My attempt at Mars last night

[greenkat]

Geeees its tiny even with 3x barlow

How do you guys get such big images of the planets ?

[omneferuss]

To answer your Q. (rhetorically, that is.. )

Apart from larger scopes ..by using a camera with a smaller chip, and 'resampling' / resizing in processing

[greenkat]

Cheers Omneferuss

Next time I will try with the LPI rather than the DSI, it has much smaller chip

Is it possible to stack barlow lenses? ( a 3x inside a 2x for instance)

What about using an extender tube?

Would these give me a bigger image ?

Cheers

Greenkat

[omneferuss]

Yes and yes.. solong as your seeing supports it, etc etc.. trade-offs/balances to meet. I look forward to seeing your results!

[arad85]

Imaging at longer focal lengths helps with scale. Starman's effective focal length is 25metres!!!!

[russ]

Switching to the smaller chip LPI should help the image scale, although not sure how sensitive the LPI is?

Perhaps look for a cheap 4-5x barlow to go with the 200P, as the 200P is only f5. There is an Imagemate 4x on Buy'n'sell for £32. That would get you operating at f20 (4 metre).

[arad85]

There is an Imagemate 4x on Buy'n'sell for £32.

Looks to be £150 to me.... I'd have bought it in an instant if it were £32

[greenkat]

25 meters

Ok, my maths isnt great, so, using a 200mm f5 newt, what would be needed to get that sort of focal length ?

Would i be better imaging planets thru my Meade ETX90 tube at f13.8 mounted on the heq5pro ? or would they be a bit dim for photographing with a small appature ?

Thanks for the advice

Greenkat

[arad85]

To get to 25m on your system (1m focal length) you'd need 2x 5x powermates stacked - or x25, giving you an effective f/125 ratio! I've not seen anyone push it beyond about x6 ish (f/66) - it's unlikely the optics/seeing would be good enough to stand that amount of mag (I may be wrong though).... The ETX90 has a focal length of 1250mm (I think) so it will gve you 25% bigger images with the same imaging setup. Having said that, due to it's aperture it will limit the resolution you can get out of the pictures... Brightness of the images are unlikely to be too much of a problem at f/25-f/50

[LukeSkywatcher]

I'm just starting to use my 2X barlow and with it Mars is still TINY. Would it be worth investing in a 3X barlow also so i can stack 2x,3x..............my scope is 130mm,f/l 650mm,f5 (i think). I know when observing Mars that your success is mainly in the hands of the Gods.

Is the Tal 3X barlow any good?. I havent got a fortune to spend.

[arad85]

Tals are the best of the cheap ones or so I'm led to believe (not had any experience so...). Mars looks tiny (smaller than pea sized) in my 2350 mm focal length C9.25 with a 6mm eyepiece in (or about 392x). You're going to struggle to get any decent views with a 'scope of that focal length. Alternatives are longish focal length refractors or SCTs as planetary 'scopes (or big dobs that have the focal length to start with....).

[LukeSkywatcher]

Thanks arad85. My other scope has a f/l of 1000 but only 3.5" of apeture......so its kind of one step forward and two steps back. I sure wont lose any sleep over not getting any kind of decent views of Mars. There are lots of other things to make sure i lose sleep. I may however still invest in a Tal 3X for general use.

Would that be pushing the 130mm scope too far?

[arad85]

It's going to depend on which eyepiece you use. A 5" 'scope isn't going to stand much over 150 - perhaps you could get away with 200x, so a 3x barlow with a 10mm EP is probably going to be the limit.

[LukeSkywatcher]

It's going to depend on which eyepiece you use. A 5" 'scope isn't going to stand much over 150 - perhaps you could get away with 200x, so a 3x barlow with a 10mm EP is probably going to be the limit.

3X barlow+10mm = 3mm..........

