What am I giving up with a compact scope?

From my understanding the smaller the scope the smaller the eye box and the less light-gathering it is capable of. These are of course generalizations. This is due to the placement of the glass pieces within the scope being so close together and overall length not being forgiving. The bigger the scope the more space there is in terms of spacing the glass pieces apart which will create a bigger eye box due to the angles it creates. Furthermore, a bigger scope allows more light to be gathered and focused onto your eye. Of course, there are high-end scopes out there that are "compact" and are exceptional in all categories. The clarity, for the most part is due to the glass/coating quality so it should not suffer that much from the compact size. 
 
From my understanding the smaller the scope the smaller the eye box and the less light-gathering it is capable of. These are of course generalizations. This is due to the placement of the glass pieces within the scope being so close together and overall length not being forgiving.

This is all true.

They have to use a more rounded piece of glass to compensate for the shorter focal point. The rounder or more domed the glass is, the more you get chromatic distortion. 
 
If you want something affordable and semi decent the UTG mini swat 3-12 or 4-16 are just barely ok IMHO but If you specifically plan on using it on a PCP or co2 and want a fantastic scope short of spending more than double or triple the price Get an MTC viper connect in any size front bell if you want a good bright clear small scope with a ridiculously wide field of view. They are well worth their price IMHO. YO!
 
Has someone noticed a difference in the parallax?

I have a Discovery VT-3 3-12x44 SF FFP, that is 10" (25cm) compact. But just the other day I noticed that when moving my head a bit the POA moved around by maybe half an inch @ 25y.

Is that normal for a scope? Normal for a compact scope? Normal for a low-priced scope? 🤔

Matthias
 
"short " is bad news for high magnification, there is no miracle when it comes to physics

Not a general rule, there are some exceptions - compare length of delta Stryker with x30 foo or x50 SFP with eg Big Nikko or others with magnification rate of x50/x60


I am afraid, to my knowledge, it is. Will try to explain by comparison - if two scopes comes from the same manufacturer, the same specs "normal" length scope will be always better optically than "short". Magnification in "short" scopes compensated by erector assembly zooming extra into less magnified by shorter focal length objective lens assembly image, it always brings a loss of resolution. However the loss may be not that dramatic in good quality scopes, but it is always there. 

This is probably why Swarovski don't do "shorts", 
 
I can deal with a loss in resolution — that just makes everything a little more fuzzy and the many purists and scope fans just can't have that. Everybody's got their priorities, we have a wonderful variety in AG. 👍🏼

Sure, I want to discern my .22 pellet holes in my target card at 100y, too, and so I rather have a higher than a lower resolution. But to me this is secondary....



Much more severe would be IF compact scopes do not really correct for parallax despite a parallax adjuster.

So, is THAT problem inherent to compact scopes — or is this just my scope that has this issue? 😊



Matthias
 
I can deal with a loss in resolution — that just makes everything a little more fuzzy and the many purists and scope fans just can't have that. Everybody's got their priorities, we have a wonderful variety in AG. 👍🏼

Sure, I want to discern my .22 pellet holes in my target card at 100y, too, and so I rather have a higher than a lower resolution. But to me this is secondary....



Much more severe would be IF compact scopes do not really correct for parallax despite a parallax adjuster.

So, is THAT problem inherent to compact scopes — or is this just my scope that has this issue? 😊



Matthias

There is no connection between the size and a parallax adjuster , but considering that your scope is used on a recoiless gun, it is possible to test all possible "suspects" step by step to narrow down to a problem