Choosing the next step in my setup : feedback needed

Hi Maxence,
probably, to start, you could save money and take an asi 1600 MM Pro and change your startracker with an AZGTI so you can make autoguide on both axis. With an asi 1600 and 7x36 FW you can take an adapter and use camera lens (I use a lot a Samyang 135 mm). You could think to control everything with an Asiair pro.
Vittorio

I would first add a guide cam and mini guide scope to your current setup, e.g. an ASI120mm-mini with a 32mm f/4 or similar guide scope, connected to an L-bracket on your camera. That will allow you to take much longer exposures while improving star shape.  The guide cam (and maybe scope) can be re-used on a future upgrade.   My next improvement would be to get a better mount, but one that is still portable.  The EQ6-R is just about portable as long as you don't have to carry it far to the car, but there are smaller mounts that are lighter.  Then either astro-mod your camera or, preferably move to a cooled camera. Then add filters, then auto focus.

Thank you all for your feedback ! I wasn't expecting to receive such useful and kind answers so quickly ! It's really appreciated  

To answer more specifically : 

Vittorio:
Hi Maxence,
probably, to start, you could save money and take an asi 1600 MM Pro and change your startracker with an AZGTI so you can make autoguide on both axis. With an asi 1600 and 7x36 FW you can take an adapter and use camera lens (I use a lot a Samyang 135 mm). You could think to control everything with an Asiair pro.
Vittorio

@Vittorio 
I didn't realize how much a difference existed between an alt/az and an EQ mount before your post and Lynn's. I do realize I'll need to upgrade my IOptron SGP but, for the time being, it's not high on my bucket list. I just purchased my tracker brand new less than a month ago so I don't consider switching this soon though I realize the limitation of this mount and the necessity to upgrade in the future. 
Thanks for the suggestion on the ASI1600mm pro and the adapter on a camera lens. Having a proper refractor seemed like a priority to me but what I gather from your post and the other one is that I should seek to first maximize my exposure time

Lynn K:
The Pixel size is nearly the same, so the resolution will be near same.  The larger chip of the 2600 will be very demanding of the scope's imaging circle.  More likely the WO72 doublet will not be able to achieve a flat fill to accommodate the 2600 chip.  So, more likely you will be cropping the image and wasting the more expensive 2600 chip.  The 1600 will require smaller filters, which you save you a lot.

@Lynn K 
Thanks a lot for these great points. Shooting with a full-frame sensor, I was hesitant to get the 4/3 ASI 1600MM Pro and felt more comfortable with an APS-C sensor. Nonetheless, I wasn't aware of the huge difference in filters price (which seems obvious now that you mention it). 
Nonetheless, concerning the WO72 flat fill, would this issue be solved with the WO flattener ? Because I was considering this refractor for my full-frame Sony body and if it can't accommodate an APS-C sensor, I guess it will be even worse with a full frame sensor. Vignetting is one of the main issue I'm faced with my current lens (though I think I'll need to make better flats to help) and I was hoping that the WO 72 with a flattener could solve this issue. Do you think I'm misled ?
Nonetheless, you still make more than valid point on the ASI1600MM Pro versus ASI2600MM Pro so thank you for this, I'll consider buying the first one. 

Lynn K:
I would wait on narrow band filters.  There will be little advantage using them at a Bortle 3-4 site.  A Bortle 3 site will let you do longer LRGB sub frames, which is why you will need a good tracking EQ mount.  The narrow band be be applicable at your light polluted site, and you will need a better brand than ZWO.  You will need a smaller band pass to combat the light pollution such as 6nm to 3nm

I wasn't aware that ZWO was a less reliable brand for filters so thank you for this information. To be clear, I can't imagine in my light polluted site because I have nowhere to put my rig. I have but a small terrace surrounded by very high walls so that I can only see a very small portion of the sky. So I need do drive every time I want to take picture. I'm interested in narrow band because of artistic and scientific reasons as well as the possibility to image during full moon. 

