Compact system cameras

[Rob Atkins]

Hi all - I'd welcome some advice.

I'm about to buy a camera for general use, and am looking at the Olympus EPL5. This is a compact system camera, not a DSLR. Will I be able to use it for imaging with my Celestron SkyProdigy 130 ? Not a deal breaker because I have access to a Canon DSLR, but it would be convenient if I can.

Many thanks

[wxsatuser]

Think the only way with a compact is afocal although may be some else knows better.

You could buy an adapter that lets you mount a compact for afocal.

http://www.firstlightoptics.com/adaptors/skywatcher-universal-camera-adapter.html

Think you would be limited to moon and planets may be double stars.

The altazi mount is not much use for dso.

[baggywrinkle]

Basically you are restricted to afocal photography, so s special bracket is needed. With afocal work you also tend to get more vignetting of the image.  It is OK for lunar and planetary but widefield needs a lot of cropping.

[jefrs]

Sorry, they do not understand "compact system camera" :- The Olympus Pen Lite E-PL7 has interchangeable lenses. The E-PL7 is not a "compact" camera. It is an updated E-M10 without the EVF.

The E-PL7 is a mirrorless micro four thirds system camera: I have one and it is compact, it is my "pocket" camera, it's fun to have a tiny 16Mp camera that takes top quality pics.

The sensor on M43 cameras is some 2cm closer to the mount than a typical DSLR e.g. Canon, because it has no mirror.

Yes it can mount with adaptor on the telescope focus mechanism with the correct adaptor(s)

The E-PL7 has no remote cable shutter release but I suppose we can use WiFi control.

The E-PL7 tilt screen is at all the wrong angles on a telescope, so is wife's GX7. The 130SLT is actually my wife's telescope, as I'm a physicist-engineer (radiological metrologist) I get to be the tech support.

Hence I prefer one of my Panasonic M43 with their fully articulated screens. My G5 cannot do time lapse, my GH4 costs an arm and a leg.

Mirrorless cameras do have the sensor exposed when the lens is removed (permanent live view). I got some black smuts on the sensor changing the lens in the dark (I can clean sensors but prefer not to) Be careful. Hence I recommend always fitting a Barlow and/or eyepiece in a clean room to seal the sensor housing up: black smut problem solved.

Due to the short sensor to mount distance I am getting some issues with back focus. I find something like a thin adaptor ring onto a 2X Barlow w/o eyepiece or a 2cm M43/T2 adaptor onto a "short nose" is giving best results so far as other configurations with an eyepiece inserted seem to want the camera closer to the secondary mirror than the focus mechanism will permit. Either that or I get very severe vignetting. If an eyepiece will fit inside the T-adaptor i.e. 37mm long, then an eyepiece can just about be used; most are longer or too wide.

I have not solved this yet, in fact I came on the forum just now to see if I could find out how others are mounting cameras to reflectors.

My alternative is to put the camera on the Star Adventurer EQ mount with a 500mm or 800mm reflex lens i.e. a telescope lens, but that lacks the Goto of the Celestron. I am old enough to remember clockwork EQ mounts Alignment can be fun because you have to see Polaris and it doesn't always cooperate.

[jefrs]

I re-read the OP's post.

Rob is considering the E-PL5 which is probably discontinued hence should be even cheaper than the E-PL7 which has many better features than the E-PL5/6. The E-PL6 was a cosmetic upgrade but the E-PL7 is a big step, I think they are trying out some stuff for the new E-M5 mk.2

One advantage of Panasonic over Olympus for this work is the sensor is mounted on a heat sink, hence less noise from long exposures which do heat the sensor up: the sensor is right behind the monitor screen and the back does get warm to the touch, which produces "hot pixels". The G5 has an allow body frame and the GH4 chassis is designed as an effective heat sink; they stay cold. I have never used the G6 but it has more features than the G5 and could be ideal.

