Is a 140mm ED refractor better than 102mm ED for astrophotography?

[Kunwar]

hi all

I have two scopes both f/7 ED doublets - an APM 140mm and a 102mm Altair Astro. I mount them on a HEQ5 pro mount and a Berlebach Uni 28 tripod. I also have a Canon 600D DSLR and a focal reducer for the 102mm scope. I have so far tried astrophotography with the 102mm scope- Jupiter, Saturn, Mars, the Moon and DSOs. 

I initially bought the 140mm scope for visual only but have been recently curious if there is any benefit in using the larger scope for photography or should I stick with the 4 inch? I know the larger scope would be better for lunar and planetary photography and I intend to use it for that, so the question is directed more towards DSOs, especially galaxies. So far I have enjoyed taking pics of galaxies and wonder if there is any benefit in using the larger scope for this (before I go investing hard earned cash in my setup eg a focal reducer for the 140mm and a larger mount). Or is the juice not worth the squeeze here?

Any advice appreciated!

[newbie alert]

The apm 140 would indeed  be a superb tool for dso

Which model is it?

[StarryEyed]

You'll probably need to jump up a class or two of mount to keep that 140 pointing in the same place for any length of time given its longer focal length and image scale. But that's not to say you couldn't try. Which is the only true way of knowing. 

[Kunwar]

1 hour ago, newbie alert said:

The apm 140 would indeed  be a superb tool for dso

Which model is it?

Its a great scope also more compact than I expected. It's she one with the 2.5 inch focuser and 989mm FL.

[Kunwar]

1 hour ago, StarryEyed said:

You'll probably need to jump up a class or two of mount to keep that 140 pointing in the same place for any length of time given its longer focal length and image scale. But that's not to say you couldn't try. Which is the only true way of knowing. 

I've quite a basic setup as I don't use autoguider, only scope, mount, focal reducer and a dslr. I take only 60 sec subs but take lots of them. So the setup is not so heavy and I'm trying to keep it as simple as possible for now, so I might give it a try on HEQ5 first then move up in gear when the need arises. Fingers crossed.