Ideal Wide field scope for a full frame dslr?

[AntHart]

Hi,

Im looking for a wide field portable refractor to use with my 6d dslr.

i have a Samyang 135mm f2 ..this is more of an upgrade in focal length

i realise my camera isn’t the ‘best’ for using with a scope being full frame without a flattener so I’ll have to take this extra cost in to account.

ive been looking at..

1.WO red/space/whitecat range (no flat req). 250mm

2.WO ZS61 or  ZS73 fpl-53 (plus flattener). 360mm/390mm

3.Altair 72 edf fpl-53 (deluxe cnc imaging version) plus flattener. 432mm

4. Altair Starwave 80ed-r (fpl-53 version)plus flattener. 555mm

 

Would be great to hear any recommendations from you guys using any of these scopes..or ones I’ve not though of..

Cheers

 

 

 

[wxsatuser]

Out of the four, most likely the Redcat.

Flat field, reasonably fast, widefield and a 44mm circle.

[MattJenko]

Why not a Canon 400L for that kind of focal length?

[rl]

What is the mount (and therefore the weight limit?) If it's a star adventurer you're stuck with a 5kg all-up limit.

Is this going to be unguided?

I've owned the ZS61+flattener on a SA mount and it was very good over an APS-C sensor with 60sec subs. sometimes 120s. Can't usefully comment on the rest.

[ThomasF1234]

The RedCat would be a good option or something like the Zenithstar 73 however you would need a flattener for that I think

[AntHart]

13 hours ago, MattJenko said:

Why not a Canon 400L for that kind of focal length?

I can only find used in poor condition (mpb) in 300mm, can’t find a 400mm in budget, plus I believe I’d get better glass quality in a telescope?...plus I don’t need the auto focus, extra weight etc.

Cheers

[AntHart]

12 hours ago, rl said:

What is the mount (and therefore the weight limit?) If it's a star adventurer you're stuck with a 5kg all-up limit.

Is this going to be unguided?

I've owned the ZS61+flattener on a SA mount and it was very good over an APS-C sensor with 60sec subs. sometimes 120s. Can't usefully comment on the rest.

Hi,

my mount is an eq6-pro...yes, I know it’s not a ‘portable’ mount but I’m happy carting it around  

I’d only go un guided on the RedCat up to about 90s subs, anything over that FL I’d guide.

Cheers

 

[AntHart]

10 hours ago, ThomasF1234 said:

The RedCat would be a good option or something like the Zenithstar 73 however you would need a flattener for that I think

I really like the Z73, I’d need a flattener yeah for full frame..

im surprised no one has mentioned anything about the Altair or any other brands apart from william optics.

[RayD]

I'd second the RedCat.  It's very good value for money and certainly portable.

[rl]

What do you mean by wide-field in this context? Do you have a set list of targets you're going to try? The EQ6R will carry virtually any scope you can pick up with one hand. 

Is there any mileage in looking for a scope with a built-in flattener? Looking ahead, this preserves all of your back focus for incidentals like filter wheels, flip mirrors et cetera, and this sort of scope is usually designed to cover a 44mm diameter imaging circle.. I've always likes my TS65Q for this reason. It's obsolete now but it has a 70mm successor. It's a chunky little beast but no problem for an EQ6. Of scopes affordable to most people, it is the best engineered of the ones I've seen with regard to astrophotography. The very early ones had issues with pinched optics in the cold, but that was very quickly fixed. 

 

https://www.teleskop-express.de/shop/index.php/cat/c224_Flatfield-APO-Refractor-Teleskope.html

 

RL

Edited April 30, 2020 by rl
link added

[michael8554]

Canon 6D is a great imaging DSLR, with big pixels, and low noise at high ISO, I have one.

But those big pixels make it unsuitable for shorter focal lengths.

Image scale is about 5.4arcsecs/pixel at 250mm,

In other words, seriously Undersampled, yielding coarse resolution images

2.4arcsecs/pixel at 555mm might be okay.

I use mine at 1280mm FL, which is 1arcsec/pixel, some might consider that a tad Oversampled if anything.

Michael

[AntHart]

2 hours ago, rl said:

What do you mean by wide-field in this context? Do you have a set list of targets you're going to try? The EQ6R will carry virtually any scope you can pick up with one hand. 

Is there any mileage in looking for a scope with a built-in flattener? Looking ahead, this preserves all of your back focus for incidentals like filter wheels, flip mirrors et cetera, and this sort of scope is usually designed to cover a 44mm diameter imaging circle.. I've always likes my TS65Q for this reason. It's obsolete now but it has a 70mm successor. It's a chunky little beast but no problem for an EQ6. Of scopes affordable to most people, it is the best engineered of the ones I've seen with regard to astrophotography. The very early ones had issues with pinched optics in the cold, but that was very quickly fixed. 

 

https://www.teleskop-express.de/shop/index.php/cat/c224_Flatfield-APO-Refractor-Teleskope.html

 

RL

Hi  

Basically I’m a beginner imager, I bought my mount 2nd hand a few years back, i chose to buy something heavy duty and way over the top to ‘future proof myself’ in a round about way...plus the price was too good to pass on.

Ive only ever used it with a naff cheap frac for visual and also attaching my dslr to it with lenses, all with the hand controller.

