Astro Buer

Thanks @tomato. I think you're right in saying it will be OK. I'm going to roll with it for now... It just seemed a little strange for it to be racked out this far when the spacing is (almost) correct. But as you say, autofocus routines do not move the focuser very much. 

Thanks fro your reply! 

Hi! 

I recently purchased an Esprit 120ED which I am using in conjunction with a ZWO ASI1600.

According to the manual the Flattener requires 75mm of back focus. I have Astrodon Filters that are 3mm - so adding 1mm to the spacing requirement means I need 76mm - So 77mm was the closest I could get for a first test.  I am achieving this by using the following:

Flattener ---- Extender Tube (comes with scope) 21mm ----- OAG 16.5mm ----- 11mm spacer ----- 2mm Spacer ----- EFW Filter Wheel 20mm ----- 6.5mm distance to sensor = 77mm

Here are some images from the manual and my setup (sorry for the rubbish photo, I don't have callipers!) 

When using this setup I have to rack the focuser pretty much all the way out to achieve focus? up to around 7.5 on the focuser scale - which goes up to 9. I don't like the idea of the focuser being racked out this much. I'm also worried that when I use autofocus, as we know sometimes there are problems! if the focuser goes searching for a new position it might hit the end of the draw tube thus potentially causing damage. The theory suggests adding more space would reduce the overall draw, but this goes against the spacing measurement required. 

Do I need a different adaptor to connect the imaging train to the flattener. Something like this?

https://www.firstlightoptics.com/adapters/astro-essentials-m48-to-t2-adapter.html

I know some people might say 'well, you can achieve focus so that's all that matters' but it doesn't seem right that the focuser needs to be racked this far out, especially if the spacing is correct.

Any advice welcome.

Another advantage of an OAG, is you should not have any differential flexure (which @rickwayne nodded to when he mentioned rigidity) 

Differential flexure is when parts of the imaging system shift, when others do not. This can lead to unreliable guiding. 

IMHO, an OAG is worth the hassle. You can also buy a helical focuser (if you go down the ZWO route) to make setting up easier. 

https://www.firstlightoptics.com/zwo-accessories/zwo-125-helical-focuser.html

Tenerife is a very good choice. It’s extremely accessible as you can drive up to the base of Teide at 2,200m to be above the clouds. There are also a lot of parking bays up there which makes setting up a breeze. Bang for buck it’s an excellent astro holiday. 

As for other things to do on the island, you’d be surprised what you can find when you head away from the main tourist areas. 

Another option is La Palma, which in my opinion is more dramatic with the views over the Caldera, and it’s a touch darker than Tenerife, but not a deal breaker by any means. The most structure I have ever seen in the central core Milky Way (from the northern hemisphere) was from Tenerife last June. The only problem with La Palma is there are not as many accessible spots at the top in which to set up. But that’s not to say there aren’t any... once I bumped into a gentlemen nestled into a nook precariously on the side of the caldera with his dob he’d ferried all the way from Holland...! Anything is possible. 

With the Canaries, if you want ease, Tenerife is best. If you want a little bit of extra drama, go La Palma

On 19/12/2018 at 01:15, Andyb90 said:

You need to be a bit careful when unscrewing nut 2 shown in the photo below. It is the inner nut and is behind an inner ring (highlighted in Blue on the photo). You wouldn't want to knock that ring as any damage could affect star shape. It's not high risk you just need to ease the nut loose. I used this Draper socket set to get over that ring and loosen the bolt.

https://www.drapertools.com/product/16442/1-4inch-Sq-Dr-Metric-Socket-Set-(20-Piece)

The ratchet is just the right size. Any similar set would work.

You've probably seen in the earlier posts, but just in case you missed it the mounting foot has rubber stuck to it. That peels off to reveal 4 screws. Undo them and you can get to the 2 screw heads to hold them in place whilst you undo the nuts within the OTA.

One other thing. I tilted the OTA to one side and this helped the inner nut stay within the ratchet head once released from the screw. Just avoids any risk of the nut falling into the OTA.

Andy.

Thank you for your detailed account. Very much appreciated!! 

