Hi guys. In the next few months I'll move my setup in a remote hosting astrofarm here in Italy. At the beginning I thought of installing my FRA 400 with the 10micron GM1000, to have greater ease of use and to become familiar with remote imaging. Now, however, I'm thinking of optimizing the setup by adding a second OTA with a longer focal length, also considering that I still have quite a bit of load capacity available. The optics will be used independently, either one or the other depending on the target. I would be thinking of an Askar 107 PHQ or 120 APO with a 294mm. However I have to study an effective way to install the setup. So, in your experience, is it better to place OTAs side by side or place them one on top of the other? In the first case the center of gravity would be lower but it would be more difficult to balance the Dec axis, in the second case I would have a higher center of gravity but easier balancing. Obviously the flexions will have to be minimal to be able to use the GM1000 effectively, so I'm thinking of personally building all the necessary plates and supports directly in my workshop.
Dual setup: side-by-side vs one-on-top
Well Written Insightful Respectful Engaging
Where to, If I may ask? Regarding the dual setup I have used both and both can work quite well, all depends on the sturdiness of the arrangements. A side by side plate offer potentially the better stiffness at a price of higher mass (but at a lower radius). If being co-axial isn't a requisite then I'd tend to prefer the side by side arrangement and even more so if the two scopes are of comparable girth. If there is significant difference then a vertical stack-up is to be preferable as the size of the plate needs to be significantly larger. One thing to be concern in case of side-by-side is potential shading by the outbuilding in some positions for the scope sitting at the longer arm. I disagree that a side-by-side configuration is more difficult to balance in Dec, if anything it makes it easier.
Helpful
Thank you for your answer Andrea. I'll move the setup in Manciano, at DeepLab, as soon as the new 4-position box is ready. The OTAs will be of significantly different mass, the FRA 400 weighs around 4 kg while the 107 is around 10 kg. I can overcome the weight difference by moving the Pegasus Power Box towards the FRA 400, but the difference is still notable. However, I don't understand how a side-by-side setup can be easier to balance in DEC: by placing the axis horizontally and the optics at the zenith, the DEC axis should rotate bringing the heavier OTA downwards. Or at least, that's what I imagine. To balance I would have to bring the heavier OTA closer to the axis of the mount, but this requires an additional clamp that allows me to slide the coupling bar of the two OTAs horizontally.
Well Written Insightful Respectful
Leonardo Landi:
To balance I would have to bring the heavier OTA closer to the axis of the mount, but this requires an additional clamp that allows me to slide the coupling bar of the two OTAs horizontally.
*I'm not sure I get it. The typical side-by-side bar has two clamps and you shift the whole assembly within the mount's head clamp, sideways.
I used both, to be fair I would use one or the other depending on the case. in your case side by side looks pretty obvious as the difference in size and weight doesn't seem to be so huge. I would recommend a TGAD if you plan using both scope at the time with the same framing. otherwise you will lose a lot of time with shims into the dovetail.
I actually piggyback my Samyang 135 and 533MM on my FSQ and I suspect some flexure as I have weird star shape. but I use a 3d printed bracket.
My 2 cents haha
I actually piggyback my Samyang 135 and 533MM on my FSQ and I suspect some flexure as I have weird star shape. but I use a 3d printed bracket.
My 2 cents haha
Leonardo Landi:
Hi guys. In the next few months I'll move my setup in a remote hosting astrofarm here in Italy. At the beginning I thought of installing my FRA 400 with the 10micron GM1000, to have greater ease of use and to become familiar with remote imaging. Now, however, I'm thinking of optimizing the setup by adding a second OTA with a longer focal length, also considering that I still have quite a bit of load capacity available. The optics will be used independently, either one or the other depending on the target. I would be thinking of an Askar 107 PHQ or 120 APO with a 294mm. However I have to study an effective way to install the setup. So, in your experience, is it better to place OTAs side by side or place them one on top of the other? In the first case the center of gravity would be lower but it would be more difficult to balance the Dec axis, in the second case I would have a higher center of gravity but easier balancing. Obviously the flexions will have to be minimal to be able to use the GM1000 effectively, so I'm thinking of personally building all the necessary plates and supports directly in my workshop.
