happy

 

 

Thank you very much for your post, i was waiting something like that, so if you confirm that MPCC is as good as any flattener to be used for ST80 then i can go for it, i thought the coma corrector is only used for reflectors such as SCT/Newt/Mak...etc, didn't know it can be used for Refr and do the same job as flattener, this is a relief, and to make it even more relief, one dy later i will buy a reflector of whatever kind which may need a coma corrector, so it is like i have an item that can be used later for something else, but you are the only one mentioned to me for now about coma corrector to be used with ST80. 

In all cases, i said that a flattener isn't the top priority item right now, i just added or asked about it to see if i can use one for ST80 to correct anything needed to be corrected, which the field curvature, but i am also like you, i don't care much about this issue, and i was hoping for a flattener that i can use even on APO triplet later, so it will be like an item to be used on another scope later, and most likely i will stuck with SkyWatcher scopes in the future except maybe SCT.

I did shoot with this scope and Ha filter, i didn't see CA at all because it is a mono, and later if i added RGB i don't know if that CA will be there too, or is that CA only with color[OSC] cameras?

I do have Baader Contrast Booster which is designed to kill that CA, i can use it for some shots and added to Ha or NB filters, i never asked about CA solution here, my only questions were about focuser and flattener for field curvature, i never mentioned CA anywhere, but you only mentioned it for me.

 

[tooth_dr]

15 minutes ago, TareqPhoto said:

Imaging Venus with ST80? i am not that much crazy yet, will, for planetary i have an eye on 11" SCT or 7" Mak from SW, but this scope is my plan in next year, i delay visual and imaging of planetry for the future, i will never try to do that with my ST80 even if i bought a planetary camera and 5X barlow, so i wasn't talking about planetary, i was talking about DSO only.

I knew you would say that, it was just an example.  How do I put it - the ST80 is not a scope for imaging its for visual or guiding

[TareqPhoto]

4 minutes ago, parallaxerr said:

Unfortunately that one won't fit. There are two synta focuser formats, normal and small. You'll need the small, which you already know is 86mm.

Ah ok, then i have to pass it, i have no choice then but GSO ones, i will see where is the best store/vendor to buy from.

Thank you very much!