3 hours ago, Jkulin said:

Yep just rotate the "Captains Wheel" and it will separate.

Its not rocket science and really is very simple.

Thank you! Much appreciated ?

Sorry to bump and old(ish) thread here, but I have a very newbie question.

Before I start tugging and pulling at my beloved Esprit; how do you actually remove the focuser from the OTA? I’ve looked online but cannot fine the answer.

Is it simply a case of spinning back the captains wheel and the focuser detaches? Is there anything else I should be aware of/risks of this mod?

Sorry again for such a noob question. Just want to make sure I approach this the right way, first time. 

On 27/12/2017 at 10:54, MattJenko said:

Missed this thread till now. Shame on me. Some awesome work being done with this little mount.

I have not had my SA out for a while after a house move, but here are some of the images managed over the last 18 months with it, all unguided with both scope setup and a Canon 450d/50mm lens. Also showing off the mono rig on a Berlebach tripod to keep the whole thing low and out of the wind.

 

Wonderful images! May I ask what is the little dovetail clamp you have to attach the scope to the SA? 

10 minutes ago, Victor Boesen said:

Amazing photo! What tripod did you use it with? It must have been a beefy one to be able to carry the weight of the WO?

Thanks Victor!

I was using a carbon fibre tripod (Eddie - Three Legged Thing) but I have a rock bag that attaches to the three legs, which I weigh down with four bricks. I've also used a few very large bottle of water as well which seems to work well.

It's not ideal but I've found it a good, cheap way to add more stability  

It's a great little bit of kit, and has an ST4 port which means you can guide (albeit only in RA) but better that than nothing!

I've only been shooting deep sky for 2 months, but this was my first image captured with the SA and although it has plenty of processing problems, I was quite happy with it for my first go! 

120x19 Lights / 15 Darks / 15 Flats / 30 Bias

WO ZS61 / Sony A7S / Guided with PHD

I would not hesitate to recommend it, it's a great little bit of kit to throw in the back of the car (ok, don't throw it in the back of the car) to drive out to those darker skies if, like me, you live under a permanent orange glow... 

On 19/10/2017 at 20:18, AdamT said:

Have you got any pics of it all set up with the guide scope?

Sorry it's taken me a little while to get this image up! Here's the setup with the guide scope attached.

This is with the clutch open so it's well balanced  

On 18/10/2017 at 15:02, happy-kat said:

If you have the sony a7s from what I've seen don't update the firmware, you'll lose any benefit on long exposure imaging. Sony and their infamous star eating issue on exposures over 30 seconds.

Funnily enough I have never updated the firmware on my A7S. I'm still on v1.10.

Does this mean I don't have the dreaded star eater algorithm? I was under the impression it affected all the cameras from day dot. I wasn't aware it was 'introduced' in a later firmware update? I'd like to be wrong about this one... ! 

On 18/10/2017 at 14:40, agthomson said:

A bit late to the party, so you may already have everything in place, but you're right in that you'll need the M48 to T2 adapter plus the T2 to Sony E adapter. What I found through this setup was that my overall spacing from lens to sensor was too long by just over 12mm. Spacing sees very important on this setup. With my mirrorless A6000 I had to replace the end part of the Flat61 (essentially a 20mm extension tube) with a 7.5mm piece to get the right distance. I can swap this out for a LP filter if required.

The ZS61 plus the Star Adventurer seems like a great combo that does allow for future guiding if you require slightly longer exposures, but given you're on Sony you may be limiting them anyways.

Thanks for the input. I am indeed all 'in place'. Scope arrived last week, now just need some clear skies for testing! 

It balances great on the SA with the Orion Guidescope. Just the right size and focal length for a beginner like me and a great grab and go setup (decent skies are an hours drive for me) Thanks for everyone's input  

On 11/10/2017 at 22:30, AdamT said:

This is what I managed with a WO ZS61 & a full frame nikon D810 on the star adventure, not a great image i know but it will give you some idea of what you can expect regards field flatness you would be better off leaving your sony in full frame mode and crop later if required. 