I'm not a huge fan of multiple OTAs on a single mount but if that's what you want to do, side by side is ALWAYs mechanically better. I've discussed the reasons in multiple talks--most recently at AIC in 2022: https://www.adamblockstudios.com/articles/secrets-long-focal-length-imaging-john-hayes.
John
I clearly vote for side by side, because of:
1. there are no rings on the market, which have the sturdiness required and have also an acceptable weight.
2. you can use a 4" mounting dove tail on a 10M, which provides the required robustness. 3" is clearly not sufficient.
3. alignment is much easier. See image below...
4. you can use one model for booth. Piggy-back you will need 2 due to flexure. Tested with 80mm@480...no chance to get that performing.
5. piggy back increases the inertia unacceptably
6. the high slew-rate of a 10M will extremely stress a piggy-back construction
7. settle time increases dramatically. The system will swing.
8. More ware-off due to to inertia
9. More counterweight is needed (more stress for the mount)
10. balancing is much easier
... and many more
To put it bluntly: Piggy-back is a no-no on a 10M. You degrade the performance massively.
Here an example, why a serious setup piggy-back makes little sense. This is my setup CDK14 and a TEC140 on a GM2000 on a 4" carrier dove tail.
1. there are no rings on the market, which have the sturdiness required and have also an acceptable weight.
2. you can use a 4" mounting dove tail on a 10M, which provides the required robustness. 3" is clearly not sufficient.
3. alignment is much easier. See image below...
4. you can use one model for booth. Piggy-back you will need 2 due to flexure. Tested with 80mm@480...no chance to get that performing.
5. piggy back increases the inertia unacceptably
6. the high slew-rate of a 10M will extremely stress a piggy-back construction
7. settle time increases dramatically. The system will swing.
8. More ware-off due to to inertia
9. More counterweight is needed (more stress for the mount)
10. balancing is much easier
... and many more
To put it bluntly: Piggy-back is a no-no on a 10M. You degrade the performance massively.
Here an example, why a serious setup piggy-back makes little sense. This is my setup CDK14 and a TEC140 on a GM2000 on a 4" carrier dove tail.
Helpful
Ruediger:
I clearly vote for side by side, because of:
1. there are no rings on the market, which have the sturdiness required and have also an acceptable weight.
2. you can use a 4" mounting dove tail on a 10M, which provides the required robustness. 3" is clearly not sufficient.
3. alignment is much easier. See image below...
4. you can use one model for booth. Piggy-back you will need 2 due to flexure. Tested with 80mm@480...no chance to get that performing.
5. piggy back increases the inertia unacceptably
6. the high slew-rate of a 10M will extremely stress a piggy-back construction
7. settle time increases dramatically. The system will swing.
8. More ware-off due to to inertia
9. More counterweight is needed (more stress for the mount)
10. balancing is much easier
... and many more
To put it bluntly: Piggy-back is a no-no on a 10M. You degrade the performance massively.
Here an example, why a serious setup piggy-back makes little sense. This is my setup CDK14 and a TEC140 on a GM2000 on a 4" carrier dove tail.
*It's a bloody FRA 400, not even 3 kgs all told, he could put at the end of a stick and it will still work...
*It's a bloody FRA 400, not even 3 kgs all told, he could put at the end of a stick and it will still work...
It wont - tried with TS80-480 which is of the same size category. Even with rock solid rings always flexure.
Well, try better because it works for me and it is even heavier.
andrea tasselli:
Well, try better because it works for me and it is even heavier.
Congratulations it is working for your specific setup. But to conclude, it must work also in general, with other setups, especially an unguided 10M, is more than ambitious. If your results are good for you - perfectly fine! But I was not satisfied, I have tried harder and made my experience and improved it. That simple and no need to "motivate" me.
The OP is using a 10M and goes probably unguided. Working with 10M and their models has nothing in common with other mounts. What your setup compensates with OAG guiding cannot be transferred to a 10M setup. e.g. thermal expansion of the rings play a role, which gets more complex when you stack scopes.
Basically, the OP was asking for experiences and advice. That was given. He can decide what he is going to do. Period.