I'm already using:

2X barlow+6mm = 3mm

So that pretty much cancels that one out. You are right though, at that magnification (216X) i feel the scope is at its limit (if not slightly over). I get great (what i consider great) views of the moon at that magnification but i honestly dont think i could squeeze anymore out of it.

Thanks for the help. Its been very useful.

[omneferuss]

f/5 scope, + 2x, +5x = f/5 x10 = f/50

Usable FL I'd expect between 3 & 5m... under favourable conditions,

unless jumping to larger apertures and migrating to SCT format for managable tube-length, ..and appropriately larger mount capacity.

bigger and blurrier will not be very satisfying.

a smaller increment of f/ratio and more experience at finer focus and better exposure, plus better processing- to allow image stretching/rescaling- will give far more than ludicrous inappropriate barlowing ever will.

To get to 25m on your system (1m focal length) you'd need 2x 5x powermates stacked - or x25, giving you an effective f/125 ratio! I've not seen anyone push it beyond about x6 ish (f/66) - it's unlikely the optics/seeing would be good enough to stand that amount of mag (I may be wrong though).... The ETX90 has a focal length of 1250mm (I think) so it will gve you 25% bigger images with the same imaging setup. Having said that, due to it's aperture it will limit the resolution you can get out of the pictures... Brightness of the images are unlikely to be too much of a problem at f/25-f/50

[omneferuss]

...remembering that a camera is far more sensitive than the eye, and that something like a ToUcam operates about the range of a 5mm EP.. (eg, like your LPI..rather than the DSI..more like 10-15mm ??)

I would hazzard a guess that if you operate your LPI at optimal performance you'll get twice the image-scale of the DSI.. managing best data capture and processing will possibly reveal more.. balancing the to's and fro's of it all..

.....it's your omelette.. your ingredients.. recipes are only a guide.

[arad85]

f/5 scope, + 2x, +5x = f/5 x10 = f/50

I was saying to get to a 25m focal length with that 'scope would require a multiplier of 25, so he'd need two 5x barlows - which is impractical to say the least !

[russ]

Looks to be £150 to me.... I'd have bought it in an instant if it were £32

hehe i think you have Powermate and Imagemate mixed up....AE Imagemate was on for £32

[arad85]

hehe i think you have Powermate and Imagemate mixed up....AE Imagemate was on for £32

LOL.. and I can't even blame alcohol for that mistake.....

[russ]

I saw the Powermate for £150 too. I only look in the hope i can get a Powermate for £80-90.

[greenkat]

...remembering that a camera is far more sensitive than the eye, and that something like a ToUcam operates about the range of a 5mm EP.. (eg, like your LPI..rather than the DSI..more like 10-15mm ??)

I would hazzard a guess that if you operate your LPI at optimal performance you'll get twice the image-scale of the DSI.. managing best data capture and processing will possibly reveal more.. balancing the to's and fro's of it all..

.....it's your omelette.. your ingredients.. recipes are only a guide.

Haha, I wouldnt recomend one of my olmettes

Cheers for the advice & maths info everyone

Gonna have a go with the LPI next time and take LOTS more subs

[omneferuss]

I was saying to get to a 25m focal length with that 'scope would require a multiplier of 25, so he'd need two 5x barlows - which is impractical to say the least !

Gotcha ! my mistook.. ..makes more sense now I read yer right

[beamish]

Looks to be £150 to me.... I'd have bought it in an instant if it were £32

Thats the TV, but there's a 4x Imagemate for sale at 32 quid !!

OOps Russ has covered it ,besides it's now sold

[russ]

They don't hang around those Imagemates.

[MikeD]

You could try Eyepiece projection.

I use my standard skywatcher 10mm EP and an Eyepiece projection adaptor (£10 second hand) with my 10" F4.8 newt/ DMK21.

you can further increase the image scale by placing the camera further away from the EP with an extender tube.

I have no idea what Fl I am imaging at but it must be close to what I would get with a 5X imagmate.

Mike.