[Rob Atkins]

Thanks jefrs - that's great advice. I'm going to try and find the right adaptor and give it a try. I like the value of the EPL5 right now so will probably buy that one.

[jefrs]

Thanks jefrs - that's great advice. I'm going to try and find the right adaptor and give it a try. I like the value of the EPL5 right now so will probably buy that one.

It's a nice pocket camera but you might also look at the Panasonic G6 which will give you the much needed remote shutter release: should also be cheapish - under £400 w.lens, less than £270 used i.e. similar prices to E-PL5 but the E-PL7 is only a little more (and big upgrade over the E-PL5). My G5 cannot do time lapse but apparently the G6 can. Having said that the G5 has a remote socket so I can use the time lapse feed from the motorised EQ mount.

The E-PL7 is an updated E-M10 without the EVF but having both flavours I can baldly state that the Pannies are better built: I had a switch knob fall off an E-M1 and the shoddy plastic hot shoe cover for the E-PL7 self destructed. Unlike entry-level DSLR the kit lenses on M43 are pretty good glass, although the 14-42EZ does have reports of jamming and which is why I use the PZ14-42 on the E-PL7.

My E-PL7 does suffer from a hot sensor when shooting video, burst shots and long exposures, wrong camera for job. My Pannies (except wife's GX7) have the sensor firmly mounted on a heat sink, they do not get hot. Keeping the sensor cool can be important for astro work.

[jefrs]

Thanks jefrs - that's great advice. I'm going to try and find the right adaptor and give it a try. I like the value of the EPL5 right now so will probably buy that one.

For adaptor rings I would Google up one of our telescope specialist companies and then phone them to make sure you get the right thing. Imo it's not the usual Ebay T2 to M43 adaptor ring we want.

The "T" is for Tamron, not Telescope and it's a M42x0.75 metric thread (as opposed to the Praktica M42x1.0 lens mount), but "M43" is "micro four thirds" naming a lens mount system that uses a "four thirds" (4/3)  size sensor.

I now have several adaptors. The normal length when mounting a legacy lens e.g. Pentax-K is about 35mm from sensor with a M43-PK adaptor. T2/M43 adaptors can come as 35mm length from sensor for reflex lenses or without the 2cm extension tube, some have a tube that usefully unscrews. There is about 15mm from mount to sensor and OEM M43 lenses are designed to focus the image at that range.

[jefrs]

I have since found prime focus mounting using a M4/3 is to find a short T to M4/3 "15mm" adaptor (they usually come with a sleeve to convert to "45mm" and screw it onto the 2-in adaptor on the telescope focuser.  Then fit camera, The M4/3 cameras have a short back focus (no mirror box) so the normal 45mm deep camera adaptor will be too deep and the telescope focuser wants to try to get inside the telescope. 
Eyepiece projection mount is better, for one thing the sensor is not open to the elements,  The eyepiece fits inside the adaptor which can be screwed to the 1¼ plate or to a Barlow. The camera fits to a sliding tube to adjust back focus, without which the eyepiece can get too close to the sensor and will never focus. 

I now have various cameras to play with  E-PL7, G5, G7, GH4, E-M5ii. The G5 tech is too old. We do need a Bulb, Live-Bulb, Live-Time. The E-M5ii has 5-axis stabilisation and it works a treat. The GH4 heat sink is impressive and really does remove electronic noise, it is also biased to sweep stray electrons from the sensor; which is why the Olympus cam shoot video for about 4 minutes before things turn magenta, and the Panasonic indefinitely.  Both have advanced functions. Noise reduction should be turned off or they will remove faint stars, both can do a form of stacking in-camera but we don't want that. Remove hot pixels by re-mapping the sensors before use. The sensors are only 16Mp but that is big enough to print over 4-ft- by 3-ft. For low light sensitivity, sensor size is completely irrelevant; as a retired radio-metrologist I can quote chapter and verse on that.; the important thing is the light gathering aperture, the F-number.