Roger Nichol:
I would first add a guide cam and mini guide scope to your current setup, e.g. an ASI120mm-mini with a 32mm f/4 or similar guide scope, connected to an L-bracket on your camera. That will allow you to take much longer exposures while improving star shape.  The guide cam (and maybe scope) can be re-used on a future upgrade.   My next improvement would be to get a better mount, but one that is still portable.  The EQ6-R is just about portable as long as you don't have to carry it far to the car, but there are smaller mounts that are lighter.  Then either astro-mod your camera or, preferably move to a cooled camera. Then add filters, then auto focus.

@Roger Nichol 

Thanks for the suggested path to improvement. I'll seek to maximize my exposure time first, with a guide cam and guide scope. The L-bracket is a really good suggestion, thank for that too. 

Patrick Graham:
This may be too basic for where you're at and I hope I haven't insulted you but for me, taking small step and working my way up to more advanced techniques really helped me.

@Patrick Graham 

There's absolutely no insult, you gave really good advice and it's much appreciated, as well as you kind words

Bottom line : I think I'll go for auto-guiding then an ASI1600MM pro (don't want to astro-mod my cam, better have a dedicated camera) and then an apochromatic refractor. I underestimated the importance of a good GEM and I want to thank you for letting me know, but as I said, I just bought my SGP and took 2 pictures with it so I'll let me outgrow it before upgrading  

Thanks again ; I hope I didn't make a faux-pas by answering to everyone in a single post, it seemed to me that it was the better option compared to flooding the discussion.

I think you are pretty close on the mark with what to start with.   I started with a DSLR and a skyguider pro.    It's a great little mount and you can get some great pics with it. I've gotten an 8 min exposure at 250mm with a redcat 51, unguided, completely by accident one time ( my computer went to sleep while the shutter was open) and had sharp stars still to my astonishment.    And if portability is what you are after that's a great start.     If you can though, try to swing a proper go to equitorial mount like an HEQ 5 or an ioptron GEM 28 or CEM 26.  For twice the cost of the SGP they are nearly as portable and wayy more capable.   DSLRs are easier to use and more versatile, but if you plan to use that A7 strictly for AP, then maybe I'd consider a one shot color dedicated cam.  But if you want to use it for other stuff too then I'd go for the A7 and upgrade later.

If anything, consider giving yourself more room to grow with a mount.  It's the most important component of your set up.   Then maybe throw in a star tracker like Move shoot move or something for portable wide field stuff for convenience.    But if you do decide on the skyguider, it's a great little mount, although I decided to get a CEM26 a couple months later, I'm still happy to own the SGP for certain applications.    Just consider what you want to do with your equipment and go from there.

If you can though, try to swing a proper go to equitorial mount like an HEQ 5 or an ioptron GEM 28 or CEM 26.  For twice the cost of the SGP they are nearly as portable and wayy more capable.   DSLRs are easier to use and more versatile, but if you plan to use that A7 strictly for AP, then maybe I'd consider a one shot color dedicated cam.  But if you want to use it for other stuff too then I'd go for the A7 and upgrade later.

If anything, consider giving yourself more room to grow with a mount.  It's the most important component of your set up.   Then maybe throw in a star tracker like Move shoot move or something for portable wide field stuff for convenience.    But if you do decide on the skyguider, it's a great little mount, although I decided to get a CEM26 a couple months later, I'm still happy to own the SGP for certain applications.    Just consider what you want to do with your equipment and go from there.

@HagglePig412 

Big thanks for the mounts suggested, I took a look at the IOptron GEM28/CEM26 and it's exactly the kind of mount I wished I knew existed earlier haha
I first got into astrophoto by stacking ten of hundreds of very short exposure pictures (1sec @ 200mm) and I bought the SkyGuider Pro because the process was way too annoying for too little result. At this time, I didn't know the difference between a star tracker and a proper mount and, furthermore, wasn't quite sure if I would like astrophoto. So the SGP seemed like the most reasonnable option to me. 
Reading all the great suggestions in this discussion, I now realize the importance of a proper mount and know that I will have to upgrade to something like the GEM28 in the future. For now, since the SkyguiderPro is already bought and I have fun with it, I'll will keep using it and learn with it until I outgrow it   

Olaf Fritsche:
A weak part of your equipment might be your lens. I tried several telephoto zoom lenses and none delivered satisfying results. A fixed focus lens was much better for me (CANON EF 200mm F2.8L II USM). Maybe the Zenithstar or a space cat would be a good next step. 

