Mirror lock up is certainly the way to go as vibration is the enemy of long focal lenth imaging. Live view is currently used to advantage for manual focusing in this type of photography too. Beyond the 800mm setting, the maximum in the K5 menu the SR may not be enough to cancel out vibration at extreme focal lengths and mirror lock up with shutter time delay would probably be better.

Considering the growing popularity of using telescopes & spotting scopes with DSLR's for astronomical & long focal length wildlife photography perhaps there is an opening for another category, there is after all a category for everyones excellent 'Macro' images ...'Specialist' seems to be the only other option to post in at the moment plus the other extreme in focal lengths would create a nice balance in the images posted so please go ahead, a poll would be interesting.

We could still use Specialist or Landscape for the wide field related subjects.

Would suggest category... Telescope/Spotting Scope/Telephoto

Mike

Well I know a bit about astrophotography but DSLR's ...I'm still on the learning curve there and doing so with the K5.

The K5 instructions do say a manual focus lens which would probably include a telescope by way of a PK T-adapter but to be honest not sure if 'catch in focus' mode will work, if it does the Moon would be a good test but might struggle with stars or darker subjects. This mode might only be useful to find focus manually using the telescope rack & pinion focuser then it would have to be hands-off using a cable release a few moments after the any vibration has died down after manual focusing.

I was out doing a quick test of the K5 on the Moon the other night using a Pentax 67 800mm EDIF lens, will post an image soon under a new thread with further information rather than hijack Ted's thread here.

Mike

Newtonians are renowned for lack of back focus but here are some options others have used to solve the problem. These modifications are difficult and not advised.


1. Custom fit a low profile focuser rather than the standard rack & pinion focuser usually fitted, this 'might' give enough adjustment to reach focus.

2. Move the primary mirror 'up' the optical tube to compensate focus issue.

3. Have a newtonian telescope custom made to reach focus with your imaging device/setup.

4. Sell it and buy a refractor or cassegrain reflector, both designs usually have more back focus than a Newtonian.

Newtonians have traditionally been used for visual but with imaging comes focus issues. When designed with imaging in mind Newtonians are relatively inexpensive and produce great results.

Mike

At the risk of hijacking Ted's thread there are some prime astronomical telescopes out there with optics to outperform the best dedicated camera telephoto lenses ...less glass but finest quality and in some cases calcium fluorite crystal.

As you say the drawback is lack of autofocus though motor focusers are currently in use all that would be needed is a fast focuser with a way of interfacing with a DSLR autufocus system, perhaps just a connector lead.

The technology is there we just need some clever people to marry everything together.

Mike

Just looking for Pentax DSLR Moon & astro shots on the forum for reference when testing my K5 and came across yours Ted ...fantastic result there, quality result!
Prime focus telescope shots are certainly the way to go and refractors seldom disappoint. A flat field low power barlow lens (1.4X -1.6x)and screw in OR slot in extension tubes can increase the image size and retain definition to the edge of the frame...much like an enlarger lens onto paper but in the case the sensor OR film.
Eyepiece projection is good for the planets where higher power is required but as you found hard to get everything in focus across the entire field.

I would love to see more astro related images done with Pentax DSLR's as mostly Canikon dominated.

Mike

Posted my claim form 13.12.10 for £120 (K-5 18-135 lens kit).

Mike

Hello Alan

Welcome aboard, fairly new here myself.

Mike

Just been checking my K5 today, first flash on white card at f22 and could only find one tiny barely detectable diffuse smudge at extreme upper right of frame easily cloned out. (Invisible when wider than f22)
Then used the wall mounted light box allowing f40 and the tiny smudge barely resolved any more with no other marks to speak of.

The only other thing was a hot pixel at extreme right of frame which vanished after one pixel mapping routine.

So ...I'm quite happy and going to keep the camera, certainly no problem here but sure those with the issue will get their cameras replaced soon.

K5 Kit(18-135mm lens) Serial No. 3865...

Mike

Well just over a week in transit due to the severe weather conditions here my K5(18-135mm)lens kit arrived at 4pm today. With temperatures dipping to -14 last night and no let up in the frost all day there was no surprise to see condsensation forming on the cardboard box soon as I took it indoors. For now I have only opened the camera box but left the camera & lens with caps on in the bubble wrap until it comes up to room temperature, don't want to get condensation inside until tested but for now the serial No 3865...

Fingers crossed ...but my first impressions through the wrap are one of a camera that is surprisingly compact with a solid quality weight feel and same for the lens which is surprisingly compact...both very nice indeed!

Mike

Well still no sign of my K5 today due to the postal backlog caused by the weather so must check this on arrival, however I do have concerns regarding the current situation.
This is my first DSLR I can safely say that whatever the case may be with my sensor on arrival I shall be sticking with the K5 until the issue is resolved or camera replaced as I firmly believe in the build quality and innovation of Pentax products. It would be so easy to jump ship and go with an alternative brand which I can fully understand for those that use Pentax cameras to make a living.

For those like myself that use a camera mostly as a hobby I would quote this..."Houston, we have a problem" & "Let's work the problem people".

Up until last year I worked for a small company working in carbon fibre products though I don't want to be specific on products or company names but needless to say we were small compared to the other big two though we were well aware of each other. Although small we produced high quality & innovative products beating the two larger companies in most respects we simply did not have the capital for expensive advertising campaigns and offer sponsorship deals to end users. A while back we went through a bad period of product returns due to manufacturing defects caused by a combination of faulty raw materials and method of assembly but due to our faithful customers and very fair returns policy we were able to pull through and invest in new machinery and improve product quality and be competitive worlwide.

I can see this situation from both sides of the fence and if this turns out to be as big a problem as first appears I'm confident Pentax will find a solution and expect they will be as fair as financially viable for them. From this side of the fence if we jump ship now when Pentax has a resolvable issue with one of it's most exciting cameras yet we run the risk of Pentax again being the underdogs ...and perhaps delaying the release of a K4, K3 or ....

Mike