A Wratten 38A or even #47 (Violet) can be good for a very bright Venus even with a small aperture.



I think they're at their closest and most visible at 06:30 BST 05/10/17 (Thursday) for me.



I can't see detail on Venus with anything less than 130mm, and even then I find it much easier on a setting twilight Venus. Mars isn't going to be more than a red dot until opposition. I think I may try the bino's with this conjunction if the weather lets me.

 

Venus can be overbearingly bright, even in twilight. Try the highest magnification you reasonably can, that will cut down some glare. You should be able to see the phase anyway.

 

Well, the rule of thumb lunar limit for your scope (60x per inch) would be 138x, so 133x could work. You aren't really looking for detail on Venus and Mars yet really anyway, so just getting them big enough to kill some glare and see the phase should be enough.

What does the Moon look like at 133x with your scope? If the image is pretty good it should work on a twilight Venus and Mars.

 

I figured you were kidding about the Barlow lol. Although, a Barlow element threaded directly into the 10mm SvBony Aspheric technically turns it into a 6.25mm.



I've done this with a 10mm Luminos to give 208x on my 102mm Mak. Venus should reach a declination of at least 5° for you at around 06:50 on Thursday and still be visible. If I can I'll use my 102mm Mak with the Vixen mount as it's more easily moved to my top lawn for better low altitude eastern views. I'm itching to test new eyepieces in the binoviewers.

 

Yeah, it's amazing how you can move just a few metres and see something you thought was hitherto hidden. It's fun to watch Venus's phase change over time. You can see the phase even at low magnifications but the higher the magnification, the less the glare. I bet it was moving pretty quickly lol. I'm looking forward to the Mars opposition as I plan to use bigger scopes to view it next year. I have some interesting filters for it. Last year the #82A revealed the northern polar cap really nicely. Mars has to be within half an AU to be anything other than a red dot. It is 0.718 AU at the moment and counting. I'm glad you had a good session.

 

The Celestron Omni and T-adapter Barlows have removable Barlow elements.

http://agenaastro.com/celestron-1-25-universal-t-adapter-2x-barlow-93640.html



http://agenaastro.com/celestron-1-25-2x-omni-barlow-lens.html

 

I have a 235mm SCT and I'm getting a GSO 150mm, f/6 Newtonian OTA for my EQ5. My disability precluded my using the SCT on Mars last year, but I've made a lot of progress in physiotherapy this year. I think Dob's are OK for fast, low power. But for high magnification, if you don't have a GOTO you're going to need an EQ with slo mo at least.

 

I forgot about this site, can take a while to load, and I can't open in Maxthon screen now, but it's fun.

https://www.solarsystemscope.com/

 

Friday's looking better weather wise. 06:30 BST. Altitude 12.9 ~ 13°. Venus is 0.718 AU. I was wrong earlier, Mars is actually 1.66 AU from Earth. I thought 0.7 sounded a tad close lol. Mars has to be about half an AU away, or 75 million kilometres, to see any surface detail.

 

You just won't see any detail until it's basically at opposition. Mars is quite small really, I mean you'd notice it if it fell in your backyard lol, but it's much smaller than the gas giants. As a consequence you can't really see detail like Jupiter or Saturn. Viewing Mars at about 200x is a bit like looking at the Full Moon unaided. You can see certain features and with prolonged observation sessions eventually you will recognise many of them. Syrtis Major can often be easily identified and was the first thing to be properly observed on Mars I think. It always fascinates me that the overall seeing can be very good, but the transparency can let it down, or even vice versa.

https://en.wikipedia.org/wiki/Antoniadi_scale

I was observing the Moon for a bit this morning with an f/11, 90mm Omegon Mak for 25x with a 40mm SvBony Plossl, I've modified it a bit (changed the eyeguard & drawtube). As the Moon was virtually full (Harvest Moon) and there was a lot of 50 kph cloud passing I thought I'd keep magnifications to around 25x and 40x. The Omegon's not so sharp much above 50x anyway.



But I'm starting to like it. Eye relief and placement seem quite good compared to larger 40mm Plossls.



It's not bad for the money. I think the coating is basic, and the field stop is small, but after a tiny bit of customising it's looking like a keeper.