The Zwo ASIair Pro is one of the gears I love. But to take advantage of it, you should use a dedicated astro camera. So ist would be an expensive double step. If you can afford it, then go for it.

As for the camera, I use a ZWO ASI294MM Pro. It's the successor of the 1600 and it's improved pretty much. But it is a mono camera, so you would need a filter wheel and some filters. I do not understand any bad statements regarding the filters of ZWO. They are not as expansive as the filters of other brands, and you can find a lot of great pictures taken with these filters. Either way: To buy a mono camera + a filter wheel + a set of filters is a big financial step. Maybe for you a colour camera would be a reasonable choice?

@Olaf Fritsche 

Yeah, I do feel like my lens is a weak part of my current equipment. It's not the fastest lens out there and while it's sharp enough, the zoom factor is really suboptimal for astrophoto. 

You're right about the ZWO ASIAIR Pro, after some consideration and a lot of reading, I've installed N.I.N.A to try with my camera next time the skies are clear then I'll probably get me a ZWO ASI120MM-mini guide camera and the 30mm f/4 guide scope to guide through PHD2. Depending on how long my exposure are with this setup and how faint nebulosity are captured with my undmodded cam, I'll see what the next logical steps are. If I feel I'm more limited by the cam factor, I'll probably buy a dedicated astrocam (thanks for the ASI294MM Pro, it looks indeed more promising than the 1600MM !) and if it's the lens, I'll get me a small refractor. I know that the mono camera, filter wheel and filters is a big financial step but shooting mono with filters is way more appealing to me than using a color camera  

Thanks again for all the feedback and food for thoughts ! I apologize for the time I took to answer but the posts in this thread really got me thinking and I did a lot of personal research on your suggestions and pondered over my own goal in astrophoto  
Again, the support and quality of feedback is really appreciated !

Don't worry, you'll still get great images with your skyguider,. They track very accurately if you are balanced well, it just might take a few tries to frame things up with test exposures. Here's a few tips.
​​​​​​1. take time to get your polar alignment right. After you put on your declination bracket, if your rig is heavy enough to need it, check it again and fine tune it.

2. Get an autoguider.  They work great on an SGP.  You should be able to get at least 2 min subs unguided up to 300mm but an autoguider will let you stretch that to 5 or 6 mins maybe better. They will also let you use scopes up to around 70mm for several mins, and you can use sharp cap with them to really nail your polar alignment.  Then when you upgrade to a better mount, you can use it on that.  I use a ZWO 120mini mono and an SVbony 30mm guide scope.  200$ all together.   

3. Balance slightly east heavy. Especially when guiding.  It let's the gears mesh and prevents them from floating and blurring your stars.

All in all it's a great little mount and will let you take some great wide field shots. With proper balance and guiding, you should be able to get close to the 11 lb payload capacity and still get good sub exposure times.   I really like my SGP and you will too.  The alt az base kinda sucks, but it's certainly useable.  If your PA moves after you tighten everything down, you can still make some fine adjustment with it all snug.

Hi Maxence,
i didnt read through all responses, since i'm a bit in a hurry.
But i started with the same Tamron lens, and i think the performance of this lens is rather poor. At least mine is.
The stars were unround just halfway to the corners with APS-C, it has only f/5.6 at high magnification, and the zoom used to change independently, as soon as i aimed more towards zenith.

Maybe you could think about getting a fast lens with fixed focal length, like a Samyang 135, which gives pinpoint stars. I think apart of this, your actual setup is an easy-travel everywhere setup, which you'll still use when you own a mount with telescope and dedicated camera.

CS Hoschie