Im now looking to take a step up and look for a small telescope. The reason I use the word ‘wide field’ is because I’m told it’s the best first step - dslr with a small wide refractor.

hence I’m looking for something around 250-500mm...I know that’s a wide range in FL which will be great for certain objects and not suitable for others.

also, your comment on the flattener, its an add on item, it’s not ‘built in’ at least in the scopes I’ve looked at...I just thought it was something I’d need using full frame sensor.

Then... there is my sensor size/pixel size to consider...under and over sampling...trying to get the magic 1-2 sweet spot using the (pixel/FLx206.3) calculation...I think that’s correct..

This leaves me stuck!

With my camera (6d) that calculates to around 700- 800mm FL to be considered a good match.

I know using a shorter focal length scope (300-400mm ish) isn’t the best idea but my thinking is, I’ll still have that scope once I eventually upgrade my camera.

An astro camera is probably a bit above my level yet, especially as once I Do upgrade I’ll go the mono route and filters which is the end goal for most i imagine.

Im starting to go down the rabbit hole now!ha

Im basically just looking for my first imaging telescope to use with my 6d for now and also in the future with a dedicated Astro cam and Have a FL that’s wide enough to get those larger objects, be nice and sharp and spur me on to delve deeper in to the hobby.

Not asking for much am I! ..sorry for the long reply 👍🏼

 

 

[AntHart]

1 hour ago, michael8554 said:

Canon 6D is a great imaging DSLR, with big pixels, and low noise at high ISO, I have one.

But those big pixels make it unsuitable for shorter focal lengths.

Image scale is about 5.4arcsecs/pixel at 250mm,

In other words, seriously Undersampled, yielding coarse resolution images

2.4arcsecs/pixel at 555mm might be okay.

I use mine at 1280mm FL, which is 1arcsec/pixel, some might consider that a tad Oversampled if anything.

Michael

Hi Michael,

WOW! 1280mm...I wince at even thinking of that FL at my level..complete imaging beginner.

ive read a lot about sampling/ arc sec per pixel, not going to say I fully understand it all but I get it. 
 

Basically...my camera is great..but it’s rubbish if it’s on a small wide field refractor. 
To get the best from it my FL needs to be long...and for a beginner that’s not really the way I want to go.

Are you saying, in complete dummy terms I either need a different/dedicated Astro camera to make best use of a small wide refractor OR have to buy a long FL scope if I want to use my 6d

This is why I love this hobby!...Nothing at all is simple which is what makes it so rewarding to get a cracking image  

Cheers 

[AntHart]

1 hour ago, michael8554 said:

Canon 6D is a great imaging DSLR, with big pixels, and low noise at high ISO, I have one.

But those big pixels make it unsuitable for shorter focal lengths.

Image scale is about 5.4arcsecs/pixel at 250mm,

In other words, seriously Undersampled, yielding coarse resolution images

2.4arcsecs/pixel at 555mm might be okay.

I use mine at 1280mm FL, which is 1arcsec/pixel, some might consider that a tad Oversampled if anything.

Michael

also, I’ve seen the word ‘seeing’ being used in these calculations.

youll probably get a laugh out of this...is that more to do with sky quality (bortle) that the weather?ha! Eg would 20% seeing relate to a something like bortle 5

if that’s the case, I tend to travel to image and camp out over night, the location is a bortle 2/3. My home is a bortle 6  

Cheers...and sorry if that’s not at all what ‘seeing means’ 

[rl]

Better can be the enemy of good sometimes. The way I see it from the above posts:

• You have an extremely capable mount and the enthusiasm to carry it as a portable. It is probably the thing you're most likely to keep. I've done the same with an AZ-EQ6.
• You are prepared to guide. 
• The widefield element in the equation is only there because people say it's easier. That much is true..tracking errors are less important at shorter focal lengths. But a guider takes that issue away provided everything else is mechanically sound. .
• You have a good camera with biggish pixels. It's an excellent camera for weddings and holidays...I'm not sure how long you will be satisfied with it as an astro camera. Most people end up making the jump to something more specialised. But it will always be useful for those widefield shots where you need a 35mm sensor. And it's certainly a great start.
• For deep  sky work the  (painful) software learning curve is the same pretty much regardless of scope. You still need to learn PHD2, Autostakkert, APT, Photoshop or their alternatives. 
• Most prime focus setups are undersampled. If you're obsessing too much over this, you're looking at high-res lunar or planetry imaging with high frame rates. Seeing and tracking errors make matching the scope resolution to the pixel size a bit pointless for long exposures.

Personally I think the Redcat is a bit limiting. It's small, light and optically fast, compact and bijou, but it's only like a better camera lens. I'd love one for holidays...

The rite of passage for many people with good reason is the Skywatcher ED80. At 600mm native it's a step up in focal length..the flattener brings that down a bit. And they're always good as a second scope.

But you could go longer on that mount budget permitting..the mount would take an ED100 plus flattener if that were to suit yout target choice. That is still a portable option given you're driving.

Have a good look at the targets you wish to image. It's worthwhile doing the maths to see how they would look for various OTAs. There is only one M31 and M42...

Paralysis of analysis!

 

[wxsatuser]

Many nebulae are very large, 250mm will fit a lot with their surroundings and show them off nicely.