Great image Adam  

38 minutes ago, fireballxl5 said:

shout out for the versatility of the light-weight Tak FS60CB system - some images for your consideration at 252mm (reducer @ f4.2), 366mm (flattener @ f6.1) and 610mm (1.7x extender with flattener ~f10). Admittedly used on an AstroTrac rather than the SA...any excuse to post some of my photos 

HTH, Andy

 

Antares & Rho Oph @ F4.2

NA and Pelican @ F6.1

M20 @ F10

Sun & Moon @ F10

Thanks Andy! Fantastic pics!!  

1 hour ago, ollypenrice said:

I would look at it this way: the mount has a maximum payload and a maximum tracking accuracy. Both, not just one, have to be respected. Payload is obviously easy - you just weigh what you are putting on the mount. Accuracy is more difficult. The unit that matters is resolution measured in arcseconds per pixel. This value is derived from focal length and pixel size, so focal length alone is not a useful term. (Long focal length with big pixels equals short focal length with small pixels in terms of resolution, stating it simply.)

I think that the best information will come from published images in which the user states what camera, at what focal length, was being used. To turn this into arcseconds per pixel you can use a number of online calculators such as this one: http://www.12dstring.me.uk/fovcalc.php

Olly

Thanks again Olly. Very much appreciated 

1 hour ago, ollypenrice said:

The idea that focal length and chip size are related is an error imported from the daytime camera world via something called 'crop factor.' I would ignore all this completely. It is utterly meaningless. Keep it nice and simple in astrophotography and you won't go wrong. You have a focal length, determined by your scope's optics. This is a simple and non-negotiable fact. You have a chip size of x by y, also non negotiable. Then you have your pixel size, which (allied to you focal length) specifies your resolution in arcseconds per pixel. Your chip size simply speciifies how much sky you cover. It has absolutely no effect whatever on your resolution. (That derives from focal length and pixel size. The number of pixels you have is also irrelevant.)

Olly

Edit: Crossed with Adam J but we are saying the same things.

Really appreciate your input and explanation Olly. Very insightful and good to know! Thanks for your knowledge  its so very helpful to get me on the right track. 

1 hour ago, Adam J said:

Changing to a crop frame mode from full frame will not increase your focal length, it will only reduce your field of view, the focal length stays the same. However using it in APS-C mode is probably a good idea anyway as the ZS61 is not going to fully illuminate and give you a flat frame over a full frame sensor.

The resolution will stay the same as that is governed by focal length and the pixel size, always think about arcseconds / pixel and take a look at the BBC Sky at night Field of View Calculator. The large pixels of the A7S are probably not the best match for such a short focal length and may make the stars look a little square? But to be honest its still a great camera for astro work.

Thank you, that's a great insight and I obviously have a lot of reading to do! 

2 minutes ago, Adam J said:

The ZS61 has better optics than the TS scope i posted so if you are not bothered by the shorter focal length then go for the WO ZS61 I would do. I only noted the other scope due to you wanting over 400mm of focal length. The main difference is that the ZS61 uses FPL-53 glass so the color correction will be much better.

Yes, well I had a thought earlier today that I can put my cameras in APS-C mode which when using the WO ZS61 would give me a focal length of 540mm, should I want to experiment with that... albeit at a loss of resolution. But I also have an A7R 1 and 2 (un-modded) which have much larger sensors and if I can shoot using a lower ISO (if I can get the tracking working well for longer subs) will still give me a decent resolution image to work with.

It's all just a learning curve for me, and if I can get good success by using shorter focal lengths before potentially moving on to more advanced setups and longer focal lengths, then that is a good thing for my confidence  

3 hours ago, AdamT said:

I would recommend getting the flat 61 with a full frame or APS-c. I also had to get an M48 DLSR adaptor as the spacing is critical, You may need an additional spacer if you sony is mirrorless. Its a great little scope not sure id want to go any longer on the SA, but i haven't guided on it yet and if i was going to do it i may as well get the AZ-EQ6 out, saying that i have seen a few people getting good results using 400mm lenses and guiding the RA to limit the PEC.

Also worth mentioning that you can screw a 2" light pollution filter in the flattener and its got a nice built in rotator, everything screws together so no compression rings with is also a nice touch. 

