4 replies to this topic

[AstroLabrium]

Hello everyone,

 

My name is Erasmo, I’m from Botucatu, São Paulo, Brazil. My house sits at 838 meters elevation, in a region classified as Bortle 5, with SQM readings around 19.5.

 

I observe from my backyard, which is shielded from direct streetlight thanks to high walls. The horizon is limited because of this, but I don’t have tall buildings around, and the altitude helps a bit with sky quality.

 

My current setup:

 

• GSO Newtonian 150mm f/5
• Mount: Bresser EXOS-2 / EQ5 with OnStep GOTO
• Eyepieces: SVBONY Plössl 25mm, SWA 9mm, Ultra Wide 6mm
• Barlow 2x
• Filters: UHC and Lunar
• Camera (for now): Smartphone Galaxy A55

 

I plan to buy the ZWO ASI585MC PRO for deep sky imaging, and later I’ll add autoguiding for long exposures.

 

Right now I’m researching guidescopes and guide cameras. I’ve seen many setups using either the ZWO 30f4 or SVBONY 50mm f/4 combined with the ASI120MM Mini.

 

Given my current setup and mount, which combo would you recommend for stable autoguiding?

Is the ASI120MM Mini still a solid choice in 2025, or are there better or cheaper alternatives now?

 

Also — for a Bortle 5 suburban backyard like mine — do you consider any filter essential besides UHC and lunar, especially for nebulae and galaxies?

 

I appreciate any suggestions and would love to hear from others shooting under suburban skies!

 

Thanks,

Erasmo

Edited by AstroLabrium, 17 April 2025 - 02:34 PM.

[fmendes]

Hey Erasmo, fellow brazilian here, although living abroad.

 

I'd go with the 50mm guidescope. In my experience, the 30mm is too short, although a lot of people use it. All my guidescopes are 50mm.

 

About the camera, I use for many years the 120MM mini, and it is a good match for the 50mm guidescope. Recently I've been testing the Ogma GP662C that was selling for a good price but seems to be out of stock. That could work a bit better with a shorter guidescope due to the higher resolution. Note that this is a color camera - not a problem, but will perform slightly different than a mono camera. 

 

Filters: with Bortle 5, you can get good images with a simple IR/UV filter, or maybe a broadband such as Optolong L-pro, Orion SkyGlow Imaging (5561, the one I use) or others. This will allow you to image galaxies, reflection and dark nebulae. For emission nebulae, you may use your UHC (make sure it is designed for imaging, not visual, they are different) or a narrow band filter such as Optolong L-eNHance or similar. These filters sometimes go on sale on AliExpress, keep an eye open.

 

Cameras: unless you have a good reason to use ZWO (such as AsiAir), there are cheaper options. Touptek cameras are on the market for a while, and they work fine. The Ogma I mentioned above is a Touptek with different colors and firmware.

 

Finally, there's a photography forum in Portuguese: https://forum.fotografos.online/ and I'm trying to gather more astrophotographers who speak Portuguese. If you're interested, take a look!

[AstroLabrium]

Hi Felipe,

 

Great to see another Brazilian here — even living abroad!

 

Thanks a lot for your detailed reply. I was already feeling that the 30mm guidescope might be too short, and it’s good to hear your real-world experience confirming that. I’ll probably go for the 50mm based on your advice.

 

As for the ASI120MM Mini, it’s great to know it still holds up in 2025, even with all the new options on the market. I hadn’t heard about the Ogma GP662C before — even if it’s sold out, I’ll research it for future reference. Sounds like an interesting alternative.

 

Your filter suggestions were also super helpful. I hadn’t seriously considered a broadband filter like the L-Pro for galaxies and dark nebulae from a Bortle 5 sky, and about the UHC I currently own — I suspect it’s designed for visual, not imaging. I’ll double-check that to avoid using it wrong.

 

I’ll definitely take a look at the Portuguese photography forum you mentioned. I’m still building my network in this hobby, so it will be great to connect with more astrophotographers in our language.

 

Thanks again for your warm and helpful reply!

 

Clear skies,
Erasmo

[Dan_I]

   Hello,

 

welcome to CN Erasmo !

 

IMHO don't spend money yet on an L-pro filter or similar. The benefit of using such filter for broadband objects like galaxies is controversial. Besides throwing out some useful signal, it will disturb deeply the color balance. 

 

Personnaly I image under Bortle 7 without any light-pollution filter and I get satisfactory results. Dealing with gradients and color casts is easy nowadays with the recent software tools.

Edited by Dan_I, 17 April 2025 - 04:22 PM.

[AstroLabrium]

Hi Dan,

 

Thanks again for your reply — your point about filters and modern software really made me reflect!

 

Unfortunately, the sky hasn’t been very cooperative here lately — lots of clouds and rain in my city. Even for planetary observation, at the moment only Mars is decently placed in the sky.

 

The last time I managed to observe was with Jupiter, and I was only using my 25mm and 9mm eyepieces (without the Barlow). Despite Jupiter being relatively low on the horizon that night, I could clearly see the four Galilean moons, and even distinguish the main cloud bands — although they looked more like subtle grayish streaks against the bright 6500K-like white disk, almost like a sharp LED bulb.

 

That observation left me wondering: perhaps the Bortle 5 classification applies more to the region around my city, but from my own backyard, at least on that night, the sky seemed more favorable than I expected. I took that as a positive sign for future deep sky attempts!

 

Thanks for sharing your experience and for the advice on focusing more on image processing rather than filters early on. I’ll definitely take that to heart.

 

Clear skies!
Erasmo