I have to say I am leaning towards the WO ZS61. Good optics and a good focal length for a modest mount like the Star Adventurer. You're right I would need a few adaptors to connect my A7S to the flattener. An M48 to T2, then an E Mount to T2 adaptor as well if my research is correct? 

http://www.365astronomy.com/Adapter-from-M48-2-inch-filter-thread-to-T2-Low-Profile.html

and

http://www.365astronomy.com/365Astronomy-T-Ring-SONY-Alpha-E-Mount-Nex-T2-Lens-Adapter-Ring.html

I already have an Astronomik CLS filter clipped into my A7S, so hoping this will do the trick.

I am so close to pulling the trigger on this...

Thanks for all your advice. The SGL community is awesome  

6 hours ago, Adam J said:

huum thats odd I see it listed as only 2.1kg for the OTA only? I have never been too sure about guiding on a star adventurer to be honest I am not sure how well guiding will work in RA only. My friend does not guide his setup so I cant comment on how well it copes once you add the weight of a guide camera. He uses a 1100D so its fine for 2 min subs with the camera / flatter / OTA.  Maybe with one of those 30mm QHY guide scope packages???

Yes, my bad. I was looking at the weight at the very top of the listing which makes it a little confusing...! I don't expect hubble-esque results with the Star Adventurer and guiding! but I feel it is going to be a good way to at learn, and the guiding equipment can be used on better scopes and mounts should I upgrade in the future. 

Thanks for your help! 

Baby steps  

20 minutes ago, artem said:

Hello Astro Buer, I actually have this small piece of biest  and it is a light machine F4.9, beside many others factors but one main reason did make me buy this APO!  the fact that you must not play around with millimeter adapters to find or reach the perfect focus "a 5 element flat field APO", all you need to do is attach your CCD & EOS or NIKON to the APO and focus with a BAHTINOV MASK until you have the perfect star and you are done.. the Focuser can handle heavy CCD also " I use SBIG ST10XME + FW " is a heavy piece of CCD but also use a CANON 600D-a..

Cheers

Martin

 

Thanks for the advice Martin! And yes, good to know about the focussing... anything to make life easier given that AP is a fairly steep learning curve! 

Thanks again!  

8 hours ago, Adam J said:

I know someone who uses this scope to great effect on the Star Adventurer:

http://www.365astronomy.com/TS-INED-APO-70-420mm-Carbon-Fiber-Tube-2-Micro-Crayford-Focuser.html

I think that a ZS61 is also a great choice though at a little shorter focal length.

Thanks Adam J! At 3.4kg I thought that might be tipping the scales a little with the guidecam on there as well. But maybe I'm being a little too cautious as to not overload the mount... but as it's been a success for your friend that's encouraging for me. 

Looks like a lovely little scope at a good price! Thanks for your advice! I really appreciate it  

10 hours ago, Scooot said:

I don't think you lose aperture when extending but maybe I'm mistaken? The extender inserts into the OTA and increases the focal length from 355mm to 600mm. I do use the tak field flattener but I'm not an experienced imager so not qualified to advise I'm afraid. I also use it with the extender although I must confess I'm not sure whether I should or not. Most of my imaging has been of the moon wth it. I bought it from Ian King who I'm sure would give good advice if you were interested. Its a very versatile setup, I've been considering on and off getting the 76mm objective upgrade at some point as well. So it can be converted to a 76mm refractor although I'm not sure the Sky Adventurer would be able to handle that.

On the negative side I have read comments that the blue signal is not quite right, or maybe as good as it should be, for deep Sky imaging. I think it was Olly that pointed this out.

Sorry, I think I'm getting my terminology mixed up regarding apertures! (Thinking in DSLR world!) Thanks for your honest review  definitely given me food for thought. 

1 hour ago, AdamT said:

A little under 400mm but have you considered a WO ZS61.

Thanks for your reply AdamT! what a lovely compact little setup (I'm a bit of a sucker for the WO product line I'll admit) are there any accessories you would recommend with this scope? 

Looks fantastic though, as all the replies have been so far. 

Thanks so much